Maps of erosivity,which are also commonly referred to as isoerodent maps,have played a critical role in soil conservation efforts in the United States and around the world.Currently available erosivity maps for the Un...Maps of erosivity,which are also commonly referred to as isoerodent maps,have played a critical role in soil conservation efforts in the United States and around the world.Currently available erosivity maps for the United States are either outdated,conflict with erosivity benchmarking studies,or utilized less advanced spatial mapping methods.Furthermore,it is possible that the same underlying issues with US maps are impacting global maps as well.In this study,we used more than 340015-min,fixed-interval precipitation gauges to update the isoerodent map of the conterminous United States.Erosivity values were interpolated using universal kriging under several spatial model configurations and resolutions.The optimal spatial model was selected based on which result had the lowest sample variogram error.Rainfall,erosivity,and erosivity density maps were compared to existing products.Some average annual and annual erosivity results were compared to high-quality erosivity benchmarking publications.Erosivity values from both RUSLE2 and Panagos et al.(2017)were generally lower in the eastern United States and mixed in the western United States compared to our results.Topographic effects resulted in much greater erosivity differences in this study as compared to prior maps.Benchmark comparisons revealed that erosivity maps from this study and others were lower than the benchmark by 14%or more(up to 38%).These findings suggest current practices of storm omission and intensity dampening correction need to be revisited,especially in locations with relatively low-to-moderate rainfall erosivity such as the Midwest or Northeast United States,for example.展开更多
Current watershed-scale,nonpoint source pollution models do not represent the processes and impacts of agricultural best management practices on water quality with sufficient detail.A Water Erosion Pre-diction Project...Current watershed-scale,nonpoint source pollution models do not represent the processes and impacts of agricultural best management practices on water quality with sufficient detail.A Water Erosion Pre-diction Project-Water Quality(WEPP-WQ)model was recently developed which is capable of simulating nonpoint source pollutant transport in nonuniform hillslope conditions such as those with BMPs.However,WEPP-WQ has not been validated for these conditions,and prior validation work only eval-uated calibrated performance rather than uncalibrated performance,with the latter being most relevant to model applications.This study evaluated uncalibrated and calibrated model performance in two plot-scale,artificial rainfall studies.179 observations were compared to corresponding WEPP-WQ simulations of runoff,sediment yield,and soluble and particulate nutrient forms for both nitrogen and phosphorus.Uncalibrated validation results were mixed for the different field conditions,model configurations,and prediction variables.Nash-Sutcliffe Efficiencies for uncalibrated simulations of uniform conditions were generally greater than 0.6 except for soluble nitrogen predictions which were poor.Simulations of nonuniform conditions were generally'unsatisfactory'except for runoff predictions which were quite good(NSE=0.78).Performance was improved substantially for almost all endpoints with calibration.Some exceptions to this occurred because the objective function for calibration was based on log-space differences so as to more equally-weight calibration of unsaturated conditions that tend to produce lesser runoff volumes and sediment yields.Calibrated results for both uniform and nonuniform condi-tions were generally'satisfactory'or'good'according to widely accepted model performance criteria.展开更多
The Water Erosion Prediction Project(WEPP)model has been widely used for estimating runoff and soil loss.The evaluation of the latest version(version 2021.133)under a range of environmental conditions can provide conf...The Water Erosion Prediction Project(WEPP)model has been widely used for estimating runoff and soil loss.The evaluation of the latest version(version 2021.133)under a range of environmental conditions can provide confidence to its users.The objectives of this study were to evaluate the WEPP model for runoff and soil loss predictions using 1159 plot years of rainfall-runoff events data from field experi-mental plots with various climates,soils,topographies,and crops.WEPP runoff and soil loss predictions were compared to the observations before and after input parameter calibration.The results showed good predictions of runoff and soil loss were obtained with both the uncalibrated and calibrated WEPP model for all considered scales with Nash-Sutcliffe model efficiencies(NSE)over 0.4.The calibration of input baseline effective hydraulic conductivity(k_(e)),baseline critical shear stress(τ_(c)),baseline rill erod-ibility(k_(r)),and baseline interrill erodibility(k_(i))improved WEPP model performance with NSE values of 0.98 and 0.91 for average annual runoff and soil loss predictions,respectively.The WEPP model tended to underestimate the runoff and soil loss for large events with runoff over 100 mm and soil loss over 120t/ha.Good event runoff and soil loss predictions(NSE ≥0.4)were obtained for the most common cropping/management systems considered,including corn,cotton,tilled fallow,and wheat after calibration.This study illustrates the most recent WEPP model's performance for runoff and soil loss predictions,and provides a comprehensive set of results.展开更多
文摘Maps of erosivity,which are also commonly referred to as isoerodent maps,have played a critical role in soil conservation efforts in the United States and around the world.Currently available erosivity maps for the United States are either outdated,conflict with erosivity benchmarking studies,or utilized less advanced spatial mapping methods.Furthermore,it is possible that the same underlying issues with US maps are impacting global maps as well.In this study,we used more than 340015-min,fixed-interval precipitation gauges to update the isoerodent map of the conterminous United States.Erosivity values were interpolated using universal kriging under several spatial model configurations and resolutions.The optimal spatial model was selected based on which result had the lowest sample variogram error.Rainfall,erosivity,and erosivity density maps were compared to existing products.Some average annual and annual erosivity results were compared to high-quality erosivity benchmarking publications.Erosivity values from both RUSLE2 and Panagos et al.(2017)were generally lower in the eastern United States and mixed in the western United States compared to our results.Topographic effects resulted in much greater erosivity differences in this study as compared to prior maps.Benchmark comparisons revealed that erosivity maps from this study and others were lower than the benchmark by 14%or more(up to 38%).These findings suggest current practices of storm omission and intensity dampening correction need to be revisited,especially in locations with relatively low-to-moderate rainfall erosivity such as the Midwest or Northeast United States,for example.
文摘Current watershed-scale,nonpoint source pollution models do not represent the processes and impacts of agricultural best management practices on water quality with sufficient detail.A Water Erosion Pre-diction Project-Water Quality(WEPP-WQ)model was recently developed which is capable of simulating nonpoint source pollutant transport in nonuniform hillslope conditions such as those with BMPs.However,WEPP-WQ has not been validated for these conditions,and prior validation work only eval-uated calibrated performance rather than uncalibrated performance,with the latter being most relevant to model applications.This study evaluated uncalibrated and calibrated model performance in two plot-scale,artificial rainfall studies.179 observations were compared to corresponding WEPP-WQ simulations of runoff,sediment yield,and soluble and particulate nutrient forms for both nitrogen and phosphorus.Uncalibrated validation results were mixed for the different field conditions,model configurations,and prediction variables.Nash-Sutcliffe Efficiencies for uncalibrated simulations of uniform conditions were generally greater than 0.6 except for soluble nitrogen predictions which were poor.Simulations of nonuniform conditions were generally'unsatisfactory'except for runoff predictions which were quite good(NSE=0.78).Performance was improved substantially for almost all endpoints with calibration.Some exceptions to this occurred because the objective function for calibration was based on log-space differences so as to more equally-weight calibration of unsaturated conditions that tend to produce lesser runoff volumes and sediment yields.Calibrated results for both uniform and nonuniform condi-tions were generally'satisfactory'or'good'according to widely accepted model performance criteria.
文摘The Water Erosion Prediction Project(WEPP)model has been widely used for estimating runoff and soil loss.The evaluation of the latest version(version 2021.133)under a range of environmental conditions can provide confidence to its users.The objectives of this study were to evaluate the WEPP model for runoff and soil loss predictions using 1159 plot years of rainfall-runoff events data from field experi-mental plots with various climates,soils,topographies,and crops.WEPP runoff and soil loss predictions were compared to the observations before and after input parameter calibration.The results showed good predictions of runoff and soil loss were obtained with both the uncalibrated and calibrated WEPP model for all considered scales with Nash-Sutcliffe model efficiencies(NSE)over 0.4.The calibration of input baseline effective hydraulic conductivity(k_(e)),baseline critical shear stress(τ_(c)),baseline rill erod-ibility(k_(r)),and baseline interrill erodibility(k_(i))improved WEPP model performance with NSE values of 0.98 and 0.91 for average annual runoff and soil loss predictions,respectively.The WEPP model tended to underestimate the runoff and soil loss for large events with runoff over 100 mm and soil loss over 120t/ha.Good event runoff and soil loss predictions(NSE ≥0.4)were obtained for the most common cropping/management systems considered,including corn,cotton,tilled fallow,and wheat after calibration.This study illustrates the most recent WEPP model's performance for runoff and soil loss predictions,and provides a comprehensive set of results.
