Search Results (20)

For the management of the water cycle, it is essential to comprehend evapotranspiration (ET) and how it changes over time and space, especially in relation to vegetation. Here, using the Priestley–Taylor Jet Propulsion Laboratory (PT-JPL) model, we explored the spatiotemporal variations in ET across different time scales during 1982–2018 in the Wuding River Basin. We also quantitatively evaluated the driving mechanisms of climate and vegetation changes on ET changes. Results showed that the ET estimate by the PT-JPL model showed good agreement (R² = 0.71–0.84) with four ET products (PML, MOD16A2, GLASS, FLDAS). Overall, the ET increased significantly at a rate of 3.11 mm/year (p < 0.01). Spatially, ET in the WRB is higher in the southeast and lower in the northwest. Attribution analysis indicated that vegetation restoration (leaf area index) was the dominant driver of ET changes (99.93% basin area, p < 0.05), exhibiting both direct effects and indirect mediation through the Vapor Pressure Deficit. Temperature influences emerged predominantly through vegetation feedbacks rather than direct climatic forcing. These findings establish vegetation restoration as a key driver of regional ET, providing empirical support for optimizing revegetation strategies in semi-arid environments. Full article

Wind erosion can cause land degradation and other harmful effects. Examining the ecosystem windbreak and sand fixation service (WSFS) from the perspectives of supply and demand plays a crucial role in the continuous regulation of regional wind erosion. Through the enhancement of the revised wind erosion equation (RWEQ) model, integrated with uncertainty analysis, scenario simulation, and environmental factors calculation, the dynamic simulation of the supply of ecosystem windbreak and sand fixation service (WSFSS) and the demand of ecosystem windbreak and sand fixation service (WSFSD) in the Wuding River Basin in China was achieved, and specifically, a simulation framework for WSFSD and WSFSS was constructed. The results show that: (1) the uncertainty analysis can calculate the upper and lower limits of the range of parameter x (downwind distance) in the RWEQ model, and changes in the parameter x can make the simulation results of WSFSS and WSFSD more reasonable; (2) In the past 20 years, the WSFSS has shown a spatial distribution pattern of high in the northwest and low in the southeast. In terms of time, the annual WSFSS has shown a fluctuating growth trend with a growth rate of 8.06 t/a. The monthly WSFSS has shown a rising-fluctuating-declining trend; (3) The rationality of WSFSD was indirectly verified through the setting of scenario simulation. In terms of time, across the 252 months under study (January 2000–December 2020), 85% of the months witnessed WSFSD within the range of 1.0–1.4 kg/m² in the Wuding River Basin. At the same time, the WSFSD also presented seasonal variation patterns. The WSFSD was relatively high in spring (March–May) and relatively low in summer (July–September) each year. Full article

Over the past two decades, large-scale ecological restoration in the Loess Plateau has significantly transformed land use and land cover (LULC) in the Wuding River Basin (WRB), improving ecological governance and environmental conditions. This study examines the spatiotemporal evolution of LULC and its driving factors from 2000 to 2020, employing methods such as the LULC dynamic degree, transfer matrix, migration trajectory, and geographical detector. Results show that (1) grassland dominates the basin’s LULC (78.16%), with decreases in cropland and desert areas, and expansions in grassland, forest, and urban areas. Water bodies show minimal fluctuations. The mean annual dynamic degree of LULC types (from highest to lowest) is as follows: forest > desert > urban > water > cropland > grassland. The overall dynamic degree fluctuated, initially decreasing (0.85%–0.68%), then increasing (0.68–0.89%), followed by another decline (0.89–0.30%). (2) LULC patterns follow a northwest-to-southeast gradient, with primary transitions from desert and cropland to grassland and secondary transitions to forest, urban, and water bodies. Spatial migration mainly shifts westward and northward. (3) Under the single-factor influence, natural factors, especially slope (7.2–36.4%) and precipitation (6.1–22.3%), are the primary drivers of LULC changes, with population density (7.9%) and GDP (27.5%) influencing urban areas. In the interaction of factors, topography and climate (40.5–66.1%) primarily drive increases in cropland, forest, and grassland, while human activities and climate (24.8–36.7%) influence urban and water area expansion. Desert area reduction is largely driven by climatic factors (40.3%). The interaction between two factors shows either a bi-factorial or nonlinear enhancement effect, suggesting that their combined influence offers stronger explanatory power than any single factor alone. This study highlights significant LULC changes in the WRB, driven by both natural factors and human activities, contributing to enhanced ecological governance and land use sustainability. Full article

To investigate the spatial and temporal changes in fractional vegetation coverage (FVC) and their driving forces in different regions of the Inner Mongolia section of the Yellow River Basin, this paper observed the spatial trends and stability of FVC in these regions based on the MOD13Q1 information regarding the 2000–2020 period as a data source. It used the dimidiate pixel model to invert FVC, and based on the centre of gravity migration model, the coefficient of variation and the Mann–Kendall and Sen’s slope estimator test, it studied the spatial variation trend and stability of FVC in the four relevant areas of the Inner Mongolia section; an attribution analysis using a geodetector was also conducted. The following results were found: (1) in terms of temporal FVC change in the relevant areas, from 2000 to 2020, the overall FVC showed an increasing trend, indicating an obvious hierarchy of change as per different seasonal scales (summer > growing season > fall > spring). There is a mutation point in FVC in different areas, and the FVC sequence is random. (2) Regarding spatial change, the overall FVC showed a trend of being high in the eastern regions and low in the western regions and low–high–low from the north to the south; the stability of the Hetao Irrigation District–Wuliangsuhai Area changed more significantly with the successive seasons, and the degraded areas of FVC were mainly distributed in the city centre of the Kundulun River–Daheihe River Area and in the Hetao Irrigation District in the summer. (3) In terms of driving factors, soil type had a relatively higher explanatory power regarding the Hetao Irrigation District–Wuliangsuhai Area, rainfall had a relatively higher explanatory power regarding the Morin River–Wuding River Area and the Kundulun River–Daheihe River Area, and land use had a relatively higher explanatory power regarding the Ten Kongtui–Heidaigou Area. Full article

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. Full article

The study of river sediment is a broad and complex field. One of the very important parameters is suspended particle size (SPS), which is indispensable for understanding water–sediment dynamics. As one of the most serious soil erosion areas in the world, the Loess Plateau delivers a large amount of sediment to the Yellow River and its numerous tributaries. Studies on riverine SPS in the Loess Plateau have received extensive attention. In this study, we investigate the spatiotemporal variations of SPS in the Loess Plateau rivers and analyze the driving factors along with their relative importance. Through the analysis of SPS data from 62 hydrological stations, the results indicated the spatial distribution of SPS was similar in the 1980s and 2010s, with both coarser particles mainly distributed in the northern rivers and finer particles mainly distributed in the southern rivers. During the 1980s to the 2010s, the mean SPS on the Loess Plateau decreased from 33 μm to 20 μm, with mean reductions of 42.0%, 29.4%, 46.3%, and 36.8% in the northern, western, southwestern, and southeastern basins, respectively. The most significant changes in SPS were observed in the Kuye, Wuding and Jalu River basins in the northern region, with decreases ranging from 27 to 73 μm. In the 1980s, topography (slope) and human management, followed by precipitation, were the key factors affecting SPS variability, contributing 25.7%, 25.9% and 24.0%, respectively. In the 2010s, the explanatory power of topographic slope on SPS variability declined by 16.6%, and other natural factors no longer significantly influenced SPS variability. The results of this study can serve as a reference for integrated basin management and sustainable ecosystem development in river catchments around the world. Full article

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. Full article

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. Full article

Following consecutive years of governance efforts, there has been a substantial reduction in sediment transport in the Yellow River, resulting in significant changes in its water–sediment dynamics. This necessitates precise monitoring of sediment-bearing tributary inflows, a crucial requirement for effective governance strategies on the Loess Plateau’s current developmental stage. While satellite remote sensing technology has been widely used to estimate suspended particulate matter concentration (C_SPM) in open water bodies like oceans and lakes, its application in narrow rivers presents challenges related to hybrid pixel and proximity effects. As a result, the effectiveness and competence of satellite remote sensing in monitoring C_SPM in such confined river environments are reduced. This study attempted to use unmanned aerial vehicle (UAV) remote sensing with multispectral technology to invert C_SPM in the Wuding River, a sediment-bearing Yellow River tributary. A novel C_SPM concentration inversion model was introduced for highly turbid river settings. The results showed that the accuracy of the new band ratio model in this study is significantly improved compared with the existing models. The validation dataset had a coefficient of determination (R²) of 0.83, a root mean square error (RMSE) of 3.73 g/L, and a mean absolute percentage error (MAPE) of 44.95% (MAPE is 40.68% at 1–20 g/L, and 12.37% at >20 g/L). On this basis, the UAV also monitored the impacts of heavy rainfall on the C_SPM, resulting in a rapid rise and fall in C_SPM over a period of ten hours. This study demonstrated the potential of UAV remote sensing for C_SPM monitoring in extremely turbid narrow rivers (tens to tens of meters), especially before and after rainfall sediment production events, which can provide technical support for accurate sediment management and source identification in the main tributaries of the Yellow River and help realize the goal of high-quality development of the Yellow River Basin. Full article

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. Full article

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. Full article

Investigating the coupling coordination relationship between water resources, ecology and the economy is the basis process for watershed governing to achieve sustainable development. Taking the Wuding River watershed (one of the largest tributaries of the Yellow River) as an example, we used the coupling coordination model to analyze the coupling coordination relationship of the water–ecology–economy system between 2001 and 2020, and then used grey correlation and partial correlation analyses to explore the main influencing factors and cross-county characteristic of the coupling coordination. The results show that the water, ecology and economy subsystems changed slightly before 2007. After 2007, the economy developed rapidly, while the water and ecology increased for a short time and then decreased after 2013. The water–ecology–economy coupling coordination was on the verge of dysfunctional decline. Water and ecology were the main influencing factors on the coupling coordination. The coupling coordination showed a cross-county characteristic. Water and ecology in upstream counties had significant positive correlations with the coupling coordination in downstream counties. The economy subsystem in upstream counties, however, had significant negative correlations with water and ecology in downstream counties. Our findings provide an empirical mode to measure transregional characteristics of coupling coordination and could support the construction of a coordination governance mode in the Wuding River watershed. Full article

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. Full article

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. Full article

Understanding and quantifying changes in hydrological systems due to human interference are critical for the implementation of adaptive management of global water resources in the changing environment. To explore the implications of hydrological variations for water resources management, the Wuding River Basin (WRB) in the Loess Plateau, China, was selected as a case study. Based on the Budyko-type equation with a time-varying parameter n, a human-induced water–energy balance (HWEB) model was proposed to investigate the hydrological variability in the WRB. The investigation showed that runoff continuously reduced by 0.424 mm/a during 1975–2010, with weakly reducing precipitation and increasing groundwater exploitation causing a decrease in groundwater storage at a rate of 1.07 mm/a, and actual evapotranspiration accounting for more than 90% of precipitation having an insignificantly decreasing trend with a rate of 0.53 mm/a under climate change (decrease) and human impact (increase). Attribution analysis indicated that human-induced underlying surface condition change played a dominant role in runoff reduction by driving an increase in actual evapotranspiration, and that mainly impacted the overall decrease in runoff compounded by climate change during the entire period. It is suggested that reducing the watershed evapotranspiration and controlling groundwater exploitation should receive greater attention in future basin management. Full article