Morphodynamic Classification of Morocco's Steep Coasts using multivariate methods and remote data

Morphodynamic Classification of Morocco's Steep Coasts using multivariate methods and remote data | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Morphodynamic Classification of Morocco's Steep Coasts using multivariate methods and remote data Isamil Farhaoui, Mohamed Dakki, Abdelmalek Saloui This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4197543/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract The Moroccan coastline extends for 2,130,80 km on the East Atlantic an Western Mediterranean coasts. It shows a high diversity of estuaries, bays, beaches and steep coasts. Despite its ecological, economic, and recreational importance, Morocco does not have a comprehensive inventory of its coastal landscapes. This study attempts to develop a primary classification of Moroccan steep coasts, based on a descriptive inventory of these landscapes, using 12 morphodynamic criteria that we mainly measured on satellite images. To achieve the said classification, we organized the steep coasts and the criteria in a binary matrix, which we treated with the hierarchical ascending classification method (CAH) and Factorial Correspondence Analysis. The results of this treatment provides a clustering scheme where we distinguish six different groups of cliffs, each of them being subdivided to 2 or 3 subgroups. Three categories of criteria appear as determinant in this classification: morphometric (length, area, and elevation), geologic (dominant rock and geologic eras), hydrodynamic (swells), and aerodynamic (wind). However, the two first criteria have the most significant influence on the classification. This classification, mainly based on satellite data, remains preliminary and requires improvements such using some field data. Finally, the raw and compiled data collected in this study constitute database composed of 175 cliffs, described using parametric criteria; this database is a contribution to the national wetlands inventory and is essential to promoting their conservation as well as management. Morocco steep coasts remote data morphodynamic classification Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Figure 14 Figure 15 Introduction The littoral, often defined as the sea-continent interface (Prémaillon, 2018 ), covers both rocky and soft marine coasts, as well as estuarine areas (estuaries, deltas and lagoons). Among these, steep coasts are formed of consolidated materials, of whatever nature and hardness (Limber, 2012 ), with a seaward slope of over 40° (Davidson-Arnott, 2012 ), which can reach 90°, giving rise to steep cliffs (Emery et al, 1982). These inclined landscapes, raised above the coastline, may be submersible by sea water (Pérez-Alberti et al, 2019), even at their foot or set back from the it, but yet still be subject to the sea influences. Coastal spaces are of great importance, hosting almost one quarter of the human population (Small et al, 2003), to whom they offer diverse and abundant resources (food, energy, mining, etc.). Moreover, these spaces are natural ecosystems that have acquired specific geomorphological, climatic, botanical, faunistic, and aesthetic characteristics acquired over long evolutionary processes linked to the sea, making them original. Steep landforms are generally a key source of sediment for coastal bottoms and beaches (Young et al, 2006; Brooks et al, 2010; Mushkin et al, 2016 ), especially as they account for around 80% of the world's coastlines (Emery et al, 1982). When compared to other North African countries, Morocco has the longest marine coastline, stretching some 3,500 km, of which around 86 km are beaches and 2,131 km are cliffs (Mansoum et al, 2016). This coastline, interrupted by around 300 estuarine mouths, is sinuous at the Rif and Atlas Mountains foothills, but sub-linear along the low plains and coastal plateaus (Weisrock, 1985 ). These variations have generated a panoply of coastal ecosystems, whose diversity is evident in physical, ecological, touristic, and socio-economic dimensions. Despite their advantages and heritage value, 50% of steep coastlines have suffered severe degradation since the early 19th century (O'connor and Crowe, 2005; Lasgaa et al, 2010 ; Davidson, 2014 ) due to both human and climatic factors. In addition, they are still less studied than those of soft coasts, probably because they are less coveted by man (Prémaillon, 2018 ), especially when it comes to urban and industrial development (Bird, 2016 ). Several classifications of coasts were attempted worldwide; they are often partial although some are intended to be general. Many of these (Augier, 1982 ; Polunin and Walters, 1985; Bissardon et al, 1997; etc.) have been compiled as part of the European Corine Biotope Programme. These classifications, carried out for Europe, sometimes for ecological purposes, are supposed to be partially applicable to the North African coasts, because of the many specific features (climatic, hydrodynamic, geomorphological, etc.) that they cannot cover. Hill (2004) have suggested a general morphological classification of steep coasts, which divided them into 15 categories, based on several physical criteria: nature and strength of materials, stratification mode, sea-cliff relationship, inclination, cliff activity/inactivity, etc. Other authors, considering fewer parameters, have broaden this classification; for example, Pérez-Alberti and Gómez-Pazo ( 2019 ) introduced new variants solely based on topography; distinguishing three categories of escarpments: cliffs with a convex or concave slope; flat-topped cliffs without an associated posterior plain; flat-topped cliffs with an associated posterior plain. This paper is an attempt to classify the Morocco's steep coasts using multiple physical criteria, at both local and hinterland levels. We obtained the majority of these criteria using remote sensing (satellite images), complemented by mapping techniques (Geographic Information System). Those criteria were analysed using multivariate methods, recognised for their effectiveness in landscape typology. Alongside this classification, the collection of these parameters contributed to enrich the inventory of Morocco's coastal wetlands. Tools & Methods General approach A literature review on steep coastlines, in particular on their classification, revealed a wide range of existing classification criteria, some of which relate to marine hydrodynamic (e.g. swell, waves, upwelling). Other classifications refer to geomorphological or geological characteristics (e.g. nature or structure of rocks, erosion, etc.) of the coast and its proximate hinterland (Duperret et al 2004; Mortimore et al, 2004; Bezerra et al, 2011; Carpenter et al, 2014, Pérez-Alberti and Gómez-Pazo, 2019), while few classifications are based on ecological or conservation criteria (Ciccarelli et al, 2016). The present study attempts to classify Morocco's steep coastal landforms with the help of multivariate analyses (Benzecri 1977; Hill et al, 1980; Lebreton et al, 1976; Dakki 1987; Alaoui et al, 2017; Al Mahfadi et al 2021). For that, we used a panel of physical attributes, that we can obtain by remote sensing (from satellite data) or from maps. This means that we did not use some classification criteria suggested by some authors and which need field data measurable on site. The first step of our work was to delineate all Moroccan steep coastal areas (Figure 1), in a way to obtain distinct units, as homogeneous as possible; the limits of these units correspond their contact with other types of coastal landscapes. We then described each unit using the selected classification criteria (Figure 2). Organised in a binary matrix, the values of each attribute are transformed into modalities using different standardised methods; this led to a homogeneous matrix that can be processed by multivariate classification techniques. Selection and presentation of the classification criteria The criteria used are hydrodynamic, geological and, above all, morphometric (Table 1), most of which can be compiled or measured from maps (i.e. geological criteria) or satellite sources (i.e. Google Earth platform). Nevertheless, a field visit enabled us to verify or refine certain data. The measurements are approximate, but they are still suitable for multivariate analyses, since these latter remain relatively stable for slight data variations. We illustrated below the major morphometric measurements we have done (Figure 2). Descriptors used as classification parameters of Morocco's sea cliffs. Variables Definition Methods and tools used Classes Code Title 1 2 3 4 SA Surface area (ha) Area of the seafront surface of the cliff, in its horizontal projection. Area of the delimitation polygon of the seafront surface, calculated by ArcGIS ≤ 20,00 20,01-100 100,01-400 > 400 L Cliff length (m) Length of cliff measured at its foot, parallel to the coastline Measure provided by Google Earth platform ≤ 1000 1001-4000 4001-8000 > 8000 AR Cliff altitude at its roof (m) Elevation of the highest point of the cliff top ≤ 20 21-80 81-250 > 250 AF Cliff altitude at its foot (m) Elevation of the lowest level of the cliff foot ≤ 2,0 2,1-3,0 3,1-7,0 > 7,0 AS Average slope of the cliff (%) Average inclination of the cliff's seafront Ratio of the cliff's height (AR-AF) to its width (referred to the cliff polygon) ≤ 20,00 20,01-30 30,01-60 > 60,00 SM Maximum swell (m) Maximum mean swell height for last 10 years Mean of the annual values obtained at https://www.puertos.es/en-us/oceanografia/Pages/portus.aspx ≤ 5,00 5,01-7 >7,00 SD Direction of the swell (°) Direction of prevailing swell (W), referred to the general direction of the coast (C) Angle between W and C directions, W is obtained at https://www.puertos.es/ en-us/oceanografia/pages/portus.aspx ≤ 30 31-60 61-90 WS Wind speed (m/s) Mean of the monthly maximum wind speed for the last 10 years Calculated on the basis of data obtained at www.windfinder.com ≤ 20,00 20,01-22 22,01-24 WD Wind direction (°) Direction of prevailing winds (W), referred to the general direction of the coast (C) Angle between W and C directions, W is obtained at www.windfinder.comand ≤ 30 31-60 61-90 SC Sea-Cliff distance Distance between the low tide line and the cliff foot : mean of distances at 3 radials Estimated using Google Earth, and when possible, corrected in the field 40,0 NR Nature of rocks* Dominant type of rock making up the cliff Obtained from various geological maps of different scales AG CA FG SC GE Geological era** Geological Era of the dominant rocks making up the cliffs 0-I II III IV * Nature of rocks (classes): AG: Andesites/Gneiss; CA: Limestone/Eolianites/Calcarenites; FG: Flysch/Grès; SC: Schist ** Geological eras (classes): 0-I: Precambrian/Palaeozoic; II: Secondary; III: Tertiary; IV: Quaternary Table 2 Morocco's littoral sectors: subdivisions used to inventory the sea cliffs. Name Code Description Mediterranean, Oriental MO Mediterranean littoral to the Eastern Rif and Lower Moulouya, coast with variable configuration Mediterranean, Central MC Mediterranean littoral of the Central Rif, generally high cliffs frequently separated by rivers Mediterranean, Tingitane Peninsula MT Mediterranean littoral of the Western Rif, high and long cliffs, separated by large coastal plains Atlantic, North AN Atlantic littoral of Western Rif and the Gharb domains, long and low cliffs, catted in dunes Atlantic, Medium AM Atlantic littoral of the Central plateau domain, coast with variable configuration Atlantic, High Atlas AH Atlantic littoral of the High Atlas domain, continuous landscape of cliffs of a mountainous slopes Atlantic, Anti-Atlas AA Atlantic littoral of the Anti-Atlas domain, continuous landscape of cliffs separated by estuaries Atlantic, Sahara AS Atlantic littoral of the Sahara domain, very long cliffs, most of them being in contact with the sea Morphometric criteria Seven characteristics of the local steep coastline were recorded; their measurement was carried out on the Google Earth platform (i.e. altitude, surface area, etc.), using images that best reflect the reality of the landscape. Hydrodynamic criteria These are measurable parameters that best reflect the effects of marine dynamics on the coast. These marine forces are expressed by the swell and its direction, as well as by wind (direction and speed), the latter having a major influence on the swell. Geological criteria Two qualitative criteria were used: the nature of the dominant ground/rock and the geological age of the dominant land. Delineation of steep coastline units Initially, the Moroccan coastline was divided into eight large sectors defined by their general morphology, including that of the hinterland, and their direction (Table 2). These sectors were then broken down into 76 more homogeneous sub-sectors, inside which we delineated only steep coasts that constitute continuous units, totalizing 175 cliff units to be classified. These sectors correspond to the different geological structures defined in Morocco, some of them being heterogeneous, in the sense that they show a lateral variability of coastal landscapes. Generally, the limits of a cliff unit have been set at large estuaries or lagoon openings, but other factors can be used to delineate units (topographical accidents, change of direction, change in distance between the sea and the cliff, etc.). Despite our efforts, this homogeneity is not always perfect; in some steep coastal segments, we did not consider all small wadis as discontinuities, mainly when these wadis have small coastal watershed. The values of the classification parameters (attributes) correspond then to an average or to the value of the dominant landscape. Statistical analyses In order to classify steep coastlines, we first used the Factorial Correspondence analysis (FCA), method that has become widely used (Lebreton, 1976; Hill et al, 1980; Dakki, 1987; Lebreton et al, 1988; Bonin et al, 1990) and recommended for processing binary matrices designed to search for similarities between rows (elements to be classified) and columns (variables used for the classification). This method provides a good visualization of the ordination of the matrix rows and columns, as point clouds in the first 2-4 first axes of the analysis, but it's not always easy to distinguish clear groups inside these clouds, mainly in case of a high number of points. That why we combined the FCA technique with the Hierarchical Agglomerative Clustering (HAC) method, which provides a classification of the matrix columns/rows in a tree structure of nested classes (Nakache et al, 2004). The HAC method, based on the same parameters used in the FCA approach (Table 1), consists in grouping individuals (sea cliffs) iteratively according to their similarity, starting with the closest and gradually building up a dendrogram with all individuals at the root. Similarities are calculated between individuals and then between increasingly heterogeneous groups. The classes obtained by this method can be represented in the CFA point clouds, using only different colours or symbols. Results Classification of coastal steep landforms in morocco Results of the Factorial Correspondence analysis Histogram of inertia In order to interpret the similarities between individuals (and variables), we extracted the first 20 dimensions defined by the analysis, but after examining the histogram of inertia Figure 2), it became apparent that the total inertia is greater than that of the 0.95 quintile of random distribution (77.74% compared with 57.85%). We then restricted the interpretation to the first four axes of the analysis, considering that they provide a good summary of the dissimilarities between the Moroccan coastal escarpments. The first two axes of the analysis cumulate 17.79% of the total dataset inertia; this rate is well above the reference value of 10.95%, but remains low, in the sense that the F1-F2 plane represents only 17.79% of the total variability of the cloud of individuals (and variables). We therefore examined this variability also in the F3-F4 plane. Significance of the FCA first planes The dispersion of the cliffs in the F1xF2 and F3xF4 planes does not reveal clear defined groups, but it shows possible gradients of organisation along the four axes (Figure 4). In order to determine the cliff descriptors that are likely to explain these gradients, we have projected them (using their class values, as determined in Table 1) onto the planes F1xF2 and F3xF4 (Figure 5). Axis 1 is well correlated (visually) at least with four quantitative parameters, which together express the size of the cliffs. The best descriptor that explain this axis are the surface area (SA), followed by the length (L) of the cliff and the distance between the sea and the cliff foot (SC). It seems that most of the higher cliffs tend to be set back from the shoreline. The altitudes of the cliff roof (AR) and the cliff foot (AF) reflect this same gradient, but to a lesser degree; however, we note that the cliffs with the highest foot altitude have rather low roofs. Axis 2 contrasts the cliffs with the highest roof (AF4) with those whose base is close to the water; it also shows a gradual variation in the average slope (AS), which is independent of the cliff size. In addition, this axis express the discriminant role of the geology, in its both representations: nature of rocks, which vary along this axis, and geological eras, as the ancient eras are distinct one from the other and both from the Tertiary and the Quaternary, which characterises the same cliffs. In the plane F3xF4, two descriptors provide a high significance of the cliff similarities: the cliff altitude at its roof, which isolates on both axes the highest value of this parameter from the others, and the nature of rocks, which separates the Schist cliffs from the other rock cliffs. Four other descriptors (geological era, cliff altitude at its foot, average slope and direction of the swell) slightly contribute to the significance of the axis 3. Does the geographic location of the cliffs play any role in their FCA organisation In addition to the search of the significance of the FCA first axes, we explored the hypothesis that the geographic distribution of the cliffs may play a special role in their classification, as the littoral is highly shaped by the geology of its terrains and incidentally by the sea hydrodynamic. We then represented the eight littoral sectors, intuitively defined above, on the two FCA planes F1xF2 and F3xF4 (Figure 6). Most of the sectors have their cliffs grouped in a same zone of the FCA plane F1xF2, what means that they are homogeneous, in the sense that their cliffs have similar characteristics. This is particularly clear for the sectors adjacent to the coastal Sahara plateau, the Atlantic High Atlas and the Central Rif on the Mediterranean side. The five other sectors are slightly heterogeneous, as the cliffs of each of them are subdivided in two distinct groups. On another hand, a clear segregation is revealed between the Sahara sector and all others (Figure 6), although no geographic positioning parameter was used among the selected classification criteria. Such segregation can also be detected between other sectors, even less clearly. In other words, the FCA, dominantly based on physiographical parameters, expresses partly the spatial variation of the geology throughout this country. Results of the HAC: towards a classification of the Moroccan sea steep coasts The main result of the Hierarchical Agglomerative Clustering is a dendrogram (Figure 7), where several groups are differentiated; we used the first and the second clustering levels to distinguish a first classification, which provides six large groups of cliffs. Using then the third and the fourth clustering levels, each of these groups is subdivided to 2 or 3 subgroups, thereby providing a total of 12 more homogeneous groups. In order to better illustrate this classification and to facilitate its understanding, the groups/classes are projected on the FCA plane F1xF2 (Figure 8), using different colors to make easy their distinction. Group 1. Saharan cliffs, cut in limestone plateau of Secondary era, with medium elevation and slope and low to medium length, occasionally washed by the sea waters. These steep coasts have four common characters; two are relative to the geology (limestone of the secondary era) and two others are to the wind (low speed and almost perpendicular direction to the coast). These cliffs are relatively inclined, but very rarely vertical; most of them are deed cliffs, having their foot unreachable by the sea waters. HAC has split this group to two subgroups, more clear on the FCA plane F3xF4 (Figure 9): Subgroup 1.1 , which stands out with the low area of the cliff's seafront and the low marine swell, which corroborates with the frequently low wind force. Subgroup 1.2 , containing cliffs of medium to large seafront area, with low to medium roof elevation, and low foot elevation, rarely washed by the sea waters. Both subgroups are found at the southern part of the Saharan coastal plateau, north and south of Ad-Dakhla Bay, but the Subgroup 1.2 contains some cliffs of the oceanic slopes of the Anti-Atlas Mountains and southern coats of the High Atlas. Group 2: Long Saharan sea cliffs, cut in limestone plateaus These cliffs present geological and marine hydrodynamic similarities; indeed, most of them are cut in Tertiary limestone of the Saharan plateaus between Dr'a Mouth and Aftissate fishing village, but the seven Northern ones (Coast of Tantan-Akhfennir) are cut in the Secondary era sandstone rocks. This coastal domain is exposed to winds with generally low force, almost perpendicular to the cliffs, and to moderate to low swells. These cliffs have a minimum length of 1 km, and frequently exceeding 4 km; they have moderate to medium inclination, and low to medium roof elevation, explaining the low or medium area of their seafront. This group is divided by HAC into two sub-groups, which are well distinct in the F3xF4 plane (Figure 10): Subgroup 2.1 , including cliffs with medium length and low roof and foot elevations, explaining their low and medium seafront area; they have also low to medium inclination and relatively long distance to the coastline. Subgroup 2.2 , to which belong the longest cliffs of Morocco, most of them being over 8 km long, with vertical to sub-vertical inclination and a foot close to the coastline, making their foot regularly washed by sea waters. Group 3: High cliffs of limestone or sandstone mountain foothills (of Secondary age) This group of steep coasts is relatively heterogeneous, as it extends over the coastal sections of different mountains (Rif, Central Plateau and High Atlas). Indeed, the only common character between the majority of these coasts is the geology, as they are built in limestone or sandstone of Secondary era. On the contrary, the two subgroups highlighted by the HAC appear less heterogeneous on the F3xF4 FCA plane (Figure 11): - Subgroup 3.1 , composed of steep cliffs of high to medium roof elevation, washed by high to medium swells, as their foot is very close to the sea coastline. They are exposed to lateral strong winds. - Subgroup 3.2 , composed of steep and very high cliffs (roof over 250 m), explaining their large seafront area and their arched form. Group 4: Small Mediterranean cliffs of low mountain foothills of Tertiary limestone All the escarpments of this homogeneous group are located on the North-East coasts of Morocco, more precisely in the Kebdana foothills. These limestone low mountains of the Tertiary era are driven by several intermittent ravines, making the coast cut-out in short and steep cliffs, with low roof altitude and seafront area, but with high elevation of their foot, making it unreachable by the Mediterranean waters. This configuration results in the genesis of a gravelly and inclined beach between the cliffs and the sea. This coast receives lateral winds with medium force, accompanied by lateral low swells. Group 5: High cliffs of short to medium length at mountain foothills These cliffs are found at the foothills of the Rif and Atlas Mountains, in the flysch or sandstone of the Secondary, Palaeozoic or even Precambrian age. They have a seafront of small area and are exposed to winds of medium force, almost perpendicular direction to the coast, generating then medium to high swells. This heterogeneous group is split by the HAC to three subgroups (Figure 13): - Subgroup 5.1 , dead cliffs of variable length, with low roof elevation, but high foot elevation; they are cut in the secondary age rocks, most of them being in the coastal area of the Anti-Atlas Mountains. - Subgroup 5.2 , live cliffs of small seafront area, with medium or high slope, washed by the sea waters at their foot. They belong to the central Rif foothills. - Subgroup 5.3 , steep to vertical small cliffs, with a low roof but their foot is in a high position in relation to the coastline. In their great majority, they belong to the Atlantic High Atlas foothills. Group 6: Small and low elevation cliffs of northern coastal plains and plateaux This is a heterogeneous group, shared between the North Eastern Moroccan coasts and the northern and middle Atlantic coasts. Their seafront has small area, generally with low slope and low roof elevation, as their immediate hinterland corresponds to coastal plains or low plateaux. Most of the cliffs are cut in limestone, more rarely in metamorphic or sandstone rocks, of Secondary to Quaternary, and even Primary eras. This group is split by the HAC to three subgroups (Figure 14): - Subgroup 6.1 , containing cliffs of Tertiary-quaternary limestone, with short length and low roof elevation and slope, and their foot, even almost close to the coastline, is exceptionally in contact with the seawaters. These coasts are submitted to winds of low force but generally sub-perpendicular to the coastline, and generating high energy swells, perpendicularly directed towards the coastline. - Subgroup 6.2 , composed of cliffs quite similar to the former subgroup, with the difference that these have low to medium slope, and their foot is close to the coastline, in a way to be regularly in contact with the sea waters. These coasts are submitted to winds of medium force. - Subgroup 6.3 , which stands out for its short to medium length cliffs, with variable slope, some of them being cut in secondary age sandstone and andesite of primary age. The swells are medium to high and move in a direction perpendicular to sub-perpendicular to the coast. We note that the subgroup 6.1 is intermediary between the two other subgroups, which are well separated on the third FCA axis. Discussion Through this study, we aimed to provide a first classification of the Morocco's steep coasts, mainly based on remote morphometric data accessible on satellite images and on public databases and maps. Using 12 descriptors and two complementary multivariate methods (HCA and FCA), we obtained a classification scheme that distinguished six different types (groups) of steep coasts split into 12 subtypes (subgroups). The descriptors that play a determinant role in this classification (by explaining the four first axes of the FCA) belong to different categories (geology, size, relation with the coastline, maximum swell, etc.). This confirms the great significance of the morphometric, geologic and hydrodynamic criteria in the obtained classification, which is likely to valid their use by several authors (Emery and Kuhn, 1982 ; Sunamura, 1985 ; Benumof and Griggs, 1999 ; Hill 2004; Bezerra et al., 2008 ; Ikeda et al., 2019; Pérez-Alberti and Gómez-Pazo, 2019 ). It is also clear that the geographical position of cliffs on both Atlantic and Mediterranean coasts plays a determinant role in this classification, since the cliffs belonging to the same littoral sector constitute more or less homogeneous groups in the FCA plans. This result seems normal, as different geological structures and hydrodynamics, greatly variable in space, configure the morphology of the coast, and induce different aerodynamic and hydrodynamic conditions. Indeed, in contact with the sea, the different mountains (Rif, Kebdana, Central Plateau, High Atlas and Anti-Atlas) have highly shaped the coasts, giving them, for example, more or high roof elevation but with variable length, depending on the hydrographic network organisation. On the contrary, the Gharb-Loukkos and the Saharan coastal plateaux and dunes generate long and low cliffs, generally with moderate to high slope. Some users of classifications may be frustrated when the clustering parametric methods (HCA) do not provide clear 'types', but groups that can overlap each other. However, the six groups of coasts distinguished in this research are clearly different, since we can classify them in a dichotomous scheme, using the following morphometric parameters: position in relation to the coastline: dead or live cliff, this latter being permanently or very frequently washed by the sea waters, at least at their base; size : length and elevation, which can also provide information on the shape (profile) of the steep coast seafront; roof seafront profile: with arched roof (cut in foothill of coastal mountains) or horizontal roof (cut in a plateau); slope of the seafront façade, which inform on its transversal profile. Most of the criteria used in this research have a week and indirect ecological significance, compared to those used in American or European habitat typologies (Cowardin et al., 1979 ; ECC, 1991 ; De Villers, 2001). In Morocco, in order to establish an ecological classification of the littoral cliffs (Dakki 2022 ), some of these criteria are combined with other parameters that have ecological significance. On another hand, an essay of implementing the multivariate approach used in this research to other regions will certainly provide significant results and contribute to refining this approach, mainly the use of remote sensing data as alternative to the time-consuming filed measures. We should reminder that the classification process we implemented in the present study has made it possible to initiate a database on the steep coasts of Morocco, which can serve as a basis to describe them for management or conservation purposes. Conclusion This research, aiming a classification of sea steep coasts, is part of a Moroccan wetland inventory and classification programme, based on databases and multivariate analyses (see Dakki 2022 ). The sea cliff classification has the particularity to use remote sensing and public data that are easily and quickly accessible. The 12 selected criteria, treated with HCA and illustrated by FCA, led to a clustering scheme regrouping 175 steep coats to six different coast classes, that we split to 2 or 3 subgroups. Both hydromorphic and geologic criteria significantly contribute to this classification, which also incorporates the geographical segregation of the coasts, even using any positioning criteria. Most classification users prefer simplified hierarchical classifications (as dichotomous schemes) to clusters based on multivariate analyses. This research has the advantage to identify significant criteria on which users can base (even partially) their own hierarchical scheme, the choice of the criteria depending on the objective of the classification. We can resume the most significant criteria useful for Moroccan steep in few categories of parameters, related to the size of the cliff, its position in relation to the coastline and its seafront profile and inclination. We consider our classification as a national scheme, which we will confirm or improve through its implementation in ecological, geomorphological or management domains. We think that the database we constituted on Morocco's steep coasts will be a reference for several users. Declarations Author Contribution he funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript Acknowledgement This research has received no external funding References Alaoui, A., Olengoba, B., Ettaki, B., Zerouaoui, J., 2017. Ageneric methodology for clustering to maximises inter-cluster inertia. ijacsa 8 . Available at: https://doi. org/10. 14569/IJACSA. 2017. 081125 [Accessed: November 14th 2021]. Al-Mahfadi, A. 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Ciccarelli, D., Picciarelli, P., Bedini, G., Sorce, C., 2016. Mediterranean Sea cliff plants: morphological and physiological responses to environmental conditions. Journal of Plant Ecology 9, 153–164. Available at : https://doi. org/10. 1093/jpe/rtv042 [Accessed: March 15th 2023]. Cowardin L.M., Carter V., Golet F.C. & LaRoe E.T., 1979 . Classification of wetlands and deep-water habitats of the United States. U.S. Department of Interior, Fish and Wildlife Service, Washington , D.C. pp. 1-131. Available at: https://www.fws.gov/wetlands/Documents/Classification-of-Wetlands-and Deepwater-Habitats-of-the-United-States.pdf . Dakki, M., 1987. Ecosystèmes d'eau courante du haut Sebou (Moyen Atlas) : études typologiques et analyses écologique et biogéographique des principaux peuplements entomologiques. Travaux de l’institut scientifique , série zoologie N°42 Rabat. Dakki, M., 2022. Classification écologique des zones humides du Maroc. Travaux de l’institut scientifique, Rabat , série générale, 2022, N°9, ISSN :1114-9256, ISBN : 978-9920-9442-8-1. Davidson, N., 2014. How much wetland has the world lost? Long-term and recent trends in global wetland area. Marine and Freshwater Research 65, 936–941. Available at: https://doi. org/10. 1071/MF14173 [Accessed: January 25th, 2022]. Davidson-arnott, R., 2012. Introduction to Coastal Processes and Geomorphology. Cambridge university press , Available at: https://books.google.co.ma/books?hl=fr&lr=&id=ZtGoDwAAQBAJ&oi=fnd&pg=PR11&dq=Davidson-arno [Accessed: April 25th, 2022]. Duperret, A., Genter, A., Martinez, A., & Mortimore, R. N., 2004 . Coastal chalk cliff instability in NW France : Role of lithology, fracture pattern and rainfall. Geological Society, London, Engineering Geology Special Publications, 20(1), 33‑55. Available at: https://doi.org/10.1144/GSL.ENG.2004.020.01.03 [Accessed: July 25th 2023]. Devillers P., Devillers-Terschuren J. & Vander-Linden C., 2001. PHYSIS 798 Palaearctic Habitat Classification. Database. Updated to 10 799 December 2001. Institut royal des Sciences Naturelles, Bruxelles. Emery, K., Kuhn, G., 1982. Sea cliffs: their processes. GSA Bulletin 93 (7): 644–654. Available at : https://doi.org/10.1130/0016-7606(1982)932.0.CO;2[Accessed : November. 14 th. 2020]. ECC 1991 . Corine Biotopes manual, a method to identify and describe consistently sites of major importance for nature conservation: Data specifications –. Office for Official Publications of the European Communities , 2, 300 pp. Hill, M. O., Gauch, H. G., 1980. Detrended correspondence analysis: an improved ordination technique. Classification and ordination. Section of Ecology and Systematics , Cornell University, Ithaca, New York 14850, USA. Available at: https://link.springer.com/article/10.1007/BF00048870 [Accessed: November 17th, 2022]. Mushkin, A., Katz, O., Crouvi, O., Alter, S. R., Shemesh, R., 2016 . Sediment contribution from Israel’s coastal cliffs into the Nile’s littoral cell and its significance to cliff-retreat mitigation efforts. Engineering Geology 215, 91–94. Available at: https://doi. org/10. 1016/j. enggeo. 2016. 11. 005. Mansoum, M., Benali, A., 2016 . Les littoraux marocains : changement climatique et stratégies de gestion. Paysages géographiques n° 2 . Available at : https://www. researchgate. net/publication/327117108. Nakache, J. -P., Confais, J., 2004. Approche pragmatique de la classification : arbres hiérarchiques, partitionnements. Editions TECHNIP . Mortimore, R. N., Lawrence, J., Pope, D., Duperret, A., Genter, A., 2004. Coastal cliff geohazards in weak rock: the UK Chalk cliffs of Sussex. Geological Society, London, Engineering Geology Special Publications 20, 3–31. Available at: https://doi.org/10.1144/GSL.ENG.2004.020.01.02. Ikeda, J., & Testik, F. Y., 2019 . Morphodynamics of beach-cliff systems in the Santa Barbara littoral cell. Ocean Engineering , 172, 350‑360. Available at: https://doi.org/10.1016/j.oceaneng.2018.11.056. Lasgaa, H., Sbai, A., Boumeaza, T., 2010. The Mediterranean coastline of northeastern Morocco between the degradation of the natural heritage and the need for the Integrated Management of Coastal Zones . Acts of the Round Table “Integrated Management of Coastal Areas 40–54. Lebreton, H. Tournier., Lebreton, J. D., 1976. Etude de l'avifaune du Parc National de la Vanoise. VI. Recherches d'ordre quantitatif sur les Oiseaux forestiers de Vano . Lebreton, J. D., Chessel, D., Richardot-Coulet, M. e., Yoccoz, N., 1988 . L’analyse des relations espèces-milieu par l’analyse canonique des correspondances. Acta Oecologica-Oecologia Generalis . Available at: https://www. researchgate. net/publication/292282521. Limber, P, W., 2012 . Beach and Sea Cliff Dynamics as a Driver of Rocky Coastline Evolution. Earth and Ocean Sciences. Duke University. Available at: http://www. pdfdrive. com/iv-beach-and-sea-cliff-dynamics-as-a-driver-of-rocky-coastline-evolution-by-patrick-wayland e55539050. Html. O’Connor, N. E., Crowe, T. P., 2005. Biodiversity loss and ecosystem functioning: distinguishing between number and identity of species. Ecology 86, 1783–1796. Pérez-Alberti, A., Gómez-Pazo, A., 2019. The Rocky Coasts of Northwest Spain. Department of Geography, Faculty of Geography and History , University of Santiago de Compostela, Praza da Universidade 1, 15782 Santiago de Compostela, Galicia, Spain. Available at: https://link.springer.com/chapter/10.1007/978-3-319-93169-2_2 [Accessed: November 10th 2021]. Polunin, O., Walters, M., 1985 . A guide to the vegetation of Britain and Europe, oxford University Press . Available at : https://doi.org/10.1002/jqs.3390010113. Prémaillon, M., 2018 . Hiérarchisation des facteurs d’érosion des falaises côtières du site au globe (PhD Thesis). Université Paul Sabatier-Toulouse III. Small, C., Nicholls, R. J., 2003 . A global analysis of human settlement in coastal zones. Journal of Coastal Research 19, 584–599. Sunamura, T., & Kraus, N. C.,1985. Prediction of average mixing depth of sediment in the surf zone. Marine Geology , 62(1-2), 1–12. doi:10. 1016/0025-3227(84)90051-3. Weisrock, A., 1985 . Les falaises de la côte atlantique marocaine de Safi à Bedouzza (Cap Cantin). (The cliffs of the at/antic Moroccan coast between Safi and Bedouzza. Bulletin de l'Association de géographes français 62, 93–104. Available at : https://doi. org/10. 3406/bagf. 1985. 1286. Young, A. P., Ashford, S. A., 2006 . Application of Airborne LIDAR for Seacliff Volumetric Change and Beach-Sediment Budget Contributions. Journal of Coastal Research 222, 307–31. Additional Declarations No competing interests reported. Supplementary Files Appendix.docx Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4197543","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":286265579,"identity":"c902d865-ae50-4f6a-b606-8f01adc246f2","order_by":0,"name":"Isamil Farhaoui","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA+ElEQVRIiWNgGAWjYBAC9gYGNhDNAyYTCmyAJGPjAXxaeA6gaDFIA2lpIEoLFBgcBlP4tbCfffbgR8VhGT7+04kfHhict1vbfhhoS41NNE4tPOnmhj1nDvOwSeRulkgwuJ287UwiUMuxtNwGHFrsGdLYJHjbQFp4N4C1mB0AamFsOIxTCw//MzbJvyAt/Gc3/0gwOJdsdv4hAS0SaWzSYFsYcrcBbTlgZ3aDkC0Sz9ikZc6kg/yyzSLBIDnB7AbQlgQ8fuHhT2OTfFNhbS/ff3bzzR8VdvZm59MfPvhQY4NTCwZIBKtMIFY5CNiTongUjIJRMApGBgAAZiJbwOCxTvkAAAAASUVORK5CYII=","orcid":"","institution":"Literature and Human Sciences Faculty of Mohammedia, University Hassan II,","correspondingAuthor":true,"prefix":"","firstName":"Isamil","middleName":"","lastName":"Farhaoui","suffix":""},{"id":286265581,"identity":"6b066e81-31da-4c08-9b4e-310fede8779e","order_by":1,"name":"Mohamed Dakki","email":"","orcid":"","institution":"GREPOM/BirdLife","correspondingAuthor":false,"prefix":"","firstName":"Mohamed","middleName":"","lastName":"Dakki","suffix":""},{"id":286265583,"identity":"4f0f80f3-75de-4f19-93bf-cb71f9ea1915","order_by":2,"name":"Abdelmalek Saloui","email":"","orcid":"","institution":"University Hassan II, Literature and Human Sciences Faculty of Mohammedia","correspondingAuthor":false,"prefix":"","firstName":"Abdelmalek","middleName":"","lastName":"Saloui","suffix":""}],"badges":[],"createdAt":"2024-04-01 01:59:25","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4197543/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4197543/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":54165689,"identity":"28dea8ac-62ae-4d12-97e4-7e4e18218846","added_by":"auto","created_at":"2024-04-05 13:28:32","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":535944,"visible":true,"origin":"","legend":"\u003cp\u003eSpatial distribution of Morocco's rugged coastline.\u003c/p\u003e","description":"","filename":"Figure1.png","url":"https://assets-eu.researchsquare.com/files/rs-4197543/v1/336300c1e2dc3cfe0f5227d2.png"},{"id":54165691,"identity":"3257b423-d5ff-42a1-a006-105dc662efd7","added_by":"auto","created_at":"2024-04-05 13:28:32","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1275149,"visible":true,"origin":"","legend":"\u003cp\u003eMethods used for measuring the geometric criteria of sea cliffs.\u003c/p\u003e","description":"","filename":"Figure2.png","url":"https://assets-eu.researchsquare.com/files/rs-4197543/v1/b972f2af29b515cea5e2fa58.png"},{"id":54165688,"identity":"82a43bcb-5b9c-40be-adc6-96a9d737ff16","added_by":"auto","created_at":"2024-04-05 13:28:32","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":62670,"visible":true,"origin":"","legend":"\u003cp\u003eHistogram of total inertia of the FCA factors.\u003c/p\u003e","description":"","filename":"Figure3.png","url":"https://assets-eu.researchsquare.com/files/rs-4197543/v1/c530f2dfd216c59810fb2340.png"},{"id":54165694,"identity":"7b37543c-27b4-4da8-b972-8657ca225765","added_by":"auto","created_at":"2024-04-05 13:28:32","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":49117,"visible":true,"origin":"","legend":"\u003cp\u003eGeneral organisation of the cliffs along the four first FCA axes.\u003c/p\u003e","description":"","filename":"Figure4.png","url":"https://assets-eu.researchsquare.com/files/rs-4197543/v1/5438153a3891ba2a64a46f4f.png"},{"id":54165697,"identity":"dbe3ad45-6fac-4674-8fd9-6e4e72e7e4c2","added_by":"auto","created_at":"2024-04-05 13:28:32","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":101112,"visible":true,"origin":"","legend":"\u003cp\u003eDistribution patterns of the cliff descriptors in the FCA planes F1xF2 (above) and F3xF4 (below).\u003c/p\u003e","description":"","filename":"Figure5.png","url":"https://assets-eu.researchsquare.com/files/rs-4197543/v1/d66572be121bd79aeb233aee.png"},{"id":54165693,"identity":"0b9da8b3-1c5b-451a-a6c0-7359a9bb087c","added_by":"auto","created_at":"2024-04-05 13:28:32","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":221500,"visible":true,"origin":"","legend":"\u003cp\u003eDistribution of the cliffs according to the sectors subdivisions on the FCA planes 'F1xF2' (above) and 'F3 x F4' (below).\u003c/p\u003e","description":"","filename":"Figure6.png","url":"https://assets-eu.researchsquare.com/files/rs-4197543/v1/a1bd6d150e235d29d461acec.png"},{"id":54166913,"identity":"f511a7e7-9909-4e88-a29e-24ec115dce72","added_by":"auto","created_at":"2024-04-05 13:36:35","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":195561,"visible":true,"origin":"","legend":"\u003cp\u003eHAC dendrogram of the Moroccan coastal steep coasts.\u003c/p\u003e","description":"","filename":"Figure7.png","url":"https://assets-eu.researchsquare.com/files/rs-4197543/v1/98f4b3720cfb6cb0a9e86ff2.png"},{"id":54166914,"identity":"f4d066ce-9299-43e9-b090-99cb42666ad3","added_by":"auto","created_at":"2024-04-05 13:36:35","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":198288,"visible":true,"origin":"","legend":"\u003cp\u003eHAC results: Projection of the groups on the FCA planes F1xF2 (above) and F3xF4 (below).\u003c/p\u003e","description":"","filename":"Figure8.png","url":"https://assets-eu.researchsquare.com/files/rs-4197543/v1/e5593388b5b18bfd0adc2318.png"},{"id":54165699,"identity":"ec7bf23b-f485-4690-9f5e-58e3602f8c64","added_by":"auto","created_at":"2024-04-05 13:28:32","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":61493,"visible":true,"origin":"","legend":"\u003cp\u003eHAC results: Group 1 in the FCA planes F1xF2 (left) and F3xF4 (right).\u003c/p\u003e","description":"","filename":"Figure9.png","url":"https://assets-eu.researchsquare.com/files/rs-4197543/v1/c9d7620056a876427c44367b.png"},{"id":54165700,"identity":"6fdb5480-1016-444c-9b29-73fdd322850b","added_by":"auto","created_at":"2024-04-05 13:28:32","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":55879,"visible":true,"origin":"","legend":"\u003cp\u003eHAC results: Group 2 in the FCA planes F1xF2 (left) and F3xF4 (right).\u003c/p\u003e","description":"","filename":"Figure10.png","url":"https://assets-eu.researchsquare.com/files/rs-4197543/v1/c991c871a128e768574f2b41.png"},{"id":54165701,"identity":"a21faef6-becf-4652-ae8a-323d798a863d","added_by":"auto","created_at":"2024-04-05 13:28:32","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":33682,"visible":true,"origin":"","legend":"\u003cp\u003eGroup 3 in the FCA planes F1xF2 (left) and F3xF4 (right).\u003c/p\u003e","description":"","filename":"Figure11.png","url":"https://assets-eu.researchsquare.com/files/rs-4197543/v1/7ea1a9d1d35138f05832ef50.png"},{"id":54165698,"identity":"490bee2e-5b58-44c5-acc1-4c59d112c1aa","added_by":"auto","created_at":"2024-04-05 13:28:32","extension":"png","order_by":12,"title":"Figure 12","display":"","copyAsset":false,"role":"figure","size":16595,"visible":true,"origin":"","legend":"\u003cp\u003eHAC results: Group 4 in the FCA planes F1xF2 (left) and F3xF4 (right).\u003c/p\u003e","description":"","filename":"Figure12.png","url":"https://assets-eu.researchsquare.com/files/rs-4197543/v1/1d81dbcea18d317959f832d0.png"},{"id":54166912,"identity":"13b0c24a-10b7-49d8-b1ae-4d99f0c4bf6b","added_by":"auto","created_at":"2024-04-05 13:36:34","extension":"png","order_by":13,"title":"Figure 13","display":"","copyAsset":false,"role":"figure","size":39096,"visible":true,"origin":"","legend":"\u003cp\u003eHAC results: Group 5 in the FCA planes F1xF2 (left) and F3xF4 (right).\u003c/p\u003e","description":"","filename":"Figure13.png","url":"https://assets-eu.researchsquare.com/files/rs-4197543/v1/cb13e57776190b80f902a51b.png"},{"id":54165704,"identity":"c23ab561-2c82-482f-a294-27477fd08edc","added_by":"auto","created_at":"2024-04-05 13:28:33","extension":"png","order_by":14,"title":"Figure 14","display":"","copyAsset":false,"role":"figure","size":37600,"visible":true,"origin":"","legend":"\u003cp\u003eHAC results: Group 6 in the FCA planes F1xF2 (left) and F3xF4 (right).\u003c/p\u003e","description":"","filename":"Figure14.png","url":"https://assets-eu.researchsquare.com/files/rs-4197543/v1/b3f12cb0a8f3414fc3b649ed.png"},{"id":54165696,"identity":"ace5e64c-c4e5-46a5-93df-bd24981fe288","added_by":"auto","created_at":"2024-04-05 13:28:32","extension":"png","order_by":15,"title":"Figure 15","display":"","copyAsset":false,"role":"figure","size":2601517,"visible":true,"origin":"","legend":"\u003cp\u003eGeographical distribution of cliff groups.\u003c/p\u003e","description":"","filename":"Figure15.png","url":"https://assets-eu.researchsquare.com/files/rs-4197543/v1/83baaea8181bc4811b3c19d4.png"},{"id":54167550,"identity":"79a2f822-8310-4818-b407-0216c7939c4d","added_by":"auto","created_at":"2024-04-05 13:44:36","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":6438495,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4197543/v1/98d281aa-ad86-4211-b98d-8823b013a1d1.pdf"},{"id":54166917,"identity":"d377492c-cade-4ab7-a60f-1d300758cdc7","added_by":"auto","created_at":"2024-04-05 13:36:40","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":64919,"visible":true,"origin":"","legend":"","description":"","filename":"Appendix.docx","url":"https://assets-eu.researchsquare.com/files/rs-4197543/v1/2745c997bcc10b5e700c52c9.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Morphodynamic Classification of Morocco's Steep Coasts using multivariate methods and remote data","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe littoral, often defined as the sea-continent interface (Pr\u0026eacute;maillon, \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2018\u003c/span\u003e), covers both rocky and soft marine coasts, as well as estuarine areas (estuaries, deltas and lagoons). Among these, steep coasts are formed of consolidated materials, of whatever nature and hardness (Limber, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2012\u003c/span\u003e), with a seaward slope of over 40\u0026deg; (Davidson-Arnott, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2012\u003c/span\u003e), which can reach 90\u0026deg;, giving rise to steep cliffs (Emery et al, 1982). These inclined landscapes, raised above the coastline, may be submersible by sea water (P\u0026eacute;rez-Alberti et al, 2019), even at their foot or set back from the it, but yet still be subject to the sea influences.\u003c/p\u003e \u003cp\u003eCoastal spaces are of great importance, hosting almost one quarter of the human population (Small et al, 2003), to whom they offer diverse and abundant resources (food, energy, mining, etc.). Moreover, these spaces are natural ecosystems that have acquired specific geomorphological, climatic, botanical, faunistic, and aesthetic characteristics acquired over long evolutionary processes linked to the sea, making them original.\u003c/p\u003e \u003cp\u003eSteep landforms are generally a key source of sediment for coastal bottoms and beaches (Young et al, 2006; Brooks et al, 2010; Mushkin et al, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2016\u003c/span\u003e), especially as they account for around 80% of the world's coastlines (Emery et al, 1982).\u003c/p\u003e \u003cp\u003eWhen compared to other North African countries, Morocco has the longest marine coastline, stretching some 3,500 km, of which around 86 km are beaches and 2,131 km are cliffs (Mansoum et al, 2016). This coastline, interrupted by around 300 estuarine mouths, is sinuous at the Rif and Atlas Mountains foothills, but sub-linear along the low plains and coastal plateaus (Weisrock, \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e1985\u003c/span\u003e). These variations have generated a panoply of coastal ecosystems, whose diversity is evident in physical, ecological, touristic, and socio-economic dimensions.\u003c/p\u003e \u003cp\u003eDespite their advantages and heritage value, 50% of steep coastlines have suffered severe degradation since the early 19th century (O'connor and Crowe, 2005; Lasgaa et al, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Davidson, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2014\u003c/span\u003e) due to both human and climatic factors. In addition, they are still less studied than those of soft coasts, probably because they are less coveted by man (Pr\u0026eacute;maillon, \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2018\u003c/span\u003e), especially when it comes to urban and industrial development (Bird, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2016\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eSeveral classifications of coasts were attempted worldwide; they are often partial although some are intended to be general. Many of these (Augier, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e1982\u003c/span\u003e; Polunin and Walters, 1985; Bissardon et al, 1997; etc.) have been compiled as part of the European \u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eCorine\u003c/span\u003e Biotope Programme. These classifications, carried out for Europe, sometimes for ecological purposes, are supposed to be partially applicable to the North African coasts, because of the many specific features (climatic, hydrodynamic, geomorphological, etc.) that they cannot cover.\u003c/p\u003e \u003cp\u003eHill (2004) have suggested a general morphological classification of steep coasts, which divided them into 15 categories, based on several physical criteria: nature and strength of materials, stratification mode, sea-cliff relationship, inclination, cliff activity/inactivity, etc.\u003c/p\u003e \u003cp\u003eOther authors, considering fewer parameters, have broaden this classification; for example, P\u0026eacute;rez-Alberti and G\u0026oacute;mez-Pazo (\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2019\u003c/span\u003e) introduced new variants solely based on topography; distinguishing three categories of escarpments: cliffs with a convex or concave slope; flat-topped cliffs without an associated posterior plain; flat-topped cliffs with an associated posterior plain.\u003c/p\u003e \u003cp\u003eThis paper is an attempt to classify the Morocco's steep coasts using multiple physical criteria, at both local and hinterland levels. We obtained the majority of these criteria using remote sensing (satellite images), complemented by mapping techniques (Geographic Information System). Those criteria were analysed using multivariate methods, recognised for their effectiveness in landscape typology. Alongside this classification, the collection of these parameters contributed to enrich the inventory of Morocco's coastal wetlands.\u003c/p\u003e"},{"header":"Tools \u0026 Methods","content":"\u003ch2\u003eGeneral approach\u003c/h2\u003e\n\u003cp\u003eA literature review on steep coastlines, in particular on their classification, revealed a wide range of existing classification criteria, some of which relate to marine hydrodynamic (e.g. swell, waves, upwelling). Other classifications refer to geomorphological or geological characteristics (e.g. nature or structure of rocks, erosion, etc.) of the coast and its proximate hinterland (Duperret et al 2004; Mortimore et al, 2004; Bezerra et al, 2011; Carpenter et al, 2014, P\u0026eacute;rez-Alberti and G\u0026oacute;mez-Pazo, 2019), while few classifications are based on ecological or conservation criteria (Ciccarelli et al, 2016).\u003c/p\u003e\n\u003cp\u003eThe present study attempts to classify Morocco\u0026apos;s steep coastal landforms with the help of multivariate analyses (Benzecri 1977; Hill et al, 1980; Lebreton et al, 1976; Dakki 1987; Alaoui et al, 2017; Al Mahfadi et al 2021). For that, we used a panel of physical attributes, that we can obtain by remote sensing (from satellite data) or from maps. This means that we did not use some classification criteria suggested by some authors and which need field data measurable on site.\u003c/p\u003e\n\u003cp\u003eThe first step of our work was to delineate all Moroccan steep coastal areas (Figure\u0026nbsp;1), in a way to obtain distinct units, as homogeneous as possible; the limits of these units correspond their contact with other types of coastal landscapes. We then described each unit using the selected classification criteria (Figure\u0026nbsp;2).\u003c/p\u003e\n\u003cp\u003eOrganised in a binary matrix, the values of each attribute are transformed into modalities using different standardised methods; this led to a homogeneous matrix that can be processed by multivariate classification techniques.\u003c/p\u003e\n\u003ch2\u003eSelection and presentation of the classification criteria\u003c/h2\u003e\n\u003cp\u003eThe criteria used are hydrodynamic, geological and, above all, morphometric (Table 1), most of which can be compiled or measured from maps (i.e. geological criteria) or satellite sources (i.e. Google Earth platform). Nevertheless, a field visit enabled us to verify or refine certain data. The measurements are approximate, but they are still suitable for multivariate analyses, since these latter remain relatively stable for slight data variations. We illustrated below the major morphometric measurements we have done (Figure 2).\u003c/p\u003e\n\u003col\u003e\n \u003cli\u003eDescriptors used as classification parameters of Morocco\u0026apos;s sea cliffs.\u003c/li\u003e\n\u003c/ol\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"18.548387096774192%\" colspan=\"2\"\u003e\n \u003cp\u003e\u003cstrong\u003eVariables\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.963133640552996%\" rowspan=\"2\"\u003e\n \u003cp\u003e\u003cstrong\u003eDefinition\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"30.52995391705069%\" rowspan=\"2\"\u003e\n \u003cp\u003e\u003cstrong\u003eMethods and tools used\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"26.95852534562212%\" colspan=\"4\"\u003e\n \u003cp\u003e\u003cstrong\u003eClasses\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"9.620253164556962%\"\u003e\n \u003cp\u003e\u003cstrong\u003eCode\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"31.139240506329113%\"\u003e\n \u003cp\u003e\u003cstrong\u003eTitle\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.430379746835444%\"\u003e\n \u003cp\u003e\u003cstrong\u003e1\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.70886075949367%\"\u003e\n \u003cp\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.455696202531644%\"\u003e\n \u003cp\u003e\u003cstrong\u003e3\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.645569620253164%\"\u003e\n \u003cp\u003e\u003cstrong\u003e4\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"4.377880184331797%\"\u003e\n \u003cp\u003eSA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.170506912442397%\"\u003e\n \u003cp\u003eSurface area (ha)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.963133640552996%\"\u003e\n \u003cp\u003eArea of the seafront surface of the cliff, in its horizontal projection.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"30.52995391705069%\"\u003e\n \u003cp\u003eArea of the delimitation polygon of the seafront surface, calculated by ArcGIS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.566820276497696%\"\u003e\n \u003cp\u003e\u0026le; 20,00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.6036866359447%\"\u003e\n \u003cp\u003e20,01-100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.488479262672811%\"\u003e\n \u003cp\u003e100,01-400\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"5.299539170506913%\"\u003e\n \u003cp\u003e\u0026gt; 400\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"4.377880184331797%\"\u003e\n \u003cp\u003eL\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.170506912442397%\"\u003e\n \u003cp\u003eCliff length (m)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.963133640552996%\"\u003e\n \u003cp\u003eLength of cliff measured at its foot, parallel to the coastline\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"30.52995391705069%\" rowspan=\"3\"\u003e\n \u003cp\u003eMeasure provided by Google Earth platform\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.566820276497696%\"\u003e\n \u003cp\u003e\u0026le; 1000\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.6036866359447%\"\u003e\n \u003cp\u003e1001-4000\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.488479262672811%\"\u003e\n \u003cp\u003e4001-8000\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"5.299539170506913%\"\u003e\n \u003cp\u003e\u0026gt; 8000\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"6.301824212271973%\"\u003e\n \u003cp\u003eAR\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.398009950248756%\"\u003e\n \u003cp\u003eCliff altitude at its roof (m)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"34.49419568822554%\"\u003e\n \u003cp\u003eElevation of the highest point of the cliff top\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.45273631840796%\"\u003e\n \u003cp\u003e\u0026le; 20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.945273631840797%\"\u003e\n \u003cp\u003e21-80\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.779436152570481%\"\u003e\n \u003cp\u003e81-250\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.628524046434494%\"\u003e\n \u003cp\u003e\u0026gt; 250\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"6.301824212271973%\"\u003e\n \u003cp\u003eAF\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.398009950248756%\"\u003e\n \u003cp\u003eCliff altitude at its foot (m)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"34.49419568822554%\"\u003e\n \u003cp\u003eElevation of the lowest level of the cliff foot\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.45273631840796%\"\u003e\n \u003cp\u003e\u0026le; 2,0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.945273631840797%\"\u003e\n \u003cp\u003e2,1-3,0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.779436152570481%\"\u003e\n \u003cp\u003e3,1-7,0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.628524046434494%\"\u003e\n \u003cp\u003e\u0026gt; 7,0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"4.377880184331797%\"\u003e\n \u003cp\u003eAS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.170506912442397%\"\u003e\n \u003cp\u003eAverage slope of the cliff (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.963133640552996%\"\u003e\n \u003cp\u003eAverage inclination of the cliff\u0026apos;s seafront\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"30.52995391705069%\"\u003e\n \u003cp\u003eRatio of the cliff\u0026apos;s height (AR-AF) to its width (referred to the cliff polygon)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.566820276497696%\"\u003e\n \u003cp\u003e\u0026le; 20,00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.6036866359447%\"\u003e\n \u003cp\u003e20,01-30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.488479262672811%\"\u003e\n \u003cp\u003e30,01-60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"5.299539170506913%\"\u003e\n \u003cp\u003e\u0026gt; 60,00\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"4.377880184331797%\"\u003e\n \u003cp\u003eSM\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.170506912442397%\"\u003e\n \u003cp\u003eMaximum swell (m)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.963133640552996%\"\u003e\n \u003cp\u003eMaximum mean swell height for last 10 years\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"30.52995391705069%\"\u003e\n \u003cp\u003eMean of the annual values obtained at https://www.puertos.es/en-us/oceanografia/Pages/portus.aspx\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.566820276497696%\"\u003e\n \u003cp\u003e\u0026le; 5,00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.6036866359447%\"\u003e\n \u003cp\u003e5,01-7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.488479262672811%\"\u003e\n \u003cp\u003e\u0026gt;7,00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"4.377880184331797%\"\u003e\n \u003cp\u003eSD\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.170506912442397%\"\u003e\n \u003cp\u003eDirection of the swell\u0026nbsp;(\u0026deg;)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.963133640552996%\"\u003e\n \u003cp\u003eDirection of prevailing swell (W), referred to the general direction of the coast (C)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"30.52995391705069%\"\u003e\n \u003cp\u003eAngle between W and C directions, W is obtained at https://www.puertos.es/ en-us/oceanografia/pages/portus.aspx\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.566820276497696%\"\u003e\n \u003cp\u003e\u0026le; 30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.6036866359447%\"\u003e\n \u003cp\u003e31-60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.488479262672811%\"\u003e\n \u003cp\u003e61-90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"4.377880184331797%\"\u003e\n \u003cp\u003eWS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.170506912442397%\"\u003e\n \u003cp\u003eWind speed (m/s)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.963133640552996%\"\u003e\n \u003cp\u003eMean of the monthly maximum wind speed for the last 10 years\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"30.52995391705069%\"\u003e\n \u003cp\u003eCalculated on the basis of data obtained at www.windfinder.com\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.566820276497696%\"\u003e\n \u003cp\u003e\u0026le; 20,00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.6036866359447%\"\u003e\n \u003cp\u003e20,01-22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.488479262672811%\"\u003e\n \u003cp\u003e22,01-24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"4.377880184331797%\"\u003e\n \u003cp\u003eWD\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.170506912442397%\"\u003e\n \u003cp\u003eWind direction (\u0026deg;)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.963133640552996%\"\u003e\n \u003cp\u003eDirection of prevailing winds (W), referred to the general direction of the coast (C)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"30.52995391705069%\"\u003e\n \u003cp\u003eAngle between W and C directions, W is obtained at www.windfinder.comand\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.566820276497696%\"\u003e\n \u003cp\u003e\u0026le; 30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.6036866359447%\"\u003e\n \u003cp\u003e31-60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.488479262672811%\"\u003e\n \u003cp\u003e61-90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"4.377880184331797%\"\u003e\n \u003cp\u003eSC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.170506912442397%\"\u003e\n \u003cp\u003eSea-Cliff distance\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.963133640552996%\"\u003e\n \u003cp\u003eDistance between the low tide line and the cliff foot\u0026nbsp;: mean of distances at 3 radials\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"30.52995391705069%\"\u003e\n \u003cp\u003eEstimated using Google Earth, and when possible, corrected in the field\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.566820276497696%\"\u003e\n \u003cp\u003e\u0026lt; 5.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.6036866359447%\"\u003e\n \u003cp\u003e5,0-21,0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.488479262672811%\"\u003e\n \u003cp\u003e21,0-40,0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"5.299539170506913%\"\u003e\n \u003cp\u003e\u0026gt; 40,0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"4.377880184331797%\"\u003e\n \u003cp\u003eNR\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.170506912442397%\"\u003e\n \u003cp\u003eNature of rocks*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.963133640552996%\"\u003e\n \u003cp\u003eDominant type of rock making up the cliff\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"30.52995391705069%\" rowspan=\"2\"\u003e\n \u003cp\u003eObtained from various geological maps of different scales\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.566820276497696%\"\u003e\n \u003cp\u003eAG\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.6036866359447%\"\u003e\n \u003cp\u003eCA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.488479262672811%\"\u003e\n \u003cp\u003eFG\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"5.299539170506913%\"\u003e\n \u003cp\u003eSC\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"6.301824212271973%\"\u003e\n \u003cp\u003eGE\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.398009950248756%\"\u003e\n \u003cp\u003eGeological era**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"34.49419568822554%\"\u003e\n \u003cp\u003eGeological Era of the dominant rocks making up the cliffs\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.45273631840796%\"\u003e\n \u003cp\u003e0-I\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.945273631840797%\"\u003e\n \u003cp\u003eII\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.779436152570481%\"\u003e\n \u003cp\u003eIII\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.628524046434494%\"\u003e\n \u003cp\u003eIV\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e*\u0026nbsp;Nature of rocks (classes): AG: Andesites/Gneiss; CA: Limestone/Eolianites/Calcarenites; FG: Flysch/Gr\u0026egrave;s; SC: Schist\u003c/p\u003e\n\u003cp\u003e**\u0026nbsp;Geological eras (classes): 0-I: Precambrian/Palaeozoic; II: Secondary; III: Tertiary; IV: Quaternary\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTable 2 Morocco\u0026apos;s littoral sectors: subdivisions used to inventory the sea cliffs.\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"21.21212121212121%\"\u003e\n \u003cp\u003e\u003cstrong\u003eName\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.496012759170654%\"\u003e\n \u003cp\u003e\u003cstrong\u003eCode\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"71.29186602870813%\"\u003e\n \u003cp\u003e\u003cstrong\u003eDescription\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"21.21212121212121%\" valign=\"top\"\u003e\n \u003cp\u003eMediterranean, Oriental\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.496012759170654%\" valign=\"top\"\u003e\n \u003cp\u003eMO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"71.29186602870813%\"\u003e\n \u003cp\u003eMediterranean littoral to the Eastern Rif and Lower Moulouya, coast with variable configuration\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"21.21212121212121%\" valign=\"top\"\u003e\n \u003cp\u003eMediterranean, Central\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.496012759170654%\" valign=\"top\"\u003e\n \u003cp\u003eMC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"71.29186602870813%\"\u003e\n \u003cp\u003eMediterranean littoral of the Central Rif, generally high cliffs frequently separated by rivers\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"21.21212121212121%\" valign=\"top\"\u003e\n \u003cp\u003eMediterranean, Tingitane Peninsula\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.496012759170654%\" valign=\"top\"\u003e\n \u003cp\u003eMT\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"71.29186602870813%\"\u003e\n \u003cp\u003eMediterranean littoral of the Western Rif, high and long cliffs, separated by large coastal plains\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"21.21212121212121%\" valign=\"top\"\u003e\n \u003cp\u003eAtlantic, North\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.496012759170654%\" valign=\"top\"\u003e\n \u003cp\u003eAN\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"71.29186602870813%\"\u003e\n \u003cp\u003eAtlantic littoral of Western Rif and the Gharb domains, long and low cliffs, catted in dunes\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"21.21212121212121%\" valign=\"top\"\u003e\n \u003cp\u003eAtlantic, Medium\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.496012759170654%\" valign=\"top\"\u003e\n \u003cp\u003eAM\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"71.29186602870813%\"\u003e\n \u003cp\u003eAtlantic littoral of the Central plateau domain, coast with variable configuration\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"21.21212121212121%\" valign=\"top\"\u003e\n \u003cp\u003eAtlantic, High Atlas\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.496012759170654%\" valign=\"top\"\u003e\n \u003cp\u003eAH\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"71.29186602870813%\"\u003e\n \u003cp\u003eAtlantic littoral of the High Atlas domain, continuous landscape of cliffs of a mountainous slopes\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"21.21212121212121%\" valign=\"top\"\u003e\n \u003cp\u003eAtlantic, Anti-Atlas\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.496012759170654%\" valign=\"top\"\u003e\n \u003cp\u003eAA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"71.29186602870813%\"\u003e\n \u003cp\u003eAtlantic littoral of the Anti-Atlas domain, continuous landscape of cliffs separated by estuaries\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"21.21212121212121%\" valign=\"top\"\u003e\n \u003cp\u003eAtlantic, Sahara\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.496012759170654%\" valign=\"top\"\u003e\n \u003cp\u003eAS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"71.29186602870813%\"\u003e\n \u003cp\u003eAtlantic littoral of the Sahara domain, very long cliffs, most of them being in contact with the sea\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003ch3\u003eMorphometric criteria\u003c/h3\u003e\n\u003cp\u003eSeven characteristics of the local steep coastline were recorded; their measurement was carried out on the Google Earth platform (i.e. altitude, surface area, etc.), using images that best reflect the reality of the landscape.\u003c/p\u003e\n\u003ch3\u003eHydrodynamic criteria\u003c/h3\u003e\n\u003cp\u003eThese are measurable parameters that best reflect the effects of marine dynamics on the coast. These marine forces are expressed by the swell and its direction, as well as by wind (direction and speed), the latter having a major influence on the swell.\u003c/p\u003e\n\u003ch3\u003eGeological criteria\u003c/h3\u003e\n\u003cp\u003eTwo qualitative criteria were used: the nature of the dominant ground/rock and the geological age of the dominant land.\u003c/p\u003e\n\u003ch2\u003eDelineation of steep coastline units\u003c/h2\u003e\n\u003cp\u003eInitially, the Moroccan coastline was divided into eight large sectors defined by their general morphology, including that of the hinterland, and their direction (Table\u0026nbsp;2). These sectors were then broken down into 76 more homogeneous sub-sectors, inside which we delineated only steep coasts that constitute continuous units, totalizing 175 cliff units to be classified.\u003c/p\u003e\n\u003cp\u003eThese sectors correspond to the different geological structures defined in Morocco, some of them being heterogeneous, in the sense that they show a lateral variability of coastal landscapes.\u003c/p\u003e\n\u003cp\u003eGenerally, the limits of a cliff unit have been set at large estuaries or lagoon openings, but other factors can be used to delineate units (topographical accidents, change of direction, change in distance between the sea and the cliff, etc.). Despite our efforts, this homogeneity is not always perfect; in some steep coastal segments, we did not consider all small wadis as discontinuities, mainly when these wadis have small coastal watershed. The values of the classification parameters (attributes) correspond then to an average or to the value of the dominant landscape.\u003c/p\u003e\n\u003ch2\u003eStatistical analyses\u003c/h2\u003e\n\u003cp\u003eIn order to classify steep coastlines, we first used the Factorial Correspondence analysis (FCA), method that has become widely used (Lebreton, 1976; Hill et al, 1980; Dakki, 1987; Lebreton et al, 1988; Bonin et al, 1990) and recommended for processing binary matrices designed to search for similarities between rows (elements to be classified) and columns (variables used for the classification). This method provides a good visualization of the ordination of the matrix rows and columns, as point clouds in the first 2-4 first axes of the analysis, but it\u0026apos;s not always easy to distinguish clear groups inside these clouds, mainly in case of a high number of points. That why we combined the FCA technique with the Hierarchical Agglomerative Clustering (HAC) method, which provides a classification of the matrix columns/rows in a tree structure of nested classes (Nakache et al, 2004).\u003c/p\u003e\n\u003cp\u003eThe HAC method, based on the same parameters used in the FCA approach (Table 1), consists in grouping individuals (sea cliffs) iteratively according to their similarity, starting with the closest and gradually building up a dendrogram with all individuals at the root. Similarities are calculated between individuals and then between increasingly heterogeneous groups. The classes obtained by this method can be represented in the CFA point clouds, using only different colours or symbols.\u003c/p\u003e"},{"header":"Results","content":"\u003ch2\u003eClassification of coastal steep landforms in morocco\u003c/h2\u003e\n\u003ch3\u003eResults of the Factorial Correspondence analysis\u003c/h3\u003e\n\u003ch4\u003eHistogram of inertia\u003c/h4\u003e\n\u003cp\u003eIn order to interpret the similarities between individuals (and variables), we extracted the first 20 dimensions defined by the analysis, but after examining the histogram of inertia Figure 2), it became apparent that the total inertia is greater than that of the 0.95 quintile of random distribution (77.74% compared with 57.85%). We then restricted the interpretation to the first four axes of the analysis, considering that they provide a good summary of the dissimilarities between the Moroccan coastal escarpments.\u003c/p\u003e\n\u003cp\u003eThe first two axes of the analysis cumulate 17.79% of the total dataset inertia; this rate is well above the reference value of 10.95%, but remains low, in the sense that the F1-F2 plane represents only 17.79% of the total variability of the cloud of individuals (and variables). We therefore examined this variability also in the F3-F4 plane.\u003c/p\u003e\n\u003ch4\u003eSignificance of the FCA first planes\u003c/h4\u003e\n\u003cp\u003eThe dispersion of the cliffs in the F1xF2 and F3xF4 planes does not reveal clear defined groups, but it shows possible gradients of organisation along the four axes (Figure 4).\u003c/p\u003e\n\u003cp\u003eIn order to determine the cliff descriptors that are likely to explain these gradients, we have projected them (using their class values, as determined in Table\u0026nbsp;1) onto the planes F1xF2\u0026nbsp;and F3xF4\u0026nbsp;(Figure 5).\u003c/p\u003e\n\u003cp\u003eAxis 1 is well correlated (visually) at least with four quantitative parameters, which together express the size of the cliffs. The best descriptor that explain this axis are the surface area (SA), followed by the length (L) of the cliff and the distance between the sea and the cliff foot (SC). It seems that most of the higher cliffs tend to be set back from the shoreline. The altitudes of the cliff roof (AR) and the cliff foot (AF) reflect this same gradient, but to a lesser degree; however, we note that the cliffs with the highest foot altitude have rather low roofs.\u003c/p\u003e\n\u003cp\u003eAxis 2 contrasts the cliffs with the highest roof (AF4) with those whose base is close to the water; it also shows a gradual variation in the average slope (AS), which is independent of the cliff size. In addition, this axis express the discriminant role of the geology, in its both representations: nature of rocks, which vary along this axis, and geological eras, as the ancient eras are distinct one from the other and both from the Tertiary and the Quaternary, which characterises the same cliffs.\u003c/p\u003e\n\u003cp\u003eIn the plane F3xF4, two descriptors provide a high significance of the cliff similarities: the cliff altitude at its roof, which isolates on both axes the highest value of this parameter from the others, and the nature of rocks, which separates the Schist cliffs from the other rock cliffs. Four other descriptors (geological era, cliff altitude at its foot, average slope and direction of the swell) slightly contribute to the significance of the axis 3.\u003c/p\u003e\n\u003ch4\u003eDoes the geographic location of the cliffs play any role in their FCA organisation\u003c/h4\u003e\n\u003cp\u003eIn addition to the search of the significance of the FCA first axes, we explored the hypothesis that the geographic distribution of the cliffs may play a special role in their classification, as the littoral is highly shaped by the geology of its terrains and incidentally by the sea hydrodynamic. We then represented the eight littoral sectors, intuitively defined above, on the two FCA planes F1xF2 and F3xF4 (Figure\u0026nbsp;6).\u003c/p\u003e\n\u003cp\u003eMost of the sectors have their cliffs grouped in a same zone of the FCA plane F1xF2, what means that they are homogeneous, in the sense that their cliffs have similar characteristics. This is particularly clear for the sectors adjacent to the coastal Sahara plateau, the Atlantic High Atlas and the Central Rif on the Mediterranean side. The five other sectors are slightly heterogeneous, as the cliffs of each of them are subdivided in two distinct groups. On another hand, a clear segregation is revealed between the Sahara sector and all others (Figure 6), although no geographic positioning parameter was used among the selected classification criteria. Such segregation can also be detected between other sectors, even less clearly. In other words, the FCA, dominantly based on physiographical parameters, expresses partly the spatial variation of the geology throughout this country.\u003c/p\u003e\n\u003ch3\u003eResults of the HAC: towards a classification of the Moroccan sea steep coasts\u003c/h3\u003e\n\u003cp\u003eThe main result of the Hierarchical Agglomerative Clustering is a dendrogram (Figure\u0026nbsp;7), where several groups are differentiated; we used the first and the second clustering levels to distinguish a first classification, which provides six large groups of cliffs. Using then the third and the fourth clustering levels, each of these groups is subdivided to 2 or 3 subgroups, thereby providing a total of 12 more homogeneous groups.\u003c/p\u003e\n\u003cp\u003eIn order to better illustrate this classification and to facilitate its understanding, the groups/classes are projected on the FCA plane F1xF2 (Figure 8), using different colors to make easy their distinction.\u003c/p\u003e\n\u003ch4\u003eGroup 1. Saharan cliffs, cut in limestone plateau of Secondary era, with medium elevation and slope and low to medium length, occasionally washed by the sea\u0026nbsp;waters.\u003c/h4\u003e\n\u003cp\u003eThese steep coasts have four common characters; two are relative to the geology (limestone of the secondary era) and two others are to the wind (low speed and almost perpendicular direction to the coast). These cliffs are relatively inclined, but very rarely vertical; most of them are deed cliffs, having their foot unreachable by the sea waters. HAC has split this group to two subgroups, more clear on the FCA plane F3xF4 (Figure\u0026nbsp;9):\u003c/p\u003e\n\u003cul class=\"decimal_type\"\u003e\n \u003cli\u003e\u003cstrong\u003e\u003cem\u003eSubgroup 1.1\u003c/em\u003e\u003c/strong\u003e, which stands out with the low area of the cliff\u0026apos;s seafront and the low marine swell, which corroborates with the frequently low wind force.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003e\u003cem\u003eSubgroup 1.2\u003c/em\u003e\u003c/strong\u003e, containing cliffs of medium to large seafront area, with low to medium roof elevation, and low foot elevation, rarely washed by the sea waters.\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eBoth subgroups are found at the southern part of the Saharan coastal plateau, north and south of Ad-Dakhla Bay, but the Subgroup 1.2 contains some cliffs of the oceanic slopes of the Anti-Atlas Mountains and southern coats of the High Atlas.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eGroup 2: Long Saharan sea cliffs, cut in limestone plateaus\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThese cliffs present geological and marine hydrodynamic similarities; indeed, most of them are cut in Tertiary limestone of the Saharan plateaus between Dr\u0026apos;a Mouth and Aftissate fishing village, but the seven Northern ones (Coast of Tantan-Akhfennir) are cut in the Secondary era sandstone rocks. This coastal domain is exposed to winds with generally low force, almost perpendicular to the cliffs, and to moderate to low swells.\u003c/p\u003e\n\u003cp\u003eThese cliffs have a minimum length of 1\u0026nbsp;km, and frequently exceeding 4\u0026nbsp;km; they have moderate to medium inclination, and low to medium roof elevation, explaining the low or medium area of their seafront. This group is divided by HAC into two sub-groups, which are well distinct in the F3xF4 plane (Figure\u0026nbsp;10):\u003c/p\u003e\n\u003cul class=\"decimal_type\"\u003e\n \u003cli\u003e\u003cstrong\u003e\u003cem\u003eSubgroup 2.1\u003c/em\u003e\u003c/strong\u003e, including cliffs with medium length and low roof and foot elevations, explaining their low and medium seafront area; they have also low to medium inclination and relatively long distance to the coastline.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003e\u003cem\u003eSubgroup 2.2\u003c/em\u003e\u003c/strong\u003e, to which belong the longest cliffs of Morocco, most of them being over 8\u0026nbsp;km long, with vertical to sub-vertical inclination and a foot close to the coastline, making their foot regularly washed by sea waters.\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003e\u003cstrong\u003eGroup 3: High cliffs of limestone or sandstone mountain foothills (of Secondary age)\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis group of steep coasts is relatively heterogeneous, as it extends over the coastal sections of different mountains (Rif, Central Plateau and High Atlas). Indeed, the only common character between the majority of these coasts is the geology, as they are built in limestone or sandstone of Secondary era. On the contrary, the two subgroups highlighted by the HAC appear less heterogeneous on the F3xF4 FCA plane (Figure 11):\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003e- Subgroup 3.1\u003c/em\u003e\u003c/strong\u003e, composed of steep cliffs of high to medium roof elevation, washed by high to medium swells, as their foot is very close to the sea coastline. They are exposed to lateral strong winds.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003e- Subgroup 3.2\u003c/em\u003e\u003c/strong\u003e, composed of steep and very high cliffs (roof over 250\u0026nbsp;m), explaining their large seafront area and their arched form.\u003c/p\u003e\n\u003ch3\u003eGroup 4: Small Mediterranean cliffs of low mountain foothills of Tertiary limestone\u003c/h3\u003e\n\u003cp\u003eAll the escarpments of this homogeneous group are located on the North-East coasts of Morocco, more precisely in the Kebdana foothills. These limestone low mountains of the Tertiary era are driven by several intermittent ravines, making the coast cut-out in short and steep cliffs, with low roof altitude and seafront area, but with high elevation of their foot, making it unreachable by the Mediterranean waters. This configuration results in the genesis of a gravelly and inclined beach between the cliffs and the sea. This coast receives lateral winds with medium force, accompanied by lateral low swells.\u003c/p\u003e\n\u003ch3\u003eGroup 5: High cliffs of short to medium length at mountain foothills\u003c/h3\u003e\n\u003cp\u003eThese cliffs are found at the foothills of the Rif and Atlas Mountains, in the flysch or sandstone of the Secondary, Palaeozoic or even Precambrian age. They have a seafront of small area and are exposed to winds of medium force, almost perpendicular direction to the coast, generating then medium to high swells. This heterogeneous group is split by the HAC to three subgroups (Figure 13):\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003e- Subgroup 5.1\u003c/em\u003e\u003c/strong\u003e, dead cliffs of variable length, with low roof elevation, but high foot elevation; they are cut in the secondary age rocks, most of them being in the coastal area of the Anti-Atlas Mountains.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003e- Subgroup 5.2\u003c/em\u003e\u003c/strong\u003e, live cliffs of small seafront area, with medium or high slope, washed by the sea waters at their foot. They belong to the central Rif foothills.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003e- Subgroup 5.3\u003c/em\u003e\u003c/strong\u003e, steep to vertical small cliffs, with a low roof but their foot is in a high position in relation to the coastline. In their great majority, they belong to the Atlantic High Atlas foothills.\u003c/p\u003e\n\u003ch3\u003eGroup 6: Small and low elevation cliffs of northern coastal plains and plateaux\u003c/h3\u003e\n\u003cp\u003eThis is a heterogeneous group, shared between the North Eastern Moroccan coasts and the northern and middle Atlantic coasts. Their seafront has small area, generally with low slope and low roof elevation, as their immediate hinterland corresponds to coastal plains or low plateaux. Most of the cliffs are cut in limestone, more rarely in metamorphic or sandstone rocks, of Secondary to Quaternary, and even Primary eras.\u003c/p\u003e\n\u003cp\u003eThis group is split by the HAC to three subgroups (Figure\u0026nbsp;14):\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003e- Subgroup 6.1\u003c/em\u003e\u003c/strong\u003e, containing cliffs of Tertiary-quaternary limestone, with short length and low roof elevation and slope, and their foot, even almost close to the coastline, is exceptionally in contact with the seawaters. These coasts are submitted to winds of low force but generally sub-perpendicular to the coastline, and generating high energy swells, perpendicularly directed towards the coastline.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003e- Subgroup 6.2\u003c/em\u003e\u003c/strong\u003e, composed of cliffs quite similar to the former subgroup, with the difference that these have low to medium slope, and their foot is close to the coastline, in a way to be regularly in contact with the sea waters. These coasts are submitted to winds of medium force.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003e- Subgroup 6.3\u003c/em\u003e\u003c/strong\u003e, which stands out for its short to medium length cliffs, with variable slope, some of them being cut in secondary age sandstone and andesite of primary age. The swells are medium to high and move in a direction perpendicular to sub-perpendicular to the coast.\u003c/p\u003e\n\u003cp\u003eWe note that the subgroup 6.1 is intermediary between the two other subgroups, which are well separated on the third FCA axis.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThrough this study, we aimed to provide a first classification of the Morocco's steep coasts, mainly based on remote morphometric data accessible on satellite images and on public databases and maps. Using 12 descriptors and two complementary multivariate methods (HCA and FCA), we obtained a classification scheme that distinguished six different types (groups) of steep coasts split into 12 subtypes (subgroups). The descriptors that play a determinant role in this classification (by explaining the four first axes of the FCA) belong to different categories (geology, size, relation with the coastline, maximum swell, etc.). This confirms the great significance of the morphometric, geologic and hydrodynamic criteria in the obtained classification, which is likely to valid their use by several authors (Emery and Kuhn, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e1982\u003c/span\u003e; Sunamura, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e1985\u003c/span\u003e; Benumof and Griggs, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e1999\u003c/span\u003e; Hill 2004; Bezerra et al., \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2008\u003c/span\u003e; Ikeda et al., 2019; P\u0026eacute;rez-Alberti and G\u0026oacute;mez-Pazo, \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2019\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIt is also clear that the geographical position of cliffs on both Atlantic and Mediterranean coasts plays a determinant role in this classification, since the cliffs belonging to the same littoral sector constitute more or less homogeneous groups in the FCA plans. This result seems normal, as different geological structures and hydrodynamics, greatly variable in space, configure the morphology of the coast, and induce different aerodynamic and hydrodynamic conditions. Indeed, in contact with the sea, the different mountains (Rif, Kebdana, Central Plateau, High Atlas and Anti-Atlas) have highly shaped the coasts, giving them, for example, more or high roof elevation but with variable length, depending on the hydrographic network organisation. On the contrary, the Gharb-Loukkos and the Saharan coastal plateaux and dunes generate long and low cliffs, generally with moderate to high slope.\u003c/p\u003e \u003cp\u003eSome users of classifications may be frustrated when the clustering parametric methods (HCA) do not provide clear 'types', but groups that can overlap each other. However, the six groups of coasts distinguished in this research are clearly different, since we can classify them in a dichotomous scheme, using the following morphometric parameters:\u003c/p\u003e \u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003eposition in relation to the coastline: dead or live cliff, this latter being permanently or very frequently washed by the sea waters, at least at their base;\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003esize : length and elevation, which can also provide information on the shape (profile) of the steep coast seafront;\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eroof seafront profile: with arched roof (cut in foothill of coastal mountains) or horizontal roof (cut in a plateau);\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eslope of the seafront fa\u0026ccedil;ade, which inform on its transversal profile.\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e \u003cp\u003eMost of the criteria used in this research have a week and indirect ecological significance, compared to those used in American or European habitat typologies (Cowardin et al., \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e1979\u003c/span\u003e; ECC, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e1991\u003c/span\u003e; De Villers, 2001). In Morocco, in order to establish an ecological classification of the littoral cliffs (Dakki \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2022\u003c/span\u003e), some of these criteria are combined with other parameters that have ecological significance.\u003c/p\u003e \u003cp\u003eOn another hand, an essay of implementing the multivariate approach used in this research to other regions will certainly provide significant results and contribute to refining this approach, mainly the use of remote sensing data as alternative to the time-consuming filed measures.\u003c/p\u003e \u003cp\u003eWe should reminder that the classification process we implemented in the present study has made it possible to initiate a database on the steep coasts of Morocco, which can serve as a basis to describe them for management or conservation purposes.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis research, aiming a classification of sea steep coasts, is part of a Moroccan wetland inventory and classification programme, based on databases and multivariate analyses (see Dakki \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). The sea cliff classification has the particularity to use remote sensing and public data that are easily and quickly accessible. The 12 selected criteria, treated with HCA and illustrated by FCA, led to a clustering scheme regrouping 175 steep coats to six different coast classes, that we split to 2 or 3 subgroups. Both hydromorphic and geologic criteria significantly contribute to this classification, which also incorporates the geographical segregation of the coasts, even using any positioning criteria.\u003c/p\u003e \u003cp\u003eMost classification users prefer simplified hierarchical classifications (as dichotomous schemes) to clusters based on multivariate analyses. This research has the advantage to identify significant criteria on which users can base (even partially) their own hierarchical scheme, the choice of the criteria depending on the objective of the classification. We can resume the most significant criteria useful for Moroccan steep in few categories of parameters, related to the size of the cliff, its position in relation to the coastline and its seafront profile and inclination.\u003c/p\u003e \u003cp\u003eWe consider our classification as a national scheme, which we will confirm or improve through its implementation in ecological, geomorphological or management domains. We think that the database we constituted on Morocco's steep coasts will be a reference for several users.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003ehe funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eThis research has received no external funding\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eAlaoui, A., Olengoba, B., Ettaki, B., Zerouaoui, J., 2017. \u003cem\u003eAgeneric methodology for clustering to maximises inter-cluster inertia. ijacsa 8\u003c/em\u003e. Available at: https://doi. org/10. 14569/IJACSA. 2017. 081125 [Accessed: November 14th 2021].\u003c/li\u003e\n\u003cli\u003eAl-Mahfadi, A. 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Available at : https://doi. org/10. 3406/bagf. 1985. 1286.\u003c/li\u003e\n\u003cli\u003eYoung, A. P., Ashford, S. A., 2006\u003cem\u003e. Application of Airborne LIDAR for Seacliff Volumetric Change and Beach-Sediment Budget Contributions. Journal of Coastal Research\u003c/em\u003e 222, 307\u0026ndash;31.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Morocco, steep coasts, remote data, morphodynamic classification","lastPublishedDoi":"10.21203/rs.3.rs-4197543/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4197543/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe Moroccan coastline extends for 2,130,80 km on the East Atlantic an Western Mediterranean coasts. It shows a high diversity of estuaries, bays, beaches and steep coasts. Despite its ecological, economic, and recreational importance, Morocco does not have a comprehensive inventory of its coastal landscapes. This study attempts to develop a primary classification of Moroccan steep coasts, based on a descriptive inventory of these landscapes, using 12 morphodynamic criteria that we mainly measured on satellite images. To achieve the said classification, we organized the steep coasts and the criteria in a binary matrix, which we treated with the hierarchical ascending classification method (CAH) and Factorial Correspondence Analysis. The results of this treatment provides a clustering scheme where we distinguish six different groups of cliffs, each of them being subdivided to 2 or 3 subgroups. Three categories of criteria appear as determinant in this classification: morphometric (length, area, and elevation), geologic (dominant rock and geologic eras), hydrodynamic (swells), and aerodynamic (wind). However, the two first criteria have the most significant influence on the classification.\u003c/p\u003e \u003cp\u003eThis classification, mainly based on satellite data, remains preliminary and requires improvements such using some field data. Finally, the raw and compiled data collected in this study constitute database composed of 175 cliffs, described using parametric criteria; this database is a contribution to the national wetlands inventory and is essential to promoting their conservation as well as management.\u003c/p\u003e","manuscriptTitle":"Morphodynamic Classification of Morocco's Steep Coasts using multivariate methods and remote data","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-04-05 13:28:26","doi":"10.21203/rs.3.rs-4197543/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"274dda45-2683-4298-bd1d-5e081f00f845","owner":[],"postedDate":"April 5th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-04-05T13:36:40+00:00","versionOfRecord":[],"versionCreatedAt":"2024-04-05 13:28:26","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4197543","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4197543","identity":"rs-4197543","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}