runoff

摘要： Based on GIS technology and AnnAGNPS model,the outputs of runoff and soil erosion in different periods of seven typical agroforestry watersheds in Funiu Mountains were studied.The results showed that after the implementation of the project of returning farmland to forests and ecological industrialization in the study watersheds in the Funiu Mountains,the function of soil and water conservation has been continuously enhanced.Compared with 2000,in 2020,the average surface runoff of the seven watersheds decreased by 40.7 mm,and the soil erosion amount decreased by 5.41 t/hm;the watershed runoff had a significant positive correlation with slope (P < 0.05),a significant negative correlation with forest land area ratio (P < 0.05),but no significant correlation with agricultural land ratio;soil erosion was negatively correlated with forest land (P < 0.05),but positively correlated with farmland (P < 0.05);and the average spatial variation coefficient of soil erosion was 160%,which was 4.35 times that of runoff,and the uncertainty of factors affecting soil erosion was much higher than that of runoff.

摘要： In work features of a hydrological regime of catchments of the river of the Pripyat in climate change are considered.Researches of meteorological characteristics of the given territory show the tendency to growth,both tem­peratures of air,and precipitation,evaporation from a surface of water and ground also show the tendency to increase.That is not unequivocally re­flected in change of a course of hydrological characteristics waters objects of territory.On a part of pools of the rivers the mid-annual runoff of water in the rivers in time tends to growth,and Change of levels of subsoil waters decreases for parts-on a turn-here,as a rule,tends a course in time oppo­site to a mid-annual runoff of water in the rivers.Change of the maximal temperature of water in the rivers in time repeats the tendency of a course of a runoff of water in them,i.e.at increase in a runoff of water in the riv­ers-the maximal temperature increases,and at reduction-decreases.The increase in temperature of a superficial component of a runoff of the rivers occurs because of the general increase in temperature of air in considered territory.Silt charge waters in all territory decreases,despite of increase in quantity of atmospheric precipitation and increases or reduction of a runoff of water in the rivers.The relationship between the water runoff layer and precipitation and soil moisture has a certain time delay.The average annual water temperature over time shows a tendency to increase at almost all stations,while the change in the maximum water temperature in rivers over time has a multidirectional tendency and to a greater extent depends on the change in water depth in the river,a decrease in high water maximums and frequent thaws,etc.The studies carried out show that the preservation of moisture in thick layers of soil(0 cm-100 cm)contributes to an increase in water flow in rivers and in the modern conditions of Polesie of Ukraine this will solve a number of problems with the provision of high-quality water resources for various industries and the population.

摘要： Water budget closure is a method used to study the balance of basin water storage and the dynamics of relevant hydrological components(e.g.,precipitation,evapotranspiration,and runoff).When water budget closure is connected with terrestrial water storage change(TWSC)estimated from Gravity Recovery and Climate Experiment(GRACE)data,variations in basin runoff can be understood comprehensively.In this study,total runoff variations in the Yangtze River Basin(YRB)and its sub-basins are examined in detail based on the water budget closure equation.We compare and combine mainstream precipitation and evapotranspiration models to determine the best estimate of precipitation minus evapotranspiration.In addition,we consider human water consumption,which has been neglected in earlier studies,and discuss its impact.To evaluate the effectiveness and accuracy of the combined hydrological models in estimating subsurface runoff,we collect discharge variations derived from in situ observations in the YRB and its sub-basins and compare these data with the models’final estimated runoff variations.The estimated runoff variations suggest that runoff over the YRB has been increasing,especially in the lower sub-basins and in the post-monsoon season,and is accompanied by apparent terrestrial water loss.

摘要： The soil-rock mixed spoil heaps are prone to severe soil erosion during heavy rain,causing severe land degradation and ecological and environmental damage.Nevertheless,past research on the erosion on spoil heaps has focused on soil particles that were readily eroded and disregarded the rock fragments(RF)that were not readily eroded.To explore the effect of the RF embedded in spoil heaps on the hydraulics of and erosion caused by concentrated runoff,scour-erosion experiments were implemented on three types of spoil heaps:RF=7%,RF=45%,and RF=69%.The RF clearly reduced runoff and erosion on steep spoil heaps.As the RF increased from 7%to 69%,the runoff intensity and runoff coefficient decreased by 72.9%-79.1%and 83.2%-84.1%respectively,and the sediment concentration,soil denudation rate,and total soil loss decreased by 36.0%-47.8%,83.7%-87.1%,and 87.0%-92.3%,respectively.Narrow rills were generated during the experiments,and the RF distinctly influenced the rill characteristics.High contents of RF restrained rill retreating and undercutting,and promoted rill widening.With an increase in RF,the flow shear stress and stream power gradually decreased,and the Darcy-Weisbach roughness coefficient increased.These findings imply that the RF dissipated the flow energy and reduced soil detachment capacity and sediment transport capacity.Soil detachment is strongly related to the Darcy-Weisbach roughness coefficient,Reynolds number,and runoff intensity,which may be the preferred descriptors of soil detachment.The current findings indicate that embedded rock fragments could effectively reduce soil loss on steep spoil heaps.

摘要： 1.Introduction to the project The Three Gorges Project is a key backbone project for the management and development of the Yangtze River.Its dam site is located in the middle section of the Xiling Gorge at the main stream of the Yangtze River,in Sandouping Town,Yichang City,Hubei Province,with a control basin area of about 1×10^(6)km^(2),an average annual flow of 14300 m^(3)·s^(-1),an average annual runoff of 4.51×10^(11) m^(3),a normal water level at an elevation(EL)of 175 m,and a corresponding reservoir capacity of 3.93×10^(10) m^(3).

摘要： In order to explore the spatial and temporal changes of runoff and sediment in the Taohe River and its driving mechanism,Spearman correlation coefficient method,Mann-Kendell mutation test method and ordered clustering method were used to analyze the changes of runoff and sediment discharge and their driving factors in four hydrological stations along the Taohe River from 1957 to 2016.The results showed that the correlation between runoff and sediment of the four hydrological stations along the Taohe River was significant,and the correlation coefficient was 0.728-0.984.The runoff and sediment transport in the interval showed an increasing and decreasing trend.The decrease rate of runoff was 133.82%-216.17%higher than that of Xiabagou station,and the decrease rate of sediment transport was 250.49%-4766.33%higher than that of Xiabagou station.The mutation year of the Taohe River runoff occurred in 1986,and the maximum decrease was 35%.The water-sediment relationship curves of different periods showed that the sediment discharge of the four stations changed abruptly around 1990,and the maximum reduction before and after the mutation was up to 73%,and the sediment discharge in the river channel decreased significantly.The research showed that human activities were the main driving factors for the change of water-sediment relationship in the Taohe River.

摘要： As an important water source and ecological barrier in the Yellow River Basin,the source region of the Yellow River(above the Huangheyan Hydrologic Station)presents a remarkable permafrost degradation trend due to climate change.Therefore,scientific understanding the effects of permafrost degradation on runoff variations is of great significance for the water resource and ecological protection in the Yellow River Basin.In this paper,we studied the mechanism and extent of the effect of degrading permafrost on surface flow in the source region of the Yellow River based on the monitoring data of temperature and moisture content of permafrost in 2013–2019 and the runoff data in 1960–2019.The following results have been found.From 2013 to 2019,the geotemperature of the monitoring sections at depths of 0–2.4 m increased by 0.16°C/a on average.With an increase in the thawing depth of the permafrost,the underground water storage space also increased,and the depth of water level above the frozen layer at the monitoring points decreased from above 1.2 m to 1.2–2 m.64.7%of the average multiyear groundwater was recharged by runoff,in which meltwater from the permafrost accounted for 10.3%.Compared to 1960-1965,the runoff depth in the surface thawing period(from May to October)and the freezing period(from November to April)decreased by 1.5 mm and 1.2 mm,respectively during 1992–1997,accounting for 4.2%and 3.4%of the average annual runoff depth,respectively.Most specifically,the decrease in the runoff depth was primarily reflected in the decreased runoff from August to December.The permafrost degradation affects the runoff within a year by changing the runoff generation,concentration characteristics and the melt water quantity from permafrost,decreasing the runoff at the later stage of the permafrost thawing.However,the permafrost degradation has limited impacts on annual runoff and does not dominate the runoff changes in the source region of the Yellow River in the longterm.

摘要： This study was meant to ensure that there is proper and efficient conservation of soil and water using geospatial tools to enable us identify priority areas to carry out conservation. Over the past years, various fields of study have established how critical it is to conserve these natural resources in the ecosystem and to ensure sustainability in not only green livelihoods but also to enhance living conditions of the life on earth. The aim of this research was to generate high priority sites for establishing soil and water conservation techniques in the Lower Bogoria Landscapes in Baringo, Kenya using GIS-based multicriteria decision analysis. Various criteria were analyzed to generate the final conservation priority sites, such as land use land cover, rainfall runoff, soil erosion and slope. The criteria were assigned weights using the AHP technique and overlayed using the weighted overlay tools to produce the final outputs. Land use land cover maps were generated using supervised maximum likelihood technique, rainfall run-off maps were generated using the SCS-CN method and soil erosion maps were generated using RUSLE model. The final soil and water conservation maps showed that high and moderate priority areas requiring the establishment of techniques and mechanisms to control soil erosion and conserve water increased from 1990 to 2020. In 2020, more than 50% of the total study area was classified as moderate to high priority for water and soil conservation. Soil and water conservation structures such as water pans, percolation tanks, farm ponds and stop dams should be constructed in such areas.

摘要： Changing climatic conditions and extensive human activities have influenced the global water cycle.In recent years,significant changes in climate and land use have degraded the watershed ecosystem of the Ebinur Lake Basin in Xinjiang,Northwest China.In this paper,variations of runoff,temperature,precipitation,reference evapotranspiration,lake area,socio-economic water usage,groundwater level and water quality in the Ebinur Lake Basin from 1961 to 2015 were systematically analyzed by the Mann-Kendall test methods(M-K)mutation test,the cumulative levelling method,the climate-sensitive method and land-use change index.In addition,we evaluated the effects of human activities on land use change and water quality.The results reveal that there was a significant increase in temperature and precipitation from 1961 to 2015,despite a decrease in reference evapotranspiration.The Wenquan station was not significantly affected by human activities as it is situated at a higher altitude.Runoff at this station increased significantly with climate warming.In contrast,runoff at the Jinghe station was severely affected by numerous human activities.Runoff decreased without obvious fluctuations.The contributions of climate change to runoff variation at the Jinghe and Wenquan stations were 46.87%and 58.94%,respectively;and the contributions of human activities were 53.13%and 41.06%,respectively.Land-use patterns in the basin have changed significantly between 1990 and 2015:urban and rural constructed lands,saline-alkali land,bare land,cultivated land,and forest land have expanded,while areas under grassland,lake,ice/snow and river/channel have declined.Human activities have dramatically intensified land degradation and desertification.From 1961 to 2015,both the inflow into the Ebinur Lake and the area of the lake have declined year by year;groundwater levels have dropped significantly,and the water quality has deteriorated during the study period.In the oasis irrigation area below the runoff pass,human activities mainly influenced the utilization mode and quantity of water resources.Changes in the hydrology and quantity of water resources were driven primarily by the continuous expansion of cultivated land and oasis,as well as the growth of population and the construction of hydraulic engineering projects.After 2015,the effects of some ecological protection projects were observed.However,there was no obvious sign of ecological improvement in the basin,and some environmental problems continue to persist.On this basis,this study recommends that the expansion of oasis should be limited according to the carrying capacity of the local water bodies.Moreover,in order to ensure the ecological security of the basin,it is necessary to determine the optimal oasis area for sustainable development and improve the efficiency of water resources exploitation and utilization.

摘要： The increasing shortage in water resources is a key factor affecting sustainable socio-economic development in the arid region of Northwest China(ARNC). Water shortages also affect the stability of the region's oasis ecosystem. This paper summarizes the hydrological processes and water cycle of inland river basins in the ARNC, focusing on the following aspects: the spatial-temporal features of water resources(including air water vapor resources, runoff, and glacial meltwater) and their driving forces; the characteristics of streamflow composition in the inland river basins; the characteristics and main controlling factors of baseflow in the inland rivers; and anticipated future changes in hydrological processes and water resources. The results indicate that:(1) although the runoff in most inland rivers in the ARNC showed a significant increasing trend, both the glaciated area and glacial ice reserves have been reduced in the mountains;(2) snow melt and glacier melt are extremely important hydrological processes in the ARNC, especially in the Kunlun and Tianshan mountains;(3) baseflow in the inland rivers of the ARNC is the result of climate change and human activities, with the main driving factors being the reduction in forest area and the over-exploitation and utilization of groundwater in the river basins; and(4) the contradictions among water resources, ecology and economy will further increase in the future. The findings of this study might also help strengthen the ecological, economic and social sustainable development in the study region.