Starting from the supposition of time-space substitution, the Langbein-Schumm's Law was applied to deal with response of fluvial erosion System to the changes in mean annual Precipitation induced by global green-h...Starting from the supposition of time-space substitution, the Langbein-Schumm's Law was applied to deal with response of fluvial erosion System to the changes in mean annual Precipitation induced by global green-house warming. As a result, a simple method was put forward to predict change in sediment yield, with Ningxia Hui Autonomous Region in the northern fringe of the Loess Plateau of China as an example. Results show that, even the change in mean annual precipitation is the same, the direction and magnitude of the resultant chang in sediment yteld would be quite different in fferent physico-geographical zones. When mean annual precipitation is increased, sediment yield in arid or semi-arid areas with a mean anntal Peripitation of less than 400 mm will be increased, while sediment yield in sub-humid or humid areas with a mean annual precipitation of more than 400 mm will be decreased.Additionally, the complex response of fluvial erosion system in time series due to the lag of change in vegetation behind the changn in precipitation has also been qualitatively discussed in this paper.展开更多
Fluvial sediment transport data is a very important data for effective water resource management.However,acquiring this data is expensive and tedious hence sediment yield modeling has become an alternative approach in...Fluvial sediment transport data is a very important data for effective water resource management.However,acquiring this data is expensive and tedious hence sediment yield modeling has become an alternative approach in estimating river sediment yields.In Ghana,several sediment yield predicting models have been developed to estimate the sediment yields of ungauged rivers including the Pra River Basin.In this paper,10 months sediment yield data of the Pra River Basin was used to evaluate the existing sediment yield predicting models of Ghana.A regression analysis between predicted sediment yield data derived from the models and the observed suspended sediment yields of the Pra Basin was done to determine the extent of estimation of observed sediment yields.The prediction of suspended sediment yield was done for 4 out of 5 existing sediment yield predicting models in Ghana.There were variations in sediment yield between observed and predicted suspended sediments.All predicted sediment yields were lower than observed data except for equation 3 where the results were mixed.All models were found to be good estimators of fluvial sediments with the best model being equation 4.Sediment yield tends to increase with drainage basin area.展开更多
By scouring experiments, the changeable process and characteristics of sediment yield in the hillslope-gully side erosion system with different coverage degrees and spatial locations of grass were studied. Five grass ...By scouring experiments, the changeable process and characteristics of sediment yield in the hillslope-gully side erosion system with different coverage degrees and spatial locations of grass were studied. Five grass coverage degrees of 0, 30%, 50%, 70%, 90%, three spatial locations of grass （upslope, mid-slope, low-slope） and two water inflow rates of 3.2 L/min, 5.2 L/min were applied to a 0.5 by 7 m soil bed in scouring experiments. Results showed that the sediment yield decreased with the increase of grass coverage degree at 3.2 L/min water inflow rate in scouring experiments and the sediment yield with different grass locations on the sloping surface was in the order of upper 〉 middle 〉 lower. At 5.2 L/min water inflow rate, the differences of sediment yield among various grass coverage degrees were increased, whereas the changeable tendency of sediment yield with different grass locations on the whole sloping surface was not very obvious. The proportion of sediment yield from the gully side increased in an exponential relationship with the increase of grass coverage degree When the grass was located on the lower position of hillslope, the influence for accelerating gully erosion is the greatest.展开更多
Sediment has been identified as a significant threat to water quality and channel clogging that in turn may lead to river flooding. With the increasing awareness of the impairment from sediment to water bodies in a wa...Sediment has been identified as a significant threat to water quality and channel clogging that in turn may lead to river flooding. With the increasing awareness of the impairment from sediment to water bodies in a watershed, identifying the locations of the major sediment sources and reducing the sediment through management practices will be important for an effective watershed management. The annualized agricultural non-point source pollution(AnnAGNPS) model and newly developed GIS interface for it were applied in a small agricultural watershed, Redrock Creek watershed, Kansas, in this pilot study for exploring the effectiveness of using this model as a management tool. The calibrated model appropriately simulated monthly runoff and sediment yield through the practices in this study and potentially suggested the ways of sediment reduction through evaluating the changes of land use and field operation in the model for the purpose of watershed management.展开更多
Wind and water erosion are among the most important causes of soil loss, and understanding their interactions is important for estimating soil quality and environmental impacts in regions where both types of erosion o...Wind and water erosion are among the most important causes of soil loss, and understanding their interactions is important for estimating soil quality and environmental impacts in regions where both types of erosion occur. We used a wind tunnel and simulated rainfall to study sediment yield, particle-size distribution and the fractal dimension of the sediment particles under wind and water erosion. The experiment was conducted with wind ero- sion firstly and water erosion thereafter, under three wind speeds （0, 11 and 14 m/s） and three rainfall intensities （60, 80 and 100 ram/h）. The results showed that the sediment yield was positively correlated with wind speed and rain- fall intensity （P〈0.01）. Wind erosion exacerbated water erosion and increased sediment yield by 7.25%-38.97% relative to the absence of wind erosion. Wind erosion changed the sediment particle distribution by influencing the micro-topography of the sloping land surface. The clay, silt and sand contents of eroded sediment were also posi- tively correlated with wind speed and rainfall intensity （P〈0.01）. Wind erosion increased clay and silt contents by 0.35%-19.60% and 5.80%-21.10%, respectively, and decreased sand content by 2.40%-8.33%, relative to the absence of wind erosion. The effect of wind erosion on sediment particles became weaker with increasing rainfall intensities, which was consistent with the variation in sediment yield. However, particle-size distribution was not closely correlated with sediment yield （P〉0.05）. The fractal dimension of the sediment particles was significantly different under different intensities of water erosion （P〈0.05）, but no significant difference was found under wind and water erosion. The findings reported in this study implicated that both water and wind erosion should be controlled to reduce their intensifying effects, and the controlling of wind erosion could significantly reduce water erosion in this wind-water erosion crisscross region.展开更多
The Yellow River basin is well known for its high sediment yield. However, this sediment yield has clearly decreased since the 1980 s, especially after the year 2000. The annual average sediment yield was 1.2 billion ...The Yellow River basin is well known for its high sediment yield. However, this sediment yield has clearly decreased since the 1980 s, especially after the year 2000. The annual average sediment yield was 1.2 billion tons before 2000, but has significantly decreased to 0.3 billion tons over the last 10 years. Changes in discharge and sediment yield for the Yellow River have attracted the attention of both the Central Government and local communities. This study aimed to identify the individual contributions of changes in precipitation and human activities(e.g. water conservancy projects, terracing, silt dams, socio-economic and needs, and soil and water conservation measures) to the decrease in discharge and sediment yield of the Yellow River. The study used both improved the hydrological method and the soil and water conservation method. The study focused on discharge analysis for the upper reaches and the investigation of sediments for the middle reaches of the river. The results showed that discharge and sediment yield have both presented significant decreasing trends over the past 50 years. Precipitation showed an insignificant decreasing trend over the same period. The annual average discharge decreased by 5.68 billion m3 above Lanzhou reach of the Yellow River from 2000 to 2012; human activities(e.g. socio-economic water use) contributed 43.4% of the total reduction, whereas natural factors(e.g. evaporation from lakes, wetlands and reservoirs) accounted for 56.6%. The decrease in annual discharge and sediment yield of the section between Hekouzhen station and Tongguan station were 12.4 billion m3 and 1.24 billion tons, respectively. Human activities contributed 76.5% and 72.2% of the total reduction in discharge and sediment yield, respectively, and were therefore the dominant factors in the changes in discharge and sediment yield of the Yellow River.展开更多
This paper focuses on the effects of precipitation and vegetation coverage on runoff and sediment yield in the Jinsha River Basin. Results of regression analysis were taken as input variables to investigate the applic...This paper focuses on the effects of precipitation and vegetation coverage on runoff and sediment yield in the Jinsha River Basin. Results of regression analysis were taken as input variables to investigate the applicability of the adaptive network-based fuzzy inference system （ANFIS） to simulating annual runoff and sediment yield. Correlation analysis indicates that runoff and sediment yield are positively correlated with the precipitation indices, while negatively correlated with the vegetation indices. Furthermore, the results of stepwise regression show that annual precipitation is the most important factor influencing the variation of runoff, followed by forest coverage, and their contributions to the variation ofrunoffare 69.8% and 17.3%, respectively. For sediment yield, rainfall erosivity is the most important factor, followed by forest coverage, and their contributions to the variation of sediment yield are 49.3% and 24.2%, respectively. The ANFIS model is of high precision in runoff forecasting, with a relative error of less than 5%, but of poor precision in sediment yield forecasting, indicating that precipitation and vegetation coverage can explain only part of the variation of sediment yield, and that other impact factors, such as human activities, should be sufficiently considered as well.展开更多
Simulated results of water yield, sediment yield, surface runoff,subsurface runoff, peak flow, evapo- transipiration, etc., in theTeba catchment, Spain, using SWRRB (Simulator for Water Resources inRural Basins) model...Simulated results of water yield, sediment yield, surface runoff,subsurface runoff, peak flow, evapo- transipiration, etc., in theTeba catchment, Spain, using SWRRB (Simulator for Water Resources inRural Basins) model are presented and the related problems arediscussed. The results showed that water yield And sediment yieldcould be satisfactorily simulated using SWRRB model. The accuracy ofthe annual water Yield simulation in the Teba catchment was up to83.68/100, which implied that this method could be effectively Usedto predict the annual or inter-annual water yield and to realize thequantification of geographic elements And processes of a river basin.展开更多
In recent years, the role of human activities in changing sediment yield has become more apparent for the construction of hydraulic engineering and water conservation projections in the Upper Yangtze River, but it has...In recent years, the role of human activities in changing sediment yield has become more apparent for the construction of hydraulic engineering and water conservation projections in the Upper Yangtze River, but it has not been evaluated at the macro scale. Taking Sichuan Province and Chongqing City as an example, this paper studies the relationship between socio-economic factors and sediment yield in the Upper Yangtze River based on section data in 1989 and 2007. The results show that sediment yield is significantly correlated with population density and cultivated area, in which the former appears to be more closely related to sediment yield. Moreover, in the relation of sediment yield vs. population density, a critical value of population density exists, below which the sediment yield increases with the increase of population density and over which the sediment yield increases with the decrease of population density. The phenomenon essentially reflects the influence of natural factors, such as topography, precipitation and soil property, and some human activities on sediment yield. The region with a higher population density than critical value is located in the east of the study area and is characterized by plains, hills and low mountains, whereas the opposite is located in the west and characterized by middle and high mountains. In the eastern region, more people live on the lands with a low slope where regional soil erosion is slight; therefore, sediment yield is negatively related with population density. In contrast, in the western region, the population tends to aggregate in the areas with abundant soil and water resources which usually lead to a higher intensity of natural erosion, and in turn, high-intensity agricultural practices in these areas may further strengthen local soil erosion. It is also found that population tends to move from the areas with bad environment and high sediment yield to the areas with more comfortable environment and less sediment yield. The natural factors have greater influence on sediment yield of western region than that of eastern region. Generally, the natural factors play a dominant role on sediment yield in the Upper Yangtze River.展开更多
This paper examines the experimental study on influence of material component to non-linear relation between sediment yield and drainage network development completed in the Lab. The area of flume drainage system is 8...This paper examines the experimental study on influence of material component to non-linear relation between sediment yield and drainage network development completed in the Lab. The area of flume drainage system is 81.2 m2, the longitudinal gradient and cross section slope are from 0.0348 to 0.0775 and from 0.0115 to 0.038, respectively. Different model materials with a medium diameter of 0.021 mm, 0.076 mm and 0.066 mm cover three experiments each. An artificial rainfall equipment is a sprinkler-system composed of 7 downward nozzles, distributed by hexagon type and a given rainfall intensity is 35.56 mm/hr.cm2. Three experiments are designed by process-response principle at the beginning the ψ shaped small network is dug in the flume. Running time spans are 720 m, 1440 minutes and 540 minutes for Runs I, IV and VI, respectively. Three experiments show that the sediment yield processes are characterized by delaying with a vibration. During network development the energy of a drainage system is dissipated by two ways, of which one is increasing the number of channels (rill and gully), and the other one is enlarging the channel length. The fractal dimension of a drainage network is exactly an index of energy dissipation of a drainage morphological system. Change of this index with time is an unsymmetrical concave curve. Comparison of three experiments explains that the vibration and the delaying ratio of sediment yield processes increase with material coarsening, while the number of channel decreases. The length of channel enlarges with material fining. There exists non-linear relationship between fractal dimension and sediment yield with an unsymmetrical hyperbolic curve. The absolute value of delaying ratio of the curve reduces with time running and material fining. It is characterized by substitution of situation to time.展开更多
As a major sediment area in the upper Yangtze River, Jialing River basin experienced substantial land-use changes, many water conservancy projects were constructed from the 1980 s onward to promote water and soil cons...As a major sediment area in the upper Yangtze River, Jialing River basin experienced substantial land-use changes, many water conservancy projects were constructed from the 1980 s onward to promote water and soil conservation. The water and sediment yield at the watershed outlet was strongly affected by these water conservation works, including ponds and reservoirs, which should be considered in the modelling. In this study, based on the observed data of the Weicheng River catchment, the relationships between precipitation, runoff, vegetation, topography and sediment yield were analyzed, a distributed runoff and sediment yield model(WSTD-SED) was developed, and the hydrological processes of different land-use scenarios were simulated by using the model. The main results are summarized as follows: 1) there is an alternating characteristic in river channels and reservoirs in the Jialing River hilly area, with scour occurring in wet years and deposit occurring in dry years. 2) Most of the sediment deposited in river channels and reservoirs is carried off by the largest flood in the year. 3) The model yielded plausible results for runoff and sediment yield dynamics without the need of calibration, and the WSTD-SED model could be usedto obtain qualitative estimates on the effects of land use change scenarios. 4) The modelling results suggest that a 10% increase in cropland(dry land) reforestation results in a 0.7% decrease in runoff and 1.5% decrease in sediment yield.展开更多
This study addresses the morphometric variables that determine the sediment yield in Wadi AI-Arja through the analysis of the impact of different morphometric characteristics along the course of the valley on its sedi...This study addresses the morphometric variables that determine the sediment yield in Wadi AI-Arja through the analysis of the impact of different morphometric characteristics along the course of the valley on its sediment yield, as well as the analysis of spatial and formal dimensions and morphologies of the basin and its relationship to the sediment yield. The study also addresses the size of variation in the volume of sediment yield of the river tributaries that make up the water network of the valley under the differences of its mor- phometric and hydrological characteristics. The study found several results, most notably： The classification of Wadi AI-Arja basin according to the hypsometric integral value （72.1%） within an uneven topography, which in- creases the force of the erosive activity and the size of the sediment yield if the basin was exposed to moist climatic periods. The study also showed the presence of convergence in the intra-spaces between the river tributaries in the water network. This increases the volume of water flows when these tributaries meet with each other and thus increasing their erosive ability and sediment yield. The study also showed the presence of marked variation in the sediment yield of the river tributaries depending on the differences in its morphometric characteristics. The results of the step-wise regression analysis confirmed the importance of the morphometric and hydrological variables, and plant coverage in interpreting the variation in the size of the sediment yield of the river tributaries of different stream order in Wadi AI-Arja basin, where these variables interpreted 43% of the total variation, with statistical significance less than 0.05.展开更多
One of the most common types of soil degradation is water erosion.It reduces soil quality at the erosion site and may cause sedimentation issues at the deposition site.This phenomenon is estimated using a variety of m...One of the most common types of soil degradation is water erosion.It reduces soil quality at the erosion site and may cause sedimentation issues at the deposition site.This phenomenon is estimated using a variety of models.The Revised Universal Soil Loss Equation(RUSLE)model is the most often used,due to its consistence and low data requirement.It is useful for estimating annual soil loss at the watershed scale.To investigate the relationship between soil erosion and sediment deposition,the combined RUSLE and Sediment Delivery Ratio(SDR)models are used.The Wadi El Hachem watershed is a coastal and mountainous Mediterranean basin with rugged topography and high degree of climatic aggressiveness.Both of these characteristics can have an immediate effect on soil erosion and sediment yield.This research includes estimating the Average Annual Soil Loss(A)and Sediment Yield(SY)in the Wadi El Hachem watershed,mapping different RUSLE factors as well as A and SY,and studying the influence of rainfall erosivity(R)on A and SY in dry and rainy years.The A results vary from 0 to 410 t·ha^(-1)·yr^(-1)with an annual average of 52 t·ha^(-1)·yr^(-1).The Renfro's SDR model was selected as the best model for estimating SY,with standard error,standard deviation,coefficient of variation,and Nash–Sutcliffe efficiency(NSE)values of 0.38%,0.02,0.07%,and 1.00,respectively.The average SY throughout the whole watershed is around 27 t·ha^(-1)·yr^(-1).The SY map for the entire Wadi El Hachem watershed revealed that sediment production zones are mainly concentrated in the Northeast of the basin,at the basin’s outlet,and in the tributaries of the dam.The simulation results of soil loss and sediment yield in dry and rainy years revealed that R is one of the main factors affecting soil erosion and sediment deposition in the Wadi El Hachem watershed.The mean difference in R factor between dry year and rainy year is 671 MJ·mm·ha^(-1)·h^(-1)·yr^(-1).As a result of this fluctuation,the soil loss and sediment yield have increased by 15 and 8 t·ha^(-1)·yr^(-1),respectively.The results of this research can be used to provide scientific and technical support for conservation and management strategies of the Wadi El Hachem watershed.展开更多
Land disturbance and land restoration are important factors influencing runoff production and sediment yield in the semi-arid loess regions of China. This study compared the runoff production and sediment yield during...Land disturbance and land restoration are important factors influencing runoff production and sediment yield in the semi-arid loess regions of China. This study compared the runoff production and sediment yield during the early stage after land disturbance（ESLD） with those during restoring stage after land disturbance（RSLD）. Grey relational analysis was used to analyse the importance of each one of the influencing factors（vegetation, rainfall, soil and topography） in affecting the runoff production and sediment yield. Our results showed that during ESLD, topography was the most critical factor controlling the runoff production, while soil was the most important factor controlling the sediment yield. During RSLD, vegetation was more important in affecting runoff production, while rainfall was more important in affecting sediment yield. In additional, this study demonstrated that both the runoff production and the sediment yield can be effectively reduced by restoring vegetation on severely-disturbed lands, thus providing an important theoretical basis for better implementations of the Grain for Green Program. Our results revealed that the vegetation types of Hippophae rhamnoides＋Pinus tabulaeformis and H. rhamnoides are better plant selections for land restoration in this area, especially for relatively gentle slopes（i.e., less than 20 degrees）.展开更多
The Loess Plateau of China has experienced a lengthy drought and severe soil erosion.Changes in precipitation and land use largely determine the dynamics of runoff and sediment yield in this region. Trend and mutation...The Loess Plateau of China has experienced a lengthy drought and severe soil erosion.Changes in precipitation and land use largely determine the dynamics of runoff and sediment yield in this region. Trend and mutation analyses were performed on hydrological data(1981–2012) from the Yanwachuan watershed in the Loess Plateau Gully Region to study the evolution characteristics of runoff and sediment yield. A time-series contrasting method also was used to evaluate the effects of precipitation and soil and water conservation(SWC) on runoff and sediment yield. Annual sediment yield declined markedly from 1981 to 2012 although there was no significant change in annual precipitation and annual runoff. Change points of annual runoff and annual sediment yield occurred in 1996 and 1997,respectively. Compared with that in the baseline period(1981–1996), annual runoff and annual sediment yield in the change period(1997–2012)decreased by 17.0% and 76.0%, respectively, but annual precipitation increased by 6.3%. Runoff decreased in the flood season and normal season, but increased in the dry season, while sediment yield significantly declined in the whole study period. The SWC measures contributed significantly to the reduction of annual runoff(137.9%) and annual sediment yield(135%) and were more important than precipitation. Biological measures(forestland and grassland) accounted for 61.04% of total runoff reduction, while engineering measures(terraces and dams) accounted for 102.84% of total sediment yield reduction. Furthermore, SWC measures had positive ecological effects. This study provides a scientific basis for soil erosion control on the Loess Plateau.展开更多
The purpose of this paper is to apply ＂Soil and Water Assessment Tool （SWAT）＂ model to assess the impacts of climate change and deforestation on stream discharge and sediment yield from Phu Luong watershed in Nort...The purpose of this paper is to apply ＂Soil and Water Assessment Tool （SWAT）＂ model to assess the impacts of climate change and deforestation on stream discharge and sediment yield from Phu Luong watershed in Northern Viet Nam. Among the three climate change scenarios B 1, B2, and A2, representing low, medium, and high levels of greenhouse gas emission, respectively were set up for Viet Nam, the B2 scenario was selected for this study. Two land use scenarios （S1-2030 and $2-2050） were formulated combination with climate change in WSAT simulation. In B2 climate change scenario, mean temperature increases 0.7℃（2030） and 1.3 ℃ （2050）; annual rainfall increases 2.1% （2030） and 3.80% （2050） respect to baseline scenario. The results show that the stream discharge is likely to increase in the future during the wet season with increasing threats of sedimentation.展开更多
Soil erosion by water is one of the most important land degradation processes in the sloping rainfed lands in Pakistan. A study was conducted in the Dhrabi watershed of Pakistan to evaluate sediment yield associated w...Soil erosion by water is one of the most important land degradation processes in the sloping rainfed lands in Pakistan. A study was conducted in the Dhrabi watershed of Pakistan to evaluate sediment yield associated with rainfall-runoff under various land-use practices. Five sub-catchments with sizes varying from 1.5 to 350 ha were selected for measurement of rainfall, runoff and sediment yield. Soil conservation techniques were also introduced to reduce the soil erosion. All runoff events occurred in the summer especially during monsoon season （July-September）. Sediment yield of two small gully catchments ranged from 4.79 to 8.34 t/ha/yr in 2009, a relatively dry year. In 2010, the annual sediment yield was 8.15 to 12.31 t/ha. Terraced catchment with arable crops produced annual 4.1 t/ha of sediment as compared to 12.31 t/ha by the adjacent gully catchment showing high potential of terraces in reducing erosion. Runoff coefficients calculated for these catchments vary from 0.09 to 0.75. The macro and micro nutrients present in the sediment indicate that these nutrients are being depleted due to soil erosion.展开更多
This paper synthesized the principal land denudation processes and their role in determining riverine suspended sediment yields(SSY) in two typical geographical environments of the Upper Yangtze River Basin in China a...This paper synthesized the principal land denudation processes and their role in determining riverine suspended sediment yields(SSY) in two typical geographical environments of the Upper Yangtze River Basin in China and the Volga River Basin in Eastern Europe. In the Upper Yangtze River Basin, natural factors including topography, climate,lithology and tectonic activity are responsible for the spatial variation in the magnitude of denudation rates.Human disturbances have contributed to the temporal changes of soil erosion and fluvial SSY during the past decades. On one hand, land use change caused by deforestation and land reclamation has played an important role in the acceleration of sediment production from the central hilly area and lower Jinsha catchment; On the other hand, diverse soil conservation practices(e.g., reforestation,terracing) have contributed to a reduction of soil erosion and sediment production since the late 1980 s.It was difficult to explicitly decouple the effect of mitigation measures in the Lower Jinsha River Basindue to the complexity associated with sediment redistribution within river channels(active channel migration and significant sedimentation). The whole basin can be subdivided into seven sub-regions according to the different proportional inputs of principal denudation processes to riverine SSY. In the Volga River Basin, anthropogenic sheet, rill and gully erosion are the predominant denudation processes in the southern region, while channel bank and bed erosion constitutes the main source of riverine suspended sediment flux in the northern part of the basin. Distribution of cultivated lands significantly determined the intensity of denudation processes.Local relief characteristics also considerably influence soil erosion rates and SSY in the southern Volga River Basin. Lithology, soil cover and climate conditions determined the spatial distribution of sheet, rill and gully erosion intensity, but they play a secondary role in SSY spatial variation.展开更多
Watershed as an entry point acts as a beginning to address the issues of sustainable rainwater management for improving livelihoods. Extraction of watershed parameters using Geographical Information System (GIS) and u...Watershed as an entry point acts as a beginning to address the issues of sustainable rainwater management for improving livelihoods. Extraction of watershed parameters using Geographical Information System (GIS) and use of simulation models is the current trend for hydrologic evaluation of watersheds. In the present study, the open Source Tool Quantum GIS 2.2.0 was used for preparation of maps to verify the spatial extent of the area. The Soil and Water Assessment Tool (SWAT) having an interface with Arc-View GIS software (ArcGIS 10.1 with Arc SWAT 2012 extension) was selected for the estimation of runoff and sediment yield from Kaneri watershed, located in Western Maharashtra region. The coefficient of determination (R<sup>2</sup>) for the monthly and yearly runoff was obtained as 0.849 and 0.951 respectively for the calibration period 1979 to 2000 and 0.801 and 0.950 respectively for the validation period 2001-2013. The R<sup>2</sup> value in estimating the monthly and yearly sediment yield during calibration period was computed as 0.722 and 0.788 respectively. The R<sup>2</sup> for monthly and yearly sediment yield values for validation period was observed to be 0.565 and 0.684 respectively.展开更多
Soil erosion is a global phenomenon, which results in sedimentation and siltation of reservoirs of major rivers. Remote sensing data provide a synoptic view from which several surface parameters can be derived to asse...Soil erosion is a global phenomenon, which results in sedimentation and siltation of reservoirs of major rivers. Remote sensing data provide a synoptic view from which several surface parameters can be derived to assess the sedimentation yield in the reservoirs. Hence estimation of sediment yield has become one of the important tasks for planners, engineers and decision makers. The present study in Govindsagar catchment, Lalitpur District, Uttar Pradesh (India), has been carried out using IRS LISS III data to analyse land use/cover characteristics besides drainage basin characterstics. Subsequently, Sediment Yield Index (SYI) of Govindsagar catchment has been estimated using surface derivatives and morphometric parameters using empirical formulae. Integration of results obtained from satellite data and morphometric analysis suggests that the Govindsagar catchment has very low rate of sediment yield i.e. 0.07 ha·m/year indicating a gentle slope and sustainable land use practices in the catchment. Low sediment yield also suggests less erosion in the catchment areas and healthy land use/cover scenario.展开更多
文摘Starting from the supposition of time-space substitution, the Langbein-Schumm's Law was applied to deal with response of fluvial erosion System to the changes in mean annual Precipitation induced by global green-house warming. As a result, a simple method was put forward to predict change in sediment yield, with Ningxia Hui Autonomous Region in the northern fringe of the Loess Plateau of China as an example. Results show that, even the change in mean annual precipitation is the same, the direction and magnitude of the resultant chang in sediment yteld would be quite different in fferent physico-geographical zones. When mean annual precipitation is increased, sediment yield in arid or semi-arid areas with a mean anntal Peripitation of less than 400 mm will be increased, while sediment yield in sub-humid or humid areas with a mean annual precipitation of more than 400 mm will be decreased.Additionally, the complex response of fluvial erosion system in time series due to the lag of change in vegetation behind the changn in precipitation has also been qualitatively discussed in this paper.
文摘Fluvial sediment transport data is a very important data for effective water resource management.However,acquiring this data is expensive and tedious hence sediment yield modeling has become an alternative approach in estimating river sediment yields.In Ghana,several sediment yield predicting models have been developed to estimate the sediment yields of ungauged rivers including the Pra River Basin.In this paper,10 months sediment yield data of the Pra River Basin was used to evaluate the existing sediment yield predicting models of Ghana.A regression analysis between predicted sediment yield data derived from the models and the observed suspended sediment yields of the Pra Basin was done to determine the extent of estimation of observed sediment yields.The prediction of suspended sediment yield was done for 4 out of 5 existing sediment yield predicting models in Ghana.There were variations in sediment yield between observed and predicted suspended sediments.All predicted sediment yields were lower than observed data except for equation 3 where the results were mixed.All models were found to be good estimators of fluvial sediments with the best model being equation 4.Sediment yield tends to increase with drainage basin area.
基金National Basic Research Program of China,No.2007CB407201National Key Technology R&D Program,No.2006BAB06B01-06Science and Technique Development Foundation of YRIHR,No.200603
文摘By scouring experiments, the changeable process and characteristics of sediment yield in the hillslope-gully side erosion system with different coverage degrees and spatial locations of grass were studied. Five grass coverage degrees of 0, 30%, 50%, 70%, 90%, three spatial locations of grass （upslope, mid-slope, low-slope） and two water inflow rates of 3.2 L/min, 5.2 L/min were applied to a 0.5 by 7 m soil bed in scouring experiments. Results showed that the sediment yield decreased with the increase of grass coverage degree at 3.2 L/min water inflow rate in scouring experiments and the sediment yield with different grass locations on the sloping surface was in the order of upper 〉 middle 〉 lower. At 5.2 L/min water inflow rate, the differences of sediment yield among various grass coverage degrees were increased, whereas the changeable tendency of sediment yield with different grass locations on the whole sloping surface was not very obvious. The proportion of sediment yield from the gully side increased in an exponential relationship with the increase of grass coverage degree When the grass was located on the lower position of hillslope, the influence for accelerating gully erosion is the greatest.
文摘Sediment has been identified as a significant threat to water quality and channel clogging that in turn may lead to river flooding. With the increasing awareness of the impairment from sediment to water bodies in a watershed, identifying the locations of the major sediment sources and reducing the sediment through management practices will be important for an effective watershed management. The annualized agricultural non-point source pollution(AnnAGNPS) model and newly developed GIS interface for it were applied in a small agricultural watershed, Redrock Creek watershed, Kansas, in this pilot study for exploring the effectiveness of using this model as a management tool. The calibrated model appropriately simulated monthly runoff and sediment yield through the practices in this study and potentially suggested the ways of sediment reduction through evaluating the changes of land use and field operation in the model for the purpose of watershed management.
基金financially supported by the Special Program for Basic Research of the Ministry of Science and Technology, China (2014FY210100)the National Natural Science Foundation of China (41171422, 41271298)the West Light Foundation of the Chinese Academy of Sciences
文摘Wind and water erosion are among the most important causes of soil loss, and understanding their interactions is important for estimating soil quality and environmental impacts in regions where both types of erosion occur. We used a wind tunnel and simulated rainfall to study sediment yield, particle-size distribution and the fractal dimension of the sediment particles under wind and water erosion. The experiment was conducted with wind ero- sion firstly and water erosion thereafter, under three wind speeds （0, 11 and 14 m/s） and three rainfall intensities （60, 80 and 100 ram/h）. The results showed that the sediment yield was positively correlated with wind speed and rain- fall intensity （P〈0.01）. Wind erosion exacerbated water erosion and increased sediment yield by 7.25%-38.97% relative to the absence of wind erosion. Wind erosion changed the sediment particle distribution by influencing the micro-topography of the sloping land surface. The clay, silt and sand contents of eroded sediment were also posi- tively correlated with wind speed and rainfall intensity （P〈0.01）. Wind erosion increased clay and silt contents by 0.35%-19.60% and 5.80%-21.10%, respectively, and decreased sand content by 2.40%-8.33%, relative to the absence of wind erosion. The effect of wind erosion on sediment particles became weaker with increasing rainfall intensities, which was consistent with the variation in sediment yield. However, particle-size distribution was not closely correlated with sediment yield （P〉0.05）. The fractal dimension of the sediment particles was significantly different under different intensities of water erosion （P〈0.05）, but no significant difference was found under wind and water erosion. The findings reported in this study implicated that both water and wind erosion should be controlled to reduce their intensifying effects, and the controlling of wind erosion could significantly reduce water erosion in this wind-water erosion crisscross region.
基金National Basic Research Program of China,No.2011CB403303National Key Technology R&D Program,No.2013BAC05B04National Natural Science Foundation of China,No.41571276
文摘The Yellow River basin is well known for its high sediment yield. However, this sediment yield has clearly decreased since the 1980 s, especially after the year 2000. The annual average sediment yield was 1.2 billion tons before 2000, but has significantly decreased to 0.3 billion tons over the last 10 years. Changes in discharge and sediment yield for the Yellow River have attracted the attention of both the Central Government and local communities. This study aimed to identify the individual contributions of changes in precipitation and human activities(e.g. water conservancy projects, terracing, silt dams, socio-economic and needs, and soil and water conservation measures) to the decrease in discharge and sediment yield of the Yellow River. The study used both improved the hydrological method and the soil and water conservation method. The study focused on discharge analysis for the upper reaches and the investigation of sediments for the middle reaches of the river. The results showed that discharge and sediment yield have both presented significant decreasing trends over the past 50 years. Precipitation showed an insignificant decreasing trend over the same period. The annual average discharge decreased by 5.68 billion m3 above Lanzhou reach of the Yellow River from 2000 to 2012; human activities(e.g. socio-economic water use) contributed 43.4% of the total reduction, whereas natural factors(e.g. evaporation from lakes, wetlands and reservoirs) accounted for 56.6%. The decrease in annual discharge and sediment yield of the section between Hekouzhen station and Tongguan station were 12.4 billion m3 and 1.24 billion tons, respectively. Human activities contributed 76.5% and 72.2% of the total reduction in discharge and sediment yield, respectively, and were therefore the dominant factors in the changes in discharge and sediment yield of the Yellow River.
基金supported by the National Natural Science Foundation of China (Grant No. 40971012)International Science and Technology Cooperation Program of China (Grants No. 2011DFA20820 and 2011DFG93160)Tsinghua University Independent Scientific Research Program (Grant No.20121080027)
文摘This paper focuses on the effects of precipitation and vegetation coverage on runoff and sediment yield in the Jinsha River Basin. Results of regression analysis were taken as input variables to investigate the applicability of the adaptive network-based fuzzy inference system （ANFIS） to simulating annual runoff and sediment yield. Correlation analysis indicates that runoff and sediment yield are positively correlated with the precipitation indices, while negatively correlated with the vegetation indices. Furthermore, the results of stepwise regression show that annual precipitation is the most important factor influencing the variation of runoff, followed by forest coverage, and their contributions to the variation ofrunoffare 69.8% and 17.3%, respectively. For sediment yield, rainfall erosivity is the most important factor, followed by forest coverage, and their contributions to the variation of sediment yield are 49.3% and 24.2%, respectively. The ANFIS model is of high precision in runoff forecasting, with a relative error of less than 5%, but of poor precision in sediment yield forecasting, indicating that precipitation and vegetation coverage can explain only part of the variation of sediment yield, and that other impact factors, such as human activities, should be sufficiently considered as well.
基金Project (No. B/II-923262) supported by the Marie Curie Research Bursary, European Union.
文摘Simulated results of water yield, sediment yield, surface runoff,subsurface runoff, peak flow, evapo- transipiration, etc., in theTeba catchment, Spain, using SWRRB (Simulator for Water Resources inRural Basins) model are presented and the related problems arediscussed. The results showed that water yield And sediment yieldcould be satisfactorily simulated using SWRRB model. The accuracy ofthe annual water Yield simulation in the Teba catchment was up to83.68/100, which implied that this method could be effectively Usedto predict the annual or inter-annual water yield and to realize thequantification of geographic elements And processes of a river basin.
基金Commonweal Special Project of the Minislry of Water Resources of China, No.2007SHZ0901034 National Natural Science Foundation of China, No.40971012 Acknowledgements We are grateful to Data Center for Resources and Environmental Sciences of Chinese Academy of Sciences for providing the data of soil and to China Meteorological Administration for providing the data of precipitation.
文摘In recent years, the role of human activities in changing sediment yield has become more apparent for the construction of hydraulic engineering and water conservation projections in the Upper Yangtze River, but it has not been evaluated at the macro scale. Taking Sichuan Province and Chongqing City as an example, this paper studies the relationship between socio-economic factors and sediment yield in the Upper Yangtze River based on section data in 1989 and 2007. The results show that sediment yield is significantly correlated with population density and cultivated area, in which the former appears to be more closely related to sediment yield. Moreover, in the relation of sediment yield vs. population density, a critical value of population density exists, below which the sediment yield increases with the increase of population density and over which the sediment yield increases with the decrease of population density. The phenomenon essentially reflects the influence of natural factors, such as topography, precipitation and soil property, and some human activities on sediment yield. The region with a higher population density than critical value is located in the east of the study area and is characterized by plains, hills and low mountains, whereas the opposite is located in the west and characterized by middle and high mountains. In the eastern region, more people live on the lands with a low slope where regional soil erosion is slight; therefore, sediment yield is negatively related with population density. In contrast, in the western region, the population tends to aggregate in the areas with abundant soil and water resources which usually lead to a higher intensity of natural erosion, and in turn, high-intensity agricultural practices in these areas may further strengthen local soil erosion. It is also found that population tends to move from the areas with bad environment and high sediment yield to the areas with more comfortable environment and less sediment yield. The natural factors have greater influence on sediment yield of western region than that of eastern region. Generally, the natural factors play a dominant role on sediment yield in the Upper Yangtze River.
基金Joint project by National Natural Science Foundation of China and Ministry of Water Resources of China, No.59890200 National Na
文摘This paper examines the experimental study on influence of material component to non-linear relation between sediment yield and drainage network development completed in the Lab. The area of flume drainage system is 81.2 m2, the longitudinal gradient and cross section slope are from 0.0348 to 0.0775 and from 0.0115 to 0.038, respectively. Different model materials with a medium diameter of 0.021 mm, 0.076 mm and 0.066 mm cover three experiments each. An artificial rainfall equipment is a sprinkler-system composed of 7 downward nozzles, distributed by hexagon type and a given rainfall intensity is 35.56 mm/hr.cm2. Three experiments are designed by process-response principle at the beginning the ψ shaped small network is dug in the flume. Running time spans are 720 m, 1440 minutes and 540 minutes for Runs I, IV and VI, respectively. Three experiments show that the sediment yield processes are characterized by delaying with a vibration. During network development the energy of a drainage system is dissipated by two ways, of which one is increasing the number of channels (rill and gully), and the other one is enlarging the channel length. The fractal dimension of a drainage network is exactly an index of energy dissipation of a drainage morphological system. Change of this index with time is an unsymmetrical concave curve. Comparison of three experiments explains that the vibration and the delaying ratio of sediment yield processes increase with material coarsening, while the number of channel decreases. The length of channel enlarges with material fining. There exists non-linear relationship between fractal dimension and sediment yield with an unsymmetrical hyperbolic curve. The absolute value of delaying ratio of the curve reduces with time running and material fining. It is characterized by substitution of situation to time.
基金financial support from the Ministry of Water Resources special funds for scientific research (Grant No. 20131037)National Natural Science Foundation of China (Grant No. 41001018)One Hundred Young Persons Project of Institute of Mountain Hazards and Environment (Grant No. SDSQB-2010-02)
文摘As a major sediment area in the upper Yangtze River, Jialing River basin experienced substantial land-use changes, many water conservancy projects were constructed from the 1980 s onward to promote water and soil conservation. The water and sediment yield at the watershed outlet was strongly affected by these water conservation works, including ponds and reservoirs, which should be considered in the modelling. In this study, based on the observed data of the Weicheng River catchment, the relationships between precipitation, runoff, vegetation, topography and sediment yield were analyzed, a distributed runoff and sediment yield model(WSTD-SED) was developed, and the hydrological processes of different land-use scenarios were simulated by using the model. The main results are summarized as follows: 1) there is an alternating characteristic in river channels and reservoirs in the Jialing River hilly area, with scour occurring in wet years and deposit occurring in dry years. 2) Most of the sediment deposited in river channels and reservoirs is carried off by the largest flood in the year. 3) The model yielded plausible results for runoff and sediment yield dynamics without the need of calibration, and the WSTD-SED model could be usedto obtain qualitative estimates on the effects of land use change scenarios. 4) The modelling results suggest that a 10% increase in cropland(dry land) reforestation results in a 0.7% decrease in runoff and 1.5% decrease in sediment yield.
文摘This study addresses the morphometric variables that determine the sediment yield in Wadi AI-Arja through the analysis of the impact of different morphometric characteristics along the course of the valley on its sediment yield, as well as the analysis of spatial and formal dimensions and morphologies of the basin and its relationship to the sediment yield. The study also addresses the size of variation in the volume of sediment yield of the river tributaries that make up the water network of the valley under the differences of its mor- phometric and hydrological characteristics. The study found several results, most notably： The classification of Wadi AI-Arja basin according to the hypsometric integral value （72.1%） within an uneven topography, which in- creases the force of the erosive activity and the size of the sediment yield if the basin was exposed to moist climatic periods. The study also showed the presence of convergence in the intra-spaces between the river tributaries in the water network. This increases the volume of water flows when these tributaries meet with each other and thus increasing their erosive ability and sediment yield. The study also showed the presence of marked variation in the sediment yield of the river tributaries depending on the differences in its morphometric characteristics. The results of the step-wise regression analysis confirmed the importance of the morphometric and hydrological variables, and plant coverage in interpreting the variation in the size of the sediment yield of the river tributaries of different stream order in Wadi AI-Arja basin, where these variables interpreted 43% of the total variation, with statistical significance less than 0.05.
基金the framework of the SWATCH project (Prima project)funded by the DGRSDT,Algeria
文摘One of the most common types of soil degradation is water erosion.It reduces soil quality at the erosion site and may cause sedimentation issues at the deposition site.This phenomenon is estimated using a variety of models.The Revised Universal Soil Loss Equation(RUSLE)model is the most often used,due to its consistence and low data requirement.It is useful for estimating annual soil loss at the watershed scale.To investigate the relationship between soil erosion and sediment deposition,the combined RUSLE and Sediment Delivery Ratio(SDR)models are used.The Wadi El Hachem watershed is a coastal and mountainous Mediterranean basin with rugged topography and high degree of climatic aggressiveness.Both of these characteristics can have an immediate effect on soil erosion and sediment yield.This research includes estimating the Average Annual Soil Loss(A)and Sediment Yield(SY)in the Wadi El Hachem watershed,mapping different RUSLE factors as well as A and SY,and studying the influence of rainfall erosivity(R)on A and SY in dry and rainy years.The A results vary from 0 to 410 t·ha^(-1)·yr^(-1)with an annual average of 52 t·ha^(-1)·yr^(-1).The Renfro's SDR model was selected as the best model for estimating SY,with standard error,standard deviation,coefficient of variation,and Nash–Sutcliffe efficiency(NSE)values of 0.38%,0.02,0.07%,and 1.00,respectively.The average SY throughout the whole watershed is around 27 t·ha^(-1)·yr^(-1).The SY map for the entire Wadi El Hachem watershed revealed that sediment production zones are mainly concentrated in the Northeast of the basin,at the basin’s outlet,and in the tributaries of the dam.The simulation results of soil loss and sediment yield in dry and rainy years revealed that R is one of the main factors affecting soil erosion and sediment deposition in the Wadi El Hachem watershed.The mean difference in R factor between dry year and rainy year is 671 MJ·mm·ha^(-1)·h^(-1)·yr^(-1).As a result of this fluctuation,the soil loss and sediment yield have increased by 15 and 8 t·ha^(-1)·yr^(-1),respectively.The results of this research can be used to provide scientific and technical support for conservation and management strategies of the Wadi El Hachem watershed.
基金funded by the National Science and Technology Support Plan of China(2015BAD07B02)
文摘Land disturbance and land restoration are important factors influencing runoff production and sediment yield in the semi-arid loess regions of China. This study compared the runoff production and sediment yield during the early stage after land disturbance（ESLD） with those during restoring stage after land disturbance（RSLD）. Grey relational analysis was used to analyse the importance of each one of the influencing factors（vegetation, rainfall, soil and topography） in affecting the runoff production and sediment yield. Our results showed that during ESLD, topography was the most critical factor controlling the runoff production, while soil was the most important factor controlling the sediment yield. During RSLD, vegetation was more important in affecting runoff production, while rainfall was more important in affecting sediment yield. In additional, this study demonstrated that both the runoff production and the sediment yield can be effectively reduced by restoring vegetation on severely-disturbed lands, thus providing an important theoretical basis for better implementations of the Grain for Green Program. Our results revealed that the vegetation types of Hippophae rhamnoides＋Pinus tabulaeformis and H. rhamnoides are better plant selections for land restoration in this area, especially for relatively gentle slopes（i.e., less than 20 degrees）.
基金supported by the National Natural Science Foundation of China (51239009, 41171034)Shaanxi Provincial Natural Science Foundation of China (Key) Project (2013JZ012)+1 种基金Shaanxi Provincial Key Laboratory Project of Department of Education (14JS059)Shaanxi Provincial Water Conservancy Science and Technology Project (2016slkj-11)
文摘The Loess Plateau of China has experienced a lengthy drought and severe soil erosion.Changes in precipitation and land use largely determine the dynamics of runoff and sediment yield in this region. Trend and mutation analyses were performed on hydrological data(1981–2012) from the Yanwachuan watershed in the Loess Plateau Gully Region to study the evolution characteristics of runoff and sediment yield. A time-series contrasting method also was used to evaluate the effects of precipitation and soil and water conservation(SWC) on runoff and sediment yield. Annual sediment yield declined markedly from 1981 to 2012 although there was no significant change in annual precipitation and annual runoff. Change points of annual runoff and annual sediment yield occurred in 1996 and 1997,respectively. Compared with that in the baseline period(1981–1996), annual runoff and annual sediment yield in the change period(1997–2012)decreased by 17.0% and 76.0%, respectively, but annual precipitation increased by 6.3%. Runoff decreased in the flood season and normal season, but increased in the dry season, while sediment yield significantly declined in the whole study period. The SWC measures contributed significantly to the reduction of annual runoff(137.9%) and annual sediment yield(135%) and were more important than precipitation. Biological measures(forestland and grassland) accounted for 61.04% of total runoff reduction, while engineering measures(terraces and dams) accounted for 102.84% of total sediment yield reduction. Furthermore, SWC measures had positive ecological effects. This study provides a scientific basis for soil erosion control on the Loess Plateau.
文摘The purpose of this paper is to apply ＂Soil and Water Assessment Tool （SWAT）＂ model to assess the impacts of climate change and deforestation on stream discharge and sediment yield from Phu Luong watershed in Northern Viet Nam. Among the three climate change scenarios B 1, B2, and A2, representing low, medium, and high levels of greenhouse gas emission, respectively were set up for Viet Nam, the B2 scenario was selected for this study. Two land use scenarios （S1-2030 and $2-2050） were formulated combination with climate change in WSAT simulation. In B2 climate change scenario, mean temperature increases 0.7℃（2030） and 1.3 ℃ （2050）; annual rainfall increases 2.1% （2030） and 3.80% （2050） respect to baseline scenario. The results show that the stream discharge is likely to increase in the future during the wet season with increasing threats of sedimentation.
文摘Soil erosion by water is one of the most important land degradation processes in the sloping rainfed lands in Pakistan. A study was conducted in the Dhrabi watershed of Pakistan to evaluate sediment yield associated with rainfall-runoff under various land-use practices. Five sub-catchments with sizes varying from 1.5 to 350 ha were selected for measurement of rainfall, runoff and sediment yield. Soil conservation techniques were also introduced to reduce the soil erosion. All runoff events occurred in the summer especially during monsoon season （July-September）. Sediment yield of two small gully catchments ranged from 4.79 to 8.34 t/ha/yr in 2009, a relatively dry year. In 2010, the annual sediment yield was 8.15 to 12.31 t/ha. Terraced catchment with arable crops produced annual 4.1 t/ha of sediment as compared to 12.31 t/ha by the adjacent gully catchment showing high potential of terraces in reducing erosion. Runoff coefficients calculated for these catchments vary from 0.09 to 0.75. The macro and micro nutrients present in the sediment indicate that these nutrients are being depleted due to soil erosion.
基金support for this study was jointly provided by the Chinese Academy of Sciences (No. ZCX2-XB3-09)the Ministry of Science and Technology of China (No. 2011BAD31B03)
文摘This paper synthesized the principal land denudation processes and their role in determining riverine suspended sediment yields(SSY) in two typical geographical environments of the Upper Yangtze River Basin in China and the Volga River Basin in Eastern Europe. In the Upper Yangtze River Basin, natural factors including topography, climate,lithology and tectonic activity are responsible for the spatial variation in the magnitude of denudation rates.Human disturbances have contributed to the temporal changes of soil erosion and fluvial SSY during the past decades. On one hand, land use change caused by deforestation and land reclamation has played an important role in the acceleration of sediment production from the central hilly area and lower Jinsha catchment; On the other hand, diverse soil conservation practices(e.g., reforestation,terracing) have contributed to a reduction of soil erosion and sediment production since the late 1980 s.It was difficult to explicitly decouple the effect of mitigation measures in the Lower Jinsha River Basindue to the complexity associated with sediment redistribution within river channels(active channel migration and significant sedimentation). The whole basin can be subdivided into seven sub-regions according to the different proportional inputs of principal denudation processes to riverine SSY. In the Volga River Basin, anthropogenic sheet, rill and gully erosion are the predominant denudation processes in the southern region, while channel bank and bed erosion constitutes the main source of riverine suspended sediment flux in the northern part of the basin. Distribution of cultivated lands significantly determined the intensity of denudation processes.Local relief characteristics also considerably influence soil erosion rates and SSY in the southern Volga River Basin. Lithology, soil cover and climate conditions determined the spatial distribution of sheet, rill and gully erosion intensity, but they play a secondary role in SSY spatial variation.
文摘Watershed as an entry point acts as a beginning to address the issues of sustainable rainwater management for improving livelihoods. Extraction of watershed parameters using Geographical Information System (GIS) and use of simulation models is the current trend for hydrologic evaluation of watersheds. In the present study, the open Source Tool Quantum GIS 2.2.0 was used for preparation of maps to verify the spatial extent of the area. The Soil and Water Assessment Tool (SWAT) having an interface with Arc-View GIS software (ArcGIS 10.1 with Arc SWAT 2012 extension) was selected for the estimation of runoff and sediment yield from Kaneri watershed, located in Western Maharashtra region. The coefficient of determination (R<sup>2</sup>) for the monthly and yearly runoff was obtained as 0.849 and 0.951 respectively for the calibration period 1979 to 2000 and 0.801 and 0.950 respectively for the validation period 2001-2013. The R<sup>2</sup> value in estimating the monthly and yearly sediment yield during calibration period was computed as 0.722 and 0.788 respectively. The R<sup>2</sup> for monthly and yearly sediment yield values for validation period was observed to be 0.565 and 0.684 respectively.
文摘Soil erosion is a global phenomenon, which results in sedimentation and siltation of reservoirs of major rivers. Remote sensing data provide a synoptic view from which several surface parameters can be derived to assess the sedimentation yield in the reservoirs. Hence estimation of sediment yield has become one of the important tasks for planners, engineers and decision makers. The present study in Govindsagar catchment, Lalitpur District, Uttar Pradesh (India), has been carried out using IRS LISS III data to analyse land use/cover characteristics besides drainage basin characterstics. Subsequently, Sediment Yield Index (SYI) of Govindsagar catchment has been estimated using surface derivatives and morphometric parameters using empirical formulae. Integration of results obtained from satellite data and morphometric analysis suggests that the Govindsagar catchment has very low rate of sediment yield i.e. 0.07 ha·m/year indicating a gentle slope and sustainable land use practices in the catchment. Low sediment yield also suggests less erosion in the catchment areas and healthy land use/cover scenario.
