Dam failure analysis and flood disaster simulation under various scenarios.

The aim of this study is to analyze the effects of a possible dam failure under various scenarios and to generate a flood hazard map for two consecutive dams located in a study area with a dense-residential region and a heavy-traffic highway. Two consecutive dams consist of Elmali 2, a concrete-buttress dam and Elmali 1, an earth-fill gravity dam in the upstream and downstream, respectively. Hydrologic Engineering Center-River Analysis System (HEC-RAS) was used to develop a dam failure model. Dam failure scenarios were examined regarding three main criteria: the Breach Formation Time (BFT), the Number of Failed Buttresses (NFB) of Elmali 2, and the Reservoir Volume Ratio (RVR) of Elmali 1. Accordingly, flood peak depth (Hp), peak flow rate (Qp), peak velocity (vp), and time to reach the peak (tp) are discussed. The results showed that BFT and NFB of Elmali 2 were highly effective on these values, whereas RVR of Elmali 1 had no significant effect. Moreover, the total area affected by potential floods was calculated with a comparative areal change analysis using flood inundation and flood hazard maps obtained. Estimated damage costs indicate that in the worst-case scenario, more than 500 buildings will be affected in the region.

Hydrological performance of rain gardens having Calendula officinalis plant with varied planting mixtures.

The rain gardens (RGs) have been one of the best management practices in cities to reduce the impact of urban flooding. However, very little is known about various design parameters of RGs, viz., the type of plantation, planting mixtures, and RG dimensions. This study pertains to examining the influence of planting mixtures on the variations of percolation rates of the RG with Calendula officinalis plant and without plants. Six types of planting mixtures in different experimental RGs have been tried. It has been observed that the percolation rate increases with a higher percentage of compost in the planting mixture for RGs with and without plants. The percolation rate is highest for the planting mixture having 25% compost. The runoff rate reduces with a higher percentage of compost in the planting mixture for RGs with C. officinalis and bare surfaces. No runoff is produced in RGs with plant having a compost of more than 20% in the planting mixture. The outcome of the study will be useful in deciding the composition of the planting mixture which will keep the RG plant healthy and at the same time improve the hydrological performance leading to lowering urban flooding magnitude.

The concept for innovative Comprehensive Assessment of Lowland Rivers.

Current river assessment methods focus on evaluating a single aspect (e.g. the physical and chemical quality of the water or its hydromorphological state) and usually do not integrate various factors. The lack of an interdisciplinary method makes it difficult to correctly assess the condition of a river as a complex ecosystem significantly influenced by humans. This study aimed to develop a novel Comprehensive Assessment of Lowland Rivers (CALR) method. It is designed to integrate and evaluate all-natural and anthropopressure-related elements that influence a river. The CALR method was developed using the Analytic Hierarchy Process (AHP). The application of the AHP allowed the assessment factors to be determined and given weights to define the importance of each assessment element. As a result of AHP analyses, the following ranks were determined for the six main parts of the CALR method: hydrodynamic assessment (0.212), hydromorphological assessment (0.194), macrophyte assessment (0.192), water quality assessment (0.171), hydrological assessment (0.152) hydrotechnical structures assessment (0.081). In the comprehensive assessment of lowland rivers, each of the six elements listed above is rated on a scale of 1-5 (where 5 means very good and 1 bad) and multiplied by an appropriate weighting. After summing up the obtained results, a final value is obtained, classifying the river. CALR can be successfully applied to all lowland rivers thanks to its relatively simple methodology. The widespread use of the CALR method may facilitate the assessment process and enable the comparison of the condition of lowland rivers worldwide. The research conducted in this article is one of the first attempts to develop a comprehensive method for evaluating rivers that considers all aspects.

Investigating impact of CORDEX-based predicted climatic and LCM-based LULC scenarios on hydrologic response of a semi-gauged Indian catchment.

The present study aims at documenting the impact of different climate and land use change scenarios on runoff in the Kangsabati River basin. While the study relies on India Meteorological Department (IMD), National Oceanic and Atmospheric Administration's Physical Sciences Laboratory (NOAA-PSL), and a multi-model ensemble of six driving models from Coordinated Regional Downscaling Experiment-Regional Climate Models (CORDEX RCM) for climate data input, it depends on IDRISI Selva's Land Change Modeller (LCM) and Soil and Water Assessment Tool (SWAT) model to generate projected land use land change maps and simulate its streamflow response, respectively. A total of four land use and land cover (LULC) scenarios, representing four projected land use change, were modelled across three climatic scenarios, called Representative Concentration Pathways (RCPs). With runoff being predominantly impacted more by climate change than LULC, volumetric runoff is expected to be 12-46% higher than the baseline period of 1982-2017. Conversely, while surface runoff is expected to decrease by 4-28% in lower parts of the basin, it will increase by 2-39% in the rest of it, depending on the subtle alterations in land use and climatic variability.

National-scale geodatabase of catchment characteristics in the Philippines for river management applications.

Quantitative descriptions of stream network and river catchment characteristics provide valuable context for enabling geomorphologically-informed sustainable river management. For countries where high-quality topographic data are available, there are opportunities to enable open access availability of baseline products from systematic assessment of morphometric and topographic characteristics. In this study, we present a national-scale assessment of fundamental topographic characteristics of Philippine river systems. We applied a consistent workflow using TopoToolbox V2 to delineate stream networks and river catchments using a nationwide digital elevation model (DEM) acquired in 2013 and generated through airborne Interferometric Synthetic Aperture Radar (IfSAR). We assessed morphometric and topographic characteristics for 128 medium- to large-sized catchments (catchment area > 250 km2) and organised the results in a national-scale geodatabase. The dataset realises the potential of topographic data as part of river management applications, by enabling variations in hydromorphology to be characterised and contextualised. The dataset is used to reveal the diversity of stream networks and river catchments in the Philippines. Catchments have a continuum of shapes (Gravelius compactness coefficient ranges from 1.05 to 3.29) with drainage densities that range from 0.65 to 1.23 km/km2. Average catchment slope ranges from 3.1 to 28.1° and average stream slope varies by more than an order of magnitude from 0.004 to 0.107 m/m. Inter-catchment analyses show the distinctive topographic signatures of adjacent river catchments; examples from NW Luzon highlight topographic similarity between catchments whereas examples from Panay Island shown marked topographic differences. These contrasts underline the importance of using place-based analyses for sustainable river management applications. By designing an interactive ArcGIS web-application to display the national-scale geodatabase, we improve data accessibility and enable users to freely access, explore and download the data (https://glasgow-uni.maps.arcgis.com/apps/webappviewer/index.html?id=a88b9ca0919f4400881eab4a26370cee). The national-scale geodatabase provides a baseline understanding of fundamental topographic characteristics in support of varied geomorphological, hydrological and geohazard susceptibility applications.

Ecological Flow Response Analysis to a Typical Strong Hydrological Alteration River in China.

Ecological flow is an important indicator for reflecting the stability of a watershed ecosystem. The calculation of ecological discharge under hydrological variation has become a research hot-spot. The Ganjiang River south of Poyang Lake in China was taken as an example in this study. Hydrological Alteration Diagnosis System methods were used to detect the change-points. The Distributed Time Variation Gain Model (DTVGM) was used to carry out runoff restoration. The Probability-weighted Flow Duration Curve was applied to calculate the ecological flow. The results showed that: (1) The hydrological alteration of the Waizhou Station occurred in 1991, the annual runoff increased by 10%, and the Gini coefficient (GI) increased by 0.07 after the change-point. The change in precipitation was the main driving factors. (2) The R value and NSE of the DTVGM were greater than 0.84, which represents the feasibility of the model used to restore runoff. (3) Compared to the traditional hydrological method, the proposed method can better reflect the inter-annual difference of ecological flow, flow ranges for high, normal, and low flow years are 398-3771 m3/s, 352-2160 m3/s, and 277-1657 m3/s, respectively. The calculation method of ecological flow in rivers considering hydrological variation can more scientifically reflect the impact of hydrological variation on ecological flow process, ecological flow under different human activities that can be calculated, such as dam control, water intake and water transfer, furthermore, it also provides a scientific basis for water resources planning and allocation under changing environment.

Stormwater quantity and quality control performance of bioretention systems: A literature review.

Bioretention systems, as one of the most widely used modern stormwater management tools, have outstanding performance in capturing runoff, mitigating peak flow, delaying outflow occur time, and improving effluent quality. We reviewed the research of hydrologic and water quality performance of bioretention systems around the world from different perspectives, including the structure and classification of bioretention systems, the mechanisms of runoff and pollutants regulation of bioretention systems, the hydrologic and water quality performances of bioretention systems, the runoff control and water purification evaluation models of bioretention systems, as well as the influencing factors of runoff control and water purification efficiency. We proposed that future research should focus on hydrologic and water quality of bioretention systems, e.g., optimization of design configurations, revealing the mechanisms of plant action, revealing the mechanisms of microbial action, the effects of climate change on hydrologic and water quality performance, watershed/regional scale hydrologic and water quality performance, purification effect and mechanisms of emerging pollutants, maintenance methods, as well as life-cycle assessment and cost analysis. This review would provide theoretical and technical supports for research, design, construction, and maintenance of bioretention systems.

Drought and water availability analysis for irrigation and household water needs in the Krueng Jrue sub-watershed.

This study aimed to analyze drought conditions and evaluate irrigation water availability and household water needs in the Krueng Jrue sub-watershed, Aceh Province, Indonesia. The Z-score statistics method was developed to analyze the drought, and the Mock model was used to generate discharges. We performed model validation using linear regression, which produced a coefficient of determination (R 2 = 0.90**) and coefficient of regression (r = 0.95**). In general, this area had a normal Z-score for precipitation (ZSP) class with 90 events (75%) and a normal Z-score for a discharge (ZSD) class with 89 events (74.2%). There were 0-11 (0-9.2%) moderate wet, very wet, extreme wet, moderate drought, and severe drought events. The consistency between the ZSP and ZSD indices reached 85.8%, indicating consensus between the meteorological droughts that were analyzed based on rainfall (ZSP) and hydrological droughts analyzed based on water discharge (ZSD). ZSP and ZSD indices showed negative values during the dry season (April to September) and positive values during the rainy season (October to March). There was a surplus of water availability for irrigation and household water needs during the rainy season and a deficit during the dry season. However, water deficits also occurred in certain months during the rainy rendeng planting season, for example, in October 2009, 2013, 2016, and 2017 as well as in February between 2008 to 2011 and from 2014 to 2017. This observation was probably due to the influence of global climate variables that need to be substantiated. This study offers necessary information for farmers, the community, and the local government when anticipating drought phenomenon, organizing the rice planting season, and evaluating water availability in other watersheds.

[Comparison on the stormwater runoff effects of roof greening in different urban functional areas]. / 不同城市功能区实施屋顶绿化的雨洪调控效应比较.

Global climate change and the expansion of impervious surface in urban areas have increased the risk of urban flood. As a measure with low impact development (LID), roof greening can effectively reduce stormwater runoff, serving as the first barrier to prevent rainwater from entering the urban drainage system. We used the CITYgreen model to simulate and analyze the impacts of roof greening on hydrological parameters (e.g., surface runoff) in the new and old residential areas and the commercial areas in Nanjing City, and further investigated the variations in stormwater runoff effects (SRE) among these functional areas. We compared the SRE between different green roof types, and between green roofs and ground-level green spaces. The results showed that the proportion of permeable surface would increase by 28.9%, 12.5% and 49.2% respectively in the old residential area, new residential area and commercial area if all building roofs were greened. In a rainfall event with a return period of two years and a duration of 24 hours (precipitation=72 mm), the implementation of roof greening in all buildings in the three sampling areas could reduce surface runoff by 0-19.8% and reduce peak flow by 0-26.5%. The reductions in runoff by green roofs could be translated to a rainwater storage capacity of 223-2299 m3. The commercial area had the highest SRE by installing green roofs, followed by the old residential area, while the new residential area had the lowest SRE. The rainwater storage volume by per unit area of extensive green roof was about 78.6%-91.7% that of the intensive green roof. The storage capacity by per unit area of green roof was 31%-43% of that in the ground-level greenery. The results would provide scientific references for the site selection, sustainable design and incentive development of roof greening from the perspective of stormwater management.

Modelling-based methodological approach to assess the effect of urbanization on hydrology and runoff water quality: a case of study for tropical and dry regions.

It is necessary to have unified tools and methodologies for the correct understanding and quantification of urbanization effects on watershed hydrology. This study presents a modelling-based methodology developed on EPA SWMM to evaluate the effect of urbanization in conceptual watersheds using meteorological data from cities in Spain and Colombia. Results show that the effect of urbanization is significant in variables such as runoff volume, peak flow and pollutant loads, increasing these indicators in all cases. Furthermore, this effect has different dynamics for the regions evaluated. Overall, Colombian cities presented higher runoff volumes, peak flows and pollutant loads, while Spanish cities presented higher variability in these variables due to urbanization. The analysis allowed to cluster the cities within each country, using as criteria the modelled hydrological behaviour. A curve fitting procedure presented high performance rates for all the variables studied.

A river basin spatial model to quantitively advance understanding of riverine tree response dynamics to water availability and hydrological management.

Ecological condition continues to decline in arid and semi-arid river basins globally due to hydrological over-abstraction combined with changing climatic conditions. Whilst provision of water for the environment has been a primary approach to alleviate ecological decline, how to accurately monitor changes in riverine trees at fine spatial and temporal scales, remains a substantial challenge. This is further complicated by constantly changing water availability across expansive river basins with varying climatic zones. Within, we combine rare, fine-scale, high frequency temporal in-situ field collected data with machine learning and remote sensing, to provide a robust model that enables broadscale monitoring of physiological tree water stress response to environmental changes via actual evapotranspiration (ET). Physiological variation of Eucalyptus camaldulensis (River Red Gum) and E. largiflorens (Black Box) trees across 10 study locations in the southern Murray-Darling Basin, Australia, was captured instantaneously using sap flow sensors, substantially reducing tree response lags encountered by monitoring visual canopy changes. Actual ET measurement of both species was used to bias correct a national spatial ET product where a Random Forest model was trained using continuous timeseries of in-situ data of up to four years. Precise monthly AMLETT (Australia-wide Machine Learning ET for Trees) ET outputs in 30 m pixel resolution from 2012 to 2021, were derived by incorporating additional remote sensing layers such as soil moisture, land surface temperature, radiation and EVI and NDVI in the Random Forest model. Landsat and Sentinal-2 correlation results between in-situ ET and AMLETT ET returned R2 of 0.94 (RMSE 6.63 mm period-1) and 0.92 (RMSE 6.89 mm period-1), respectively. In comparison, correlation between in-situ ET and a national ET product returned R2 of 0.44 (RMSE 34.08 mm period-1) highlighting the need for bias correction to generate accurate absolute ET values. The AMLETT method presented here, enhances environmental management in river basins worldwide. Such robust broadscale monitoring can inform water accounting and importantly, assist decisions on where to prioritize water for the environment to restore and protect key ecological assets and preserve floodplain and riparian ecological function.

Optimal designs of LID based on LID experiments and SWMM for a small-scale community in Tianjin, north China.

Urban flooding and waterlogging are becoming increasingly serious due to rapid urbanization and climate change. The stormwater management philosophy of low-impact development (LID) has been applied in urban construction to alleviate these problems. The selection and placement of LID designs are the most important tasks. In this study, LID experiments were performed to calibrate the Storm Water Management Model (SWMM). Then, a multi-objective optimization model, which adopted the minimum surface runoff coefficient, surcharge time, and investment cost as objectives, was established by coupling the SWMM and non-dominated sorting genetic algorithm-II (NSGA-II). Hydrological simulations were performed with the SWMM, and optimal calculations were conducted with NSGA-II. Real-coded optimal variables containing detailed size and location information of multiple LID measures were generated, and a decision space for LID design selection was obtained. The optimization designs reduced the surface runoff coefficient from 0.7 to approximately 0.5, the conduit surcharge duration was reduced from 1.62 h to 0.04-0.47 h, and the total investment cost only ranged from 395,000-872,000 ¥. Thus, the optimization model could achieve synchronous optimization of all objectives. This study could provide valuable information for LID design with the aim of urban flooding and waterlogging control.

Recent water-level fluctuations, future trends and their eco-environmental impacts on Lake Qinghai.

The water level of Lake Qinghai, the largest lake on the Qinghai-Tibetan Plateau, has increased continuously, at an average speed of 0.21 m per year since 2005, causing a rapid expansion of the lake area. We investigated the hydrological processes of Lake Qinghai and the surrounding watershed that have influenced water level and lake area from 1956 to 2019. Relationships among water level, climate change and human activities were also assessed. Water level and lake area were positively correlated with precipitation and runoff into the lake, and negatively correlated with evaporation. Climate change factors including precipitation and runoff were the primary causes of lake level change, whereas human activities, including variation in a human footprint index, land use, and grassland irrigation, were secondary factors. A time series model forecasted that from 2020 to 2050 water levels will increase further by 2.45 m. Although this increase in water level may have some benefits, such as reduced local desertification, the expansion of lake area will continue to flood low beaches, pasture lands, near shore infrastructure and roads, and impact tourism locations. However, continued water level rise may also have negative ecological effects, such as reduce habitat of seasonal birds and reduced water quality due to erosion and sediment resuspension in shallow nearshore lake areas. Local stakeholders, government authorities, and scientists should give greater attention to anticipated changes in water level, and further ecological studies and infrastructure adaptation measures should be implemented.

Inter-basin water diversion homogenizes microbial communities mainly through stochastic assembly processes.

Inter-basin water transfer is an effective manner to achieve the optimal allocation of water resources, while accompanied by some ecological effects. The responses of microorganisms to water diversion and the ecological processes in regulating the community assembly are still unclear. Taking the eastern route of South-to-North Water Diversion Project as the study area, we investigated the microbial community patterns and the underlying assemblage processes in habitats with different hydrological connectivity, including isolated lakes, connected lakes and man-made canal. The results showed that microbial communities in the canal had higher diversity, lower dissimilarity, weaker compositional variation, and stronger co-occurrence patterns compared with that in the connected and isolated lakes. These findings suggested that the increase of connectivity among natural aquatic habitats due to water diversion can homogenize microbial communities and reduce microbial heterogeneity. The neutral and null models demonstrated the importance of stochastic processes in shaping microbial community assembly. Dispersal limitation and variable selection were the predominant mechanisms structuring microbial communities in the isolated lakes. Due to the homogenized environmental condition and the enhanced hydrologic connectivity in the canal and the connected lakes, microbial communities had higher dispersal capability and ecological drift occurred more frequently in these lotic habitats. The variations in microbial community structure were mainly driven by biotic ecological succession than abiotic factors, with positive and negative cohesion explained 63% and 25% of variability, respectively. Six taxa were considered as the potential introduced microorganisms, which may favor the nutrient biogeochemical cycling and the organic matter degradation, but may also bring ecological risks. Overall, this study provides a deeper understanding of the ecological consequences of inter-basin water diversion, and helps the regulation and management of these projects.

Characteristic of water quality indicators and its response to climate conditions in the middle and lower reaches of Lijiang River, China.

With global climate change and increasingly extreme weather conditions, the water quality of the Lijiang River Basin (LRB) is facing huge threats. At present, there is still a lack of systematic research on water quality indicators and the influence of indirect factors such as meteorological factors on it in the LRB. Therefore, this study is based on the meteorological, hydrological, and water quality data of the LRB from 2012 to 2018, using the Mann-Kendall test, Morlet wavelet method, Spearman's rank correlation coefficient, sensitivity, and contribution rate to quantitative analysis of the relationship between climate conditions and water quality indicators. The results show that the change trends of these hydrological and climatic conditions have almost no significant sudden change; precipitation and streamflow are decreasing each year; the streamflow trend exhibits time hysteresis; precipitation has a stronger influence downstream than on the local area; water quality indicators of both stations exhibited a change period of around 18 to 20 months, with the exception of pH. Water quality indicators are insensitive to precipitation and streamflow, and sensitive to humidity and wind speed; DO was negatively correlated with climate indicators apart from wind speed; almost all water quality indicators in Yangshuo are highly sensitive to air temperature, and the contribution rate of air temperature to ORP and TP reached 4.81% and 3.56%, respectively; sunshine duration has a positive impact on reducing NH4-N and TP. The difference between Yangshuo and Guilin is mostly due to the input of external sources on both sides of the Lijiang River, which results in variations in climate conditions sensitivities.

Monitoring groundwater storage in a fractured volcanic aquifer system.

The use of groundwater resources is under increasing pressure to meet the demands of the society. Despite this, the understanding of its availability is still limited when compared to other water reserves. The aquifer studied was the volcanic Serra Geral Aquifer System (SASG) located in a humid subtropical region. This research aims to explore in a pioneering way the large-scale hydrogeological processes taking place at the SASG using a unique and complementary tool of intensive field monitoring, remote sensing data, and hydrological modeling. Results showed a fast response of groundwater levels to rainfall, with an average of 29 days of lag times. We also identified areas in the southern region of the basin with higher depletion rates, with GRACE results indicating a negative trend (- 57 mm year-1) associated with a major recharge event that occurred in the region before the period monitored. Also, the interflow calculated using the MGB hydrological model showed that the flow within the limits between the soil and the volcanic rocks (different in hydraulic conductivity) varies spatially, influencing the baseflow of rivers as for slopes and soil capacity to store water.

Integrated effects of co-evolutions among climate, land use and vegetation growing dynamics to changes of runoff quantity and quality.

Climates, Land use/land cover (LULC) and vegetation growing dynamics have been regarded as the main factors affecting terrestrial hydrological process. However, the mechanisms underlying their integrated effects on terrestrial runoff and nutrient dynamics are not understood well. Here, we constructed a framework to disentangle and quantify the independent and coupled contributions of climate, LULC and vegetation leaf area index (LAI) changes to watershed runoff and nutrient yields changes. Long series of changing meteorological, LULC and LAI data between 1990 and 2020 were integrated into a factor-controlled simulation protocol in a distributed hydrological model, to quantify their comprehensive contributions (individual contribution of single factor change and coupling contribution of multiple factor synchronous changes) to runoff and nutrient changes. The results showed that changes of runoff and nutrient yields are more induced by climate change, rather than LULC and LAI transformations. Increase in annual precipitation significantly elevated runoff and nutrient yields. TP yield was more sensitive to climate change than runoff and TN yields. LULC transformation and climate change have synergistic effects on runoff and nutrient yields. Shift of vegetation areas to construction lands will amplify the effect of climate change on runoff and nutrient yields. Single LAI change has weak effect on runoff and nutrient yields, but it can significantly alter the hydrological effects derived from climate change and the synergistic effects between climate change and LULC transformation. This study considered the coupling and potential synergistic effects among climate change, LULC conversion and LAI variation, which elucidated the comprehensive effects of changing environment on runoff and nutrients evolutions in a more systematic and integrated perspective.

An integrated model for prediction of hydrologic anomalies for habitat suitability of overwintering geese in a large floodplain wetland, China.

Climate anomalies and increasing human activities cause a high frequency of extreme hydrological events in wetlands, which has put waterbirds under greater survival pressure than ever. Therefore, it is crucial to predict the impact of this phenomenon on the habitat suitability of waterbirds. This study investigated the response of the goose distribution probability to hydrological variations using the flood duration index (FD), enhanced vegetation index (EVI), and waterbirds GPS tracking data in Poyang Lake. An overwintering geese habitat suitability index (HSI) is built based on the FD, EVI, and threat index and verifies the accuracy of the model simulation. Then, the effects of drought and flood on the goose habitat especially sub-lakes with different connectivity were analyzed. The findings reveal that in dry and flood years, geese will broaden their range of feeding vegetation (more fresh or mature vegetation) in response to environmental deterioration. Both drought and flood can lead to a decline in the HSI, especially flood. Connected sub-lakes are more vulnerable to hydrological anomalies than controlled sub-lakes. This research establishes a scientific foundation for floodplain wetland hydrology management and waterbird conservation.

Optimizing payment for ecosystem services in a drinking water source watershed by quantifying the supply and demand of soil retention service.

Payment for ecosystem services (PES) plays a vital role in coordinating the relationship between ecosystem services supply and demand sides in watersheds. The upstream soil retention service brings significant off-site benefits to the downstream stakeholders. To fill gaps in the supply and demand of soil retention services for PES, we developed an approach that combined long-term observation data, hydrological model, and cost-benefit analysis. We applied and demonstrated the approach in a typical drinking water source watershed. By constructing the relationship between water clarity and the demanded trophic state, we identified the demand for soil retention as the suspended sediment concentration ≤4.4 mg L-1 at a transboundary station. Then, a well-calibrated hydrological model was applied to simulate the downstream sediment reduction under 36 upstream reforestation scenarios. Results showed that cropland reforestation effectively reduced downstream sediment loads by up to 37.8%. However, the efficiency of cropland reforestation for soil retention supply was influenced by its area, slope, and location. The cost-benefit analysis revealed that the feasible sediment reduction was 11,000 t per year, and the market-equilibrium price was 5800 CNY (Chinese Yuan, 7 CNY equaled 1 USD in 2020) per ton. The downstream side should pay 64 million CNY annually for soil retention provided by reforesting at upstream sloping cropland of 8° or above. This study suggested that the approach was helpful for integrating soil retention service supply and demand at a watershed scale to support PES decision-making.