Land Use Policy at a Climatic Crossroads: Valuing the Cost of Sea-Level Rise Inaction in Egypt’s Nile Delta

Land Use Policy at a Climatic Crossroads: Valuing the Cost of Sea-Level Rise Inaction in Egypt’s Nile Delta | 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 Land Use Policy at a Climatic Crossroads: Valuing the Cost of Sea-Level Rise Inaction in Egypt’s Nile Delta Taher Osman This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7934389/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 Nile Delta, a critical nexus of agricultural, urban, and industrial land uses, faces profound risks from sea-level rise (SLR) that challenge Egypt's national land use policy and coastal governance frameworks. This paper provides a spatially explicit economic assessment of a "no-action" policy scenario, quantifying the consequences of failing to implement adaptive land management. Using a high-resolution Digital Elevation Model and a 'bathtub' inundation model under IPCC SSP2-4.5 and SSP5-8.5 scenarios, we project the inundation of different land use types. These physical impact models are integrated with sub-national socioeconomic data to value the loss of agricultural land, damage to built-up assets, and the costs of population displacement across 16 coastal land management units. Our findings reveal catastrophic economic consequences of policy inaction, with projected damages reaching multi-trillion Egyptian pounds (L.E.) by 2100. The spatial analysis highlights a severe concentration of risk in the low-lying governorates of the Nile Delta and the megacity of Alexandria, indicating that current land use patterns are misaligned with future climate realities. The non-linear escalation of costs underscores a rapidly closing window for proactive spatial planning and cost-effective adaptation. We conclude that the economic costs of inaction—representing a failure of anticipatory land use governance—vastly exceed the investment required for adaptive measures. This study provides a data-driven rationale for integrating SLR projections into all levels of land use planning, from national strategy to local permitting, to secure Egypt's economic base, food security, and social stability. Land Use Policy Climate Adaptation Sea-Level Rise Coastal Governance Spatial Planning Cost of Inaction Nile Delta Egypt Figures Figure 1 Figure 2 Figure 3 Figure 4 1. Introduction Egypt's Mediterranean coast, particularly the Nile Delta, represents a complex and vital landscape where intense agricultural, urban, and industrial land uses converge. This region, while constituting only a fraction of the nation's territory, is the backbone of its economy and food security, hosting 43.5% of the population and generating an estimated 60.8% of its economic output (Marine Engineering Expert, 2025 ). The delta's fertile lands account for 63% of Egypt's agricultural area (Hereher, 2015 ), while its coastal cities, including the industrial hub of Alexandria, are centers of commerce and development. 1 This concentration of population and high-value land uses makes the region a focal point for national development policy, but also a zone of extreme vulnerability to climate change. The governance of coastal land is a critical challenge worldwide, as administrations seek to balance economic development with environmental protection and risk management. 2 In low-lying deltaic regions, this challenge is amplified by the threat of sea-level rise (SLR), which threatens to permanently alter land cover and render existing land use patterns untenable. 3 The Nile Delta is a global hotspot for this risk, facing a "compound effect" of eustatic SLR, land subsidence, and a severe sediment deficit following the construction of the Aswan High Dam (Marine Engineering Expert, 2025 ; Frihy, 1992 ). This convergence of pressures creates a scenario where the very land upon which the national economy is built is progressively being lost, posing a fundamental challenge to land use policy and spatial planning. To inform effective policy, it is crucial to establish an analytical baseline against which the benefits of adaptation can be measured. The "no-action" or "cost of inaction" scenario serves this purpose, providing a quantitative assessment of the damages that would occur if current land management and protection policies are not augmented to address future climate risk (Marine Engineering Expert, 2025 ). This approach frames adaptation not as a discretionary expense, but as a necessary investment in preserving the value of existing land uses and securing future development pathways (Seregina et al., 2020 ; Lincke & Hinkel, 2021 ). The economic rationale is clear: climate inaction is projected to be far more costly than proactive investment in adaptation and mitigation (World Economic Forum, 2024 ). 4 The vulnerability of the Nile Delta is well-documented, with studies consistently highlighting the potential for widespread inundation, population displacement, and economic disruption (Dasgupta et al., 2007 ; Abdrabo et al., 2023 ). However, a critical gap exists in translating these broad warnings into spatially explicit, monetized data that can directly inform land use policy and governance. As noted in the literature, effective adaptation requires a localized approach, as generic, large-scale programs often fail to address the specific needs of diverse communities and landscapes. 5 Without a granular understanding of where and when economic damages will occur, policymakers lack the evidence base needed to prioritize investments, reform zoning regulations, and guide future development toward more resilient locations. Recent scholarship in Land Use Policy emphasizes that land use planning is a central enabler of coastal climate change adaptation, but its success depends on balancing competing interests and navigating complex political and legal realities. 8 This paper addresses this gap by providing a comprehensive, sub-nationally disaggregated spatio-economic assessment of the no-action scenario for Egypt's Mediterranean coast. By quantifying the future costs of inundation across 16 distinct land management units, our research moves beyond general vulnerability assessments to offer a direct, policy-relevant analysis of the land use implications of SLR. The objective is to provide a robust, data-driven foundation for reforming coastal land use policy, demonstrating the economic imperative of proactive spatial planning and adaptation governance in one of the world's most critical and vulnerable deltaic systems. 2. Materials and Methods The methodology (Fig. 1 ) is an integrated assessment framework designed to translate the physical hazard of SLR into policy-relevant economic metrics of land use vulnerability. The process links a physical inundation model with a socioeconomic valuation model, allowing for a spatially disaggregated analysis of potential damages. 2.1 Physical Inundation Modeling The physical analysis is grounded in high-resolution spatial data to accurately map the interface of land and sea under future climate scenarios. Data and Scenarios : The primary dataset is a 5-meter resolution Digital Elevation Model (DEM) with a 1-centimeter vertical accuracy, providing a detailed topographic representation of the coastal zone (Marine Engineering Expert, 2025 ). This high-resolution data is essential for accurately modeling inundation in a low-lying deltaic environment. Sea-level projections are drawn from the IPCC's Sixth Assessment Report (AR6), using two Shared Socioeconomic Pathways: SSP2-4.5 (a medium emissions scenario) and SSP5-8.5 (a high-emissions, "worst-case" scenario) to capture a range of plausible futures (Marine Engineering Expert, 2025 ) in the study area (Fig. 2 ). The 'Bathtub' Model : A passive "bathtub" inundation model was employed to map the extent of permanent land loss. This approach identifies all land areas that are both at and below a projected sea level and hydrologically connected to the sea (Marine Engineering Expert, 2025 ). The process is formalized as: I(x, y) = {1, if D(x, y) ≤ W(x, y); 0, if D(x, y) > W(x, y)}, where: I(x, y) is a binary inundation indicator equal to 1 if the land at location (x, y) is inundated, and 0 otherwise. D(x, y) represents the Digital Elevation Model (DEM) elevation value (in meters above mean sea level). W(x, y) denotes the projected water level (e.g., sea-level rise or storm surge elevation) at the same location. While this static model does not account for dynamic processes like storm surges, it provides a robust and conservative baseline for assessing permanent changes in land cover due to SLR, a critical input for long-term land use planning. 2.2 Socioeconomic Valuation The economic valuation component overlays the inundation maps onto detailed land use and socioeconomic datasets to monetize the projected damages for each of the 16 coastal sub-units. 2.2.1 Baseline Data : A comprehensive socioeconomic profile was compiled for each sub-unit, including population, GDP, and Land Use/Land Cover (LULC) maps classifying the area into built-up, agricultural, wetland/aquaculture, and bare land categories (Marine Engineering Expert, 2025 ). The key data sources are summarized in Table 1 . Table 1 Key Data Sources for Integrated Assessment Data Type Source Use in Analysis Coastal Topography 5-meter Digital Elevation Model (DEM) with 1cm RMSE from the Egyptian Marine Survey Division (Marine Engineering Expert, 2025 ) Inundation modeling ('bathtub' approach) to determine the spatial extent of land loss. Sea-Level Rise Projections Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report (AR6) (Marine Engineering Expert, 2025 ) Defining future inundation levels for SSP2-4.5 and SSP5-8.5 scenarios across multiple time horizons. National Non-Financial Assets Credit Suisse Global Wealth Databook (Credit Suisse Research Institute, 2022 ) Establishing the national capital stock for valuation of built-up assets. Population Data Central Agency for Public Mobilization and Statistics (CAPMAS) (CAPMAS, 2024) Apportioning national asset value to sub-national units; estimating population displacement. Gross Domestic Product (GDP) Data Ministry of Planning and Economic Development (MPED) (MPED, 2024) Projecting future asset values; apportioning economic value to sub-national units. Land Use/Land Cover (LULC) Satellite Imagery Analysis (Marine Engineering Expert, 2025 ) Classifying inundated areas (e.g., built-up, agricultural) for sectoral damage assessment. Agricultural Land Value Regional Market Data (Marine Engineering Expert, 2025 ) Valuing direct loss of inundated agricultural land based on market prices per feddan. Agricultural Employment Metrics Regional Economic Data (e.g., 1 job per 2 feddans) (Gad EL Rab, 2008) Estimating job loss costs resulting from the inundation of agricultural land. Job Creation Cost National Economic Data (L.E. 0.25 million/job) (Gad EL Rab, 2008) Monetizing the cost of agricultural job losses. Relocation Cost Methodology International Climate Impact Literature (Depsky et al., 2023 ) Estimating societal costs of population displacement as a percentage (10–40%) of asset damage. 2.2.2 Valuation of Land Use Impacts: Damage to Non-Financial Assets (Built-up Land) : The value of damage to urban and industrial areas was estimated using a top-down apportionment method. The national value of non-financial assets was apportioned to each sub-unit based on its population share, then converted to a value per square kilometer of built-up land. This value was projected forward using GDP growth rates and multiplied by the inundated built-up area to calculate damages (Marine Engineering Expert, 2025 ). The formula is: C = NFA × (P_(CU))/(P_(Total)) × (A_(Inundated))/(A_(BU)) × (1 + g)^t, where C is the damage cost, NFA is the national non-financial assets, (P_(CU))/(P_(Total)) is the population share of the coastal unit, A_(BU) is the total built-up area in the unit, A_(Inundated) is the inundated built-up area, and (1 + g)^t represents the future value projection based on GDP growth rate g over time t. Agricultural Land Loss : The cost of losing agricultural land was calculated as the sum of the direct market value of the inundated land and the associated cost of job losses. The direct land value is calculated as: C_land = A_agri × P_market, where C_land is the total damage cost to the land, A_agri is the area of inundated agricultural land (in feddans), and P_market is the average market price per feddan. Based on regional data, one job is lost for every two feddans inundated, with an associated replacement cost. The job loss cost is calculated as: C_job = (A_agri / 2) × I_job, where C_job is the total cost of lost employment, and I_job is the investment required to create a new job (L.E. 0.25 million) (Marine Engineering Expert, 2025 ). Population Displacement and Relocation Costs : The cost of relocating populations from inundated residential areas was estimated as a percentage (10–40%) of the total damage to non-financial assets, a methodology consistent with international climate impact literature (Marine Engineering Expert, 2025 ). The aggregate cost of inaction for each land management unit is the sum of these three components, providing a spatially explicit valuation of the risks to different land uses. 3. Results The analysis reveals a future of severe and spatially concentrated land use risk. The economic costs of inaction grow exponentially through the 21st century, with the most vital agricultural and urban land uses facing the greatest threat. 3.1 Spatial Distribution of Inundation and Land Use Risk The physical modeling shows a stark disparity in vulnerability across the coast. The western coast and North Sinai show relatively minimal land loss. The overwhelming majority of the risk is concentrated in the low-lying Nile Delta and the city of Alexandria (Fig. 3). Under the high-emissions SSP5-8.5 scenario, by 2100, vast areas of land are projected to be permanently inundated (Table 2 ). The coastal unit of Beheira (CU3-SUB1) faces over 571 km² of inundation, the area between Rosetta and Lake Burullus (CU3-SUB2) over 521 km², and the eastern delta around Lake Manzala (CU4-SUB3) faces a catastrophic loss of nearly 970 km² (Marine Engineering Expert, 2025 ). These are not marginal changes; they represent the permanent conversion of productive and populated land to open sea, fundamentally altering the land use map of northern Egypt. This concentration of risk in the nation's economic and agricultural heartland means that the national threat from SLR is a highly localized land use planning crisis. Table 2 Projected Inundated Area ( $ km^2 $ ) by Coastal Sub-Unit in 2100 under SSP5-8.5 Coastal Sub-Unit Description Inundated Area (km2) CU1-SUB1 El Saloum / East Sidi Barrani 18.13 CU1-SUB2 West Sidi Barrani 0.80 CU1-SUB3 Marsa Matrouh 1.60 CU1-SUB4 Almaz 1.60 CU1-SUB5 El Dabaa 0.57 CU1-SUB6 Alamein 1.14 CU2-SUB1 Alexandria Governorate 35.10 CU3-SUB1 West of Rosetta Mouth (Beheira) 571.81 CU3-SUB2 Rosetta Mouth to Lake Burullus 521.96 CU3-SUB3 East of Lake Burullus 622.38 CU4-SUB1 Dakahlia Governorate 21.74 CU4-SUB2 West Damietta Governorate 30.44 CU4-SUB3 East of Damietta Governorate 969.64 CU5-SUB1 Port Said Governorate 355.10 CU6-SUB1 West Coast of Sinai 222.97 CU6-SUB2 East Coast of Sinai (El Arish) 7.26 3.2 Economic Valuation of Land Use Losses When translated into economic terms, the loss of these critical land uses carries a staggering cost. The damage is overwhelmingly concentrated in the agricultural and urban/industrial land use categories (Fig. 4 ). Agricultural Land : The loss of prime agricultural land in the delta represents a direct threat to Egypt's food security. By 2100 (SSP5-8.5), the monetized damage to agriculture in the Beheira unit (CU3-SUB1) is projected to reach L.E. 258.8 billion. In the adjacent West Burullus unit (CU3-SUB2), losses are estimated at L.E. 254.4 billion. These figures represent a potential collapse of the agricultural economy in Egypt's most productive region (Marine Engineering Expert, 2025 ). Built-Up Land : The destruction of non-financial assets in urban and industrial zones carries an even higher price. The city of Alexandria (CU2-SUB1) faces projected damages to its built-up assets (including relocation costs) of L.E. 715.6 billion by 2100. The figures for the delta governorates are catastrophic: the Beheira unit (CU3-SUB1) faces L.E. 3.3 trillion in asset and relocation costs, while the West Burullus unit (CU3-SUB2) faces nearly L.E. 2.0 trillion in damages (Marine Engineering Expert, 2025 ). 3.3 Aggregate National Cost of Inaction Summing the damages across all land use types and sub-units reveals a national cost of inaction that is economically devastating (Table 3 ). By 2100, under the high-emissions scenario, the total cost for the Beheira unit (CU3-SUB1) exceeds L.E. 3.5 trillion, while the West Burullus unit (CU3-SUB2) faces costs of L.E. 2.25 trillion. The analysis also reveals a non-linear, exponential growth in damages over time. A critical inflection point occurs after 2070, where the rate of damage accelerates dramatically (Marine Engineering Expert, 2025 ). This indicates that the threat is not a gradual, linear problem for land use planners but a rapidly accelerating crisis that will become exponentially more costly with each decade of policy inaction. Table 3 Total Monetized Cost of Inaction (Billion L.E.) by Coastal Sub-Unit in 2100 under SSP5-8.5 Coastal Sub-Unit Description Damage to Agriculture (Billion L.E.) Damage to Assets & Relocation (Billion L.E.) Total Cost (Billion L.E.) CU1-SUB1 El Saloum / East Sidi Barrani 0.0 0.17 0.17 CU1-SUB2 West Sidi Barrani 0.0 0.0 0.0 CU1-SUB3 Marsa Matrouh 0.01 2.86 2.87 CU1-SUB4 Almaz 0.02 0.001 0.02 CU1-SUB5 El Dabaa 0.01 0.06 0.07 CU1-SUB6 Alamein 0.01 1.20 1.21 CU2-SUB1 Alexandria Governorate 15.0 715.65 730.65 CU3-SUB1 West of Rosetta Mouth (Beheira) 258.8 3,292.6 3,551.4 CU3-SUB2 Rosetta Mouth to Lake Burullus 254.4 1,997.1 2,251.5 CU3-SUB3 East of Lake Burullus 288.5 221.1 509.6 CU4-SUB1 Dakahlia Governorate 0.7 442.2 442.9 CU4-SUB2 West Damietta Governorate 4.9 969.0 973.9 CU4-SUB3 East of Damietta Governorate 190.4 1,786.5 1,976.9 CU5-SUB1 Port Said Governorate 3.4 1,428.4 1,431.8 CU6-SUB1 West Coast of Sinai 0.0 21.3 21.3 CU6-SUB2 East Coast of Sinai (El Arish) 0.0004 16.3 16.3 4. Discussion The results of this study present a stark picture of the consequences of maintaining the status quo in coastal land use policy and governance. The projected multi-trillion L.E. cost of inaction is not merely an economic figure; it represents a fundamental threat to Egypt's food security, urban stability, and national development, stemming directly from a misalignment between current land use patterns and future environmental realities. 4.1 Land Use Governance under Climatic Stress The findings underscore the inadequacy of current land use planning frameworks in the face of accelerating climate change. The intense concentration of high-value agricultural and urban land uses in the most physically vulnerable, low-lying areas of the delta represents a legacy of historical development patterns that are no longer sustainable. The "no-action" scenario is, in effect, a scenario of failed land use governance, where the inability to proactively guide development away from high-risk zones leads to catastrophic and largely unavoidable losses. This aligns with broader findings in the land use policy literature, which emphasize that effective climate adaptation requires integrated planning that can manage trade-offs between competing land uses and steer development toward resilience. Without such integration, Egypt risks continuing to "lock in" future damages by permitting new development in areas destined for inundation (Marine Engineering Expert, 2025 ). 4.2 The Economic Case for a New Land Use Policy Paradigm The sheer scale of the projected losses provides a powerful economic argument for a paradigm shift in coastal land management. The cost of inaction vastly exceeds any plausible cost of proactive adaptation, reframing adaptation not as a burden but as a high-return investment in preserving the nation's land-based wealth. International research consistently shows that it is more economically rational to invest in adaptation than to absorb the long-term costs of damages (Lincke & Hinkel, 2021 ; Hallegatte et al., 2013 ; Aerts, 2018 ). Indeed, recent analyses suggest adaptation investments can yield returns of $ 2 to $ 19 for every dollar invested (World Economic Forum, 2024 ). The non-linear escalation of costs identified in our results adds a critical temporal dimension to this argument: the window for cost-effective action is closing. Delaying policy interventions will make future adaptation exponentially more expensive and, in some cases, technically unfeasible. 4.3 Policy Trade-offs and Governance Challenges Transitioning to a climate-resilient land use policy will involve navigating complex trade-offs and significant governance challenges. Key among these is the conflict between protecting high-value urban and industrial land (often requiring costly hard engineering solutions) and preserving agricultural land and coastal ecosystems (which may benefit more from nature-based solutions) (Siddik and Islam, 2024 ). Hard structures like seawalls can protect specific assets but often exacerbate erosion and land loss in adjacent areas, creating new vulnerabilities and land use conflicts (Dario et al., 2024 ). Furthermore, implementing crucial but politically difficult policies like construction setbacks, managed retreat, and land use zoning in high-risk areas requires robust governance capacity and social acceptance (Swornamma et al., 2024 ). As research on other coastal communities has shown, residents often have deep connections to place, and relocation is not a desired option, highlighting the need for inclusive and participatory planning processes that respect local values and livelihoods. Recent studies have highlighted the environmental justice implications of managed retreat and the value of co-production approaches in navigating these complex social dynamics. Overcoming these barriers will require unprecedented coordination across government ministries, the development of new legal and regulatory instruments, and the mobilization of significant financial resources from both national and international sources (World Bank Group, 2022 ). 5. Conclusions and Policy Implications This study provides a quantitative, spatially explicit assessment of the economic consequences of policy inaction in the face of sea-level rise in Egypt's Nile Delta. The core conclusion is that maintaining the current trajectory of land use and coastal management is not a viable option. The "no-action" scenario leads to the permanent loss of critical agricultural and urban land, mass population displacement, and economic damages on a scale that would fundamentally undermine national stability and development. The findings present a clear and urgent case for a fundamental reorientation of land use policy and governance in the coastal zone. Based on this analysis, we propose the following policy implications: Integrate SLR Projections into National and Local Land Use Planning : The SLR projections used in this study must be formally adopted as a baseline for all spatial planning, infrastructure development, and land use permitting in the coastal zone. A national land use policy that explicitly accounts for future inundation risk is needed to prevent the creation of new, vulnerable assets and to guide development toward safer areas. This requires moving beyond static zoning to more dynamic planning frameworks that can adapt to changing environmental conditions. Prioritize Adaptation Investment in High-Risk, High-Value Land Use Zones : The spatial concentration of risk identified in this study allows for the strategic targeting of adaptation resources. Policy and investment should be prioritized for the most vulnerable and economically critical land use zones: the urban-industrial core of Alexandria and the agricultural heartland of the Beheira, Kafr El-Sheikh, Dakahlia, Damietta, and Port Said governorates. This provides a basis for a national-level, risk-based capital investment plan for coastal resilience. Develop a Hybrid Land Management Strategy Combining Hard, Soft, and Policy Interventions : A "one-size-fits-all" approach is unsuitable for the diverse land uses of the Egyptian coast. A hybrid strategy is required, tailored to local risk profiles. This should include: Hard Engineering Protection : For irreplaceable, high-value urban and industrial land uses, hard protection measures like seawalls and dikes will be necessary but must be designed to minimize negative downdrift impacts on other land uses (Dario et al., 2024 ). Nature-Based Solutions : For agricultural lands and ecologically sensitive areas, nature-based solutions like wetland restoration and dune nourishment should be prioritized as a form of land management that can reduce erosion, buffer storm surge, and provide valuable ecosystem co-benefits (Cotton et al., 2024 ). Policy and Governance Instruments : Coast-wide implementation of non-structural measures is essential. This includes the legal enforcement of coastal construction setbacks, the reform of land use planning to guide new development away from risk zones, and the development of early warning systems. Strengthen Governance and Financial Mechanisms for Adaptation : Implementing these strategies requires overcoming significant governance and financial barriers. This necessitates establishing clear institutional mandates for coastal adaptation, fostering inter-ministerial coordination, and creating dedicated financial vehicles, such as a National Coastal Resilience Fund, to mobilize the large-scale, long-term capital required for this generational challenge. In conclusion, the threat of sea-level rise to the Nile Delta is fundamentally a land use challenge. The choice is not between action and inaction, but between a managed, strategic adaptation of land use policy and an unmanaged, chaotic retreat. The evidence presented in this paper argues that the former is the only economically rational and socially responsible path forward. Declarations Clinical trial number: not applicable Availability of Data and Materials: All data generated or analyzed during this study are included in this published article. Ethical Approval and Accordance: Not applicable. Funding: No funding was received for this study. Competing Interests: The author declares no competing interests. Consent to Participate declaration: Not applicable. Consent to Publish declaration: Not applicable. Author Contribution T.O. is the sole author of this work. T.O. conceptualized the study, conducted the analysis, prepared all figures and tables, and wrote and reviewed the manuscript. References Abdrabo, M.A. and Hassaan, M.A., 2015. An integrated framework for urban resilience to climate change—case study: sea level rise impacts on the Nile Delta coastal urban areas. Urban Climate , 14, pp.554-565. Abdrabo, M.A., Hassaan, M.A., Abdelwahab, R.G. and Elbarky, T.A., 2023. Climate change associated hazards on cultural heritage in Egypt. 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Environmental Management , 70, pp.827–839. Additional Declarations No competing interests reported. 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. 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14:38:22","extension":"xml","order_by":45,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":100987,"visible":true,"origin":"","legend":"","description":"","filename":"a20592290afb40d3b9e343d7658e757a1structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-7934389/v1/fee3f22f2e92de9bcb3e8042.xml"},{"id":96641119,"identity":"804891a1-f588-47db-a92e-ded1e34e99c0","added_by":"auto","created_at":"2025-11-24 14:38:22","extension":"html","order_by":46,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":113531,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7934389/v1/a0c3fd9a1b09d0551c5769f9.html"},{"id":96641071,"identity":"fb8e43b7-8697-40c1-94dc-1d8187e59dbe","added_by":"auto","created_at":"2025-11-24 14:38:19","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":66912,"visible":true,"origin":"","legend":"\u003cp\u003ethe Research Methodology\u003c/p\u003e","description":"","filename":"1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7934389/v1/e2d2fa5a721dac39a74cee83.jpg"},{"id":96641083,"identity":"ca57d516-2e55-4d55-afe4-beec0b888c73","added_by":"auto","created_at":"2025-11-24 14:38:20","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":155349,"visible":true,"origin":"","legend":"\u003cp\u003eThe study area (coastal units)\u003c/p\u003e","description":"","filename":"2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7934389/v1/075eda9a0987d02d06946291.jpg"},{"id":96641088,"identity":"d8ab9c68-b477-4482-b713-b400671742bd","added_by":"auto","created_at":"2025-11-24 14:38:20","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":272678,"visible":true,"origin":"","legend":"\u003cp\u003eProjected Inundated Area (km2) by Coastal Sub-Unit in 2100 under SSP5-8.5\u003c/p\u003e","description":"","filename":"3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7934389/v1/126c4799f55adb5201a82367.jpg"},{"id":96641096,"identity":"ed1a9750-5f82-4648-b62d-0f947d759f63","added_by":"auto","created_at":"2025-11-24 14:38:21","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":296255,"visible":true,"origin":"","legend":"\u003cp\u003eLand use/ land cover by Coastal Sub-Unit\u003c/p\u003e","description":"","filename":"4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7934389/v1/e38aa9a3fd1ca93580dff387.jpg"},{"id":98774947,"identity":"1daf11db-f19d-45d2-8007-ea0d2f460fd6","added_by":"auto","created_at":"2025-12-22 12:17:24","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1894570,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7934389/v1/6ea68bc5-e7a5-468a-87ab-d914012f052f.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Land Use Policy at a Climatic Crossroads: Valuing the Cost of Sea-Level Rise Inaction in Egypt’s Nile Delta","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eEgypt's Mediterranean coast, particularly the Nile Delta, represents a complex and vital landscape where intense agricultural, urban, and industrial land uses converge. This region, while constituting only a fraction of the nation's territory, is the backbone of its economy and food security, hosting 43.5% of the population and generating an estimated 60.8% of its economic output (Marine Engineering Expert, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). The delta's fertile lands account for 63% of Egypt's agricultural area (Hereher, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2015\u003c/span\u003e), while its coastal cities, including the industrial hub of Alexandria, are centers of commerce and development.\u003csup\u003e1\u003c/sup\u003e This concentration of population and high-value land uses makes the region a focal point for national development policy, but also a zone of extreme vulnerability to climate change.\u003c/p\u003e\u003cp\u003eThe governance of coastal land is a critical challenge worldwide, as administrations seek to balance economic development with environmental protection and risk management.\u003csup\u003e2\u003c/sup\u003e In low-lying deltaic regions, this challenge is amplified by the threat of sea-level rise (SLR), which threatens to permanently alter land cover and render existing land use patterns untenable.\u003csup\u003e3\u003c/sup\u003e The Nile Delta is a global hotspot for this risk, facing a \"compound effect\" of eustatic SLR, land subsidence, and a severe sediment deficit following the construction of the Aswan High Dam (Marine Engineering Expert, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2025\u003c/span\u003e; Frihy, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e1992\u003c/span\u003e). This convergence of pressures creates a scenario where the very land upon which the national economy is built is progressively being lost, posing a fundamental challenge to land use policy and spatial planning.\u003c/p\u003e\u003cp\u003eTo inform effective policy, it is crucial to establish an analytical baseline against which the benefits of adaptation can be measured. The \"no-action\" or \"cost of inaction\" scenario serves this purpose, providing a quantitative assessment of the damages that would occur if current land management and protection policies are not augmented to address future climate risk (Marine Engineering Expert, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). This approach frames adaptation not as a discretionary expense, but as a necessary investment in preserving the value of existing land uses and securing future development pathways (Seregina et al., \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Lincke \u0026amp; Hinkel, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). The economic rationale is clear: climate inaction is projected to be far more costly than proactive investment in adaptation and mitigation (World Economic Forum, \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2024\u003c/span\u003e).\u003csup\u003e4\u003c/sup\u003e\u003c/p\u003e\u003cp\u003eThe vulnerability of the Nile Delta is well-documented, with studies consistently highlighting the potential for widespread inundation, population displacement, and economic disruption (Dasgupta et al., \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2007\u003c/span\u003e; Abdrabo et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). However, a critical gap exists in translating these broad warnings into spatially explicit, monetized data that can directly inform land use policy and governance. As noted in the literature, effective adaptation requires a localized approach, as generic, large-scale programs often fail to address the specific needs of diverse communities and landscapes.\u003csup\u003e5\u003c/sup\u003e Without a granular understanding of where and when economic damages will occur, policymakers lack the evidence base needed to prioritize investments, reform zoning regulations, and guide future development toward more resilient locations. Recent scholarship in \u003cem\u003eLand Use Policy\u003c/em\u003e emphasizes that land use planning is a central enabler of coastal climate change adaptation, but its success depends on balancing competing interests and navigating complex political and legal realities.\u003csup\u003e8\u003c/sup\u003e\u003c/p\u003e\u003cp\u003eThis paper addresses this gap by providing a comprehensive, sub-nationally disaggregated spatio-economic assessment of the no-action scenario for Egypt's Mediterranean coast. By quantifying the future costs of inundation across 16 distinct land management units, our research moves beyond general vulnerability assessments to offer a direct, policy-relevant analysis of the land use implications of SLR. The objective is to provide a robust, data-driven foundation for reforming coastal land use policy, demonstrating the economic imperative of proactive spatial planning and adaptation governance in one of the world's most critical and vulnerable deltaic systems.\u003c/p\u003e"},{"header":"2. Materials and Methods","content":"\u003cp\u003eThe methodology (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) is an integrated assessment framework designed to translate the physical hazard of SLR into policy-relevant economic metrics of land use vulnerability. The process links a physical inundation model with a socioeconomic valuation model, allowing for a spatially disaggregated analysis of potential damages.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003e2.1 Physical Inundation Modeling\u003c/h2\u003e\u003cp\u003eThe physical analysis is grounded in high-resolution spatial data to accurately map the interface of land and sea under future climate scenarios.\u003c/p\u003e\u003cp\u003e\u003cb\u003eData and Scenarios\u003c/b\u003e: The primary dataset is a 5-meter resolution Digital Elevation Model (DEM) with a 1-centimeter vertical accuracy, providing a detailed topographic representation of the coastal zone (Marine Engineering Expert, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). This high-resolution data is essential for accurately modeling inundation in a low-lying deltaic environment. Sea-level projections are drawn from the IPCC's Sixth Assessment Report (AR6), using two Shared Socioeconomic Pathways: SSP2-4.5 (a medium emissions scenario) and SSP5-8.5 (a high-emissions, \"worst-case\" scenario) to capture a range of plausible futures (Marine Engineering Expert, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2025\u003c/span\u003e) in the study area (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eThe 'Bathtub' Model\u003c/b\u003e: A passive \"bathtub\" inundation model was employed to map the extent of permanent land loss. This approach identifies all land areas that are both at and below a projected sea level and hydrologically connected to the sea (Marine Engineering Expert, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). The process is formalized as: I(x, y) = {1, if D(x, y)\u0026thinsp;\u0026le;\u0026thinsp;W(x, y); 0, if D(x, y)\u0026thinsp;\u0026gt;\u0026thinsp;W(x, y)}, where:\u003c/p\u003e\u003cp\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003e\u003cem\u003eI(x, y)\u003c/em\u003e is a binary inundation indicator equal to \u003cb\u003e1\u003c/b\u003e if the land at location \u003cem\u003e(x, y)\u003c/em\u003e is inundated, and \u003cb\u003e0\u003c/b\u003e otherwise.\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003e\u003cem\u003eD(x, y)\u003c/em\u003e represents the \u003cb\u003eDigital Elevation Model (DEM)\u003c/b\u003e elevation value (in meters above mean sea level).\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003e\u003cem\u003eW(x, y)\u003c/em\u003e denotes the \u003cb\u003eprojected water level\u003c/b\u003e (e.g., sea-level rise or storm surge elevation) at the same location.\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003c/p\u003e\u003cp\u003eWhile this static model does not account for dynamic processes like storm surges, it provides a robust and conservative baseline for assessing permanent changes in land cover due to SLR, a critical input for long-term land use planning.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\u003ch2\u003e2.2 Socioeconomic Valuation\u003c/h2\u003e\u003cp\u003eThe economic valuation component overlays the inundation maps onto detailed land use and socioeconomic datasets to monetize the projected damages for each of the 16 coastal sub-units.\u003c/p\u003e\u003cp\u003e\u003cb\u003e2.2.1 Baseline Data\u003c/b\u003e: A comprehensive socioeconomic profile was compiled for each sub-unit, including population, GDP, and Land Use/Land Cover (LULC) maps classifying the area into built-up, agricultural, wetland/aquaculture, and bare land categories (Marine Engineering Expert, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). The key data sources are summarized in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eKey Data Sources for Integrated Assessment\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"3\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eData Type\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSource\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eUse in Analysis\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCoastal Topography\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e5-meter Digital Elevation Model (DEM) with 1cm RMSE from the Egyptian Marine Survey Division (Marine Engineering Expert, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2025\u003c/span\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eInundation modeling ('bathtub' approach) to determine the spatial extent of land loss.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSea-Level Rise Projections\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eIntergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report (AR6) (Marine Engineering Expert, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2025\u003c/span\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eDefining future inundation levels for SSP2-4.5 and SSP5-8.5 scenarios across multiple time horizons.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNational Non-Financial Assets\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCredit Suisse Global Wealth Databook (Credit Suisse Research Institute, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2022\u003c/span\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eEstablishing the national capital stock for valuation of built-up assets.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePopulation Data\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCentral Agency for Public Mobilization and Statistics (CAPMAS) (CAPMAS, 2024)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eApportioning national asset value to sub-national units; estimating population displacement.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGross Domestic Product (GDP) Data\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMinistry of Planning and Economic Development (MPED) (MPED, 2024)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eProjecting future asset values; apportioning economic value to sub-national units.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLand Use/Land Cover (LULC)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSatellite Imagery Analysis (Marine Engineering Expert, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2025\u003c/span\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eClassifying inundated areas (e.g., built-up, agricultural) for sectoral damage assessment.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAgricultural Land Value\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eRegional Market Data (Marine Engineering Expert, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2025\u003c/span\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eValuing direct loss of inundated agricultural land based on market prices per feddan.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAgricultural Employment Metrics\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eRegional Economic Data (e.g., 1 job per 2 feddans) (Gad EL Rab, 2008)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eEstimating job loss costs resulting from the inundation of agricultural land.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eJob Creation Cost\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNational Economic Data (L.E. 0.25\u0026nbsp;million/job) (Gad EL Rab, 2008)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eMonetizing the cost of agricultural job losses.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eRelocation Cost Methodology\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eInternational Climate Impact Literature (Depsky et al., \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2023\u003c/span\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eEstimating societal costs of population displacement as a percentage (10\u0026ndash;40%) of asset damage.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cdiv id=\"Sec5\" class=\"Section3\"\u003e\u003ch2\u003e2.2.2 Valuation of Land Use Impacts:\u003c/h2\u003e\u003cp\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003e\u003cb\u003eDamage to Non-Financial Assets (Built-up Land)\u003c/b\u003e: The value of damage to urban and industrial areas was estimated using a top-down apportionment method. The national value of non-financial assets was apportioned to each sub-unit based on its population share, then converted to a value per square kilometer of built-up land. This value was projected forward using GDP growth rates and multiplied by the inundated built-up area to calculate damages (Marine Engineering Expert, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). The formula is: C\u0026thinsp;=\u0026thinsp;NFA \u0026times; (P_(CU))/(P_(Total)) \u0026times; (A_(Inundated))/(A_(BU)) \u0026times; (1\u0026thinsp;+\u0026thinsp;g)^t, where C is the damage cost, NFA is the national non-financial assets, (P_(CU))/(P_(Total)) is the population share of the coastal unit, A_(BU) is the total built-up area in the unit, A_(Inundated) is the inundated built-up area, and (1\u0026thinsp;+\u0026thinsp;g)^t represents the future value projection based on GDP growth rate g over time t.\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003e\u003cb\u003eAgricultural Land Loss\u003c/b\u003e: The cost of losing agricultural land was calculated as the sum of the direct market value of the inundated land and the associated cost of job losses. The direct land value is calculated as: C_land\u0026thinsp;=\u0026thinsp;A_agri \u0026times; P_market, where C_land is the total damage cost to the land, A_agri is the area of inundated agricultural land (in feddans), and P_market is the average market price per feddan. Based on regional data, one job is lost for every two feddans inundated, with an associated replacement cost. The job loss cost is calculated as: C_job = (A_agri / 2) \u0026times; I_job, where C_job is the total cost of lost employment, and I_job is the investment required to create a new job (L.E. 0.25\u0026nbsp;million) (Marine Engineering Expert, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2025\u003c/span\u003e).\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003e\u003cb\u003ePopulation Displacement and Relocation Costs\u003c/b\u003e: The cost of relocating populations from inundated residential areas was estimated as a percentage (10\u0026ndash;40%) of the total damage to non-financial assets, a methodology consistent with international climate impact literature (Marine Engineering Expert, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2025\u003c/span\u003e).\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003c/p\u003e\u003cp\u003eThe aggregate cost of inaction for each land management unit is the sum of these three components, providing a spatially explicit valuation of the risks to different land uses.\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e"},{"header":"3. Results","content":"\u003cp\u003eThe analysis reveals a future of severe and spatially concentrated land use risk. The economic costs of inaction grow exponentially through the 21st century, with the most vital agricultural and urban land uses facing the greatest threat.\u003c/p\u003e\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\u003ch2\u003e3.1 Spatial Distribution of Inundation and Land Use Risk\u003c/h2\u003e\u003cp\u003eThe physical modeling shows a stark disparity in vulnerability across the coast. The western coast and North Sinai show relatively minimal land loss. The overwhelming majority of the risk is concentrated in the low-lying Nile Delta and the city of Alexandria (Fig.\u0026nbsp;3). Under the high-emissions SSP5-8.5 scenario, by 2100, vast areas of land are projected to be permanently inundated (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). The coastal unit of Beheira (CU3-SUB1) faces over 571 km\u0026sup2; of inundation, the area between Rosetta and Lake Burullus (CU3-SUB2) over 521 km\u0026sup2;, and the eastern delta around Lake Manzala (CU4-SUB3) faces a catastrophic loss of nearly 970 km\u0026sup2; (Marine Engineering Expert, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). These are not marginal changes; they represent the permanent conversion of productive and populated land to open sea, fundamentally altering the land use map of northern Egypt. This concentration of risk in the nation's economic and agricultural heartland means that the national threat from SLR is a highly localized land use planning crisis.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eProjected Inundated Area (\u003cspan\u003e$\u003c/span\u003ekm^2\u003cspan\u003e$\u003c/span\u003e) by Coastal Sub-Unit in 2100 under SSP5-8.5\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"3\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCoastal Sub-Unit\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDescription\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eInundated Area (km2)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCU1-SUB1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eEl Saloum / East Sidi Barrani\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e18.13\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCU1-SUB2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eWest Sidi Barrani\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.80\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCU1-SUB3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMarsa Matrouh\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1.60\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCU1-SUB4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAlmaz\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1.60\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCU1-SUB5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eEl Dabaa\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.57\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCU1-SUB6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAlamein\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1.14\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCU2-SUB1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAlexandria Governorate\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e35.10\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCU3-SUB1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eWest of Rosetta Mouth (Beheira)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e571.81\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCU3-SUB2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eRosetta Mouth to Lake Burullus\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e521.96\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCU3-SUB3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eEast of Lake Burullus\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e622.38\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCU4-SUB1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDakahlia Governorate\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e21.74\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCU4-SUB2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eWest Damietta Governorate\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e30.44\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCU4-SUB3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eEast of Damietta Governorate\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e969.64\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCU5-SUB1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePort Said Governorate\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e355.10\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCU6-SUB1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eWest Coast of Sinai\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e222.97\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCU6-SUB2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eEast Coast of Sinai (El Arish)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e7.26\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003e3.2 Economic Valuation of Land Use Losses\u003c/h2\u003e\u003cp\u003eWhen translated into economic terms, the loss of these critical land uses carries a staggering cost. The damage is overwhelmingly concentrated in the agricultural and urban/industrial land use categories (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003e\u003cb\u003eAgricultural Land\u003c/b\u003e: The loss of prime agricultural land in the delta represents a direct threat to Egypt's food security. By 2100 (SSP5-8.5), the monetized damage to agriculture in the Beheira unit (CU3-SUB1) is projected to reach L.E. 258.8\u0026nbsp;billion. In the adjacent West Burullus unit (CU3-SUB2), losses are estimated at L.E. 254.4\u0026nbsp;billion. These figures represent a potential collapse of the agricultural economy in Egypt's most productive region (Marine Engineering Expert, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2025\u003c/span\u003e).\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003e\u003cb\u003eBuilt-Up Land\u003c/b\u003e: The destruction of non-financial assets in urban and industrial zones carries an even higher price. The city of Alexandria (CU2-SUB1) faces projected damages to its built-up assets (including relocation costs) of L.E. 715.6\u0026nbsp;billion by 2100. The figures for the delta governorates are catastrophic: the Beheira unit (CU3-SUB1) faces L.E. 3.3 trillion in asset and relocation costs, while the West Burullus unit (CU3-SUB2) faces nearly L.E. 2.0 trillion in damages (Marine Engineering Expert, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2025\u003c/span\u003e).\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e\u003ch2\u003e3.3 Aggregate National Cost of Inaction\u003c/h2\u003e\u003cp\u003eSumming the damages across all land use types and sub-units reveals a national cost of inaction that is economically devastating (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). By 2100, under the high-emissions scenario, the total cost for the Beheira unit (CU3-SUB1) exceeds L.E. 3.5 trillion, while the West Burullus unit (CU3-SUB2) faces costs of L.E. 2.25 trillion. The analysis also reveals a non-linear, exponential growth in damages over time. A critical inflection point occurs after 2070, where the rate of damage accelerates dramatically (Marine Engineering Expert, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). This indicates that the threat is not a gradual, linear problem for land use planners but a rapidly accelerating crisis that will become exponentially more costly with each decade of policy inaction.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eTotal Monetized Cost of Inaction (Billion L.E.) by Coastal Sub-Unit in 2100 under SSP5-8.5\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"5\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCoastal Sub-Unit\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDescription\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eDamage to Agriculture (Billion L.E.)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eDamage to Assets \u0026amp; Relocation (Billion L.E.)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eTotal Cost (Billion L.E.)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCU1-SUB1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eEl Saloum / East Sidi Barrani\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.17\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.17\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCU1-SUB2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eWest Sidi Barrani\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.0\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCU1-SUB3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMarsa Matrouh\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.01\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e2.86\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e2.87\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCU1-SUB4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAlmaz\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.02\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.001\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.02\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCU1-SUB5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eEl Dabaa\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.01\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.06\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.07\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCU1-SUB6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAlamein\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.01\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e1.20\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e1.21\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCU2-SUB1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAlexandria Governorate\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e15.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e715.65\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e730.65\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCU3-SUB1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eWest of Rosetta Mouth (Beheira)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e258.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e3,292.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e3,551.4\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCU3-SUB2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eRosetta Mouth to Lake Burullus\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e254.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e1,997.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e2,251.5\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCU3-SUB3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eEast of Lake Burullus\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e288.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e221.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e509.6\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCU4-SUB1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDakahlia Governorate\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e442.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e442.9\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCU4-SUB2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eWest Damietta Governorate\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e4.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e969.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e973.9\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCU4-SUB3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eEast of Damietta Governorate\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e190.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e1,786.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e1,976.9\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCU5-SUB1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePort Said Governorate\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e3.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e1,428.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e1,431.8\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCU6-SUB1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eWest Coast of Sinai\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e21.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e21.3\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCU6-SUB2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eEast Coast of Sinai (El Arish)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.0004\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e16.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e16.3\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e"},{"header":"4. Discussion","content":"\u003cp\u003eThe results of this study present a stark picture of the consequences of maintaining the status quo in coastal land use policy and governance. The projected multi-trillion L.E. cost of inaction is not merely an economic figure; it represents a fundamental threat to Egypt's food security, urban stability, and national development, stemming directly from a misalignment between current land use patterns and future environmental realities.\u003c/p\u003e\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003e4.1 Land Use Governance under Climatic Stress\u003c/h2\u003e\u003cp\u003eThe findings underscore the inadequacy of current land use planning frameworks in the face of accelerating climate change. The intense concentration of high-value agricultural and urban land uses in the most physically vulnerable, low-lying areas of the delta represents a legacy of historical development patterns that are no longer sustainable. The \"no-action\" scenario is, in effect, a scenario of failed land use governance, where the inability to proactively guide development away from high-risk zones leads to catastrophic and largely unavoidable losses. This aligns with broader findings in the land use policy literature, which emphasize that effective climate adaptation requires integrated planning that can manage trade-offs between competing land uses and steer development toward resilience. Without such integration, Egypt risks continuing to \"lock in\" future damages by permitting new development in areas destined for inundation (Marine Engineering Expert, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2025\u003c/span\u003e).\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\u003ch2\u003e4.2 The Economic Case for a New Land Use Policy Paradigm\u003c/h2\u003e\u003cp\u003eThe sheer scale of the projected losses provides a powerful economic argument for a paradigm shift in coastal land management. The cost of inaction vastly exceeds any plausible cost of proactive adaptation, reframing adaptation not as a burden but as a high-return investment in preserving the nation's land-based wealth. International research consistently shows that it is more economically rational to invest in adaptation than to absorb the long-term costs of damages (Lincke \u0026amp; Hinkel, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Hallegatte et al., \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Aerts, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). Indeed, recent analyses suggest adaptation investments can yield returns of \u003cspan\u003e$\u003c/span\u003e2 to \u003cspan\u003e$\u003c/span\u003e19 for every dollar invested (World Economic Forum, \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). The non-linear escalation of costs identified in our results adds a critical temporal dimension to this argument: the window for cost-effective action is closing. Delaying policy interventions will make future adaptation exponentially more expensive and, in some cases, technically unfeasible.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\u003ch2\u003e4.3 Policy Trade-offs and Governance Challenges\u003c/h2\u003e\u003cp\u003eTransitioning to a climate-resilient land use policy will involve navigating complex trade-offs and significant governance challenges. Key among these is the conflict between protecting high-value urban and industrial land (often requiring costly hard engineering solutions) and preserving agricultural land and coastal ecosystems (which may benefit more from nature-based solutions) (Siddik and Islam, \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). Hard structures like seawalls can protect specific assets but often exacerbate erosion and land loss in adjacent areas, creating new vulnerabilities and land use conflicts (Dario et al., \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2024\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eFurthermore, implementing crucial but politically difficult policies like construction setbacks, managed retreat, and land use zoning in high-risk areas requires robust governance capacity and social acceptance (Swornamma et al., \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). As research on other coastal communities has shown, residents often have deep connections to place, and relocation is not a desired option, highlighting the need for inclusive and participatory planning processes that respect local values and livelihoods. Recent studies have highlighted the environmental justice implications of managed retreat and the value of co-production approaches in navigating these complex social dynamics. Overcoming these barriers will require unprecedented coordination across government ministries, the development of new legal and regulatory instruments, and the mobilization of significant financial resources from both national and international sources (World Bank Group, \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2022\u003c/span\u003e).\u003c/p\u003e\u003c/div\u003e"},{"header":"5. Conclusions and Policy Implications","content":"\u003cp\u003eThis study provides a quantitative, spatially explicit assessment of the economic consequences of policy inaction in the face of sea-level rise in Egypt's Nile Delta. The core conclusion is that maintaining the current trajectory of land use and coastal management is not a viable option. The \"no-action\" scenario leads to the permanent loss of critical agricultural and urban land, mass population displacement, and economic damages on a scale that would fundamentally undermine national stability and development. The findings present a clear and urgent case for a fundamental reorientation of land use policy and governance in the coastal zone.\u003c/p\u003e\u003cp\u003eBased on this analysis, we propose the following policy implications:\u003c/p\u003e\u003cp\u003e\u003col\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003e\u003cb\u003eIntegrate SLR Projections into National and Local Land Use Planning\u003c/b\u003e: The SLR projections used in this study must be formally adopted as a baseline for all spatial planning, infrastructure development, and land use permitting in the coastal zone. A national land use policy that explicitly accounts for future inundation risk is needed to prevent the creation of new, vulnerable assets and to guide development toward safer areas. This requires moving beyond static zoning to more dynamic planning frameworks that can adapt to changing environmental conditions.\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003e\u003cb\u003ePrioritize Adaptation Investment in High-Risk, High-Value Land Use Zones\u003c/b\u003e: The spatial concentration of risk identified in this study allows for the strategic targeting of adaptation resources. Policy and investment should be prioritized for the most vulnerable and economically critical land use zones: the urban-industrial core of Alexandria and the agricultural heartland of the Beheira, Kafr El-Sheikh, Dakahlia, Damietta, and Port Said governorates. This provides a basis for a national-level, risk-based capital investment plan for coastal resilience.\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003e\u003cb\u003eDevelop a Hybrid Land Management Strategy Combining Hard, Soft, and Policy Interventions\u003c/b\u003e: A \"one-size-fits-all\" approach is unsuitable for the diverse land uses of the Egyptian coast. A hybrid strategy is required, tailored to local risk profiles. This should include:\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003c/ol\u003e\u003c/p\u003e\u003cp\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003e\u003cb\u003eHard Engineering Protection\u003c/b\u003e: For irreplaceable, high-value urban and industrial land uses, hard protection measures like seawalls and dikes will be necessary but must be designed to minimize negative downdrift impacts on other land uses (Dario et al., \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2024\u003c/span\u003e).\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003e\u003cb\u003eNature-Based Solutions\u003c/b\u003e: For agricultural lands and ecologically sensitive areas, nature-based solutions like wetland restoration and dune nourishment should be prioritized as a form of land management that can reduce erosion, buffer storm surge, and provide valuable ecosystem co-benefits (Cotton et al., \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2024\u003c/span\u003e).\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003e\u003cb\u003ePolicy and Governance Instruments\u003c/b\u003e: Coast-wide implementation of non-structural measures is essential. This includes the legal enforcement of coastal construction setbacks, the reform of land use planning to guide new development away from risk zones, and the development of early warning systems.\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003c/p\u003e\u003cp\u003e\u003col start=\"4\"\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003e\u003cb\u003eStrengthen Governance and Financial Mechanisms for Adaptation\u003c/b\u003e: Implementing these strategies requires overcoming significant governance and financial barriers. This necessitates establishing clear institutional mandates for coastal adaptation, fostering inter-ministerial coordination, and creating dedicated financial vehicles, such as a National Coastal Resilience Fund, to mobilize the large-scale, long-term capital required for this generational challenge.\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003c/ol\u003e\u003c/p\u003e\u003cp\u003eIn conclusion, the threat of sea-level rise to the Nile Delta is fundamentally a land use challenge. The choice is not between action and inaction, but between a managed, strategic adaptation of land use policy and an unmanaged, chaotic retreat. The evidence presented in this paper argues that the former is the only economically rational and socially responsible path forward.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cul type=\"disc\"\u003e\n \u003cli\u003e\u003cstrong\u003eClinical trial number:\u0026nbsp;\u003c/strong\u003enot applicable\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eAvailability of Data and Materials:\u003c/strong\u003e All data generated or analyzed during this study are included in this published article.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eEthical Approval and Accordance:\u0026nbsp;\u003c/strong\u003eNot applicable.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eFunding:\u003c/strong\u003e No funding was received for this study.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eCompeting Interests:\u003c/strong\u003e The author declares no competing interests.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eConsent to Participate declaration:\u003c/strong\u003e Not applicable.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eConsent to Publish declaration:\u003c/strong\u003e Not applicable.\u003c/li\u003e\n\u003c/ul\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eT.O. is the sole author of this work. T.O. conceptualized the study, conducted the analysis, prepared all figures and tables, and wrote and reviewed the manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eAbdrabo, M.A. and Hassaan, M.A., 2015. An integrated framework for urban resilience to climate change\u0026mdash;case study: sea level rise impacts on the Nile Delta coastal urban areas. \u003cem\u003eUrban Climate\u003c/em\u003e, 14, pp.554-565.\u003c/li\u003e\n\u003cli\u003eAbdrabo, M.A., Hassaan, M.A., Abdelwahab, R.G. and Elbarky, T.A., 2023. Climate change associated hazards on cultural heritage in Egypt. \u003cem\u003eArchaeological Prospection\u003c/em\u003e, 30(3), pp.465-476.\u003c/li\u003e\n\u003cli\u003eAdger, W.N., Lorenzoni, I. and O\u0026apos;brien, K.L. eds., 2009. \u003cem\u003eAdapting to climate change: thresholds, values, governance\u003c/em\u003e. Cambridge university press.\u003c/li\u003e\n\u003cli\u003eAerts, J.C.J.H., 2018. 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Coastal Land Use Management Methodologies Under Pressure From Climate Change And Population Growth. \u003cem\u003eEnvironmental Management\u003c/em\u003e, 70, pp.827\u0026ndash;839.\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":"Land Use Policy, Climate Adaptation, Sea-Level Rise, Coastal Governance, Spatial Planning, Cost of Inaction, Nile Delta, Egypt","lastPublishedDoi":"10.21203/rs.3.rs-7934389/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7934389/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe Nile Delta, a critical nexus of agricultural, urban, and industrial land uses, faces profound risks from sea-level rise (SLR) that challenge Egypt's national land use policy and coastal governance frameworks. This paper provides a spatially explicit economic assessment of a \"no-action\" policy scenario, quantifying the consequences of failing to implement adaptive land management. Using a high-resolution Digital Elevation Model and a 'bathtub' inundation model under IPCC SSP2-4.5 and SSP5-8.5 scenarios, we project the inundation of different land use types. These physical impact models are integrated with sub-national socioeconomic data to value the loss of agricultural land, damage to built-up assets, and the costs of population displacement across 16 coastal land management units. Our findings reveal catastrophic economic consequences of policy inaction, with projected damages reaching multi-trillion Egyptian pounds (L.E.) by 2100. The spatial analysis highlights a severe concentration of risk in the low-lying governorates of the Nile Delta and the megacity of Alexandria, indicating that current land use patterns are misaligned with future climate realities. The non-linear escalation of costs underscores a rapidly closing window for proactive spatial planning and cost-effective adaptation. We conclude that the economic costs of inaction\u0026mdash;representing a failure of anticipatory land use governance\u0026mdash;vastly exceed the investment required for adaptive measures. This study provides a data-driven rationale for integrating SLR projections into all levels of land use planning, from national strategy to local permitting, to secure Egypt's economic base, food security, and social stability.\u003c/p\u003e","manuscriptTitle":"Land Use Policy at a Climatic Crossroads: Valuing the Cost of Sea-Level Rise Inaction in Egypt’s Nile Delta","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-11-24 14:38:12","doi":"10.21203/rs.3.rs-7934389/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":"d93f97ca-ce4c-40f5-a26c-814074ff70a2","owner":[],"postedDate":"November 24th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-12-11T08:24:38+00:00","versionOfRecord":[],"versionCreatedAt":"2025-11-24 14:38:12","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7934389","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7934389","identity":"rs-7934389","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}