Wuding River Basin Research Articles

Watershed landscape characteristics and connectivity drive river water quality under seasonal dynamics

Landscape characteristics and connectivity are pivotal determinants of river water quality within the context of water quality management. They play particularly important roles in the spread of non-point source pollution. However, previous research has not investigated their combined effects, especially in the topographically and ecologically volatile Loess Plateau, China. This study applied machine learning and positive matrix factorization techniques to water quality monitoring data for the Wuding River basin, China, from 2017 to 2021 to assess the seasonal impacts of environmental factors on river water quality. The results showed that there were spatial and seasonal variations in pollution sources, and specific thresholds for the key landscape indices that influence water quality were identified. Landscape composition and configuration have the greatest influence on the water quality parameters during the dry season, whereas connectivity and landscape configuration are more critical during the wet season. The connectivity contributions to chemical oxygen demand, the potassium permanganate index, and total phosphorus in the wet season were 19.07%, 27.47%, and 5.08% greater than in the dry season, respectively. Connectivity also made a significant contribution to the composite water quality index, accounting for 33.46% in the dry season and 36.22% in the wet season. The positive matrix factorization model identified agricultural non-point sources and mixed pollutants as the main factors affecting water quality during the dry season, whereas erosion and mixed pollution sources dominated the wet season. Critical thresholds were established for the landscape indices that affected water quality, such as a landscape shape index below 18.5 and a grassland proportion above 65%. The results can be used to develop more effective water quality management strategies and illustrate the essential role played by connectivity when tailoring water quality management strategies to seasonal variations.

Microplastic pollution characteristics and ecological risk assessment in the Wuding River Basin, China

Microplastics (MPs), as a new type of environmental pollutant, have attracted extensive attention in recent years. However, there has been relatively little research specifically focusing on MPs in the Yellow River Basin, China, particularly regarding MP migration patterns. Based on surface water and sediment samples from 19 sampling sites in the Wuding River (WDR), the abundances and characteristic distributions of MPs were analyzed, and the environmental factors affecting their distribution and potential ecological risks were evaluated. The results showed that the MP abundances in surface water and sediments of the WDR were significantly different (P < 0.05), with mean values of 2.98 ± 0.69 items/L and 419.47 ± 75.61 items/kg, respectively. In terms of MP characteristics, the most common size class was 0.1–0.5 mm in surface water. Polyethylene (PE, 32.50%) and polypropylene (PP, 27.50%) were the main polymer types of MPs in surface water. Although similar MP characteristics were observed in sediments, there were significantly more particles in the <0.1 mm particle size (P < 0.05), which was 15.0% higher than in surface water. Also, more high-density MP fragments were observed in sediment samples. The retention of MPs in sediments was influenced by the MP characteristics (density, shape, particle size) and sediment particle size. In contrast, the MP abundance in surface water was more closely related to the presence of other environmental pollutants, such as total phosphorus (WTP) and ammonia nitrogen (WAN). Temperature (T), agricultural land (AGR), and residential land (RES) only had significant effects on the distribution of MPs in surface water (P < 0.05). Potential ecological risk assessments revealed that MP pollution in sediments was more serious than in surface water, especially in the middle and lower reaches. The results of this study are important for understanding MP transport in a sandy river and for eliminating potential sources of MPs.

Cumulative sedimentation hazard map of urban areas subject to hyperconcentrated flash flood: A case study of Suide County in the Wuding River basin, China

AbstractFlash floods can carry substantial sediment, posing significant sedimentation hazards in hilly cities. The sedimentation hazard map can reproduce the sediment thickness and extent of an extreme events scenario, playing an important role in sediment risk management. However, current research primarily focuses on modeling the inundation area and depth of floods, while studying sedimentation hazard caused by flash floods in urban areas remains insufficient. This paper aims to address this gap by utilizing a numerical model that simulates hyperconcentrated flow in hilly urban areas using the two‐dimensional hydro‐sediment‐morphological model to compile the cumulative sedimentation hazard map. The model, built upon the open‐source TELEMAC‐MASCARET framework, incorporates Zhang Hongwu's formula to simulate sediment‐carrying capacity, particularly suitable for hyper‐sediment concentration near the riverbed. This paper uses the data of extreme flash flood events in the Wuding River basin in 2017 to simulate and compile the cumulative sedimentation hazard map. The hazard map delineates the sedimentation hazard extent and level attributable to overbank floodplain sedimentation. Notably, the sediment thickness is highest in areas near the levees on both sides of the Dali River. Moreover, the map illustrates the extent of channel erosion resulting from hyperconcentrated floods, which could jeopardize bank stability.

Coupling Changes in Runoff and Sediment and Their Relationships with Erosion Energy and Underlying Surface in the Wuding River Basin, China

Investigating the changes in the runoff and sediment coupling relationship in the Middle Yellow River Basin of China can not only deepen the understanding of soil loss control in arid areas, but also help solve key issues of regional ecological protection. Since the 1960s, soil- and water-conservation projects have been implemented in the Middle Yellow River Basin, inducing a significant reduction in runoff and sediment and changes in the relationship between runoff and sediment. The study identified the change points of coupling relationship between runoff and sediment in the Wuding River Basin (WRB) by constructing a diagnostic method based on coupling coordination degree and the Pettitt test; the study validated this using the Copula function and analyzed the impacts of erosion energy and underlying surface factors. The results showed the following: (1) the method based on coupling coordination degree and the Pettit test could accurately reflect the coupling relationship of runoff and sediment and identify two change points (1971 and 1996); (2) runoff and sediment in the WRB decreased gradually over three periods (P1, 1960–1970; P2, 1971–1995; P3, 1996–2020), with an average annual runoff of 15.34 × 108, 10.72 × 108, and 8.32 × 108 m3 and average annual sediment load of 1.84 × 108, 0.82 × 108, and 0.32 × 108 t, respectively; (3) the maximum possible joint design value of runoff and sediment under different return periods in P1 were all the highest, followed by P2 and P3, and the larger the return period, the higher the maximum possible joint design value; (4) runoff erosion power could promote runoff and sediment in PE (1960–2020), P1, P2 and P3 at a significant level, check dams and terrace could decrease runoff and sediment significantly in PE, and the highest contribution to runoff reduction was check dam (95.4%), while the highest contribution to sediment reduction was REP (93.8%). The study can provide a new way to analyze the changes in the runoff and sediment relationship and provide scientific support for runoff and sediment regulation in the Middle Yellow River Basin.

Effects of landscape pattern on water quality at multi-spatial scales in Wuding River Basin, China.

Urbanization and agricultural land use have led to water quality deterioration. Studies have been conducted on the relationship between landscape patterns and river water quality; however, the Wuding River Basin (WDRB), which is a complex ecosystem structure, is facing resource problems in river basins. Thus, the multi-scale effects of landscape patterns on river water quality in the WDRB must be quantified. This study explored the spatial and seasonal effects of land use distribution on river water quality. Using the data of 22 samples and land use images from the WDRB for 2022, we quantitatively described the correlation between river water quality and land use at spatial and seasonal scales. Stepwise multiple linear regression (SMLR) and redundancy analyses (RDA) were used to quantitatively screen and compare the relationships between land use structure, landscape patterns, and water quality at different spatial scales. The results showed that the sub-watershed scale is the best spatial scale model that explains the relationship between land use and water quality. With the gradual narrowing of the spatial scale range, cultivated land, grassland, and construction land had strong water quality interpretation abilities. The influence of land use type on water quality parameter variables was more distinct in rainy season than in the dry season. Therefore, in the layout of watershed management, reasonably adjusting the proportion relationship of vegetation and artificial building land in the sub-basin scale and basin scope can realize the effective control of water quality optimization.

Construction of benthic integrated biotic index and health assessment in different soil erosion areas of Wuding River Basin

Construction of benthic integrated biotic index and health assessment in different soil erosion areas of Wuding River Basin

Analysis of Spatial and Temporal Changes in Vegetation Cover and Driving Forces in the Wuding River Basin, Loess Plateau

Vegetation cover in the Loess Plateau region is an important component of ecological protection in the Yellow River Basin, and this study provides a scientific reference for further vegetation restoration. Based on Landsat images and related data, we utilized the dimidiate pixel model and Geodetector method to study the vegetation cover in the Wuding River Basin from 2000 to 2022. The results indicated the spatial and temporal distribution of the vegetation cover and its changes over the study period. Additionally, the driving factors influencing its spatial changes were also uncovered. We also propose a land use shift vegetation cover contribution formula to quantify the effect of land type change on the FVC. The study showed that (1) the overall vegetation cover of the watershed increased significantly, and the FVC showed an increasing trend from 2000 to 2013 and a slow decline from 2013 to 2022, with the gradual transformation of low-graded FVC into a higher graded one. (2) The FVC increased spatially from northwest to southeast, and the trend of future changes is mainly decreasing. (3) The strongest explanatory power for the FVC change is the land use type and its interactive combination with rainfall. (4) The conversion of grassland to cropland contributes the most to the vegetation cover at 1.52%, and the increase in the cropland area is more conducive to the increase in the vegetation cover.

Transformative Trends in Runoff and Sediment Dynamics and Their Influential Drivers in the Wuding River Basin of the Yellow River: A Comprehensive Analysis from 1960 to 2020

The correlation between runoff and sediment challenges ecological preservation and sustainable development in the Yellow River Basin. An understanding of the key factors influencing variations in runoff and sediment transport in crucial river basins is essential for effective soil erosion management within the context of ecological and economic development. The Mann–Kendall test, Pettitt test, and Morlet wavelet analysis were employed in the Wuding River Basin to analyze the trends in runoff and sediment changes from 1960 to 2020. We explored the double cumulative curve method to assess the contribution rates of precipitation and human activities to the variability of runoff and sediment transport. We explored the primary factors driving the changes in runoff and sediment transport through random forest regression analysis. (1) From 1960 to 2020, annual precipitation in the Wuding River Basin increased minimally, while annual runoff and sediment transport decreased strongly with abrupt changes. Abrupt changes in annual runoff and sediment transport occurred in 1971 and 1979, respectively. (2) The relationship between runoff and sediment transport changed in approximately 1972 and 2000. The distribution of monthly runoff became more uniform during Periods II (1973–2001) and III (2002–2020) compared to that during the baseline period (1960–1972, Period I), while sediment transport became increasingly concentrated in the flood season. (3) During Period II, the contribution rates of climate and human activities to runoff and sediment transport were 11.94% and −14.5%, respectively, compared to the baseline period. During Period III, the contribution rates of climate and human activities to runoff and sediment transport were −11.9% and −17.7%, respectively. Human activities substantially reduced runoff and sediment, with greater impacts on sediment reduction. Climate weakly influenced basin sediment transport variations. (4) The normalized difference vegetation index (NDVI) and grassland area extent had the greatest impact on runoff, while the NDVI and forest area extent affected sediment transport.

Quantitative analysis of runoff alteration based on the Budyko model with time-varying underlying surface parameters for the Wuding River Basin, Loess Plateau

The evolution of basin runoff is related to water resource development and the safety of the ecological environment. This study took the Wuding River Basin (WRB) as the study area, using trend analysis, significance tests, and the elasticity coefficient method to identify the impact factors of basin runoff change. Based on four Budyko equations and stepwise multiple linear regression analysis, a fitting equation of time-varying underlying surface parameters that considers various factors was constructed, and the contribution rates of climatic and vegetation changes to runoff change were quantified. The WRB Runoff decreased significantly (p ≤ 0.05) at a rate of −0.175 mm∙a−1 during 1982–2019, and precipitation and potential evapotranspiration showed significant increasing trends. Sensitivity of runoff changes to time-varying underlying surface parameters, precipitation, and potential evapotranspiration decreased sequentially. Simulation accuracies of the Budyko equations for runoff changes were significantly improved with time-varying underlying surface parameters. The change of vegetation factors was the dominant factor leading to runoff reduction, and the impact of climatic factors on the runoff change was characterized by “promotion first, inhibition later.” The results provide a reference for water resource development and utilization and the hydrological–ecological response in the Loess Plateau region under a changing environment.

Assessing the contributions of human activities to runoff and sediment transport change: A method for break point identification in double mass curves based on model fitting

Study regionThe upper Yellow River basin, the Wuding River basin, and the Xinshui River basin in China. Study focusThe double mass curve (DMC) is a widely used tool for assessing the contributions of human activities to runoff and sediment transport change. Scientifically identifying break points in the DMC is crucial for the assessment of human activities contribution. This study proposes a DMC break point identification method using model fitting and applies it to three watersheds with different human disturbance intensities, while also highlighting issues that should be considered in the application of DMC. New hydrological insights for the regionCompared to the baseline period, the runoff transport at Toudaoguai, Baijiachuan, and Daning stations decreased by 36.25 %, 43.68 %, and 51.17 %, with human activities contributing 109.64 %, 102.45 %, and 107.85 %, respectively. Human activities contribution was underestimated by 7.21 %, 6.88 %, and 14.45 %, respectively when using break point identification methods only based on runoff. Additionally, the trends in runoff (sediment) transport may not perfectly align with when human activities occur. The effect of human activities and climate change on runoff and sediment transport is not quantified in absolute terms, the human contributions calculated by DMC methods are only relative. The findings of this study can provide a scientific reference for the application of DMC to calculate the contribution of human activities to runoff and sediment transport change.

Do carbon sequestration and food security in urban and rural landscapes differ in patterns, relationships, and responses?

The urbanization process and implementation of various ecological restoration projects have altered the urban-rural landscape patterns and ecosystem services (ESs). Do carbon sequestration and food security, which can be found differences in patterns in both urban and rural landscapes, reflect these relationships and responses? Therefore, taking the Wuding River Basin as an example, we analyzed the variations in carbon sequestration and food security across diverse urban-rural landscapes, and the evolving trade-offs/synergies between them. The results showed that carbon sequestration and food security significantly increased in urban and rural landscapes over the past 20 years, with a greater increase observed in rural landscapes due to a substantial reduction in human pressure. The maximum increase in carbon sequestration occurred at a distance of 16.6 km from human settlements. Population decline significantly strengthened the trade-offs between carbon sequestration and food security in landscapes with high and low agricultural pressure. Conversely, in developed urban landscapes, population decline enhanced the synergistic relationship between carbon sequestration and food security. Understanding the evolving patterns of carbon sequestration and food security in different urban-rural landscapes provides important evidence for developing effective landscape planning and policy strategies, which is of great significance for promoting the sustainability of urban-rural landscapes.

Study on the relationship between ecological spatial network structure and regional carbon use Efficiency: A case study of the Wuding river basin

Plant carbon use efficiency (CUE) reflects the carbon assimilation ability and carbon sequestration potential of organisms, and is an important quantitative index in ecology. Therefore, investigating CUE can better understand and explore ecosystem carbon flux and carbon allocation patterns. In this paper, the Wuding River Basin is taken as the research area. MODIS were used to calculate CUE and explore its spatiotemporal variations. Using remote sensing environmental indicators (RSEI) extract ecological sources, and the MCR model were used to construct an ecological spatial network. By analogy with complex network theory, calculate topological indicators, and combine its ecological significance to investigate the relationship between CUE and these indicators, considering their ecological significance. The results are as follows: (1) The average CUE value slightly increased, with an overall increase in the southeastern part of the study area, minor changes in the southern parts, and an overall decrease in the western and northern parts of the basin. (2) CUE showed a strong positive correlation with closeness centrality, betweenness centrality, harmonic closeness centrality, and a negative correlation with eccentricity, while no significant correlation was found with component number.

ENSO Forcing of Rainfall Erosivity in the Wuding River Basin

Rainfall erosivity (RE) is an important indicator of the ability of rainfall to cause soil erosion and is linked to ENSO through the transport of rainfall. Accurate assessment of RE and improved understanding of RE are essential for soil erosion prediction, optimization of soil and water conservation measures, and ecological management and restoration. Therefore, the Wuding River Basin, a typical ecologically fragile area, is selected as the research area. The erosivity model based on daily rainfall was first used to calculate RE, and the temporal and periodic characteristics of RE are studied. Then the effects of the Southern Oscillation Index (SOI), the Surface Temperature of the Central East Equatorial Pacific Ocean (SST), and the Multivariate ENSO Index (MEI) on RE are explored by using cross wavelet technique. Results indicated that: (1) the concentration of rainfall leads to the largest RE values in summer compared with other seasons, accumulating about 69% of the annual RE; (2) The overall trend of increasing RE in the Wuding River basin is not significant, but shows an abrupt change in 2015; (3) the influence of the SOI and SST indices of ENSO events on RE is significant, which is shown to be a statistically significant correlation (95% confidence level), indicating that ENSO has a strong influence on the changing pattern of RE. These findings are helpful in predicting soil erosion and are significant for developing further erosion control measures.

Temporal and Spatial Distribution Characteristics and Source Analysis of Nitrate in Surface Water of Wuding River Basin

The Wuding River Basin is a first-class tributary of the Yellow River, and the quality of its water ecological environment has a profound impact on the ecological protection and high-quality development of the Yellow River Basin. In order to identify the source of nitrate pollution in the Wuding River Basin, surface water samples of the Wuding River were collected from 2019 to 2021, and the temporal and spatial distribution characteristics and influencing factors of nitrate concentration in surface water in the basin were explored. Nitrogen and oxygen isotope tracer technology and the MixSIAR model were used to qualitatively and quantitatively determine the sources of surface water nitrate and their contribution rates. The results showed that there were significant spatial and temporal differences in nitrate concentrations in the Wuding River Basin. In terms of time, the mean concentration of NO-3-N in surface water in the wet season was higher than that in the flat-water period; spatially, the mean concentration of NO-3-N in the downstream surface water was higher than that in the upstream. The spatial and temporal differences in surface water nitrate concentrations were mainly affected by rainfall runoff, soil types, and land use types. The main sources of nitrates in the surface water of the Wuding River Basin during the wet season were domestic sewage, manure, chemical fertilizers, and soil organic nitrogen, whose contribution rates were 43.3%, 27.6%, and 22.1%, respectively, and the contribution rate of precipitation was only 7.0%. There were differences in the contribution rate of nitrate pollution sources in surface water of different river sections. The contribution rate of soil nitrogen in the upstream was significantly higher than that in the downstream, which was 26.5%. The contribution rate of domestic sewage and manure in the downstream was significantly higher than that in the upstream, which was 48.9%. To provide a basis for the analysis of nitrate sources and pollution control in Wuding River and even rivers in arid and semi-arid regions.

Research on the Relationship between the Structure of Forest and Grass Ecological Spaces and Ecological Service Capacity: A Case Study of the Wuding River Basin

In recent years, the accelerated pace of urbanization has increased patch fragmentation, which has had a certain impact on the structure and ecological environment of forest–grass ecological networks, and certain protection measures have been taken in various regions. Therefore, studying the spatiotemporal changes and correlations of ecological service functions and forest–grass ecological networks can help to better grasp the changes in landscape ecological structure and function. This paper takes the Wuding River Basin as the research area and uses the windbreak and sand fixation service capacity index, soil conservation capacity, and net primary productivity (NPP) to evaluate the ecological service capacity of the research area from the three dimensions of windbreak and sand fixation, soil conservation, and carbon sequestration. The Regional Sustainability and Environment Index (RSEI) is used to extract ecological source areas, and GIS spatial analysis and the minimum cumulative resistance (MCR) model are used to extract potential ecological corridors. Referring to complex network theory, topology metrics such as degree distribution and clustering coefficient are calculated, and their correlation with ecological service capacity is explored. The results show that the overall ecological service capacity of sand fixation, soil fixation, and carbon sequestration in the research area in 2020 has increased compared to 2000, and the ecological flow at the northern and northwest boundaries of the river basin has been enhanced, but there are still shortcomings such as fragmented ecological nodes, a low degree of clustering, and poor connectivity. In terms of the correlation between topology indicators and ecological service functions, the windbreak and sand fixation service capacity index have the strongest correlation with clustering and the largest grasp, while the correlation between soil conservation capacity and eigencentrality is the strongest and has the largest grasp. The correlation between NPP and other indicators is not obvious, and its correlation with eccentricity and eigencentrality is relatively large.

Characteristics, sources and driving factors of riverine CDOM in a severe erosion basin on the Loess Plateau, China

Chromophoric dissolved organic matter (CDOM) plays a crucial role in aquatic ecosystems and biogeochemical processes. The characteristics, sources and influencing factors of riverine CDOM were determined with 56 samples collected in the Wuding River (WDR) Basin in spring and summer. The CDOM optical characteristics varied greatly during different seasons. The mean S275-295 was higher in spring than in summer, while SUVA254 exhibited the opposite result. The mean biological source index (BIX) was lower in summer than in spring, while the mean humification index (HIX) was higher in summer than in spring (p < 0.01). C1 and C3 (humic-like components) and C2 (tryptophan-like component) were extracted by parallel factor analysis (PARAFAC). C1 and C3 were prominent in summer, while C2 was prominent in spring. The effects of environmental factors on CDOM showed great differences. Chlorophyll a (Chla), dissolved organic carbon (DOC), electrical conductivity (EC) and dissolved oxygen (DO) had significant effects on the CDOM concentration (p < 0.05) in spring, while only DOC exerted significant effects on the CDOM concentration in summer. However, water quality parameters played important roles in evaluating the CDOM fluorescence components in summer. Total suspended matter (TSM) and turbidity (Tur) exerted significant effects on the humic-like fluorescence peaks (p < 0.05), while pH, Chla, DO, and EC had significant influences on tryptophan-like substances during this period. Based on redundancy analysis, precipitation, water erosion area and human activity intensity greatly affected the CDOM concentration, C1 and C3, while human activity intensity significantly affected C2 in the sub-basins in summer. CDOM was not significantly influenced by the surrounding environmental factors in spring except for the human activity intensity, which greatly influenced C1 and C3.

基于MaxEnt模型的生态系统服务需求及其簇的空间分异——以陕西省米脂县为例

PDF HTML阅读 XML下载 导出引用 引用提醒 基于MaxEnt模型的生态系统服务需求及其簇的空间分异——以陕西省米脂县为例 DOI: 10.5846/stxb202203270753 作者: 作者单位: 1.西北大学城市与环境学院;2.河南师范大学旅游学院;3.山西财经大学资源型经济转型发展研究院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金(42171256,41971271) Spatial differentiation of ecosystem services demand and its bundles based on MaxEnt model: A case study of Mizhi county, Shaanxi province, China. Author: Affiliation: 1.College of Urban and Environmental Science, Northwest University;2.Research Institute of Resource-based Economics, Shanxi University of Finance & Economics Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:从微观土地利用主体视角量化并明确生态系统服务需求的空间格局对于改善资源依赖地区农户福祉具有重要意义。本文以地处黄土丘陵沟壑区的米脂县为例，基于参与式制图与MaxEnt模型实现10类生态系统服务需求空间评估；同时，采用K-means聚类识别村域服务需求簇，并探究环境变量对服务需求及其簇空间分布的影响。结果如下：① 各类服务需求空间分异明显。供给服务中粮食和肉类供给均呈现中部高东西低的空间格局，水果供给空间分布规律相反；调节服务中土壤保持和空气净化高需求区均分布于高海拔区域，水源涵养高需求区分布于无定河流域；4类文化服务均呈现高、中、低需求区相间分布的空间格局但各等级需求区面积占比差异明显。② 研究区有食物供给需求簇、文化娱乐需求簇和生态保育需求簇等3类。其中，食物供给需求簇是当地主导的需求簇，主要分布在研究区北部和南部；文化娱乐需求簇主要集中在无定河两岸；生态保育需求簇在研究区南部紧邻文化娱乐需求簇，在北部则较为分散。③ 影响各类服务需求空间分布的主导环境因子各不相同；影响食物供给需求簇的环境变量排序为：土地利用＞海拔＞距水体距离，影响文化娱乐需求簇的环境变量排序为：距居民点距离＞距水体距离＞距旅游景点距离，影响生态保育需求簇的环境变量排序为：土地利用＞距居民点距离＞距水体距离。研究结果揭示了资源依赖地区农户生态系统服务需求及其簇的空间分异规律，可为该区域生态系统管理和政策制定提供参考。 Abstract:Quantifying and clarifying the spatial differentiation of ecosystem services demand from the perspective of micro-land use subjects is of great significance for improving the human well-being of farmers in resource-dependent areas. Taking Mizhi County in the loess hilly and gully region as a study area, we combined public participatory GIS and MaxEnt model to achieve spatial assessment of 10 ecosystem services demand. At the same time, K-means clustering was used to identify village ecosystem services demand bundles, and the impact of environmental variables on ecosystem services demand and its bundles spatial distribution was explored. The results were as follows: ① The spatial differentiation of the ecosystem services demand was varied. In the provision service, grain supply and meat supply both showed a spatial differentiation of high in the middle and low in the east, and the spatial differentiation of fruit supply was the opposite. In the regulating service, the areas with high demand for soil conservation and air purification were distributed in high-altitude areas, and the areas with high demand for water conservation were distributed in the Wuding River Basin. Four types of cultural services all showed a spatial pattern of alternating distribution of high, medium and low demand areas, but the area proportions of demand areas at different levels varied significantly. ② Three types of ecosystem services demand bundles were identified using K-means clustering: including food supply demand bundle, the cultural entertainment demand bundle, and the ecological conservation demand bundle. Among them, food supply demand bundle was the dominant local ecosystem services demand bundles, mainly distributed in the north and south of the study area. The cultural entertainment demand bundle was mainly concentrated on both sides of the Wuding River. The ecological conservation demand bundle was in the south of the study area, next to the cultural entertainment demand bundle, and in the north was more dispersed. ③ The dominant environmental factors of the spatial differentiation of various ecosystem services demand were different. The environmental variables that affect the food supply demand bundle were ranked as: land use types> altitude> distance to the water body, the environmental variables that affect the cultural and entertainment demand bundle were ranked as: distance to the accommodation> distance to the water body> distance to the scenic spot, and the environmental variables that affect the ecological conservation demand bundle were ranked as: land use types > distance to the accommodation> distance to the water body. The research results revealed the spatial differentiation law of farmers’ ecosystem services demand and its bundles in resource-dependent regions, which can provide references for ecosystem management and policy formulation in the region. 参考文献 相似文献 引证文献

Factors Affecting Runoff and Sediment Load Changes in the Wuding River Basin from 1960 to 2020

To investigate changes in runoff and sediment load in the Wuding River basin under the combined influence of climate change and human activities, trends were analyzed from 1960 to 2020, and the contribution rate of climate change and human activities was calculated. It was observed that the runoff and sediment load Mann–Kendall test value ranges at eight gauging stations were −7.42 to −3.88 and −9.28 to −3.34, respectively, indicating a significant decreasing trend in both. During the period of 1970–2000, the contribution of human activities to the reduction in runoff and sediment load was 69.9% and 75.3%, respectively. However, the impact of human activities intensified after 2001 due to the implementation of the policy of returning farmland to forests in the Wuding River basin, which contributed to 118.4% and 114.5% of the reduction in runoff and sediment load, respectively. Check dam and reservoir construction, reforestation, water diversion, and other human activities were all important factors in runoff and sediment load reduction. In particular, the total sediment retention by reservoirs in the Wuding River basin was approximately 879 million tons until 2010, and the total sediment retention by check dams was approximately 2747 million t until 2017. This study can provide support for the utilization of water resources and the construction of ecological civilization in the Wuding River basin, and can also provide a reference for the study of water and sediment changes in other basins.

Runoff response to changing environment in Loess Plateau, China: Implications of the influence of climate, land use/land cover, and water withdrawal changes

The influence of climate change and human interference bring high nonstationary characteristics that are different from the original long-term stable state. So that, investigating runoff variation and attribution under changing environments is important for implementing adaptive management of global water resources, especially on the interannual scale. In this study, the attribution of measured runoff change in the Wuding River Basin (WRB) of the Loess Plateau, China, was studied using the elasticity method based on the Budyko framework and groundwater storage change analysis on an interannual scale. The change in the measured runoff driven factors was divided into three categories: climate change, human-induced land use/land cover (HI-LULC) change, and water withdrawal change. The results show that the contribution rate of climate change was the largest (with the mean value 54.07%), followed by the HI-LULC change (with the mean value 43.85%), and the minimum is WW change (with the mean value 2.08%). Climate change had a maximum contribution to runoff change, of which precipitation was dominant, followed by relative humidity, net radiation, and wind speed; air temperature had a minimal impact. In addition, the ecological change tendency was analyzed by combining HI-LULC and NDVI data. The analysis results of ecological change tendency indicate that the policy implementation of soil and water erosion control caused the ecological restoration to some extent, but also led to a decrease in runoff. This study provides scientific and useful information for the conservation of water and soil, runoff prediction, and sustainable water resource management in the WRB, and enriches the knowledge of contribution analysis of runoff variation which can be referenced by other basins across the globe.

Driving Factors of Heavy Rainfall Causing Flash Floods in the Middle Reaches of the Yellow River: A Case Study in the Wuding River Basin, China

In the context of climate change, extreme rainfall events have greatly increased the frequency and risk of flash floods in the Yellow River Basin. In this study, the heavy rainfall and flash flood processes were studied as a system. Taking the driving factors of the heavy rainfall causing the flash floods as the main focus, the key factors of the heavy rainfall causing typical flash flood processes were identified, and the driving mechanism by which the heavy rainfall caused flash floods was revealed. Through comparative analysis of the rainfall related to 13 floods with peak discharges of greater than 2000 m3/s since measurements began at Baijiachuan hydrological station, it was found that different rainfall factors played a major driving role in the different flood factors. The factor that had the largest impact on the peak discharge was the average rainfall intensity; the factor that had the largest impact on the flood volume was the rainfall duration; and the factor that had the largest impact on the sediment volume was the maximum 1 h rainfall. The ecological construction of soil and water conservation projects on the Loess Plateau has had obvious peak-cutting and sediment-reducing effects on the flood processes driven by medium- and low-intensity rainfall events, but for high-intensity flash floods, the flood-reducing and sediment-reducing effects of these projects have been smaller. Therefore, despite the background of continuous ecological improvement on the Loess Plateau, the possibility of floods with large sediment loads occurring in the middle reaches of the Yellow River still exists.