Intensified water resources conflict will be alleviated in future in China's Loess Plateau

Intensified water resources conflict will be alleviated in future in China's Loess Plateau | 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 Intensified water resources conflict will be alleviated in future in China's Loess Plateau Ning Zhu, Jianzhong Lu, Liang Zheng, Piaoyin Zhang, Xiaoling Chen This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6551603/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 Located in arid and semi-arid region, water is always the most essential recourse for China’s Loess Plateau (LP), a region that supports tens of millions of people. In the recent 30 years, with the ecological restoration, the land cover has greatly changed in this region, vegetation coverage increased evidently. When rain falls to the ground, it is first absorbed by vegetation and then turns into runoff. As a matter of fact, runoffs on Loess Plateau are decreasing distinctly, while the evaporation represents a rising trend, which further intensifies the conflict between people and ecosystem. Here, we estimated the potential water conflict after revegetation on LP, three key areas of water use conflict are analyzed. Then, we also predict the water sustainability of Loess Plateau under climate change in 2021-2100. (1) Vegetation growth has led to a decrease in water resource on the Loess Plateau; (2) the available water resources in the Loess Plateau has been really close to its limit in 2020, especially in the central and northern Shanxi Province, the northern Shaanxi Plateau and the surrounding areas of Liupan Mountain, water shortage has already emerged; (3) as the regional climate is becoming warmer and wetter, we estimate that the water resource conflict situation in the Loess Plateau will be eased in the future(2021-2100). These findings alert that although revegetation has provided many benefits, it has caused perceptible conflicts between water use of ecosystem and human society. Our results provided some perspectives on future water management. Water conflict Vegetation carrying capacity Ecological restoration Climate change Sustainable development Loess Plateau Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Highlights Vegetation greening has intensified water resources conflict in the LP. Water resources conflict was quantified from the perspective of regional water balance. Water resources conflict will be alleviated in future (2021-2100) in the LP. Introduction In the recent 30 years, human activities had greatly changed the land cover on Loess Plateau (Zhai et al., 2015), including ecological restoration (ER), urban expansion and reclamation of cultivated land, especially ecological restoration (Feng et al., 2016). The vegetation restoration named The Grain to Green Project (GTGP), was raised by Chinese government from the end of 20th century, aiming to reduce soil erosion and restore the living environment damaged by deforestation (Deng et al., 2014). It has been one of the largest ecological restoration project implemented in the world (Wang et al., 2016; McVicar et al., 2010), changed ~3195 km 2 of cultivated-land to non-native vegetation, caused an overall 16.8% increase in vegetation coverage on Loess Plateau in last twenty years, it has made remarkable achievements in both environment, society and economy (Li et al., 2021; Wu et al., 2019). The newly planted vegetation stabilized the fragile soils on the surface, greatly reduced soil erosion (Ran et al., 2013; Wang et al., 2016), as well as enhancing carbon sequestration (Fu et al., 2011), supplying biofuel (Menz et al., 2013) and improving living environment (Jia et al., 2017; Liu et al., 2008). However, there are also some potential problems that shouldn’t be ignored, which is the newly planted vegetation will grab water from the existing ecosystems and human society (Jackson et al., 2005) while they all rely on limited precipitation. Water balance in this region will be further changed by the increasing rainfall interception and actual evapotranspiration (E) (Zhang et al., 2014). Runoffs within Loess Plateau has already presented an apparent downtrend in the last two decades (Liu et al., 2012; Liu et al., 2010), raising people’s concern on whether the water needed by ecosystems and humans will be long-termly sustainable in such a vulnerable and water-scarce environment (Zhan et al., 2014; Liang et al., 2015). Therefore, in our research, water use conflict in Loess Plateau is quantitatively assessed under the present and future scenarios. A number of literatures have focused on the growing indication of water scarcity on LP. Liang et al. (2015a) revealed the decreasing trend in streamflow of 22 catchments on Loess Plateau. Zheng et al. (2019) found water yield in over 100 hydrological stations was reduced by 22%. Jia et al. (2017) found that soil moisture declined due to afforestation across the Loess Plateau. Most of the studies have linked this phenomenon with the ecological restoration (ER) project taken in recent years and found that vegetation restoration has gradually approached the limit of carrying capacity. Liang et al. (2015b) found that ER measures have been playing a dominant role (68%) in the reduction of Q. However, the current research mainly focuses on the description and explanation of the phenomenon, instead of evaluating the situation of water resources utilization. As the reduction of water resources in the Loess Plateau, some researchers began to wonder whether water resources are sufficient for the survival of human society and ecosystems. Feng et al. (2016) estimate a threshold of NPP of 400 ± 5 g C m -2 yr -1 above which the population will suffer water shortages, and now we are approaching this sustainable water resource limits. Zhang et al. estimates areas with overplanting to be over 53% of the Loess Plateau, especially in the middle and northeast parts. Zhang Ningning et al. (2019) found that the water carrying capacity of almost all prefectures and cities on the Loess Plateau was overloaded or severely overloaded by using the relational entropy model based on the EFAST weight algorithm. However, the specified location with water conflicts remained unclear, with few research having drawn conclusion on this. Besides, there is still a blank in quantifying and spatializing water resource conflicts at a higher resolution with a relatively accurate method, as well as in its future prediction. In this article, we are aiming to map the present water conflict on LP through the water balance equation, as well as exploring what leads to those conflicts. Then we used future climate prediction data to predict how it will develop in the future (2021-2100). In our result, we considered both water consumption by ecosystems and water intake by human society, to decide whether the regional water resource is socially and ecologically sustainable after ecological restoration. It provides a reference for future water management and possible further revegetation. Study Area Loess Plateau is located in the central north of China, covering the middle reaches of the Yellow River, with an area of approximately 64000 km 2 . Located in arid and semi-arid regions, the precipitation varied from 800 mm yr -1 to 200 mm yr -1 from southeast to northwest of the region, and mainly occurs from June to September, proportions 60–70% of the annual total rainfall. Evaporation is generally higher than actual precipitation. Loess Plateau is known for its thick Loess soil (Zhu et al., 2018), the soil depth in this area is 92.2 meters on average with the maximum exceeding 300 meters (Chen et al., 1996). The Loess Plateau is one of the birthplaces of the Chinese nation, and now it supports 8.5% of the Chinese population, about 120 million people (Fu et al., 2011). Loess Plateau has long been threatened by soil erosion. In the middle of 20th century, with the population explosion, people hacked and burnt forests to make way for agriculture, which greatly aggravated soil erosion. As the ecology of the region continuously degraded, a large-scale conservation campaign, the Grain to Green Project (GTGP), was implemented by converting farmland into forest and grassland since 1999. Besides, more than 800 key dams have been built to reduce flood peaks and intercept overland flows by the end of 2006 (Liang et al., 2015a). These measures have significantly altered the landcover, resulting in noticeable changes in the hydrological regime and sediment (Mu et al., 2007). Here, we select 12 main catchments across the Loess Plateau (Figure 1), to reflect both climate change and land surface change on the hydrological processes. These catchments nearly cover the main sediment producing areas of not only Loess Plateau but the whole Yellow River Basin, contributing about 44% of annual sediment to the Yellow River. Thus, those areas are essential to the ecological environment of downstream. These catchments also contain both areas of rapid vegetation recovery and those not, then it will make convenient to the comparison in our analysis. It is of great significance to study these catchments. Data and Methods Hydrological data. Annual runoff and monthly runoff data for the period 1982–1990 and 2000-2020 were obtained from Annual Hydrological Report P. R. China, provided by Yellow River Institute of Hydraulic Research. PPT, LAI and ET. Monthly precipitation data from 1982 to 2020 was obtained from the National Climatic Center of the China Meteorological Administration (http://cdc.nmic.cn/). Yearly actual evaporation (ET) data with a resolution of 500 m were acquired from the MODIS Land Processes Distributed Active Archive Center (https://lpdaac.usgs.gov/), the Terra Moderate Resolution Imaging Spectroradiometer (MODIS) MOD16A3GF Version 6.1 Evapotranspiration/Latent Heat Flux (ET/LE) product. The algorithm used for the MOD16 data product collection is based on the logic of the Penman-Monteith equation (Penman, 1948) which includes inputs of daily meteorological reanalysis data along with MODIS remotely sensed data products. The Penman method has been shown to be the most optimal formula to capture climate change (Donohue et al., 2010; Liu et al., 2012). The yearly ET and precipitation data were used to calculate remaining available water resource. Anthropogenic water demand. Water consumption by human society was acquired from Data set of historical water intake in China (1990-2015) provided by National Tibetan Plateau Environment Data Center (Wang et al., 2022). The spatial distribution of water withdrawal in six sectors of agricultural irrigation, municipal administration, industrial production, animal husbandry, primary energy exploitation and power generation in China from 1990 to 2015 is provided with a spatial accuracy of 0.5 ° and a geographical coordinate system of WGS84. The data has been mutually proved by the statistics published by the Ministry of Water Resources. Agricultural irrigation demand was excluded in the analysis because it was included in the ET loss from the cropland NPP. Because current groundwater withdrawal only makes up 30% of human water demand, is unsustainable in the Loess Plateau (Feng et al., 2016), the human water demand is assumed to be entirely taken from runoff. Land-use. The land use data we used was obtained from GlobeLand30 dataset. The GlobeLand30 dataset developed by China is the world's first 30-meter resolution global land cover dataset, which contains ten major types of land cover, providing with more abundant and detailed global land cover spatial distribution information. We picked annual land use data from 2000 to 2020 to estimate land use changes on LP since the GTGP begins. Future climate prediction data. The future climate forecast data will be used to estimate the change trend of water resources conflict in the Loess Plateau in the future (2020-2100). The forecast data of precipitation and evapotranspiration are respectively derived from the 1-km multi-scenario and multi-model monthly precipitation data for China in 2021-2100 from the National Tibetan Plateau Data Center (Peng Shouzhang, 2022) and China historical and future projected runoff and evapotranspiration dataset (1985-2100) (Zhou Jiayue, Lu Hui, 2023). Regression Analysis Method in Removing the Effects of Climate Change from Runoff. In our analysis, we divided the time into two periods, 1982-1990 was the reference period, while 2000-2020 was the period of change. Through the regression analysis of the relationship between precipitation and runoff in the reference period of the catchment, the optimal regression equation is found, and the regression equation of precipitation and runoff in the reference period is determined and established. Then, the precipitation value of the changing period is substituted into the equation to calculate the estimated natural runoff of this period without human interference and then compare it with the observed value of the same period, to calculate the contribution rate of human activities to the runoff change, the rest part can be seen as the contribution of climate change. The calculation of Remaining Available Water Resource. In our calculation, precipitation (PPT) is regarded as the only water supply of the Loess Plateau, and the water balance of the ecology-human coupling system can be achieved if and only if the water demand of the ecosystem (ET a ) and human society(T) can be exactly met from the annual precipitation. The formula is as follows: PPT=ET a +T+△S (1) ΔS represents water storage, it is regarded as 0 on a multi-year average scale. By subtracting human water demand and actual evapotranspiration from precipitation, we define the amount of water remaining after consumption by the coupled eco-human system as the remaining available water resource(N): N=PPT- ET a -T (2) Results 1. Spatial and temporal variation of water resources in the Loess Plateau after vegetation restoration According to satellite-based observations, greenness had occupied a wide range of barren land on Loess Plateau over the past 20 years (2000-2020), as the GTGP begins in 1999. The average vegetation coverage of the whole region increased by 16.8%. The vegetation coverage of some catchments has even increased by more than 50%. And in over 80% of the region, vegetation coverage has increased. From the perspective of landcover, forests have expanded 635.28 km 2 until 2020 comparing to 2000, shrublands have enlarged 2559.73 km 2 , in short, GTGP has converted ~3195 km 2 of land in other use into planted vegetation. The landcover change is relatively small compared to the giant change in greenness. Annual NPP showed an even more significant increasing trend over the region, with the rates of 5.699 g C m -2 yr -1 (P < 0.001), in line with the annual growth rate of 0.0347m 2 ·m -2 ·yr -1 (P<0.01) in LAI from 2000 to 2020 (Figure 2), mostly in the southeast. Notably, this trend after the year 2000 was approximately two times higher than it was observed between 1982-1999 (Cao et al., 2018; Zhang et al., 2022). Greenness and NPP show the synchronous growth trend in Loess Plateau during the greening stage, indicating that this greening has translated to vegetation productivity (NPP) in LP, while the two trends could be mismatched in other regions (Qiu et al., 2021; Feng et al., 2024; S. Sarmah et al., 2021). Opposite to the growing trend of vegetation coverage, the runoff of 12 catchments in the Loess Plateau showed an obvious decreasing trend. Compared with P1 period (1982-1990), the runoff of all catchments during P2 period (2000-2020) presented a decreasing trend, with an average annual runoff reduction of 30%, among which the runoff of Puhe River, Beiluo River and Shiwangchuan decreased most significantly (Figure 3). The reduction in water yield in Loess Plateau is also a consensus, Zheng et al. (2019) found water yield in over 100 hydrological stations was reduced by 22%. In the meantime, Wang et al. (2016) found the decreasing runoffs had brought negative influences on local ecosystems. There were obvious seasonal differences in the variation of runoff, and the greatest variation occurred in the growing season (Figure 4), followed by autumn. During the growing season, the growth of vegetation needs plenty of water to support it. Liu Yu et al. (2023) also found that runoff changes were concentrated in summer and autumn when they studied the hydrological characteristics of the Jinghe River basin. This is closely related to the regulation and storage effect of restored vegetation on water sources (Mu Xingmin et al., 2004). The decrease rate of runoff in winter is the lowest, and the runoff in some basins even showed an unexpected increasing trend in January and December, which may be due to the increase of precipitation in winter, which leads to the increase of melting water from snow and ice into runoff. To figure out what leads to these changes, three attribution analysis methods, regression analysis, double accumulation curve method and elastic coefficient method were used respectively to separate the influence degree of climate change and human activities on runoff. The results show that human activities are the main cause of runoff change (103.5%), and the increase of regional total precipitation makes climate change negatively contribute to runoff change in several basins (Figure 5), as the Loess Plateau shows a wetting trend in the study period (Gao et al., 2020). Liang et al. (2015) and other research also attributed most of this reduction to ecological restoration rather than climate change. 2. Quantification of water resource conflicts from the perspective of regional water balance To evaluate and quantify the potential water resource conflicts in the Loess Plateau, the water balance equation is used to identify the change of global water resources in the Loess Plateau and quantify the remaining available water resources in LP. In the seasonally dry areas including Loess Plateau, ecosystems and human activities both depend on the same source of water, which is precipitation (Jackson et al., 2005). Here, water balance is achieved when the precipitation in the region can meet the demand by both ecosystem and human society. The results show that the available water resources in the Loess Plateau were still relatively abundant in 2001, with the average surplus reaching 138.12mm, while the available water resources in 2020 decreased significantly, with the average value only 15.42mm, indicating that the amount of water available to human society is rapidly decreasing, if this trend continues, Loess Plateau is going to face a potential water shortage in the near future. The most obvious change appears in the central and northern Shanxi Province, the northern Shaanxi Plateau and the surrounding areas of Liupan Mountain (Figure 6). A great number of places on Loess Plateau had already reached or even exceeded its water limit. In those places, water resource conflicts may have already emerged. There are several researchers also had drawn conclusion on this, Zhang et al. (2018) estimates areas with overplanting to be over 53% of the Loess Plateau, especially in the middle and northeast parts (mostly coincides with our findings), anticipating an increasingly challenging future on revegetation over the LP. Feng et al. (2016) also found that Revegetation in China’s Loess Plateau is approaching sustainable water resource limits. Exploring the causes of these changes, it is found that although the precipitation has a slight increase trend from 2001 to 2020, the sum of drastic increase trend of actual evapotranspiration and artificial water withdrawals far exceeds the increase of precipitation and becomes the main reason for the decrease of available water resources. This change is due to the rapid growth trend of vegetation to some extent. The available water resources variation in 12 basins were fitted with the observed runoff reduction rate in the basin (Figure 7), and it was found that there was a good correlation between the two factors(R 2 =0.58). The decrement of the measured runoff value well reflected the change of theoretically available water resources in the basin. The more water resources are reduced by the water balance formula, the more dramatic the runoff reduction is. Thus, no matter from the theoretical point of view or from the measured data, the results of both illustrate the indisputable fact that the available water resources in the Loess Plateau are reduced in recent years. It also proved the reliability of this method in calculating the change in regional water resource, and its results are relatively ideal. 3. The rapid growth in ET is the main reason for water conflict——take 3 key areas for example It can be found that there are three regions with particularly rapid consumption of water resources and obvious changes in available water resources (Figure 8), they are located in northeast Shanxi, central Shaanxi and southeast Gansu respectively. To find out the reason, in the northeast Shanxi (Region 1), the water use was already close to its limit in 2001 for it is the place where Taiyuan and its urban agglomeration are located, with a high population density. Although the water resource decline in this region was relatively low during 2001-2020, however, due to the water shortage in the early stage, it has become one of the regions with serious water resource conflicts. Although the actual evapotranspiration rate in this region is relatively small compared with the growth trend of the whole Loess Plateau, the increase of water withdrawal by human society is significantly higher than that in other regions. It is because in this region, the proportion of natural vegetation is relatively small, and the land use type is mainly urban and cultivated land, so the evapotranspiration increase represented by vegetation transpiration is relatively moderate here compared with other vegetation restoration areas. Three sectors, primary energy extraction (6.28mm), power generation (3.64mm) and industrial production (2.61mm), contributed the most to the increase in water withdrawals. In the future, the region should optimize the allocation of water resources by upgrading the industrial structure. In central Shaanxi (Region 2), the variation of available water resource is the most intensive, with an average reduction of 225mm. The increase of precipitation in this region is similar to that in other regions, while the change of water withdrawal by human society is relatively small. The geographical location of this region is mainly located in the northern Shaanxi Plateau where Yan 'an is located, with forest being its main land cover type, so the vegetation coverage is relatively high. In the past 20 years, the vegetation greenness (LAI) and vegetation productivity (NPP) of this region have both increased significantly. At the same time, the actual evapotranspiration in this region has shown a huge increase of 256.1mm in the past 20 years. This key factor that causes the overuse of available water resources in this region is closely related to the growth of vegetation greenness and vegetation productivity (Wang et al., 2019). Therefore, since the vegetation coverage rate in this region has reached a high degree, the further growth of vegetation should be controlled to prevent the threat of vegetation overload to regional water resources. The last key area is located near Liupan Mountain (Region 3). The decrease in available water resources in the region was also dramatic, mainly related to the dramatic increase in actual evapotranspiration. The growth of evapotranspiration in this region from 2001 to 2020 is 262.5 mm, which is much higher than the average value of the Loess Plateau. In the previous analysis, we can see that the vegetation coverage on both sides of Liupan Mountain has increased significantly, and the average NPP in this region has also increased from 414.3 g C m -2 in 2001 to 552.8 g C m -2 in 2020. Therefore, it is reasonable to speculate that the actual evapotranspiration increase in this region is also related to the large-scale restoration of vegetation. 4. Prediction of water sustainability of Loess Plateau under climate change Based on the climate simulation results of multiple climate models (GCMs) in CMIP6, the spatial-temporal variation trends of available water resources in the Loess Plateau were predicted by averaging the collection of multiple models. The analysis results show that the precipitation of the Loess Plateau tends to increase from 2020 to 2100 under both SSP2-45 (moderate emission) and SSP5-85 (high emission) scenarios, and the decreased water volume under SSP5-85 scenario has a greater increase from 500mm to 600mm. At the same time, evapotranspiration also tends to increase, but the growth rate is smaller than that of precipitation in general (Figure 9). The water consumption of human society will stabilize. Under SSP2-45 scenario, this deterioration trend is going to continue till 2050 (Figure 10). In 2050, the water conflict still exists in a wide range of Loess Plateau with the average remaining value only -15.02mm, especially in southwest LP and Region 2 (Figure 11), for precipitation growth in this period is less than evapotranspiration growth, resulting in a decrease in the amount of residual water resources. By 2100, the overall water conflict situation in the Loess Plateau will be alleviated, with 53.85mm of available water remaining. Under SSP5-85 scenario, the prediction result is more optimistic. Water tensions will begin to ease by 2050 with 63.22mm remaining, especially in southwest and central LP (Figure 11), water conflict will be alleviated to a greater extent and have been basically eliminated. By 2100, water conflicts will be eased further in the northern LP, while slightly aggravated once again in the southern and southwest LP. According to the predicting results, as the regional climate is becoming warmer and wetter, we are generally optimistic about the future situation of water resources in the Loess Plateau. However, as water conflicts in Loess Plateau are going to intensify till 2050 under SSP2-45 scenario, it is still necessary to take measures to regulate water use and continuously save water in the near future. Discussion 1. The Uncertainty of the Assessment of water resource conflict In the assessment of the overloaded region of Loess Plateau, we use precipitation, WUE and human water demand data to calculate the water resource conflict in Loess Plateau. While precipitation and evapotranspiration are stable and definite, human water demand is relatively uncertain and has a lower spatial resolution. The human water demand data we used were obtained from National Tibetan Plateau Data Center, with a 0.5-degree resolution, while the others are higher, with a 500m resolution. Therefore, it was interpolated into a 10-km grid covering the entire Loess Plateau using the Kriging Interpolation Method. All the data was unified into 10-km grids, and the result was also presented in a 10-km resolution. The water intake data itself was reliable for it was verified by the water supply data in Yellow River Water Recourses Bulletin. However, due to the low precision of water intake data, the assessment of certain regions might become inaccurate, especially for those areas at the edge of the grid, for instance, if a grid has a city cluster inside, it may increase the water intake volume in the whole grid to some extent. During the allocation of water resources on the large-scale of Loess Plateau, we assume that the critical water-use threshold is met when the water needed for vegetation productivity and the water consumption by human society can just be met from the annual precipitation. This method was used in Feng et al.’s (2016) paper in 2016, to estimate the critical NPP threshold for the whole LP. This method can only be used in large and integral geographical units, and its result is limited to the resolution of essential data being used, thus it can be imprecise in specified places. Besides, in the water cycle, the process has been simplified in this method. The indistinctive changes in water storage, evaporation of bare land, as well as the other ways for human access to water were not taken into consideration, which may lead to some uncertainties in the final result. However, those uncertainties can be reduced in our large-scale analysis. 2. Implications for Water Management Most researchers believe that the terrestrial total water storage on the Loess Plateau has decreased in past decades (Yan et al., 2013; Zhang et al., 2019), water conflicts are intensifying. At the same time, some researchers hold different views (Zeng et al., 2020; Liu et al., 2023). For instance, Zhang et al. (2022) believe that vegetation restoration has not reduced water production in the Loess Plateau for the increasing trend of precipitation had surpassed the increase of evapotranspiration, the increase in precipitation is primarily driven by the enhanced land-atmosphere interaction caused by vegetation restoration, which greatly accelerates local water recirculation and gives positive feedback to surface water production. However, a large portion of the increased surface water production has been allocated to increased soil water storage and less to surface runoff that is directly available for human use. Thus, although there is a controversy on water yield in LP, however, regardless of whether the overall water production of the Loess Plateau has increased or not, it is an indisputable fact that at least in some specific areas, the amount of water that could be directly acquired and used by humans has decreased. Although the future situation of water resources in the Loess Plateau is getting better in the long term (after 2050), however, the situation will remain grim until 2050 under SSP2-45 scenario, taking implements to save water in the near future is still necessary for the Loess Plateau. Our results can offer valuable information to future water management. As mean annual precipitation should be a major consideration for the future restoration measures for Loess Plateau (Jin et al., 2011), our prediction in future water resources (considering both future climate change and water used by human society) would be useful to support more effective restoration policies. As for vegetation restoration, in those areas where vegetation has been overloaded, especially for central Shanxi Province and central Shaanxi Province, further revegetation is not recommended. If it would be continued in other regions LP, a better matched species with lower evapotranspiration combined with larger soil water infiltration should be employed, C. korshinskii and R. pseudoacacia are recommended for vegetation restoration (Jian et al., 2015; Cao et al., 2009). To cope with the consequent water-use shortage for human society, such as Weihe and Fenhe catchments, water-saving agriculture should be promoted. Advanced irrigation techniques such as drip irrigation should be used, and drought-tolerant crops such as maize, potatoes, and soybeans should be planted to improve water utilization and productivity (Wang et al., 2023), for agriculture takes approximately 60% of surface water withdrawals over the LP. Moreover, as areas of groundwater over-exploitation still exist over LP, especially for Longmen-Sanmenxia section, more efforts should be taken on water diversion projects, to prevent land subsidence caused by over-exploitation of groundwater, as well as alleviating water supply pressure on the Loess Plateau. Conclusions Our research focuses on the sustainable use of water resources on Loess Plateau, to study whether the existing water resources in Loess Plateau is enough to support both its ecological system and human society theoretically, as the Loess Plateau was becoming greener and greener, at the same time, runoffs showed a detectable decreasing trend. We analyzed the water yield of 12 main catchments on Loess Plateau. After extracting human’s influence on runoffs, we found that runoff decreases more rapidly in those catchments with larger vegetation overloaded area. Besides, a more sharply decrease happens in growing season: a 33% reduction in annual runoff in P2(2000-2020) compared with P1(1982-1990) and a 46% reduction in runoff of growing season. Those findings illustrate that vegetation plays an important role in water yield. After calculating the regional remaining available water resources through the equilibrium in water resource, our results suggest that the water use in LP is found to be very close to its sustainable use limit throughout the Loess Plateau, while in some places it had already been overused due to either the overdraw of water by human socio-economic activities or the rapid increase of ET a (8.11 mm yr -1 ). We further mapped these places in our results, the water conflicts between ecosystem and human society mainly occur in Central south and northeastern parts of Loess Plateau under the present scenarios. Finally, the climate prediction data is used to predict the water resource conflict in the Loess Plateau in the future (by 2100). From the results, we are generally optimistic about the future situation of water resources in the Loess Plateau. However, water conflicts in Loess Plateau are going to intensify till 2050 under SSP2-45 scenario. To conclude with, it is urgent to stress the sustainable utilization of water resources in the Loess Plateau, although the water conflict on Loess Plateau tends to ease by 2100. Strategies should be identified to ensure the sustainable use of water on Loess Plateau, like building a water-saving society as well as controlling revegetation process, which will be beneficial to regional development in the long term. Declarations CRediT authorship contribution statement Ning Zhu : Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Visualization, Writing – original draft, Writing – review and editing. Jianzhong Lu : Conceptualization, Methodology，Funding acquisition, Supervision. Liang Zheng : Data curation, Investigation, Resources. PiaoYin Zhang : Data curation, Investigation, Resources. Xiaoling Chen : Conceptualization, Project administration, Resources. Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Data availability Data will be made available on request. Acknowledgements We are thankful to X.J. Shi from the Yellow River Institute of Hydraulic Research for providing Hydrological data of the Yellow River. Funding This research was funded by the National Natural Science Foundation of China (42371367), the Key Research and Development Program of Jiangxi Province in China(20243BBH81033), and the LIESMARS Special Research Funding. References Zhai, J., Liu, R., Liu, J., Huang, L., Qin, Y, 2015. 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The Grain for Green Project intensifies evapotranspiration in the revegetation area of the Loess Plateau in China [in Chinese]. Chinese Science Bulletin, 64(Z1):588-599. https://link.cnki.net/urlid/11.1784.N.20190123.1756.006 Yan, L., Liu, X., Zhou, Y., 2013. Variation in rainy season precipitation and associated water vapor transport over the chinese loess plateau during 1961-2012. Clim. Res. 58 (1), 43–53. https://doi.org/10.3354/cr01185. Zhang, K., Xie, X., Zhu, B., Meng, S., Yao, Y., 2019. Unexpected groundwater recovery with decreasing agricultural irrigation in the yellow river basin. Agr. Water Manag. 213, 858–867. https://doi.org/10.1016/j.agwat.2018.12.009. Jin, T.T., Fu, B.J., Liu, G.H., Wang, Z., 2011. Hydrologic feasibility of artificial forestation in the semi-arid Loess Plateau of China. Hydrol. Earth Syst. Sci. 15, 2519–2530. https://doi.org/10.5194/hess-15-2519-2011 Jian, S.Q., Zhao, C.Y., Fang, S.M., Yu, K., 2015. Effects of different vegetation restoration on soil water storage and water balance in the Chinese Loess Plateau. Agr. Forest Meteo. 206, 85–96. http://dx.doi.org/10.1016/j.agrformet.2015.03.009 Wang, J.C., Gao, X.R., Zhao, J., Ding, Y.L., Yang, H., Zhang, D.Y., Zhu, X.P., Zhao, X.N., 2023. Evaluation of vegetation–water mutual suitability in Helong Region of the Loess Plateau. Agric. Water Manag. 290, 108603. https://doi.org/10.1016/j.agwat.2023.108603 Cao, S., Chen, L., Yu, X., 2009. Impact of China’s grain for green project on the landscape of vulnerable arid and semi-arid agricultural regions: a case study in northern Shaanxi Province. J. Appl. Ecol. 46, 536–543. https://doi.org/10.1111/j.1365-2664.2008.01605. Liu, Y., Xie, X.H., Tursun, A., Wang, Y.B., Jiang, F.X., Zheng, B.Y., 2023. Surface water expansion due to increasing water demand on the Loess Plateau. J. Hydrol.: Regional Studies. 49, 101485. https://doi.org/10.1016/j.ejrh.2023.101485 Zeng, Y., Yang, X., Fang, N., Shi, Z., 2020. Large-scale afforestation significantly increases permanent surface water in china’s vegetation restoration regions. Agr. For. Meteorol., 290, Article 108001, https://doi.org/10.1016/j.agrformet.2020.108001. 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. 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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-6551603","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":465000337,"identity":"12ce7c64-cff1-4792-9e62-106e947cda52","order_by":0,"name":"Ning Zhu","email":"","orcid":"","institution":"Wuhan University","correspondingAuthor":false,"prefix":"","firstName":"Ning","middleName":"","lastName":"Zhu","suffix":""},{"id":465000338,"identity":"e711dcd5-20c4-423e-b996-d451d74048fa","order_by":1,"name":"Jianzhong 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Loess Plateau and the 12 catchments in Loess Plateau.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-6551603/v1/999e94631996e351eb7679af.png"},{"id":83901291,"identity":"2725d50f-60a9-4872-ad4d-dc102419bc68","added_by":"auto","created_at":"2025-06-04 09:32:13","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":152145,"visible":true,"origin":"","legend":"\u003cp\u003ea) Increase in LAI on the LP. b) Increase in NPP on the LP.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-6551603/v1/80a64a3a896c86b8db62d327.png"},{"id":83900817,"identity":"e215bcff-626c-4469-8768-5f9adf994822","added_by":"auto","created_at":"2025-06-04 09:24:13","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":145409,"visible":true,"origin":"","legend":"\u003cp\u003eDecrement rate in runoff of 12 catchments in LP.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-6551603/v1/3929b465ca23fe935393d3d1.png"},{"id":83901289,"identity":"1ae41af9-209c-48c9-98ce-c433eaf066b8","added_by":"auto","created_at":"2025-06-04 09:32:13","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":82550,"visible":true,"origin":"","legend":"\u003cp\u003eSeasonal differences in the variation of runoff in 12 catchments.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-6551603/v1/7a9df88c739f650e713e0d32.png"},{"id":83900814,"identity":"649b8bc3-88fd-43f1-891d-5e90c859e9cd","added_by":"auto","created_at":"2025-06-04 09:24:13","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":52654,"visible":true,"origin":"","legend":"\u003cp\u003eAverage results of three attribution analysis in runoff change.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-6551603/v1/b61d88b5c42aca04b7246479.png"},{"id":83900815,"identity":"81db0c47-216c-49d6-886c-570a1b04d6a1","added_by":"auto","created_at":"2025-06-04 09:24:13","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":120227,"visible":true,"origin":"","legend":"\u003cp\u003eThe remaining available water resources distribution in 2001 and 2020.\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-6551603/v1/0bc3507439550763251d1410.png"},{"id":83900819,"identity":"82b3681f-9731-4656-bda1-33314068e2a6","added_by":"auto","created_at":"2025-06-04 09:24:13","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":81111,"visible":true,"origin":"","legend":"\u003cp\u003ethe relationship between runoff decrease rate (%) and variation in available water resources of each catchment. The inset shows the distribution of 12 catchments.\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-6551603/v1/719ea9a270c86207e1390de6.png"},{"id":83900825,"identity":"a35b42b7-6655-4ed9-94f0-59ae0bf9ef28","added_by":"auto","created_at":"2025-06-04 09:24:14","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":194947,"visible":true,"origin":"","legend":"\u003cp\u003ea) Location of 3 key areas. b) Change in ET\u003csub\u003ea\u003c/sub\u003e from 2000 to 2020. c) Change in Human water intake from 2000 to 2020. d) Changes in key elements in calculating available water resources. e) Change in precipitation from 2000 to 2020.\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-6551603/v1/9593f564c96b9c3aba527d1b.png"},{"id":83900821,"identity":"1063f6a8-1c06-4a80-88f7-cb4887702c24","added_by":"auto","created_at":"2025-06-04 09:24:13","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":262314,"visible":true,"origin":"","legend":"\u003cp\u003eChange in precipitation(a-d) and evapotranspiration(e-h) in LP in 2050 and 2100 under different scenarios (SSP2-45 and SSP 5-85).\u003c/p\u003e","description":"","filename":"9.png","url":"https://assets-eu.researchsquare.com/files/rs-6551603/v1/8d20a531c0cc69cb9812816a.png"},{"id":83901290,"identity":"4266671b-10a6-488b-b3d5-6648b9e3ff1c","added_by":"auto","created_at":"2025-06-04 09:32:13","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":26436,"visible":true,"origin":"","legend":"\u003cp\u003eRemaining available water resources in 2050 and 2100 overall Loess Plateau under different scenarios (SSP2-45 and SSP 5-85).\u003c/p\u003e","description":"","filename":"10.png","url":"https://assets-eu.researchsquare.com/files/rs-6551603/v1/02bf6cbd2b6afac5c6cabf5a.png"},{"id":83900822,"identity":"4dd861b3-258e-4c53-9d87-19cbd0000507","added_by":"auto","created_at":"2025-06-04 09:24:13","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":135919,"visible":true,"origin":"","legend":"\u003cp\u003eChange in remaining available water resources in 2050 and 2100 under different scenarios (SSP2-45 and SSP 5-85).\u003c/p\u003e","description":"","filename":"11.png","url":"https://assets-eu.researchsquare.com/files/rs-6551603/v1/9c8c42d8b4f48a97279d5b2e.png"},{"id":94489838,"identity":"b79d2575-efe4-4ca1-9c59-30441a6a7227","added_by":"auto","created_at":"2025-10-27 17:06:08","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1810791,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6551603/v1/faf159c9-8b2d-4736-bdc3-133765c2f8d1.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Intensified water resources conflict will be alleviated in future in China's Loess Plateau","fulltext":[{"header":"Highlights","content":"\u003col\u003e\n \u003cli\u003eVegetation greening has intensified water resources conflict in the LP.\u003c/li\u003e\n \u003cli\u003eWater resources conflict was quantified from the perspective of regional water balance.\u003c/li\u003e\n \u003cli\u003eWater resources conflict will be alleviated in future (2021-2100) in the LP.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Introduction","content":"\u003cp\u003eIn the recent 30 years, human activities had greatly changed the land cover on Loess Plateau (Zhai et al., 2015), including ecological restoration (ER), urban expansion and reclamation of cultivated land, especially ecological restoration (Feng et al., 2016). The vegetation restoration named The Grain to Green Project (GTGP), was raised by Chinese government from the end of 20th century, aiming to reduce soil erosion and restore the living environment damaged by deforestation (Deng et al., 2014). It has been one of the largest ecological restoration project implemented in the world (Wang et al., 2016; McVicar et al., 2010), changed ~3195 km\u003csup\u003e2\u003c/sup\u003e of cultivated-land to non-native vegetation, caused an overall 16.8% increase in vegetation coverage on Loess Plateau in last twenty years, it has made remarkable achievements in both environment, society and economy (Li et al., 2021; Wu et al., 2019). The newly planted vegetation stabilized the fragile soils on the surface, greatly reduced soil erosion (Ran et al., 2013; Wang et al., 2016), as well as enhancing carbon sequestration (Fu et al., 2011), supplying biofuel (Menz et al., 2013) and improving living environment (Jia et al., 2017; Liu et al., 2008). However, there are also some potential problems that shouldn\u0026rsquo;t be ignored, which is the newly planted vegetation will grab water from the existing ecosystems and human society (Jackson et al., 2005) while they all rely on limited precipitation. Water balance in this region will be further changed by the increasing rainfall interception and actual evapotranspiration (E) (Zhang et al., 2014). Runoffs within Loess Plateau has already presented an apparent downtrend in the last two decades (Liu et al., 2012; Liu et al., 2010), raising people\u0026rsquo;s concern on whether the water needed by ecosystems and humans will be long-termly sustainable in such a vulnerable and water-scarce environment (Zhan et al., 2014; Liang et al., 2015). Therefore, in our research, water use conflict in Loess Plateau is quantitatively assessed under the present and future scenarios.\u003c/p\u003e\n\u003cp\u003eA number of literatures have focused on the growing indication of water scarcity on LP. Liang et al. (2015a) revealed the decreasing trend in streamflow of 22 catchments on Loess Plateau. Zheng et al. (2019) found water yield in over 100 hydrological stations was reduced by 22%. Jia et al. (2017) found that soil moisture declined due to afforestation across the Loess Plateau. Most of the studies have linked this phenomenon with the ecological restoration (ER) project taken in recent years and found that vegetation restoration has gradually approached the limit of carrying capacity. Liang et al. (2015b) found that ER measures have been playing a dominant role (68%) in the reduction of Q. However, the current research mainly focuses on the description and explanation of the phenomenon, instead of evaluating the situation of water resources utilization.\u003c/p\u003e\n\u003cp\u003eAs the reduction of water resources in the Loess Plateau, some researchers began to wonder whether water resources are sufficient for the survival of human society and ecosystems. Feng et al. (2016) estimate a threshold of NPP of 400 \u0026plusmn; 5 g C m\u003csup\u003e-2\u003c/sup\u003e yr\u003csup\u003e-1\u003c/sup\u003e above which the population will suffer water shortages, and now we are approaching this sustainable water resource limits. Zhang et al. estimates areas with overplanting to be over 53% of the Loess Plateau, especially in the middle and northeast parts. Zhang Ningning et al. (2019) found that the water carrying capacity of almost all prefectures and cities on the Loess Plateau was overloaded or severely overloaded by using the relational entropy model based on the EFAST weight algorithm. However, the specified location with water conflicts remained unclear, with few research having drawn conclusion on this. Besides, there is still a blank in quantifying and spatializing water resource conflicts at a higher resolution with a relatively accurate method, as well as in its future prediction.\u003c/p\u003e\n\u003cp\u003eIn this article, we are aiming to map the present water conflict on LP through the water balance equation, as well as exploring what leads to those conflicts. Then we used future climate prediction data to predict how it will develop in the future (2021-2100). In our result, we considered both water consumption by ecosystems and water intake by human society, to decide whether the regional water resource is socially and ecologically sustainable after ecological restoration. It provides a reference for future water management and possible further revegetation.\u003c/p\u003e\n\u003ch1\u003eStudy Area\u003c/h1\u003e\n\u003cp\u003eLoess Plateau is located in the central north of China, covering the middle reaches of the Yellow River, with an area of approximately 64000 km\u003csup\u003e2\u003c/sup\u003e. Located in arid and semi-arid regions, the precipitation varied from 800 mm yr\u003csup\u003e-1\u003c/sup\u003e to 200 mm yr\u003csup\u003e-1\u003c/sup\u003e from southeast to northwest of the region, and mainly occurs from June to September, proportions 60\u0026ndash;70% of the annual total rainfall. Evaporation is generally higher than actual precipitation. Loess Plateau is known for its thick Loess soil (Zhu et al., 2018), the soil depth in this area is 92.2 meters on average with the maximum exceeding 300 meters (Chen et al., 1996). The Loess Plateau is one of the birthplaces of the Chinese nation, and now it supports 8.5% of the Chinese population, about 120 million people (Fu et al., 2011). Loess Plateau has long been threatened by soil erosion. In the middle of 20th century, with the population explosion, people hacked and burnt forests to make way for agriculture, which greatly aggravated soil erosion. As the ecology of the region continuously degraded, a large-scale conservation campaign, the Grain to Green Project (GTGP), was implemented by converting farmland into forest and grassland since 1999. Besides, more than 800 key dams have been built to reduce flood peaks and intercept overland flows by the end of 2006 (Liang et al., 2015a). These measures have significantly altered the landcover, resulting in noticeable changes in the hydrological regime and sediment (Mu et al., 2007).\u003cbr\u003eHere, we select 12 main catchments across the Loess Plateau (Figure 1), to reflect both climate change and land surface change on the hydrological processes. These catchments nearly cover the main sediment producing areas of not only Loess Plateau but the whole Yellow River Basin, contributing about 44% of annual sediment to the Yellow River. Thus, those areas are essential to the ecological environment of downstream. These catchments also contain both areas of rapid vegetation recovery and those not, then it will make convenient to the comparison in our analysis. It is of great significance to study these catchments.\u0026nbsp;\u003c/p\u003e"},{"header":"Data and Methods","content":"\u003cp\u003e\u003cstrong\u003eHydrological data.\u003c/strong\u003e Annual runoff and monthly runoff data for the period 1982–1990 and 2000-2020 were obtained from Annual Hydrological Report P. R. China, provided by Yellow River Institute of Hydraulic Research.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePPT, LAI and ET.\u003c/strong\u003e Monthly precipitation data from 1982 to 2020 was obtained from the National Climatic Center of the China Meteorological Administration\u0026nbsp;(http://cdc.nmic.cn/). Yearly actual evaporation (ET) data with a resolution of 500 m were acquired from the MODIS Land Processes Distributed Active Archive Center (https://lpdaac.usgs.gov/), the Terra Moderate Resolution Imaging Spectroradiometer (MODIS) MOD16A3GF Version 6.1 Evapotranspiration/Latent Heat Flux (ET/LE) product. The algorithm used for the MOD16 data product collection is based on the logic of the Penman-Monteith equation (Penman, 1948) which includes inputs of daily meteorological reanalysis data along with MODIS remotely sensed data products. The Penman method has been shown to be the most optimal formula to capture climate change (Donohue et al., 2010; Liu et al., 2012). The yearly ET and precipitation data were used to calculate remaining available water resource.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAnthropogenic water demand.\u003c/strong\u003e Water consumption by human society was acquired from Data set of historical water intake in China (1990-2015) provided by National Tibetan Plateau Environment Data Center (Wang et al., 2022). The spatial distribution of water withdrawal in six sectors of agricultural irrigation, municipal administration, industrial production, animal husbandry, primary energy exploitation and power generation in China from 1990 to 2015 is provided with a spatial accuracy of 0.5 ° and a geographical coordinate system of WGS84. The data has been mutually proved by the statistics published by the Ministry of Water Resources. Agricultural irrigation demand was excluded in the analysis because it was included in the ET loss from the cropland NPP. Because current groundwater withdrawal only makes up 30% of human water demand, is unsustainable in the Loess Plateau (Feng et al., 2016), the human water demand is assumed to be entirely taken from runoff.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eLand-use.\u003c/strong\u003e\u0026nbsp; The land use data we used was obtained from GlobeLand30 dataset. The GlobeLand30 dataset developed by China is the world's first 30-meter resolution global land cover dataset, which contains ten major types of land cover, providing with more abundant and detailed global land cover spatial distribution information. We picked annual land use data from 2000 to 2020 to estimate land use changes on LP since the GTGP begins.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFuture climate prediction data.\u0026nbsp;\u003c/strong\u003eThe future climate forecast data will be used to estimate the change trend of water resources conflict in the Loess Plateau in the future (2020-2100). The forecast data of precipitation and evapotranspiration are respectively derived from the 1-km multi-scenario and multi-model monthly precipitation data for China in 2021-2100 from the National Tibetan Plateau Data Center (Peng Shouzhang, 2022) and China historical and future projected runoff and evapotranspiration dataset (1985-2100) (Zhou Jiayue, Lu Hui, 2023).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eRegression Analysis Method in Removing the Effects of Climate Change from Runoff.\u003c/strong\u003eIn our analysis, we divided the time into two periods, 1982-1990 was the reference period, while 2000-2020 was the period of change. Through the regression analysis of the relationship between precipitation and runoff in the reference period of the catchment, the optimal regression equation is found, and the regression equation of precipitation and runoff in the reference period is determined and established. Then, the precipitation value of the changing period is substituted into the equation to calculate the estimated natural runoff of this period without human interference and then compare it with the observed value of the same period, to calculate the contribution rate of human activities to the runoff change, the rest part can be seen as the contribution of climate change.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eThe calculation of Remaining Available Water Resource.\u003c/strong\u003e In our calculation, precipitation (PPT) is regarded as the only water supply of the Loess Plateau, and the water balance of the ecology-human coupling system can be achieved if and only if the water demand of the ecosystem (ET\u003csub\u003ea\u003c/sub\u003e) and human society(T) can be exactly met from the annual precipitation. The formula is as follows:\u003c/p\u003e\n\u003cp\u003ePPT=ET\u003csub\u003ea\u003c/sub\u003e+T+△S \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;(1)\u003c/p\u003e\n\u003cp\u003eΔS represents water storage, it is regarded as 0 on a multi-year average scale. By subtracting human water demand and actual evapotranspiration from precipitation, we define the amount of water remaining after consumption by the coupled eco-human system as the remaining available water resource(N):\u003c/p\u003e\n\u003cp\u003eN=PPT- ET\u003csub\u003ea\u003c/sub\u003e-T \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;(2)\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003e1. \u0026nbsp; \u0026nbsp; Spatial and temporal variation of water resources in the Loess Plateau after vegetation restoration\u003c/p\u003e\n\u003cp\u003eAccording to satellite-based observations, greenness had occupied a wide range of barren land on Loess Plateau over the past 20 years (2000-2020), as the GTGP begins in 1999. The average vegetation coverage of the whole region increased by 16.8%. The vegetation coverage of some catchments has even increased by more than 50%. And in over 80% of the region, vegetation coverage has increased. From the perspective of landcover, forests have expanded 635.28 km\u003csup\u003e2\u003c/sup\u003e until 2020 comparing to 2000, shrublands have enlarged 2559.73 km\u003csup\u003e2\u003c/sup\u003e, in short, GTGP has converted ~3195 km\u003csup\u003e2\u003c/sup\u003e of land in other use into planted vegetation. The landcover change is relatively small compared to the giant change in greenness. Annual NPP showed an even more significant increasing trend over the region, with the rates of 5.699 g C m\u003csup\u003e-2\u003c/sup\u003e yr\u003csup\u003e-1\u003c/sup\u003e(P \u0026lt; 0.001), in line with the annual growth rate of 0.0347m\u003csup\u003e2\u003c/sup\u003e\u0026middot;m\u003csup\u003e-2\u003c/sup\u003e\u0026middot;yr\u003csup\u003e-1\u003c/sup\u003e(P\u0026lt;0.01) in LAI from 2000 to 2020 (Figure 2), mostly in the southeast. Notably, this trend after the year 2000 was approximately two times higher than it was observed between 1982-1999 (Cao et al., 2018; Zhang et al., 2022). Greenness and NPP show the synchronous growth trend in Loess Plateau during the greening stage, indicating that this greening has translated to vegetation productivity (NPP) in LP, while the two trends could be mismatched in other regions (Qiu et al., 2021; Feng et al., 2024; S. Sarmah et al., 2021).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eOpposite to the growing trend of vegetation coverage, the runoff of 12 catchments in the Loess Plateau showed an obvious decreasing trend. Compared with P1 period (1982-1990), the runoff of all catchments during P2 period (2000-2020) presented a decreasing trend, with an average annual runoff reduction of 30%, among which the runoff of Puhe River, Beiluo River and Shiwangchuan decreased most significantly (Figure 3). The reduction in water yield in Loess Plateau is also a consensus, Zheng et al. (2019) found water yield in over 100 hydrological stations was reduced by 22%. In the meantime, Wang et al. (2016) found the decreasing runoffs had brought negative influences on local ecosystems.\u003c/p\u003e\n\u003cp\u003eThere were obvious seasonal differences in the variation of runoff, and the greatest variation occurred in the growing season (Figure 4), followed by autumn. During the growing season, the growth of vegetation needs plenty of water to support it. Liu Yu et al. (2023) also found that runoff changes were concentrated in summer and autumn when they studied the hydrological characteristics of the Jinghe River basin. This is closely related to the regulation and storage effect of restored vegetation on water sources (Mu Xingmin et al., 2004). The decrease rate of runoff in winter is the lowest, and the runoff in some basins even showed an unexpected increasing trend in January and December, which may be due to the increase of precipitation in winter, which leads to the increase of melting water from snow and ice into \u0026nbsp;runoff.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTo figure out what leads to these changes, three attribution analysis methods, regression analysis, double accumulation curve method and elastic coefficient method were used respectively to separate the influence degree of climate change and human activities on runoff. The results show that human activities are the main cause of runoff change (103.5%), and the increase of regional total precipitation makes climate change negatively contribute to runoff change in several basins (Figure 5), as the Loess Plateau shows a wetting trend in the study period (Gao et al., 2020). Liang et al. (2015) and other research also attributed most of this reduction to ecological restoration rather than climate change.\u003c/p\u003e\n\u003cp\u003e2.\u0026nbsp; \u0026nbsp; \u0026nbsp;Quantification of water resource conflicts from the perspective of regional water balance\u003c/p\u003e\n\u003cp\u003eTo evaluate and quantify the potential water resource conflicts in the Loess Plateau, the water balance equation is used to identify the change of global water resources in the Loess Plateau and quantify the remaining available water resources in LP. In the seasonally dry areas including Loess Plateau, ecosystems and human activities both depend on the same source of water, which is precipitation (Jackson et al., 2005). Here, water balance is achieved when the precipitation in the region can meet the demand by both ecosystem and human society.\u003c/p\u003e\n\u003cp\u003eThe results show that the available water resources in the Loess Plateau were still relatively abundant in 2001, with the average surplus reaching 138.12mm, while the available water resources in 2020 decreased significantly, with the average value only 15.42mm, indicating that the amount of water available to human society is rapidly decreasing, if this trend continues, Loess Plateau is going to face a potential water shortage in the near future. The most obvious change appears in the central and northern Shanxi Province, the northern Shaanxi Plateau and the surrounding areas of Liupan Mountain (Figure 6). A great number of places on Loess Plateau had already reached or even exceeded its water limit. In those places, water resource conflicts may have already emerged. There are several researchers also had drawn conclusion on this, Zhang et al. (2018) estimates areas with overplanting to be over 53% of the Loess Plateau, especially in the middle and northeast parts (mostly coincides with our findings), anticipating an increasingly challenging future on revegetation over the LP. Feng et al. (2016) also found that Revegetation in China\u0026rsquo;s Loess Plateau is approaching sustainable water resource limits.\u003c/p\u003e\n\u003cp\u003eExploring the causes of these changes, it is found that although the precipitation has a slight increase trend from 2001 to 2020, the sum of drastic increase trend of actual evapotranspiration and artificial water withdrawals far exceeds the increase of precipitation and becomes the main reason for the decrease of available water resources. This change is due to the rapid growth trend of vegetation to some extent.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe available water resources variation in 12 basins were fitted with the observed runoff reduction rate in the basin (Figure 7), and it was found that there was a good correlation between the two factors(R\u003csup\u003e2\u003c/sup\u003e=0.58). The decrement of the measured runoff value well reflected the change of theoretically available water resources in the basin. The more water resources are reduced by the water balance formula, the more dramatic the runoff reduction is. Thus, no matter from the theoretical point of view or from the measured data, the results of both illustrate the indisputable fact that the available water resources in the Loess Plateau are reduced in recent years. It also proved the reliability of this method in calculating the change in regional water resource, and its results are relatively ideal.\u003c/p\u003e\n\u003cp\u003e3.\u0026nbsp; \u0026nbsp; \u0026nbsp;The rapid growth in ET is the main reason for water conflict\u0026mdash;\u0026mdash;take 3 key areas for example\u003c/p\u003e\n\u003cp\u003eIt can be found that there are three regions with particularly rapid consumption of water resources and obvious changes in available water resources (Figure 8), they are located in northeast Shanxi, central Shaanxi and southeast Gansu respectively.\u003c/p\u003e\n\u003cp\u003eTo find out the reason, in the northeast Shanxi (Region 1), the water use was already close to its limit in 2001 for it is the place where Taiyuan and its urban agglomeration are located, with a high population density. Although the water resource decline in this region was relatively low during 2001-2020, however, due to the water shortage in the early stage, it has become one of the regions with serious water resource conflicts. Although the actual evapotranspiration rate in this region is relatively small compared with the growth trend of the whole Loess Plateau, the increase of water withdrawal by human society is significantly higher than that in other regions. It is because in this region, the proportion of natural vegetation is relatively small, and the land use type is mainly urban and cultivated land, so the evapotranspiration increase represented by vegetation transpiration is relatively moderate here compared with other vegetation restoration areas. Three sectors, primary energy extraction (6.28mm), power generation (3.64mm) and industrial production (2.61mm), contributed the most to the increase in water withdrawals. In the future, the region should optimize the allocation of water resources by upgrading the industrial structure.\u003c/p\u003e\n\u003cp\u003eIn central Shaanxi (Region 2), the variation of available water resource is the most intensive, with an average reduction of 225mm. The increase of precipitation in this region is similar to that in other regions, while the change of water withdrawal by human society is relatively small. The geographical location of this region is mainly located in the northern Shaanxi Plateau where Yan \u0026apos;an is located, with forest being its main land cover type, so the vegetation coverage is relatively high. In the past 20 years, the vegetation greenness (LAI) and vegetation productivity (NPP) of this region have both increased significantly. At the same time, the actual evapotranspiration in this region has shown a huge increase of 256.1mm in the past 20 years. This key factor that causes the overuse of available water resources in this region is closely related to the growth of vegetation greenness and vegetation productivity (Wang et al., 2019). Therefore, since the vegetation coverage rate in this region has reached a high degree, the further growth of vegetation should be controlled to prevent the threat of vegetation overload to regional water resources.\u003c/p\u003e\n\u003cp\u003eThe last key area is located near Liupan Mountain (Region 3). The decrease in available water resources in the region was also dramatic, mainly related to the dramatic increase in actual evapotranspiration. The growth of evapotranspiration in this region from 2001 to 2020 is 262.5 mm, which is much higher than the average value of the Loess Plateau. In the previous analysis, we can see that the vegetation coverage on both sides of Liupan Mountain has increased significantly, and the average NPP in this region has also increased from 414.3 g C m\u003csup\u003e-2\u003c/sup\u003e in 2001 to 552.8 g C m\u003csup\u003e-2\u003c/sup\u003e in 2020. Therefore, it is reasonable to speculate that the actual evapotranspiration increase in this region is also related to the large-scale restoration of vegetation.\u003c/p\u003e\n\u003cp\u003e4.\u0026nbsp; \u0026nbsp; \u0026nbsp;Prediction of water sustainability of Loess Plateau under climate change\u003c/p\u003e\n\u003cp\u003eBased on the climate simulation results of multiple climate models (GCMs) in CMIP6, the spatial-temporal variation trends of available water resources in the Loess Plateau were predicted by averaging the collection of multiple models. The analysis results show that the precipitation of the Loess Plateau tends to increase from 2020 to 2100 under both SSP2-45 (moderate emission) and SSP5-85 (high emission) scenarios, and the decreased water volume under SSP5-85 scenario has a greater increase from 500mm to 600mm. At the same time, evapotranspiration also tends to increase, but the growth rate is smaller than that of precipitation in general (Figure 9). The water consumption of human society will stabilize.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eUnder SSP2-45 scenario, this deterioration trend is going to continue till 2050 (Figure 10). In 2050, the water conflict still exists in a wide range of Loess Plateau with the average remaining value only -15.02mm, especially in southwest LP and Region 2 (Figure 11), for precipitation growth in this period is less than evapotranspiration growth, resulting in a decrease in the amount of residual water resources. By 2100, the overall water conflict situation in the Loess Plateau will be alleviated, with 53.85mm of available water remaining.\u003c/p\u003e\n\u003cp\u003eUnder SSP5-85 scenario, the prediction result is more optimistic. Water tensions will begin to ease by 2050 with 63.22mm remaining, especially in southwest and central LP (Figure 11), water conflict will be alleviated to a greater extent and have been basically eliminated. By 2100, water conflicts will be eased further in the northern LP, while slightly aggravated once again in the southern and southwest LP.\u003c/p\u003e\n\u003cp\u003eAccording to the predicting results, as the regional climate is becoming warmer and wetter, we are generally optimistic about the future situation of water resources in the Loess Plateau. However, as water conflicts in Loess Plateau are going to intensify till 2050 under SSP2-45 scenario, it is still necessary to take measures to regulate water use and continuously save water in the near future.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003e1.\u0026nbsp;The Uncertainty of the Assessment of water resource conflict\u003c/p\u003e\n\u003cp\u003eIn the assessment of the overloaded region of Loess Plateau, we use precipitation, WUE and human water demand data to calculate the water resource conflict in Loess Plateau. While precipitation and evapotranspiration are stable and definite, human water demand is relatively uncertain and has a lower spatial resolution. The human water demand data we used were obtained from National Tibetan Plateau Data Center, with a 0.5-degree resolution, while the others are higher, with a 500m resolution. Therefore, it was interpolated into a 10-km grid covering the entire Loess Plateau using the Kriging Interpolation Method. All the data was unified into 10-km grids, and the result was also presented in a 10-km resolution. The water intake data itself was reliable for it was verified by the water supply data in Yellow River Water Recourses Bulletin. However, due to the low precision of water intake data, the assessment of certain regions might become inaccurate, especially for those areas at the edge of the grid, for instance, if a grid has a city cluster inside, it may increase the water intake volume in the whole grid to some extent.\u003c/p\u003e\n\u003cp\u003eDuring the allocation of water resources on the large-scale of Loess Plateau, we assume that the critical water-use threshold is met when the water needed for vegetation productivity and the water consumption by human society can just be met from the annual precipitation. This method was used in Feng et al.\u0026rsquo;s (2016) paper in 2016, to estimate the critical NPP threshold for the whole LP. This method can only be used in large and integral geographical units, and its result is limited to the resolution of essential data being used, thus it can be imprecise in specified places. Besides, in the water cycle, the process has been simplified in this method. The indistinctive changes in water storage, evaporation of bare land, as well as the other ways for human access to water were not taken into consideration, which may lead to some uncertainties in the final result. However, those uncertainties can be reduced in our large-scale analysis.\u003c/p\u003e\n\u003cp\u003e2.\u0026nbsp;Implications for Water Management\u003c/p\u003e\n\u003cp\u003eMost researchers believe that the terrestrial total water storage on the Loess Plateau has decreased in past decades (Yan et al., 2013; Zhang et al., 2019), water conflicts are intensifying. At the same time, some researchers hold different views (Zeng et al., 2020; Liu et al., 2023). For instance, Zhang et al. (2022) believe that vegetation restoration has not reduced water production in the Loess Plateau for the increasing trend of precipitation had surpassed the increase of evapotranspiration, the increase in precipitation is primarily driven by the enhanced land-atmosphere interaction caused by vegetation restoration, which greatly accelerates local water recirculation and gives positive feedback to surface water production. However, a large portion of the increased surface water production has been allocated to increased soil water storage and less to surface runoff that is directly available for human use.\u003c/p\u003e\n\u003cp\u003eThus, although there is a controversy on water yield in LP, however, regardless of whether the overall water production of the Loess Plateau has increased or not, it is an indisputable fact that at least in some specific areas, the amount of water that could be directly acquired and used by humans has decreased. Although the future situation of water resources in the Loess Plateau is getting better in the long term (after 2050), however, the situation will remain grim until 2050 under SSP2-45 scenario, taking implements to save water in the near future is still necessary for the Loess Plateau.\u003c/p\u003e\n\u003cp\u003eOur results can offer valuable information to future water management. As mean annual precipitation should be a major consideration for the future restoration measures for Loess Plateau (Jin et al., 2011), our prediction in future water resources (considering both future climate change and water used by human society) would be useful to support more effective restoration policies. As for vegetation restoration, in those areas where vegetation has been overloaded, especially for central Shanxi Province and central Shaanxi Province, further revegetation is not recommended. If it would be continued in other regions LP, a better matched species with lower evapotranspiration combined with larger soil water infiltration should be employed, C. korshinskii and R. pseudoacacia are recommended for vegetation restoration (Jian et al., 2015; Cao et al., 2009). To cope with the consequent water-use shortage for human society, such as Weihe and Fenhe catchments, water-saving agriculture should be promoted. Advanced irrigation techniques such as drip irrigation should be used, and drought-tolerant crops such as maize, potatoes, and soybeans should be planted to improve water utilization and productivity (Wang et al., 2023), for agriculture takes approximately 60% of surface water withdrawals over the LP. Moreover, as areas of groundwater over-exploitation still exist over LP, especially for Longmen-Sanmenxia section, more efforts should be taken on water diversion projects, to prevent land subsidence caused by over-exploitation of groundwater, as well as alleviating water supply pressure on the Loess Plateau.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eOur research focuses on the sustainable use of water resources on Loess Plateau, to study whether the existing water resources in Loess Plateau is enough to support both its ecological system and human society theoretically, as the Loess Plateau was becoming greener and greener, at the same time, runoffs showed a detectable decreasing trend.\u003c/p\u003e\n\u003cp\u003eWe analyzed the water yield of 12 main catchments on Loess Plateau. After extracting human’s influence on runoffs, we found that runoff decreases more rapidly in those catchments with larger vegetation overloaded area. Besides, a more sharply decrease happens in growing season: a 33% reduction in annual runoff in P2(2000-2020) compared with P1(1982-1990) and a 46% reduction in runoff of growing season. Those findings illustrate that vegetation plays an important role in water yield.\u003c/p\u003e\n\u003cp\u003eAfter calculating the regional remaining available water resources through the equilibrium in water resource, our results suggest that the water use in LP is found to be very close to its sustainable use limit throughout the Loess Plateau, while in some places it had already been overused due to either the overdraw of water by human socio-economic activities or the rapid increase of ET\u003csub\u003ea\u003c/sub\u003e (8.11 mm yr\u003csup\u003e-1\u003c/sup\u003e). We further mapped these places in our results, the water conflicts between ecosystem and human society mainly occur in Central south and northeastern parts of Loess Plateau under the present scenarios.\u003c/p\u003e\n\u003cp\u003eFinally, the climate prediction data is used to predict the water resource conflict in the Loess Plateau in the future (by 2100). From the results, we are generally optimistic about the future situation of water resources in the Loess Plateau. However, water conflicts in Loess Plateau are going to intensify till 2050 under SSP2-45 scenario.\u003c/p\u003e\n\u003cp\u003eTo conclude with, it is urgent to stress the sustainable utilization of water resources in the Loess Plateau, although the water conflict on Loess Plateau tends to ease by 2100. Strategies should be identified to ensure the sustainable use of water on Loess Plateau, like building a water-saving society as well as controlling revegetation process, which will be beneficial to regional development in the long term.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eCRediT authorship contribution statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eNing Zhu\u003c/strong\u003e: Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Visualization, Writing – original draft, Writing – review and editing. \u003cstrong\u003eJianzhong Lu\u003c/strong\u003e: Conceptualization, Methodology，Funding acquisition, Supervision. \u003cstrong\u003eLiang Zheng\u003c/strong\u003e: Data curation, Investigation, Resources. \u003cstrong\u003ePiaoYin Zhang\u003c/strong\u003e: Data curation, Investigation, Resources. \u003cstrong\u003eXiaoling Chen\u003c/strong\u003e: Conceptualization, Project administration, Resources.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDeclaration of Competing Interest\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eData will be made available on request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe are thankful to X.J. Shi from the Yellow River Institute of Hydraulic Research for providing Hydrological data of the Yellow River.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis research was funded by the National Natural Science Foundation of China (42371367), the Key Research and Development Program of Jiangxi Province in China(20243BBH81033), and the LIESMARS Special Research Funding.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eZhai, J., Liu, R., Liu, J., Huang, L., Qin, Y, 2015. Human-Induced Landcover Changes Drive a Diminution of Land Surface Albedo in the Loess Plateau (China). Remote Sens. 7, 2926-2941. https://doi.org/10.3390/rs70302926\u003c/li\u003e\n \u003cli\u003eFeng, X., Fu, B., Piao, S. et al, 2016. Revegetation in China\u0026rsquo;s Loess Plateau is approaching sustainable water resource limits. 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Hydrol.: Regional Studies. 49, 101485. https://doi.org/10.1016/j.ejrh.2023.101485\u003c/li\u003e\n \u003cli\u003eZeng, Y., Yang, X., Fang, N., Shi, Z., 2020. Large-scale afforestation significantly increases permanent surface water in china\u0026rsquo;s vegetation restoration regions. Agr. For. Meteorol., 290, Article 108001, https://doi.org/10.1016/j.agrformet.2020.108001.\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":"Water conflict, Vegetation carrying capacity, Ecological restoration, Climate change, Sustainable development, Loess Plateau","lastPublishedDoi":"10.21203/rs.3.rs-6551603/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6551603/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eLocated in arid and semi-arid region, water is always the most essential recourse for China’s Loess Plateau (LP), a region that supports tens of millions of people. In the recent 30 years, with the ecological restoration, the land cover has greatly changed in this region, vegetation coverage increased evidently. When rain falls to the ground, it is first absorbed by vegetation and then turns into runoff. As a matter of fact, runoffs on Loess Plateau are decreasing distinctly, while the evaporation represents a rising trend, which further intensifies the conflict between people and ecosystem. Here, we estimated the potential water conflict after revegetation on LP, three key areas of water use conflict are analyzed. Then, we also predict the water sustainability of Loess Plateau under climate change in 2021-2100. (1) Vegetation growth has led to a decrease in water resource on the Loess Plateau; (2) the available water resources in the Loess Plateau has been really close to its limit in 2020, especially in the central and northern Shanxi Province, the northern Shaanxi Plateau and the surrounding areas of Liupan Mountain, water shortage has already emerged; (3) as the regional climate is becoming warmer and wetter, we estimate that the water resource conflict situation in the Loess Plateau will be eased in the future(2021-2100).\u003c/p\u003e\n\u003cp\u003eThese findings alert that although revegetation has provided many benefits, it has caused perceptible conflicts between water use of ecosystem and human society. Our results provided some perspectives on future water management.\u003c/p\u003e","manuscriptTitle":"Intensified water resources conflict will be alleviated in future in China's Loess Plateau","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-06-04 09:24:09","doi":"10.21203/rs.3.rs-6551603/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":"65c2ca50-40ca-4da7-a607-c425bc04c4c5","owner":[],"postedDate":"June 4th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-10-27T14:55:36+00:00","versionOfRecord":[],"versionCreatedAt":"2025-06-04 09:24:09","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6551603","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6551603","identity":"rs-6551603","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}