Sustainable Utilization Of Water Resources Research Articles

Influence of respondents’ Differentiation of subjective response on water knowledge stock test scale: Evaluation based on two-parameter-multidimensional IRT model

Insufficient awareness of water issues is a crucial bottleneck restricting the sustainable utilization of water resources. To accurately measure citizens' water knowledge stock and overcome the differences between scales and respondents' characteristic levels on test results, the research focuses on developing and evaluating water knowledge stock test scales. The mechanism for identifying indicators is designed based on the grounded theory, and as a result, the water knowledge stock test indicator system is derived. The data was collected by the form of survey questionnaire developed with the test indicator system. A two-parameter multidimensional item response theoretical model is constructed based on item parameter estimation, data model fitting, and item information function. The survey data and optimization model are used to optimize the water knowledge stock test scale and verify the fitting degree with the characteristics of the respondents. The test information function and standard error function indicate that the scale is most informative for individuals with characteristic levels ranging from −2 to 3, resulting in a highly reliable test effect. The research has established a measurement indicator system, methodology, and presented results that serve as a foundation for measuring the stock of water knowledge.

Long-term trends in land erosion and accretion within the Meghna-Tetulia-Feni River Estuary (1973–2023)

A comprehensive comprehension of the mechanisms governing land erosion and accretion is of utmost importance in the pursuit of sustainable management strategies for estuarine environments. The present study aims to examine the enduring patterns of land erosion and accretion in the Meghna-Tetulia-Feni River Estuary in Bangladesh over a span of five decades, from 1973 to 2023. The study utilizes a dataset comprising 24 Landsat images captured during six significant years (1973, 1980, 1990, 2000, 2010, and 2023). The research employs both supervised and unsupervised classification techniques to demarcate the estuarine landscape into five distinct categories. These categories are subsequently reclassified into land and water classes for further analysis. The results suggest that there was a total land gain of 1406.91 km2 throughout the fifty-year period, with an average yearly increase of 28.14 km2. Significantly, the period spanning from 1980 to 1990 witnessed a notable increase in the net accretion rate, reaching a peak of 81.10 km2/year. Consequently, the total accretion during this period amounted to 1183.78 km2. In contrast, it is expected that the time span between 2010 and 2023 will experience a substantial decrease in land area, estimated to be roughly 705.73 km2. Given the significant geomorphological transformations and their wider economic and ecological consequences, this study proposes the implementation of an adaptable and flexible management approach that prioritizes the sustainable utilization of land and water resources in the Meghna-Tetulia-Feni River Estuary.

Spatiotemporal characteristics of evaporation in China and its response to revegetation in a typical region by a generalized complementary approach

The generalized nonlinear advection aridity (GNAA) model has been widely applied for evaporation estimations and drought assessments at regional and global scales. Here, the GNAA model was combined with a semi-empirical function for the parameter αe-B to estimate actual evaporation (E) in nine Level-I water resources regions and one typical revegetation area (i.e., the Loess Plateau) in China. The results showed that the semi-empirical function for αe-B with aridity index rescaled the original independent variable (xB) in GNAA; thus, the model satisfied the boundary condition of “y = 0, at xB-αf =0”. Moreover, the data points of E/Epa (Epa: apparent potential evaporation) and Epo/Epa (Epo: potential evaporation) were captured well by the GNAA curve with the semi-empirical function of αe-B. Further, the GNAA model showed high accuracy in simulating evaporation (ECR-B) when compared with the water balance equation, with the mean absolute error, root mean square error, and Nash-Sutcliffe efficiency values being 52 mm, 66 mm, and 0.84 respectively, over 49 basins. The multi-year mean ECR-B was 443.1 ± 14.7 mm/yr and 431.6 ± 21.2 mm/yr across China and Loess Plateau, respectively. Moreover, the annual ECR-B showed a significant upward trend during 1982–2017, and ECR-B increased rapidly before 1998, but decreased slightly after 1998 when considering 1998 as the turning point across China. Since the implementation of the large scale “Grain for Green” project on the Loess Plateau, nomalized difference vegetation index (NDVI) and precipitation increased significantly, while ECR-B showed no significant increases in both China and Loess Plateau. For the Loess Plateau, annual precipitation increased faster than annual evaporation, implying that water yield may increase. Overall, the findings would assist in clarifying the characteristics of evaporation across China and contribute to better management and sustainable utilization of regional water resources.

Coupling Simulation and Prediction of Sustainable Utilization of Water Resources in an Arid Inland River Basin under Climate Change

The arid endorheic basin of northwest China is characterized by rich land resources, water shortage, and a fragile ecological environment. The establishment of a credible coupling model of groundwater and surface water based on multi-source observation data is an effective means to study the change in basin water cycles and the sustainable utilization of water resources in the past and future. Based on the latest understanding of hydrogeological conditions, hydrology and water resource utilization data in the middle reaches of the Heihe River Basin (HRB), this paper constructs an up-to-date coupling model of surface water and groundwater to study the water balance change of the basin. The water resources data series under historical replay and CMIP5 climate model prediction are constructed to predict future changes in water resources. The study shows that, under the joint influence of natural conditions and human activities, the average annual recharge of groundwater in the study area from 1990 to 2020 is 17.98 × 108 m3/a, the average annual discharge is 18.62 × 108 m3/a, and the difference between recharge and discharge is −0.64 × 108 m3/a. The total groundwater storage is −19.99 × 108 m3, of which the groundwater storage from 1990 to 2001 was −17.52 × 108 m3 and from 2002 to 2020 was −2.47 × 108 m3. Abundant water from 2002 to 2020 in the basin significantly improved the loss of groundwater storage. Under the prediction of historical reappearance and the CMIP5 CNRM-CM5 model RCP4.5 and RCP8.5 pathways, the groundwater level of the Heihe River–Liyuanhe River inclined plain falls first because the HRB has just experienced a wet season and then rises according to future climate change. The groundwater level of the inclined plain east of the Heihe River and Yanchi basin decreases continuously because of the change in water cycle caused by human activities. The erosion accumulation plain is located in the groundwater discharge zone, and the water level is basically stable. Under the conditions of water resource development and utilization, the runoff of Zhengyixia hydrological station cannot meet the requirements of the “97 Water Dividing Plan” of the State Council in most years in the future, and the ecological and production water in the lower reaches of HRB cannot be effectively guaranteed. With the implementation of water-saving irrigation under the RCP4.5 and RCP8.5 scenarios, the runoff of Zhengyixia can meet the “97 Water Diversion Plan”. It is suggested to further improve the level of agricultural water savings in the middle reaches of the HRB and control the reasonable scale of cultivated land in order to reduce water consumption in the middle reaches of the HRB and implement sustainable utilization of water resources in the HRB.

A novel approach for quantifying water resource spatial equilibrium based on the regional evaluation, spatiotemporal heterogeneity and geodetector analysis integrated model

The distribution focuses of water resources, socio-economic development and environmental maintenance are usually mismatched, leading a gap between regional resources and the environment, as well as the disharmony of development. Water resource spatial equilibrium (WRSE) is an important yardstick for guiding regional water resource planning and sustainable utilization. However, research on the spatiotemporal heterogeneity and driving factors of WRSE is extremely lacking, and few existing studies have considered drought and flood disasters as the important reflection of WRSE. Therefore, this paper proposes a systematic integrated model for WRSE including regional evaluation, spatiotemporal heterogeneity and geodetector analysis functions, and constructs the evaluation index system considering droughts and floods. First, the performance of WRSE is quantified using the general deprivation index (GDI) innovatively. Then, combined with the Moran's I, the spatial patterns and regional differences of WRSE are analyzed. Last, the geographical detector models are employed to perform driving analysis of WRSE. The effectiveness of the model is verified in China. Results show that (1) from 2009 to 2021, the national average of WRSEI exhibits a declining trend from 0.879 in 2009 to 0.789 in 2021. (2) The areas with high WRSEI values are mainly distributed in the western provinces, whereas the eastern region has a higher percentage of imbalanced provinces. (3) Water resources per capita, added value of tertiary industry, urbanization rate and GDP per capita are key driving factors of China’ WRSE. The study provides a novel insight for WRSE improvement and is greatly helpful for developing differentiated management measures to optimize resource allocation.

Assessment of Variability and Attribution of Drought Based on GRACE in China from Three Perspectives: Water Storage Component, Climate Change, Water Balance

Understanding how drought is impacted by both natural and human influences is crucial to the sustainable utilization and protection of water resources. We established a drought severity index (DSI) based on the terrestrial water storage anomaly (TWSA) derived from the GRACE satellite to detect drought characteristics and trends over ten major river basins in China from 2002 to 2017. The influence of natural factors (terrestrial water storage components, precipitation, evapotranspiration, runoff, NDVI, and teleconnection factors (ENSO, PDO, NAO, and AO)) and a human factor (LULC) on drought were investigated and quantified from the perspective of water storage components based on the Theil–Sen trend and Mann–Kendall test method, the perspective of climate change based on cross wavelet transforms, and the perspective of water balance based on Random Forest. The results indicated that (1) almost all humid and arid basins experienced major drought periods during 2002–2006 and 2014–2017, respectively. The southern IRB and central YZRB regions exhibited notable declines in DSI trends, while the majority of the HLRB, IRB, LRB, YRB, HRB, and SWRB experienced significant increases in DSI trends; (2) abnormal groundwater decreases were the main cause of drought triggered by insufficient terrestrial water storage in most basins; (3) ENSO was the strongest teleconnection factor in most humid basins, and NAO, PDO, and AO were the strongest teleconnection factors in the arid basins and PRB. Most significant resonance cycles lasted 12–64 months in 2005–2014; and (4) the influence of an anthropogenic driver (LULC) has become as important as, or more important than, natural factors (runoff and teleconnection factors) on hydrological drought.

Information asymmetry in the graph model of conflict resolution and its application to the sustainable water resource utilization conflict in Niangziguan Springs Basin

With the increasing consumption of global water resources, research on sustainable water resource utilization has become a topic of urgent interest. Despite the promulgation of policies and laws on the protection of water resources, the sustainable utilization and development of water resources in China are still far from reaching their initially established targets. This is partly explained by real-life conflicts that arise, in which different decision makers (DMs) possess different levels of professional knowledge, social status, and even power in contexts where the parties’ ability to leverage information varies greatly. Sustainable water resource utilization conflicts between the government and factories exemplify the impact of this information asymmetry on the relationship between DMs for the purposes of conflict resolution. In this paper, it is assumed that if one DM in a conflict has more information, their information advantage will affect the policy formation of the other DM. Thus, to analyze and resolve relevant problems, the concept of information asymmetry between two DMs is integrated into the basic structure of the graph model for conflict resolution (GMCR). According to the mathematical expression of the information asymmetry preferences of DMs, a set of information asymmetry stability definitions can be introduced to determine the stable state for each DM. The sustainable water resource utilization conflict in Niangziguan Springs Basin is used as an exemplar to confirm the effectiveness and correctness of the proposed method. Stability analysis shows that when the government implements strict environmental policies by leveraging more information, factories should adjust their preference relations to follow the rules and regulations to protect water resource in practice. Finally, comprehensive sustainable utilization and development of natural resource mechanisms must be implemented not only for these factories but also for other industries in China.

Evaluation of Regional Water Ecological Economic System Sustainability Based on Emergy Water Ecological Footprint Theory—Taking the Yellow River Basin as an Example

In the article, on the basis of quantifying the emergy water ecological footprint, a sustainability evaluation system for the overall water ecological economic system of the basin and each province (region) was proposed. And using the subjective and objective combination of the Analytic Hierarchy Process (AHP) and Entropy Weight Method (EWM) to determine the weight of the indicator system, a TOPSIS model for sustainability evaluation was constructed. And taking the Yellow River Basin as an example, the results indicate that (1) Throughout the entire basin, the sustainability of the water ecological economic system showed a fluctuating upward trend year by year during the study period, from 0.37 to 0.51. (2) In each province (region), the sustainability of the water ecological economic system had gathered in space. The overall sustainability level of the upstream Sichuan, Qinghai and Gansu provinces is high, always at level (I). The overall sustainability level of the midstream Ningxia and Neimenggu was low, always at level (IV). The overall sustainability level of the downstream Shaanxi, Shanxi, Henan and Shandong provinces is high, rising gradually over time, from level (III) to level (II) or (I). Against the backdrop of the rapid development of the economy and society, the contradiction between economic and social development, ecological environment protection, and sustainable utilization of water resources is becoming increasingly severe, which has become a key factor restricting the sustainable development of the ecological economic system in Yellow River Basin. Multidimensional comprehensive evaluation of the sustainability level of the regional water ecological economic system is a prerequisite for identifying sustainable development issues in the Yellow River Basin, and also the basis for formulating targeted policies for sustainable utilization of regional water resources and high-quality economic development.

Evaluation of water resource use efficiency in Beijing-Tianjin-Hebei based on three-dimensional water ecological footprint

Water shortage and the conflict between water supply and demand have become the main constraints to the sustainable development of sustainable societies in Beijing-Tianjin-Hebei (BTH) region. Scientific evaluation of water usage efficiency and clarification of the three-dimensional water ecological footprint (EF3D) drivers are of great significance for the collaborative environmental management of BTH region. This paper firstly explores the evolution of water footprint breadth (EFsize), depth (EFdepth) and EF3D in BTH region from 2004 to 2020. Using the super-efficient SBM (Slacks-Based Measure) model with EF3D to evaluate the water use efficiency of BTH region in two scenarios. 22 impact factors were selected to analyze the dynamics affecting the change of EF3D in BTH region by using the LMDI (Logistic Mean Divided Index) model. The results show that: (1) The water resources pressure of the three provinces are in the overload state from 2004 to 2020, and the EF3D is at its maximum in 2011–2015. The EFdepth of BTH region is fluctuating up and then fluctuating down around 2012, and the most serious capital consumption of water resources stock is in Tianjin. (2) The water resources in Hebei are all in inefficient use. The water resources in Tianjin are in a state of inefficient use in some study years, and since 2014, the water resources are in a state of fluctuating increase and high efficiency. As for Beijing, the water resources are in a state of efficient use in the study years. On the whole, scenario 2 better reflects the water resources utilization efficiency situation and is more in line with the real situation. (3) The water structure and endowment of water resources are pivotal factors positively influencing the EF3D. To mitigate EF3D and achieve sustainable utilization of water resources, both Hebei and Tianjin have ample room for progress in elevating agricultural water-saving technologies, optimizing industrial structure, and enhancing water usage patterns. Agricultural water consumption is no longer the primary driver of water resource depletion in Beijing, necessitating focused attention on the impact of external water diversions in terms of local water displacement, optimization of water usage structures, and their role in supporting socio-economic development. Additionally, excessive reliance on external water diversions may entail associated risks that warrant consideration.

Spatiotemporal Variation and Factors Influencing Water Yield Services in the Hengduan Mountains, China

Conducting a quantitative assessment of water yield in mountainous areas is crucial for the management, development, and sustainable utilization of water resources. The Hengduan Mountains Region (HDMR) is a significant water-supporting area characterized by complex topography and climate changes. To analyze the spatial and temporal variations of water yield in the HDMR from 2001 to 2020, we employed the InVEST model and examined the influencing factors in conjunction with the elevation gradient. Our results indicate that: (1) The water yield in the Hengduan Mountains decreases from southeast to northwest, with the southwestern and eastern regions having high water yield values, and the high-altitude areas in the northwestern part having low water yield values. (2) The water yield in the Hengduan Mountains exhibits a decreasing trend followed by an increasing trend from 2001 to 2020, with the lowest level in 2011 and higher levels in 2004, 2018, and 2020. (3) Pixel-based trend analysis demonstrates a decreasing trend in water yield in the central and western parts of the study area, while the eastern part shows an increasing trend. (4) The climatic components, particularly precipitation, predominantly influence the spatial and temporal variations of water yield in the Transverse Mountain region. In most areas, evapotranspiration and land surface temperature have a negative impact on water yield. (5) Water yield tends to decrease and then increase on the altitudinal gradient, with precipitation and actual evapotranspiration being the factors directly affecting water yield, and land surface temperature and the proportion of forested areas having a significant indirect effect on water yield. Our study provides a scientific basis for water resources management and sustainable development in the Hengduan Mountains.

Optimal allocation of urban and rural water supply in coastal water shortage cities: The case of Yingkou City

AbstractCoastal cities play a significant role in regional economic development and national water resource supply. However, the shortage of water resources in coastal cities has become a bottleneck for sustainable economic, social and ecological development. As a typical coastal city in Liaoning province, China, Yingkou has a relatively developed economy, but faces increasingly serious water shortages. Taking Yingkou as a case study, this study analysed the current situation of urban and rural water supply and conducted a rational estimation of the water supply and demand based on the time series method in the short‐term (2025) and long‐term (2035). Then, the allocation of urban and rural water supply was carried out on the principle of priority use of surface water, sufficient use of diverted water, expanding use of unconventional water and limited use of underground water. To achieve the optimal scheme, the method of ‘allocation‐feedback‐regulation‐reallocation’ was adopted to coordinate the water sources and consumption in different districts and sectors. Overall, the results clarified the red line of water consumption in 2025 and 2035 and defined water consumption and water sources in different sectors and districts. Finally, the water supply and demand balance in Yingkou and its subdistricts was achieved with surplus water rates of 6% and 7% in 2025 and 2035, respectively. Based on these results, suggestions for the sustainable development and utilization of water resources in Yingkou and coastal cities were proposed.

Advancements in water and ecological risk assessment in the Yellow River Delta, North China: Implications for legal frameworks in environmental protection and public health

AbstractThe Yellow River Delta (YRD) is an important agricultural and industrial region in China, yet its water resources have been increasingly affected by shortages and pollution due to human activities and the impact of climate change. This has resulted in severe damage to the water ecosystem in the YRD, thereby necessitating the adoption of effective legal measures to safeguard these resources. This paper provides a comprehensive review of recent research findings on water resources and water ecology in the YRD. Specifically, it summarizes the changes and characteristics of the geographical distribution, quantity and quality of water resources in the region and analyzes the effects of climate change, economic development and population growth on water resources. In light of the vulnerability and risks to the water resources and ecosystems in this area, this paper evaluates the impact of human activities on regional water security and proposes strategies for the sustainable utilization of water resources and the protection of public health. The insights and measures presented in this paper provide valuable guidance and references for water resource management and environmental protection in the YRD.

Spatial Variation Characteristics, Influencing Factors, and Sources of Hydrogeochemical of Surface Water and Groundwater in Mountainous Area of Hutuo River

Surface runoff has dropped sharply in the mountainous area of the Hutuo River, posing a huge challenge to the sustainable use of groundwater in the North China Plain (NCP). The Taihang Mountain area is the main recharge source area of groundwater in the NCP. An in-depth study of spatial variation characteristics, influencing factors, and sources of hydrogeochemical characteristics of surface water and groundwater in the mountainous area of the Hutuo River can facilitate a comprehensive understanding of regional water resource status and sustainable utilization of water resources. Based on isotopic, hydrogeochemical, and mathematical statistics methods, this study analyzed spatial variation of hydrochemical characteristics in surface water and groundwater and its sources and main controlling factors. The results showed that the river water, well water, and spring water were all recharged by atmospheric precipitation in the mountainous areas of the Hutuo River. Under the combined influence of natural factors and human factors, the hydrogeochemical characteristics of river, well, and spring water showed large spatial differences. On the whole, the hydrochemical types of mainstreams were relatively concentrated. In the upper and lower mining reach areas, the mainstream water chemical type was dominated by Ca·Mg-SO4·HCO3, whereas that in the natural vegetation area (middle reach:between Qingshui River and Longhua River) was dominated by Ca·Mg-HCO3·SO4. In the upper stream, the main hydrochemical type of the Yukou River and Ehe River tributaries was Ca·Mg-SO4·HCO3, which was consistent with that of the main stream. The main hydrochemical types of the Muma River and Qingshui River tributaries were Ca-HCO3, Ca·Mg-HCO3, and Ca·Mg-HCO3·SO4 in the midstream. The main hydrochemical types of the Mianhe River and Yehe River tributaries were Ca-SO4, Ca·Mg-SO4, and Ca·Mg-SO4·HCO3. Mineral dissolution was still the main controlling factor for the hydrochemical characteristics of surface water and groundwater in the mountainous area of the Hutuo River. The contribution rates were 69.86% and 18.84% for mineral dissolution and human activities, respectively. Therefore, in the future, water resource utilization in the upper reaches of the Hutuo River should not only consider the issue of water quantity but also a series of water environment problems such as nitrate pollution and mining pollution caused by human activities.

Spatio-temporal dynamics of water storage across Northwest China over the past four decades

Study regionThe Northwest inland basins of China (NWC). Study focusTerrestrial water resources, especially groundwater resources, are the main source of water for human activities and for maintaining the stability of the ecological environment in NWC. Excessive consumption of water resources will seriously affect the sustainable utilization of water resources and ecological security in this region. Therefore, it is urgent to clarify the long-term changes in water storage in this area in order to handle the pressure of future water resources and the natural environment. Using GRACE satellite datasets and global hydrological models (GHMs) products, this study analyzed spatiotemporal variations in terrestrial water storage anomalies (TWSA), groundwater storage anomalies (GWSA), soil moisture, snow water equivalent, and canopy interception combined anomalies (SSCA) in NWC through the application of the water balance, trend decomposition, and empirical orthogonal decomposition methods. Furthermore, the driving factors of water storage change and feasible water resource management strategies were discussed. New hydrological insights for the regionTWSA in the NWC has experienced a continuous decline over the past nearly 40 years, while SSCA has shown a weak increasing trend (0.03 cm yr-1). Since the availability of glacial retreat data (2003–2016), glacial water storage in the NWC has decreased by 0.09 cm per year, while TWSA, SSCA, and GWSA have changed at rates of − 0.25, 0.02, and − 0.18 cm yr-1, respectively. The North Tianshan Rivers Basin has become one of the areas with the most severe groundwater depletion in China. 2005–2010 was a turning period in the changes of TWSA, followed by widespread water loss across the NWC. Glacier and snow melt are the most important factors for the decline of TWSA in the Tianshan mountains area, and over-exploitation of groundwater by human activities is a secondary factor. For other regions, Groundwater losses remain the most significant contributor to TWSA losses. The massive loss of water storage in the Tianshan Mountains area, especially the accelerated retreat of glaciers, will affect the stable water supply to the middle and lower reaches of the oasis region, perhaps leading to increased groundwater extraction, which will threaten regional water security and sustainable development. Developing a water-saving society and implementing inter-basin water transfer are feasible ways to alleviate the water resource crisis. Conducting a comprehensive analysis of all inland rivers in China helps to facilitate horizontal comparisons between various basins, thereby providing more comprehensive insights of water storage fluctuations. The data on water storage changes, extending back to 1980, provide a longer-term perspective on water resource changes in the region, which can contribute to enhancing water resource security and ecological environmental protection.

Analysis of Spatial and Temporal Variation in Sustainable Water Resources and Their Use Based on Improved Combination Weights

The sustainable use of water resources has become increasingly crucial given the present water supply and demand situation. In this study, the degree of sustainable water resource utilization in Harbin City from 2014 to 2021 was calculated using a fuzzy identification model with a combination of the “sequential relationship analysis method (G1) and coefficient of variation method (CVM)” and 18 evaluation indicators retrieved for water resources, reflecting social, economic, and ecological aspects. The study shows that (1) in terms of the research method, the combined weighting of “G1-CVM” is a feasible approach to avoid the shortcomings of single weighting and (2) in terms of the evaluation of water resources sustainable utilization, the spatial distribution of water resources in each district (county) of Harbin City has been stable over the past 8 years. The spatial distribution pattern is relatively stable, with the three regions of Binxian, Bayan, and Shuangcheng showing better sustainable water resource utilization and the three regions of Tonghe County, including the main urban area and Wuchang City, showing deteriorating sustainable water resource utilization. As a whole, the spatial distribution of sustainable water resources in the 13 districts (counties) of Harbin City from 2014 to 2021 shows a negative correlation, with the main urban area, Wuchang City, Hulan District, Bayan County, Shuangcheng District, and Yilan County showing a clustering type in the local spatial autocorrelation analysis. Based on the evaluation results, the spatial and temporal distribution characteristics of the sustainable use of water resources in Harbin are identified and found to be conducive to the timely adjustment of water resources allocation and the rational use of water resources in each district (county). Meanwhile, the research ideas and methods used in this paper can be applied to research on the sustainable use of water resources in other regions.

Tracing groundwater discharge into a coal mining subsidence lake in eastern China: Observations from water stable (δD and δ18O) and radon (222Rn) isotopes

Many coal mining subsidence lakes have formed in eastern China due to underground coal mining. Lacustrine groundwater discharge (LGD) is of great importance to the hydrological cycle and the eco-environment of lakes. However, LGD in coal mining area is rarely reported. In the study, we quantified groundwater discharge into a Huainan coal mining subsidence lake (China) using water stable (D and 18O) and radioactive (222Rn) isotopes. 222Rn and 18O mass balance models were used to independently estimate LGD. The lake water was sampled based on the horizontal and vertical profile sampling. The isotope depth profiles were weighted according to the lake bathymetry to obtain a representative isotope inventory by geographic information system (GIS) analysis. The LGD rates estimated from two models were comparable, and the values were 18 mm d−1 for the 18O and 14 ± 8 mm d−1 for the 222Rn. Compared with the LGD of Ammelshainer See lake (Germany), a subsidence lake formed by coal mining, the LGD in the study was larger, which may be related to the different hydrological conditions in different areas. By integrating the LGD rates from these two models, this study quantitatively analyzed the role of groundwater in maintaining the water balance in subsidence lakes, which is of great significance to water resources assessment and sustainable utilization of coal mining subsidence lakes in eastern China.

Afforestation reduced the deep profile soil water sustainability on the semiarid Loess Plateau

Insight into the response of deep soil moisture (SM) to land cover change is crucial for the sustainable management of regional water resources and ecosystems. However, the deep soil water budget and resilience after revegetation are not clear. In this study, seven typical land-cover patterns (artificial arbor, shrub, economic tree, pasture, abandon grassland, and natural grassland) were selected in four different study sites on the Loess Plateau of China. From May 2019 to December 2020, SM was monitored daily at ten depths along a 10 m profile in situ to assess the effect of revegetation on the vertical distribution, availability, and sustainability of soil water. The results indicated that the minimum SM moved to the deeper depth in the planted forest, while the maximum SM gradually moved to a shallower and deeper depth after the conversion of cropland to forestland and grassland, respectively. The difference in soil water use strategies under different revegetation types generated the opposite effect on deep SM availability, resilience, and sustainability. Conversion of cropland to grassland realized the deep soil available water (SAW) increment by 53.3% over the entire measurement period. Besides, the grassland promoting the deep soil water resilience (SWR) and soil water storage variation (ΔSWS) enhanced by 41.6% and 708.7% below 2 m depth, respectively. Whereas, compared to cropland, afforestation decreased the SAW, SWR, and ΔSWS by 17.2%, 10.5%, and 570.7% below 2 m depth, respectively. Furthermore, the deep SWR and ΔSWS were basically negative in the forestland, resulting in an unbalanced deep soil water budget within the year. Despite the significant disadvantages of sustaining the availability and water budget of deep soil water in artificial vegetation, constructing a reasonable land cover and vegetation structure could achieve the soil–water environment balance and the sustainable utilization of ecosystem water resources in the semiarid Chinese Loess Plateau (CLP). The findings of this study provide valuable references and guidance for sustainable vegetation conservation and water resource management and provide design and optimization solutions for vegetation restoration in similar areas of arid and semiarid regions around the world.

Effects of climate change on streamflow and nitrate pollution in an agricultural Mediterranean watershed in Northern Spain

Predicting water quality and quantity response to climate change in a watershed is very difficult due to the complexity and uncertainties in estimating and understanding future hydrological conditions. However, hydrological models could simplify the processes and predict future impacts of agricultural activities. This study aimed to evaluate the applicability of the Soil Water Assessment Tool (SWAT) model for climate change prediction of streamflow and nitrate load in an agricultural Mediterranean watershed in northern Spain. The model was first evaluated for simulating streamflow and nitrate load under rainfed agricultural conditions in the Cidacos River watershed in Navarre, Spain. Then, climate change impact analysis on streamflow and nitrate load was conducted in the short-term (2011–2040), medium-term (2041–2070), and long-term (2071–2100) future projections relative to the historical baseline period (1971–2000) under the RCP4.5 and RCP8.5 CO2 emission scenarios. The model evaluation showed a good model performance result during calibration (2000–2010) and validation (2011–2020) for streamflow (NSE = 0.82/0.83) and nitrate load (NSE = 0.71/0.68), indicating its suitability for adoption in the watershed. The climate change projection results showed a steady decline in streamflow and nitrate load for RCP4.5 and RCP8.5 in all projections, with the long-term projection scenario of RCP8.5 greatly affected. Autumn and winter saw a considerable drop in comparison to spring and summer. The decline in streamflow was attributed to the projected decrease in precipitation and increase in temperatures, while the nitrate load decline was consistent with the projected streamflow decline. Based on these projections, the long-term projection scenarios of RCP8.5 indicate dire situations requiring urgent policy changes and management interventions to minimize and mitigate the resulting climate change effects. Therefore, adapted agricultural management practices are needed to ensure sustainable water resource utilization and efficient nitrogen fertilizer application rates in the watershed to reduce pollution.

The short-range and remote analysis of virtual water trade in China

The pattern of virtual water trade within a region or region has a certain complexity. This paper uses multi-regional input-output models, local and tele-coupling theory, and geographical detectors to analyze the short-range and remote spatial pattern, change trends, and influencing factors of China's virtual water trade, which has essential research significance for the sustainable development and utilization of water resources. The results are as follows: (1) The water footprint and virtual water trade of each province in China are more likely to occur between the provinces close to each other, the local distance average distance is below 500 km, and the remote average distance is between 1100 km and 2000 km; (2) China's short-range inflow and outflow water footprint has always been the main dependent part of China's consumption and production end water resources, especially the local water footprint. The contribution of the remote water footprint has gradually been "replaced" by the short-range water footprint, and water resources only form a "small cycle" between the local and surrounding areas, becoming the main pattern of sustainable utilization of water resources in China; (3) The flow pattern of water resources in China still has a spatial imbalance and agglomeration effects. Regions with abundant water resources are net inflow and net import regions in both short-range and remote, and the net inflow and net outflow values in remote are higher than those in short-range; (4) The virtual water trade in all provinces of China tends to be close to each other. The "flow" in the trade network is mainly concentrated in the link path below 800 km. The interaction of various "flows" in short-range and remote virtual water trade results in fewer "flows" on one side and more on the other side in the industrial link path. Local virtual water trade has become an important guarantee and foundation for the utilization of water resources in all provinces and an important auxiliary to the total import virtual water trade; (5) The correlation of socio-economic factors to China's short-range and remote virtual water trade is higher than that of natural factors and scientific and technological factors. The interaction of factors contribution of a single factor more thoroughly and even far exceeds the sum of the contribution of two single factors, which can better explain the formation and change of near and long-distance virtual water trade patterns and flow on the link path.

An integrated diagnostic framework for water resource spatial equilibrium considering water-economy-ecology nexus

The mismatch of spatial distribution between water resources and human activities presents a considerable challenge to the sustainable utilization of water resources. This trend is further exacerbated by the impact of climate change and the increasingly frequent occurrence of extreme weather. Therefore, it is imperative to conduct an in-depth study on water resource spatial equilibrium (WRSE). This paper proposed an integrated diagnostic framework for WRSE considering the water-economy-ecology nexus, in which an improved evaluation index system of WRSE was constructed. The WRSE states of three criteria layers are quantified with the spatial equilibrium indices of water resource endowment, economic and social development, and ecological environment protection. The water resource spatial equilibrium index (WRSEI) was calculated using the Euclidean distance to reflect the overall spatial equilibrium state. The key influencing factors of WRSE are analyzed through the obstacle degree model. The findings indicate that: a) the WRSEI in the Yangtze River to Huaihe River Water Transfer Project (YHWTP) area showed a gradual increase from 0.641 in 2011 to 0.662 in 2020; b) the WRSE level of each criterion layer attained a general equilibrium or fair equilibrium state, and the WRSE state shows a trend from dispersion to aggregation during 2011 and 2020; c) per capita water resources, per capita gross domestic product and per capita urban wastewater discharge are the main factors limiting the realization of a benign WRSE in the YHWTP, with the obstacle degrees reaching 0.347, 0.324 and 0.326 in 2020 respectively. This framework can provide a theoretical reference for the study of WRSE, and provide a scientific basis and suggestions for policymakers to enhance WRSE and achieve sustainable utilization of water resources.