Payment for Water-Related Ecosystem Services as a Strategic Watershed Management Approach

Payments for ecosystem services (PES) have been created worldwide to assist watershed management and improve or maintain water quality. Considering their importance, we conducted a holistic review of payment for water-related ecosystem services to understand how this instrument has been applied in watershed management worldwide. First, we identified the watershed management actions considered by the PES programs and the challenges of implementing water-related PES. After we identified the methods and criteria used to define priority areas for water-related PES. Our review considered articles published on the Web of Science from 2011 to 2022. We found 236 articles relating PES to water resources, highlighting the main water conservation strategies: native vegetation conservation, native vegetation restoration, and implementing best agricultural practices. The method most frequent was interview, followed by the use of technologies, document analysis, and hydrological models. Another significant result was that priority areas for receiving PES are mainly riparian zones, areas near or with native vegetation cover, areas with higher erosion potential, steep areas, and areas with socially vulnerable communities. This review was crucial to identify efficient water resource conservation strategies and potential challenges in the implementation and development of PES programs.

Modeling and analyzing supply-demand relationships of water resources in Xinjiang from a perspective of ecosystem services

Water shortage is one bottleneck that limits economic and social developments in arid and semi-arid areas.As the impacts of climate change and human disturbance intensify across time,uncertainties in both water resource supplies and demands increase in arid and semi-arid areas.Taking a typical arid region in China,Xinjiang Uygur Autonomous Region,as an example,water yield depth(WYD)and water utilization depth(WUD)from 2002 to 2018 were simulated using the Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST)model and socioeconomic data.The supply-demand relationships of water resources were analyzed using the ecosystem service indices including water supply-demand difference(WSDD)and water supply rate(WSR).The internal factors in changes of WYD and WUD were explored using the controlled variable method.The results show that the supplydemand relationships of water resources in Xinjiang were in a slight deficit,but the deficit was alleviated due to increased precipitation and decreased WUD of irrigation.WYD generally experienced an increasing trend,and significant increase mainly occurred in the oasis areas surrounding both the Junggar Basin and Tarim Basin.WUD had a downward trend with a decline of 20.70%,especially in oasis areas.Water resources in most areas of Xinjiang were fully utilized and the utilization efficiency of water resources increased.The water yield module in the InVEST model was calibrated and validated using gauging station data in Xinjiang,and the result shows that the use of satellite-based water storage data helped to decrease the bias error of the InVEST model by 0.69×10^(8)m^(3).This study analyzed water resource supplies and demands from a perspective of ecosystem services,which expanded the scope of the application of ecosystem services and increased the research perspective of water resource evaluation.The results could provide guidance for water resource management such as spatial allocation and structural optimization of water resources in arid and semi-arid areas.

Trade-offs and synergies between ecosystem services in Yutian County along the Keriya River Basin,Northwest China

The Keriya River Basin is located in an extremely arid climate zone on the southern edge of the Tarim Basin of Northwest China,exhibiting typical mountain-oasis-desert distribution characteristics.In recent decades,climate change and human activities have exerted significant impacts on the service functions of watershed ecosystems.However,the trade-offs and synergies between ecosystem services(ESs)have not been thoroughly examined.This study aims to reveal the spatiotemporal changes in ESs within the Keriya River Basin from 1995 to 2020 as well as the trade-offs and synergies between ESs.Leveraging the Integrated Valuation of Ecosystem Services and Trade-offs(InVEST)and Revised Wind Erosion Equation(RWEQ)using land use/land cover(LULC),climate,vegetation,soil,and hydrological data,we quantified the spatiotemporal changes in the five principal ESs(carbon storage,water yield,food production,wind and sand prevention,and habitat quality)of the watershed from 1995 to 2020.Spearman correlation coefficients were used to analyze the trade-offs and synergies between ES pairs.The findings reveal that water yield,carbon storage,and habitat quality exhibited relatively high levels in the upstream,while food production and wind and sand prevention dominated the midstream and downstream,respectively.Furthermore,carbon storage,food production,wind and sand prevention,and habitat quality demonstrated an increase at the watershed scale while water yield exhibited a decline from 1995 to 2020.Specifically,carbon storage,wind and sand prevention,and habitat quality presented an upward trend in the upstream but downward trend in the midstream and downstream.Food production in the midstream showed a continuously increasing trend during the study period.Trade-off relationships were identified between water yield and wind and sand prevention,water yield and carbon storage,food production and water yield,and habitat quality and wind and sand prevention.Prominent temporal and spatial synergistic relationships were observed between different ESs,notably between carbon storage and habitat quality,carbon storage and food production,food production and wind and sand prevention,and food production and habitat quality.Water resources emerged as a decisive factor for the sustainable development of the basin,thus highlighting the intricate trade-offs and synergies between water yield and the other four services,particularly the relationship with food production,which warrants further attention.This research is of great significance for the protection and sustainable development of river basins in arid areas.

Spatiotemporal variations of ecosystem services and driving factors in the Tianchi Bogda Peak Natural Reserve of Xinjiang,China

Nature reserves play a significant role in providing ecosystem services and are key sites for biodiversity conservation.The Tianchi Bogda Peak Natural Reserve(TBPNR),located in Xinjiang Uygur Autonomous Region,China,is an important ecological barrier area in the temperate arid zone.The evaluation of its important ecosystem services is of great significance to improve the management level and ecological protection efficiency of the reserve.In the present study,we assessed the spatiotemporal variations of four ecosystem services(including net primary productivity(NPP),water yield,soil conservation,and habitat quality)in the TBPNR from 2000 to 2020 based on the environmental and social data using the Integrated Valuation of Ecosystem Services and Trade-offs(InVEST)model.In addition,the coldspot and hotspot areas of ecosystem services were identified by hotspot analysis,and the trade-off and synergistic relationships between ecosystem services were analyzed using factor analysis in a geographic detector.During the study period,NPP and soil conservation values in the reserve increased by 48.20%and 25.56%,respectively;conversely,water yield decreased by 16.56%,and there was no significant change in habitat quality.Spatially,both NPP and habitat quality values were higher in the northern part and lower in the southern part,whereas water yield showed an opposite trend.Correlation analysis revealed that NPP showed a synergistic relationship with habitat quality and soil conservation,and exhibited a trade-off relationship with water yield.Water yield and habitat quality also had a trade-off relationship.NPP and habitat quality were affected by annual average temperature and Normalized Difference Vegetation Index(NDVI),respectively,while water yield and soil conservation were more affected by digital elevation model(DEM).Therefore,attention should be paid to the spatial distribution and dynamics of trade-off and synergistic relationships between ecosystem services in future ecological management.The findings of the present study provide a reference that could facilitate the sustainable utilization of ecosystem services in the typical fragile areas of Northwest China.

Driving Forces and Their Effects on Water Conservation Services in Forest Ecosystems in China

Identifying the driving forces that cause changes in forest ecosystem services related to water conservation is essential for the design of interventions that could enhance positive impacts as well as minimizing negative impacts. In this study, we propose an assessment concept framework model for indirect-direct-ecosystem service （IN-DI-ESS） driving forces within this context and method for index construction that considers the selection of a robust and parsimonious variable set. Factor analysis was integrated into two-stage data envelopment analysis （TS-DEA） to determine the driving forces and their effects on water conservation services in forest ecosystems at the provincial scale in China. The results showed the following. 1） Ten indicators with factor scores more than 0.8 were selected as the minimum data set. Four indicators comprising population density, per capita gross domestic product, irrigation efficiency, and per capita food consumption were the indirect driving factors, and six indicators comprising precipitation, farmland into forestry or pasture, forest cover, habitat area, water footprint, and wood extraction were the direct driving forces. 2） Spearman＇s rank correlation test was performed to compare the overall effectiveness in two periods： stage 1 and stage 2. The calculated coefficients were 0.245, 0.136, and 0.579, respectively, whereas the tabulated value was 0.562. This indicates that the driving forces obviously differed in terms of their contribution to the overall effectiveness and they caused changes in water conservation services in different stages. In terms of the variations in different driving force effects in the years 2000 and 2010, the overall, stage 1, and stage 2 variances were 0.020, 0.065, and 0.079 in 2000, respectively, and 0.018, 0.063, and 0.071 in 2010. This also indicates that heterogeneous driving force effects were obvious in the process during the same period. Identifying the driving forces that affect service changes and evaluating their efficiency have significant policy implications for the management of forest ecosystem services. Advanced effectiveness measures for weak regions could be improved in an appropriate manner. In this study, we showed that factor analysis coupled with TS-DEA based on the IN-D1-ESS framework can increase the parsimony of driving force indicators, as well as interpreting the interactions among indirect and direct driving forces with forest ecosystem water conservation services, and reducing the uncertainty related to the internal consistency during data selection.

Spatiotemporal changes in water,land use,and ecosystem services in Central Asia considering climate changes and human activities

Central Asia is located in the hinterland of Eurasia,comprising Kazakhstan,Uzbekistan,Kyrgyzstan,Turkmenistan,and Tajikistan;over 93.00%of the total area is dryland.Temperature rise and human activities have severe impacts on the fragile ecosystems.Since the 1970s,nearly half the great lakes in Central Asia have shrunk and rivers are drying rapidly owing to climate changes and human activities.Water shortage and ecological crisis have attracted extensive international attention.In general,ecosystem services in Central Asia are declining,particularly with respect to biodiversity,water,and soil conservation.Furthermore,the annual average temperature and annual precipitation in Central Asia increased by 0.30℃/decade and 6.9 mm/decade in recent decades,respectively.Temperature rise significantly affected glacier retreat in the Tianshan Mountains and Pamir Mountains,which may intensify water shortage in the 21st century.The increase in precipitation cannot counterbalance the aggravation of water shortage caused by the temperature rise and human activities in Central Asia.The population of Central Asia is growing gradually,and its economy is increasing steadily.Moreover,the agricultural land has not been expended in the last two decades.Thus,water and ecological crises,such as the Aral Sea shrinkage in the 21st century,cannot be attributed to agriculture extension any longer.Unbalanced regional development and water interception/transfer have led to the irrational exploitation of water resources in some watersheds,inducing downstream water shortage and ecological degradation.In addition,accelerated industrialization and urbanization have intensified this process.Therefore,all Central Asian countries must urgently reach a consensus and adopt common measures for water and ecological protection.

Transdisciplinary research for supporting the integration of ecosystem services into land and water management in the Tarim River Basin,Xinjiang,China

There is a growing need for both science and practice domains to collaboratively and systematically seek knowledge-based strategies for sustainable development. In recent years, transdisciplinary research has emerged as a new approach that enables joint problem solving among scientists and stakeholders in various fields. In this paper, we aim to introduce transdisciplinary research for supporting the integration of the concept of eco- system services into land and water management in the Tarim River Basin, Xinjiang, Northwest China. While a large number of ecosystem service studies have helped to raise the awareness for the value of nature in China, a number of challenges remain, including an improved understanding of the relationships between ecosystem structure, functions and services, and the interaction of the various ecosystem services. A meaningful valuation of ecosystem services also requires the consideration of their strong spatial heterogeneity. In addition, ways to introduce the con- cept of ecosystem services into decision-making in China need to be explored. Thus, successful integration of the concept of ecosystem services into actual land and water management requires a broad knowledge base that only a number of scientific disciplines and stakeholders can provide jointly, via a transdisciplinary research process. We regard transdisciplinary research as a recursive process to support adaptive management that includes joint knowledge generation and integration among scientists and stakeholders. System, target, and transformation knowledge are generated and integrated during the process of （1） problem （re）definition, （2） problem analysis and strategy development, and （3） evaluation of the impact of the derived strategy. Methods to support transdisciplinary research comprise participatory modelling （actor-based modelling and Bayesian Networks modelling） and partici- patory scenario development. Actor-based modelling is a semi-quantitative method that is based on the analysis of problem perspectives of individual stakeholders as depicted in perception graphs. With Bayesian Networks, com- plex problem fields are modelled probabilistically in a simplified manner, using both quantitative data and qualitative expert judgments. These participatory methods serve to integrate diverse scientific and stakeholder knowledge and to support the generation of actually implementable management strategies for sustainable development. For the purpose of integrating ecosystem services in land and water management in the Tarim River Basin through trans- disciplinary research, collaboration among scientists and institutional stakeholders from different sectors including water, agriculture, forestry, and nature conservation is required. The challenge is to adapt methods of transdisci- plinary research to socio-cultural conditions in China, particularly regarding ways of communication and deci- sion-making.

Geospatial Evaluation for Ecological Watershed Management II: Changes in Land Use—Land Cover Influence on Ecosystems Services

Ecosystem services are a key to human survival and global sustainability. Consequently, there is the need to avoid unscrupulous or unplanned land use practices that can compromise these services in addition to the ongoing changes in the global climate whose potentially negative impact are yet to be fully comprehended thus far. The primary objective of this study was to evaluate the Land use—land cover changes of some Eastern Shore sub-watersheds of Maryland from 1986-2006 and qualitatively assess the impact of the changes on some key ecosystem services. Landsat-TM data for Maryland Eastern Shore in the United States were analyzed in ENVI and ArcGIS environment and data interpreted qualitatively. The result showed that forest lands increased during the study period and thus enhanced carbon sequestration favorable for mitigating global warming in the area. Also, the extent of surface water cover increased slightly, possibly due to rising sea level and a thus a potential threat to biodiversity and barrier islands nearby. There was also a significant increase in urban lands due to population increase and thus increase in the extent of impervious layers that could lead to reduced surface runoff and increase the potential for surface water quality impairment;this could lead to a reduction in the capacity of surface water ecosystem to provide clean/recreational waters. The increase in the extent of surface water cover was at the expense of the wetlands that shrunk, thereby threatening the coastal ecosystem’s ability to provide services such as storm and wave protection, nutrient cycling, and the protection of wildlife habitat. There was also a decrease in the extent of Agricultural lands which could lead to loss of food and fiber during the study period. There is therefore an urgent need to formulate or intensify existing policies to regulate land use from an ecological health standpoint in order to ensure sustainability of the various ecosystems within the watersheds of the Lower Eastern Shore of Maryland in the US, and similar coastal locations elsewhere.

Value Evaluation of Water Ecosystem Services——A Case Study of Changshu City

[ Objective] The study aimed to quantitatively assess the values of water ecosystem services. [ Method] Combining the market value, travel cost and restoration cost method, the ecological services and their economic values of the lake Taodangmian were assessed from aspects of water supply, recreation and tourism, water purification and biodiversity maintenance. [ Resultl For the lake Taodangmian, its freshwater supply and tourism played more positive roles in the society than the others, while the functions of water purification and biodiversity maintenance brought negative effects, which shows that the ecological environment of Taodangmian has become increasingly worse and needs to be controlled and and protected further. [ Conclusion] The research could provide scientific references for the reasonable exploitation and utilization of water resources.

The Public Water Supply Protection Value of Forests: A Watershed-Scale Ecosystem Services Analysis Based upon Total Organic Carbon

We developed a cost-based methodology to assess the value of forested watersheds to improve water quality in public water supplies. The developed methodology is applicable to other source watersheds to determine ecosystem services for water quality. We assess the value of forest land for source water mitigation of total organic carbon (TOC) through the use of linked watershed and reservoir simulation models and cost-based valuation economics. Watershed modeling results indicated that expected urbanization will increase TOC loads to Converse Reservoir (Mobile, AL). Reservoir model results indicated that future median TOC concentrations increased by 1.1 mg·L-1 between 1992 and 2020 at the source water intake. Depending upon dynamic reservoir TOC concentrations, additional drinking water treatment with powdered activated carbon (PAC) often is necessary between May and October to comply with Safe Drinking Water Act regulations. The cost for additional treatment was calculated using minimum and maximum volume treated with simulated TOC concentrations at the source water intake. Daily simulated TOC concentrations for the base scenario using 1992 land cover (3% urban) were compared with simulated TOC concentrations following forest to urban land conversion predicted in the watershed by 2020 (22% urban). The daily cost for additional drinking water treatment with PAC was calculated if simulated TOC concentrations exceeded 2.7 mg·L-1. The mean increase in daily treatment costs between base and future scenarios ranged from $91 to $95 per km2 per day for forest land water purification ecosystem services.

Ecosystem Service Flow Insights into Horizontal Ecological Compensation Standards for Water Resource: A Case Study in Dongjiang Lake Basin, China

Water supply services(WSSs) are critical for the regional water balance and water circulation, but relevant studies have not established the relationship between WSSs and human well-being. This research identifies the scope of areas that benefit from WSSs from an ecosystem service flow perspective. Moreover, the path and quantity of the flow of WSSs are simulated to provide a scientific theoretical basis for ecosystem service management and ecological compensation. The Dongjiang Lake Basin is a national priority river basin in China where ecological compensation pilot programmes concerning water resources are top priorities. Dongjiang Lake Basin experienced an increase and then a decrease in the overall supply of water, with an average net water supply of 1096–1500 mm for the years 1995, 2000, 2005 and 2010. The water demand increased each year in service beneficiary areas(SBAs), varying from 387 to 580 mm. Overall, Dongjiang Lake Basin met the net water demands of the actual SBAs in the lower reaches, but a gap in the water supply and demand emerged gradually. This research provides an understanding of the functional mechanisms for the provision, demand and flow of WSSs and provides a scientific theoretical basis for ecosystem service management and ecological compensation.

Ecological service assessment of human-dominated freshwater ecosystem with a case study in Yangzhou Prefecture, China

Freshwater ecosystems provide a host of services to humanity. These services are now rapidly being lost, not least because of the inability of making the impacts measurable. To overcome this obstacle, assessment frameworks for freshwater ecosystem services are needed. A simple water equivalent framework to assess the ecological services provided by freshwater ecosystems was developed in this study. It translated the occupation of freshwater ecosystem services into biologically freshwater volumes and then compares this consumption to the freshwater throughput, that is, the ecological capacity available in this region. In this way, we use the example of Yangzhou Prefecture, to account the main categories of human occupation of water ecosystem services. The result showed that there is a huge gap between the consumption and the supply of freshwater ecosystem services. This must encourage local government to make land-use and water management decisions both economically rational and environmentally sound.

Dynamic Analysis of Supply and Demand Coupling of Ecosystem Services in Loess Hilly Region:A Case Study of Lanzhou,China

The relationship between the supply and demand for ecosystem services(ESs)is a key issue for the rational allocation of natural resources and optimisation of sustainable development capacity.This paper investigateed the dynamic evolution features of supply and demand of four ESs in Lanzhou of China,namely,water supply,food supply,carbon fixation and soil retention services.The crosssectional data of 2005 and 2017 were used for calculating ESs value and its supply and demand through ArcGIS software,InVEST model,elastic coefficient model and coupling coordination model.Results showed that:1)from 2005 to 2017,the supply of water supply services increased,the demand of soil retention services decreased,and the supply and demand of food supply and carbon fixation services increased.The high-value areas of service supply were mainly distributed in the rocky mountain areas in the southeast and northwest with high vegetation coverage,while the high-value areas of demand were mainly distributed in the urban areas and surrounding areas with high population density.2)There were five different types of coupling relations.Water supply service was dominated by a negative coupling type D,which means that the decrease in demand for ESs has had a positive response on the supply of ESs.Negative coupling type C was the main type of food supply and carbon fixation services,which means that the increase in demand for ESs has had a negative response on the supply of ESs.All three services were supplemented by a positive coupling type A,which means that the increase in demand for ESs has had a positive response on the supply of ESs.Soil retention service generally exhibits a positive coupling type B,which means that the decrease in demand for ESs has had a negative response on the supply of ESs.3)Over the past 12 yr,the coordination degree of supply and demand of water supply,food supply and soil retention services decreased,and the coordination degree of carbon fixation service increased.Various types of ES had a low degree of coupling and coordination,showing different characteristics of temporal and spatial evolution.The areas with imbalanced ESs supply and demand were mainly distributed in urban areas dominated by construction land.The research results are valuable to the optimisation of urban and rural ecological environments and the sustainable development of territory space under the framework of ecological civilisation,including similar ecologically vulnerable areas in other developing countries.

Assessment and regulation of ocean health based on ecosystem services: Case study in the Laizhou Bay, China

The ecosystem-based management of nearshore waters requires integrated assessment of ocean health and scientific guidance on artificial regulations to promote sustainable development. Quantitative approaches were developed in this paper to assess present and near-term ocean health based on ecosystem services. Results of the case study in the Laizhou Bay of China showed that the index score of ocean health was 0.785 6 out of 1.0 at present and was expected to range from 0.555 1 to 0.804 1 in the near-term future depending on different intensities of artificial regulation of negative pressures. Specifically, the results of ocean health at present mainly indicated that cultural services and provisioning services performed essentially perfectly while supporting services and regulating services functioned less well. It can be concluded that this nearshore ecosystem would partially lose supporting and regulating services in the near-term future if the increasing pressures were not wellregulated but that all of these categories of ecosystem services could be slightly improved if the negative pressures were fully controlled. Additionally, it is recommended that publicity and education on ecosystem services especially on cultural services and regulating services should be further strengthened. The analytical process and resulting quantification provide flexible tools to guide future development of regulations so as to facilitate ecosystem-based management in the coastal zone.

Spatiotemporal characteristics and influencing factors of ecosystem services in Central Asia

Land use/land cover(LULC)change and climate change are two major factors affecting the provision of ecosystem services which are closely related to human well-being.However,a clear understanding of the relationships between these two factors and ecosystem services in Central Asia is still lacking.This study aimed to comprehensively assess ecosystem services in Central Asia and analyze how they are impacted by changes in LULC and climate.The spatiotemporal patterns of three ecosystem services during the period of 2000-2015,namely the net primary productivity(NPP),water yield,and soil retention,were quantified and mapped by the Carnegie-Ames-Stanford Approach(CASA)model,Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST)model,and Revised Universal Soil Loss Equation(RUSLE).Scenarios were used to determine the relative importance and combined effect of LULC change and climate change on ecosystem services.Then,the relationships between climate factors(precipitation and temperature)and ecosystem services,as well as between LULC change and ecosystem services,were further discussed.The results showed that the high values of ecosystem services appeared in the southeast of Central Asia.Among the six biomes(alpine forest region(AFR),alpine meadow region(AMR),typical steppe region(TSR),desert steppe region(DSR),desert region(DR),and lake region(LR)),the values of ecosystem services followed the order of AFR>AMR>TSR>DSR>DR>LR.In addition,the values of ecosystem services fluctuated during the period of 2000-2015,with the most significant decreases observed in the southeast mountainous area and northwest of Central Asia.LULC change had a greater impact on the NPP,while climate change had a stronger influence on the water yield and soil retention.The combined LULC change and climate change exhibited a significant synergistic effect on ecosystem services in most of Central Asia.Moreover,ecosystem services were more strongly and positively correlated with precipitation than with temperature.The greening of desert areas and forest land expansion could improve ecosystem services,but unreasonable development of cropland and urbanization have had an adverse impact on ecosystem services.According to the results,ecological stability in Central Asia can be achieved through the natural vegetation protection,reasonable urbanization,and ecological agriculture development.

Forecasting Loss of Ecosystem Service Value Using a BP Network: A Case Study of the Impact of the South-to-north Water Transfer Project on the Ecological Environmental in Xiangfan, Hubei Province, China

Objective To recognize and assess the impact of the South-to-north Water Transfer Project (SNWTP) on the ecological environment of Xiangfan, Hubei Province, situated in the water-out area, and develop sound scientific countermeasures. Methods A three-layer BP network was built to simulate topology and process of the eco-economy system of Xiangfan. Historical data of ecological environmental factors and socio-economic factors as inputs, and corresponding historical data of ecosystem service value (ESV) and GDP as target outputs, were presented to train and test the network. When predicted input data after 2001 were presented to trained network as generalization sets, ESVs and GDPs of 2002, 2003, 2004... till 2050 were simulated as output in succession. Results Up to 2050, the area would have suffered an accumulative total ESV loss of RMB 104.9 billion, which accounted for 37.36% of the present ESV. The coinstantaneous GDP would change asynchronously with ESV, it would go through an up-to-down process and finally lose RMB89.3 billion, which accounted for 18.71% of 2001. Conclusions The simulation indicates that ESV loss means damage to the capability of socio-economic sustainable development, and suggests that artificial neural networks (ANNs) provide a feasible and effective method and have an important potential in ESV modeling.

Spatio-temporal Changes in Water Conservation Ecosystem Service During 1990–2019 in the Tumen River Basin, Northeast China

The water conservation(WC) function of ecosystems is related to regional ecological security and the sustainable development of water resources, and the assessment of WC and its influencing factors is crucial for ecological and water resource management.The Tumen River Basin(TRB) is located in the core of the Northeast Asian ecological network and has been experiencing severe ecological crises and water shortages in recent years due to climate change and human activities. However, these crises have not been fully revealed to the extent that corresponding scientific measures are lacking. This study analyzed the spatial and temporal evolution characteristics and drivers of WC in the TRB from 1990 to 2019 based on the water yield module of the Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST) model. The results showed that: 1) under the combined effect of nature and socioeconomics, the WC depth of the TRB has slowly increased at a rate of 0.11 mm/yr in the past 30 years, with an average WC depth of 36.14 mm. 2) The main driving factor of the spatial variation in WC is precipitation, there is a significant interaction between precipitation and velocity, the interaction between each factor is higher than the contribution of a single factor, and the interactions between factors all have nonlinear enhancement and two-factor enhancement. 3) Among the seven counties and municipalities in the study area, the southern part of Helong City and the southeastern part of Longjing City are extremely important areas for WC(> 75 mm), and they should be regarded as regional water resources and ecological priority protection areas. It is foreseen that under extreme climate conditions in the future, the WC of the watershed is under great potential threat, and protection measures such as afforestation and forestation should begin immediately. Furthermore, the great interannual fluctuations in WC depth may place more stringent requirements on the choice of time scales in the ecosystem service assessment process.

Evaluation and Quantitative Attribution Analysis of Water Yield Services in the Peak-cluster Depression Basins in Southwest of Guangxi,China

Karst environmental issues have become one of the hot spots in contemporary international geological research. The same problem of water shortage is one of the hot spots of global concern. The peak-cluster depression basins in southwest of Guangxi is an important water connotation and ecological barrier areas in the Pearl River Basin of China. Thus, studying the spatial and temporal variations and the influencing factors of its water yield services is critical to achieve the sustainable development of water resources and ecological environmental protection in this region. As such, this paper uses the Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST) model to assess the spatial and temporal variabilities of water yield services and its trends in the peak-cluster depression basins in southwest of Guangxi from 2000 to 2020. This work also integrates precipitation(Pre), reference evapotranspiration(ET), temperature(Tem), digital elevation model(DEM), slope, normalized difference vegetation index(NDVI), land use/land cover(LULC) and soil type to reveal the main factors that influence water yield services with the help of Geodetector. Results show that: 1) in time scale,the total annual water yield in the study area show a fluctuating and increasing trend from 2000 to 2020, with a growth rate of 7.3753 × 10^(8)m^(3)/yr, and its multi-year average water yield was 538.07 mm;2) in spatial pattern, with high yield areas mainly distributed in the south of the study area(mainly including Shangsi County, Pingxiang City, Ningming County, Longzhou County and Jingxi County), and low yield areas mainly distributed in Baise City and Nanning City;3) the dominant factor of water yield within karst and non-karst landforms is not necessarily controlled by precipitation, and the explanation degree of DEM factors in karst areas is significantly higher than that in non-karst areas;4) amongst the climatic factors, Pre, ET and Tem are dominant in the spatial pattern of region water yield capacity. among which Pre has the highest explanatory power for the spatial heterogeneity of annual water production, with q values above0.8, and each driver showed a significant interaction on the spatial distribution of water yield, with Pre exhibiting the strongest interaction with LULC.

Benefits Evaluation of Water Resources Used for Ecosystem in Shiyang River Basin of Gansu Province

Among the numerous inland river basins in the arid northwest China,Shiyang River basin is known for its most serious water shortage that constrains its social and economic developments and for some of the worst ecological and environmental deterioration in China.The research on the value of water resources used for ecosystem is the basis for reasonable allocation of water resources between users of ecosystem and economic system.In this paper the concept of dynamic value for the ecosystem services is proposed.A modified coefficient for the ecosystem service value per unit area is proposed according to the cover degrees of biomes combined with expert consultation.Based on the developmental stage coefficient and scarcity of ecological resources,a dynamic evaluation method is proposed.The theoretical formula and simple calculation formula of the sharing benefits coefficient and benefits per unit ecological water utilization are proposed.The result shows that the benefit of unit ecological water utilization in the lower reach was greater than that in the upper reach in the Shiyang River basin.

Spatiotemporal evolution of water conservation function and its driving factors in the Huangshui River Basin, China

The Grain for Green project has had a substantial influence on water conservation in the Huangshui River Basin,China through afforestation and grassland restoration over the past two decades.However,a comprehensive understanding of the spatiotemporal evolution of water conservation function and its driving factors remains incomplete in this basin.In this study,we utilized the Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST)model to examine the spatiotemporal evolution of water conservation function in the Huangshui River Basin from 2000 to 2020.Additionally,we employed the random forest model,Pearson correlation analysis,and geographical detector(Geodetector)techniques to investigate the primary factors and factor interactions affecting the spatial differentiation of water conservation function.The findings revealed several key points.First,the high-latitude northern region of the study area experienced a significant increase in water conservation over the 21-a period.Second,the Grain for Green project has played a substantial role in improving water conservation function.Third,precipitation,plant available water content(PAWC),grassland,gross domestic product(GDP),and forest land were primary factors influencing the water conservation function.Finally,the spatial differentiation of water conservation function was determined by the interactions among geographical conditions,climatic factors,vegetation biophysical factors,and socio-economic factors.The findings have significant implications for advancing ecological protection and restoration initiatives,enhancing regional water supply capabilities,and safeguarding ecosystem health and stability in the Huangshui River Basin.