Soil erosion is a major issue in Loess Plateau,China,and quantitative analyses of sediment sources are crucial for soil erosion control.In this study,a combination of flood couplet analysis and composite fingerprint i...Soil erosion is a major issue in Loess Plateau,China,and quantitative analyses of sediment sources are crucial for soil erosion control.In this study,a combination of flood couplet analysis and composite fingerprint identification was used for historical reconstructions of soil erosion in sediment source areas in Loess Plateau.Each flood couplet was constructed based on sediment 137Cs activity,and past soil erosion was calculated using soil bulk density and storage capacity curves.The contribution rates of the sediment sources were calculated using the fingerprinting method,and the amount of erosion in the sediment source areas was estimated.The best fingerprint combination(Cr,Ni,V,and TOC)enabled a 97.2%recognition of sediment sources from 29 flood events(1956–1990)in the Loess Plateau.The contribution rates of gullies,farmland,grassland,and shrubland were 44.89%,26.38%,10.49%,and 18.24%,respectively.These four land use types contributed 1,227,751,512,and 279 tons of sediments,respectively.Re-vegetation decreased soil erosion(1966–1983),whereas deforestation increased soil erosion(1956–1965 and 1984–1990).Rational soil and water conservation measures on slopes and check dam construction in gullies are therefore suggested to mitigate erosion.展开更多
Check dams have been widely used in China’s Loess Plateau region due to their effectiveness in erosion and flood control.However,the safety and stability of the check dam decrease with the operation process,which inc...Check dams have been widely used in China’s Loess Plateau region due to their effectiveness in erosion and flood control.However,the safety and stability of the check dam decrease with the operation process,which increases the probability of dam failure during flood events and threatens local residents’ life and property.Thus,this study simulated flood process of the check dam failure in the Wangmaogou watershed in Yulin City,Shaanxi Province,China,calculated different types of inundation losses based on the flood inundation area within the watershed,and determined the number of key flood protection check dams by classifying the flood risk levels of the check dams.The results showed that 5 dams in the watershed were subject to overtopping during different rainfall return periods,which was related to their flood discharge capacity.Dam failure flood process showed a rapid growth trend followed by slow decrease,and the time of flood peak advanced with increase in the return period.After harmonization of evaluation scales,the magnitude of flood inundation losses can be ranked as:economic losses(212.409 million yuan) > life losses(10.368 million yuan) > ecological losses(6.433 million yuan).The risk value for both individual dams and the whole dam system decreases as the return period increases.The number of key flood protection check dams in the Wangmaogou watershed was 2,3,3,3,4,and 5 for floods with return periods of 10,20,30,50,100,and 200 years,respectively.The results provided a theoretical basis for the safe operation and risk evaluation of check dams in the Loess Plateau Hills watershed.展开更多
Linking landscape indexes to ecological processes is the key topic of landscape ecology.However,traditional landscape metrics based on the Patch-Mosaic Model have no ecological significance.In this study,the runoff-se...Linking landscape indexes to ecological processes is the key topic of landscape ecology.However,traditional landscape metrics based on the Patch-Mosaic Model have no ecological significance.In this study,the runoff-sediment landscape index coupling land use,topography,soil,and vegetation factors was constructed to link landscape patterns to runoff and sediment.In the study area,the runoffsediment landscape index at the class scale showed an increasing trend from 0.10 in 1995 to 0.26 in 2015.Cropland had a higher runoff-sediment landscape index compared to grassland or forestland.At the landscape scale,the runoff-sediment landscape index showed a decreasing trend since 1995;furthermore,it decreased by 36.24%in 2015 compared with the index in 1990.The runoff-sediment landscape index had higher correlations with runoff and sediment compared with traditional landscape metrics.Redundancy analysis showed that the runoffsediment landscape index had a higher contribution to runoff and sediment compared to traditional landscape metrics,explaining 90.1%of the variability.The soil erosion risk assessed by the runoff-sediment landscape index showed an increasing trend upstream of the Dali River watershed.More attention should be paid to this area in future vegetation restoration attempts,as exploring the impact of landscape pattern changes on ecological processes,especially hydrological processes,plays an important role in comprehensive watershed management.展开更多
Hydraulic erosion associated with seasonal freeze-thaw cycles is one of the most predominant factors,which drives soil stripping and transportation.In this study,indoor simulated meltwater erosion experiments were use...Hydraulic erosion associated with seasonal freeze-thaw cycles is one of the most predominant factors,which drives soil stripping and transportation.In this study,indoor simulated meltwater erosion experiments were used to investigate the sorting characteristics and transport mechanism of sediment particles under different freeze-thaw conditions(unfrozen,shallow-thawed,and frozen slopes)and runoff rates(1,2,and 4 L/min).Results showed that the order of sediment particle contents was silt>sand>clay during erosion process on unfrozen,shallow-thawed,and frozen slopes.Compared with original soils,clay and silt were lost,and sand was deposited.On unfrozen and shallow-thawed slopes,the change of runoff rate had a significant impact on the enrichment of clay,silt,and sand particles.In this study,the sediment particles transported in the form of suspension/saltation were 83.58%–86.54%on unfrozen slopes,69.24%–84.89%on shallow-thawed slopes,and 83.75%–87.44%on frozen slopes.Moreover,sediment particles smaller than 0.027 mm were preferentially transported.On shallow-thawed slope,relative contribution percentage of suspension/saltation sediment particles gradually increased with the increase in runoff rate,and an opposite trend occurred on unfrozen and frozen slopes.At the same runoff rate,freeze-thaw process had a significant impact on the relative contribution percentage of sediment particle transport via suspension/saltation and rolling during erosion process.The research results provide an improved transport mechanism under freeze-thaw condition for steep loessal slopes.展开更多
Seasonal freeze–thaw processes have led to severe soil erosion in the middle and high latitudes.The area affected by freeze–thaw erosion in China exceeds 13%of the national territory.So understanding the effect of f...Seasonal freeze–thaw processes have led to severe soil erosion in the middle and high latitudes.The area affected by freeze–thaw erosion in China exceeds 13%of the national territory.So understanding the effect of freeze–thaw on erosion process is of great significance for soil and water conservation as well as for ecological engineering.In this study,we designed simulated rainfall experiments to investigate soil erosion processes under two soil conditions,unfrozen slope(UFS)and frozen slope(FS),and three rainfall intensities of 0.6,0.9 and 1.2 mm/min.The results showed that the initial runoff time of FS occurred much earlier than that of the UFS.Under the same rainfall intensity,the runoff of FS is 1.17–1.26 times that of UFS;and the sediment yield of FS is 6.48–10.49 times that of UFS.With increasing rainfall time,rills were produced on the slope.After the appearance of the rills,the sediment yield on the FS accounts for 74%–86%of the total sediment yield.Rill erosion was the main reason for the increase in soil erosion rate on FS,and the reduction in water percolation resulting from frozen layers was one of the important factors leading to the advancement of rills on slope.A linear relationship existed between the cumulative runoff and the sediment yield of UFS and FS(R2>0.97,P<0.01).The average mean weight diameter(MWD)on the slope erosion particles was as follows:UFS0.9(73.84μm)>FS0.6(72.30μm)>UFS1.2(72.23μm)>substrate(71.23μm)>FS1.2(71.06μm)>FS0.9(70.72μm).During the early stage of the rainfall,the MWD of the FS was relatively large.However,during the middle to late rainfall,the particle composition gradually approached that of the soil substrate.Under different rainfall intensities,the mean soil erodibility(MK)of the FS was 7.22 times that of the UFS.The ratio of the mean regression coefficient C2(MC2)between FS and UFS was roughly correspondent with MK.Therefore,the parameter C2 can be used to evaluate soil erodibility after the appearance of the rills.This article explored the influence mechanism of freeze–thaw effects on loess soil erosion and provided a theoretical basis for further studies on soil erosion in the loess hilly regions.展开更多
Slope length and slope steepness are critical topographic factors(L and S)in the Universal Soil Loss Equation(USLE)and Chinese Soil Loss Equation(CSLE)for soil erosion modelling.Both slope length and slope gradient ar...Slope length and slope steepness are critical topographic factors(L and S)in the Universal Soil Loss Equation(USLE)and Chinese Soil Loss Equation(CSLE)for soil erosion modelling.Both slope length and slope gradient are potentially sensitive to spatial resolution when calculated in a GIS framework.The resolution effect on the LS factor and approaches suitable for improving the LS factor at a coarse resolution have not been well identified.To address this problem,the LS factor at 5-m and 30-m resolution in twenty-four watersheds with various terrains was estimated.And a downscale model based on matching of the lower resolution LS cumulative frequency curves to a higher resolution("Histogram Matching"method)was tested for its potential to improve LS factor estimation accuracy.In the larger relief mountainous area,compared to 5-m resolution,the 30-m resolution generated LS was generally overestimated by more than 20%and in lower relief areas underestimated by more than 15%.This bias is less than 10%in medium relief areas.The downscale model improved LS factor estimates compared to the 30-m resolution estimate by more than 10%when comparing frequency distribution curves and more than 20%in mean values in larger relief areas.The downscale model worked well in all regions except for the low relief areas,which intuitively are the low soil erosion potential areas.The results of this research help quantify the uncertainty in soil erosion estimates and may ultimately help to improve the assessment of soil erosion through its impact on LS factor estimates,especially at regional and global scales.展开更多
Freeze-thaw processes can influence hydrology,soil erosion,and morphological development by altering the connectivity between active pathways of water and sediment transport.Concentrated flow experi-ments were conduct...Freeze-thaw processes can influence hydrology,soil erosion,and morphological development by altering the connectivity between active pathways of water and sediment transport.Concentrated flow experi-ments were conducted involving frozen,shallow thawed,and unfrozen soil slopes under 1,2,and 4 L/min runoff rates at a temperature of approximately 5℃.In this study,hydrological connectivity was analysed via the simplified hydrological curve and relative surface connection function.Sediment con-nectivity was analysed via the sediment structure connectivity and sediment functional connectivity.Results indicated that hydrological connectivity was greatest on frozen slopes(FS),followed by shallow thawed slopes(STS),and unfrozen slopes(UFS)given a constant flow rate.Hydrological connectivity increased with increasing runoff rate for each freeze-thaw condition.Freezing condition and runoff rate exhibited a positive response to the hydrological connectivity.Sediment structure connectivity increased with increasing runoff rate for each slope condition.The ordering of sediment structure connectivity across freeze-thaw condition was that FS was greater than STS while STS was greater than UFS inde-pendent of flow rate.Sediment functional connectivity included longitudinal,lateral,and vertical con-nectivity components.Sediment longitudinal and vertical connectivity indicated a trend of first increasing and then decreasing under the different runoff rates and freeze-thaw conditions.For a given runoff rate,the ordering of sediment longitudinal and vertical connectivity across freeze-thaw condition was that FS was greater than STS while STS was greater than UFS.Sediment lateral connectivity exhibited a trend of first decreasing and then stabilizing.The ordering of sediment lateral connectivity across freeze-thaw condition was that UFS was greater than STS while STS was greater than FS.FS could more easily reach longitudinal and vertical penetration.Sediment longitudinal and vertical connectivity rates demonstrated increasing trends with increasing runoff rate after runoff generation stabilization and gradually approached unity.This research further improves our understanding of the hydrological and erosional mechanisms of meltwater and the generation of flooding in frozen soil conditions.展开更多
As an important soil and water conservation engineering measure,more than 100,000 check dams are constructed across the Loess Plateau;these dams play a vital role in reducing floods and sediment in the region.However,...As an important soil and water conservation engineering measure,more than 100,000 check dams are constructed across the Loess Plateau;these dams play a vital role in reducing floods and sediment in the region.However,the effects of check dams on hydrologic process are still unclear,particularly when they are deployed as a system for watershed soil and water management.This study examined the watershed hydrologic process modulated by the check dam system in a typical Loess Plateau catchment.By simulating scenarios with various numbers of check dams using a distributed physically-based hydro-logical model,the effects of the number of check dams on runoff generation and concentration were analyzed for the study catchment.The results showed that the presence of check dams reduced the peak discharge and the flood volume and extended the flood duration;the reduction effect on peak discharge was most significant among the three factors.The system of check dams substantially decreased the runoff coefficient,and the runoff coefficient reduction rate was greater for rainstorms with shorter return periods than for rainstorms with longer return periods.The check dams increased the capacity of the catchment regulating and storing floods and extended the average runoff concentration time in the catchment that flattened the instantaneous unit hydrograph.This study reveals the influencing mech-anism of check dam system on the watershed hydrological process under heavy rainstorm conditions and provides a theoretical basis for evaluating the effects of numerous check dams on regional hydrology and water resources on the Loess Plateau.展开更多
基金supported by the Project of Creating Ordos National Sustainable Development Agenda Innovation Demonstration Zone(Grant 2022EEDSKJXM005)Natural Science Foundation of China(Grant 42077073)+3 种基金Natural Science Basic Research Plan in Shaanxi Province of China(2022KJXX-62)the Project of Shaanxi Coal and Chemical Industry Group Co.,Ltd(2022SMHKJ-A-J07-02,2022SMHKJ-B-J-54)the Project of AnHui Water Resources Development Co.,Ltd(KY-2021-13)。
文摘Soil erosion is a major issue in Loess Plateau,China,and quantitative analyses of sediment sources are crucial for soil erosion control.In this study,a combination of flood couplet analysis and composite fingerprint identification was used for historical reconstructions of soil erosion in sediment source areas in Loess Plateau.Each flood couplet was constructed based on sediment 137Cs activity,and past soil erosion was calculated using soil bulk density and storage capacity curves.The contribution rates of the sediment sources were calculated using the fingerprinting method,and the amount of erosion in the sediment source areas was estimated.The best fingerprint combination(Cr,Ni,V,and TOC)enabled a 97.2%recognition of sediment sources from 29 flood events(1956–1990)in the Loess Plateau.The contribution rates of gullies,farmland,grassland,and shrubland were 44.89%,26.38%,10.49%,and 18.24%,respectively.These four land use types contributed 1,227,751,512,and 279 tons of sediments,respectively.Re-vegetation decreased soil erosion(1966–1983),whereas deforestation increased soil erosion(1956–1965 and 1984–1990).Rational soil and water conservation measures on slopes and check dam construction in gullies are therefore suggested to mitigate erosion.
基金supported by the National Natural Science Foundation of China (Grant 42077073, 42373063, 42307447)Natural Science Basic Research Plan in Shaanxi Province of China (2022KJXX-62)。
文摘Check dams have been widely used in China’s Loess Plateau region due to their effectiveness in erosion and flood control.However,the safety and stability of the check dam decrease with the operation process,which increases the probability of dam failure during flood events and threatens local residents’ life and property.Thus,this study simulated flood process of the check dam failure in the Wangmaogou watershed in Yulin City,Shaanxi Province,China,calculated different types of inundation losses based on the flood inundation area within the watershed,and determined the number of key flood protection check dams by classifying the flood risk levels of the check dams.The results showed that 5 dams in the watershed were subject to overtopping during different rainfall return periods,which was related to their flood discharge capacity.Dam failure flood process showed a rapid growth trend followed by slow decrease,and the time of flood peak advanced with increase in the return period.After harmonization of evaluation scales,the magnitude of flood inundation losses can be ranked as:economic losses(212.409 million yuan) > life losses(10.368 million yuan) > ecological losses(6.433 million yuan).The risk value for both individual dams and the whole dam system decreases as the return period increases.The number of key flood protection check dams in the Wangmaogou watershed was 2,3,3,3,4,and 5 for floods with return periods of 10,20,30,50,100,and 200 years,respectively.The results provided a theoretical basis for the safe operation and risk evaluation of check dams in the Loess Plateau Hills watershed.
基金funded by the Project of Creating Ordos National Sustainable Development Agenda Innovation Demonstration Zone(Grant 2022EEDSKJXM005)National Natural Science Foundation of China(Grant 42077073)+1 种基金Natural Science Basic Research Plan in Shaanxi Province of China(2022KJXX-62)Project of Shaanxi Provincial Transport Department(2015-11K)。
文摘Linking landscape indexes to ecological processes is the key topic of landscape ecology.However,traditional landscape metrics based on the Patch-Mosaic Model have no ecological significance.In this study,the runoff-sediment landscape index coupling land use,topography,soil,and vegetation factors was constructed to link landscape patterns to runoff and sediment.In the study area,the runoffsediment landscape index at the class scale showed an increasing trend from 0.10 in 1995 to 0.26 in 2015.Cropland had a higher runoff-sediment landscape index compared to grassland or forestland.At the landscape scale,the runoff-sediment landscape index showed a decreasing trend since 1995;furthermore,it decreased by 36.24%in 2015 compared with the index in 1990.The runoff-sediment landscape index had higher correlations with runoff and sediment compared with traditional landscape metrics.Redundancy analysis showed that the runoffsediment landscape index had a higher contribution to runoff and sediment compared to traditional landscape metrics,explaining 90.1%of the variability.The soil erosion risk assessed by the runoff-sediment landscape index showed an increasing trend upstream of the Dali River watershed.More attention should be paid to this area in future vegetation restoration attempts,as exploring the impact of landscape pattern changes on ecological processes,especially hydrological processes,plays an important role in comprehensive watershed management.
基金funded by the National Natural Science Foundation of China(U2040208,52009104,52079106,42107087)the Shaanxi Province Innovation Talent Promotion Plan Project Technology Innovation Team(2020TD-023)。
文摘Hydraulic erosion associated with seasonal freeze-thaw cycles is one of the most predominant factors,which drives soil stripping and transportation.In this study,indoor simulated meltwater erosion experiments were used to investigate the sorting characteristics and transport mechanism of sediment particles under different freeze-thaw conditions(unfrozen,shallow-thawed,and frozen slopes)and runoff rates(1,2,and 4 L/min).Results showed that the order of sediment particle contents was silt>sand>clay during erosion process on unfrozen,shallow-thawed,and frozen slopes.Compared with original soils,clay and silt were lost,and sand was deposited.On unfrozen and shallow-thawed slopes,the change of runoff rate had a significant impact on the enrichment of clay,silt,and sand particles.In this study,the sediment particles transported in the form of suspension/saltation were 83.58%–86.54%on unfrozen slopes,69.24%–84.89%on shallow-thawed slopes,and 83.75%–87.44%on frozen slopes.Moreover,sediment particles smaller than 0.027 mm were preferentially transported.On shallow-thawed slope,relative contribution percentage of suspension/saltation sediment particles gradually increased with the increase in runoff rate,and an opposite trend occurred on unfrozen and frozen slopes.At the same runoff rate,freeze-thaw process had a significant impact on the relative contribution percentage of sediment particle transport via suspension/saltation and rolling during erosion process.The research results provide an improved transport mechanism under freeze-thaw condition for steep loessal slopes.
基金the National Key Research and Development Program of China(2017YFC0403605)the National Natural Science Foundation of China(413517033)+1 种基金the State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin,China Institute of Water Resources and Hydropower Research(SKL2018CG04)the Shaanxi Province Innovation Talent Promotion Plan Project Technology Innovation Team(2018TD-037)。
文摘Seasonal freeze–thaw processes have led to severe soil erosion in the middle and high latitudes.The area affected by freeze–thaw erosion in China exceeds 13%of the national territory.So understanding the effect of freeze–thaw on erosion process is of great significance for soil and water conservation as well as for ecological engineering.In this study,we designed simulated rainfall experiments to investigate soil erosion processes under two soil conditions,unfrozen slope(UFS)and frozen slope(FS),and three rainfall intensities of 0.6,0.9 and 1.2 mm/min.The results showed that the initial runoff time of FS occurred much earlier than that of the UFS.Under the same rainfall intensity,the runoff of FS is 1.17–1.26 times that of UFS;and the sediment yield of FS is 6.48–10.49 times that of UFS.With increasing rainfall time,rills were produced on the slope.After the appearance of the rills,the sediment yield on the FS accounts for 74%–86%of the total sediment yield.Rill erosion was the main reason for the increase in soil erosion rate on FS,and the reduction in water percolation resulting from frozen layers was one of the important factors leading to the advancement of rills on slope.A linear relationship existed between the cumulative runoff and the sediment yield of UFS and FS(R2>0.97,P<0.01).The average mean weight diameter(MWD)on the slope erosion particles was as follows:UFS0.9(73.84μm)>FS0.6(72.30μm)>UFS1.2(72.23μm)>substrate(71.23μm)>FS1.2(71.06μm)>FS0.9(70.72μm).During the early stage of the rainfall,the MWD of the FS was relatively large.However,during the middle to late rainfall,the particle composition gradually approached that of the soil substrate.Under different rainfall intensities,the mean soil erodibility(MK)of the FS was 7.22 times that of the UFS.The ratio of the mean regression coefficient C2(MC2)between FS and UFS was roughly correspondent with MK.Therefore,the parameter C2 can be used to evaluate soil erodibility after the appearance of the rills.This article explored the influence mechanism of freeze–thaw effects on loess soil erosion and provided a theoretical basis for further studies on soil erosion in the loess hilly regions.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences,Grant No.XDA20040202SKL Foundation Grant No.A314021402-1718+1 种基金Na tional Natural Science Foundation of China,Grant No.41977062,41601290,41771315,41930102Program for Key Science and Technology Innovation Team in Shaanxi Province,Grant No.2014KCT-27
文摘Slope length and slope steepness are critical topographic factors(L and S)in the Universal Soil Loss Equation(USLE)and Chinese Soil Loss Equation(CSLE)for soil erosion modelling.Both slope length and slope gradient are potentially sensitive to spatial resolution when calculated in a GIS framework.The resolution effect on the LS factor and approaches suitable for improving the LS factor at a coarse resolution have not been well identified.To address this problem,the LS factor at 5-m and 30-m resolution in twenty-four watersheds with various terrains was estimated.And a downscale model based on matching of the lower resolution LS cumulative frequency curves to a higher resolution("Histogram Matching"method)was tested for its potential to improve LS factor estimation accuracy.In the larger relief mountainous area,compared to 5-m resolution,the 30-m resolution generated LS was generally overestimated by more than 20%and in lower relief areas underestimated by more than 15%.This bias is less than 10%in medium relief areas.The downscale model improved LS factor estimates compared to the 30-m resolution estimate by more than 10%when comparing frequency distribution curves and more than 20%in mean values in larger relief areas.The downscale model worked well in all regions except for the low relief areas,which intuitively are the low soil erosion potential areas.The results of this research help quantify the uncertainty in soil erosion estimates and may ultimately help to improve the assessment of soil erosion through its impact on LS factor estimates,especially at regional and global scales.
基金supported by the National Key Research and Development Program of China(No.2022YFF1300801)the National Natural Science Foundation of China(Nos.52009104,U2040208,42107087)+3 种基金the Sin0-German Mobility Programme(No.M-0427)the Shaanxi Province Innovation Talent Promotion Plan Project Technology Innovation Team(No.2020TD-023)the Natural Science Foundations of Shaanxi Province(No.2022JQ-509)Shaanxi Province Water Conservancy Science and Technology Project(2022slkj-04).
文摘Freeze-thaw processes can influence hydrology,soil erosion,and morphological development by altering the connectivity between active pathways of water and sediment transport.Concentrated flow experi-ments were conducted involving frozen,shallow thawed,and unfrozen soil slopes under 1,2,and 4 L/min runoff rates at a temperature of approximately 5℃.In this study,hydrological connectivity was analysed via the simplified hydrological curve and relative surface connection function.Sediment con-nectivity was analysed via the sediment structure connectivity and sediment functional connectivity.Results indicated that hydrological connectivity was greatest on frozen slopes(FS),followed by shallow thawed slopes(STS),and unfrozen slopes(UFS)given a constant flow rate.Hydrological connectivity increased with increasing runoff rate for each freeze-thaw condition.Freezing condition and runoff rate exhibited a positive response to the hydrological connectivity.Sediment structure connectivity increased with increasing runoff rate for each slope condition.The ordering of sediment structure connectivity across freeze-thaw condition was that FS was greater than STS while STS was greater than UFS inde-pendent of flow rate.Sediment functional connectivity included longitudinal,lateral,and vertical con-nectivity components.Sediment longitudinal and vertical connectivity indicated a trend of first increasing and then decreasing under the different runoff rates and freeze-thaw conditions.For a given runoff rate,the ordering of sediment longitudinal and vertical connectivity across freeze-thaw condition was that FS was greater than STS while STS was greater than UFS.Sediment lateral connectivity exhibited a trend of first decreasing and then stabilizing.The ordering of sediment lateral connectivity across freeze-thaw condition was that UFS was greater than STS while STS was greater than FS.FS could more easily reach longitudinal and vertical penetration.Sediment longitudinal and vertical connectivity rates demonstrated increasing trends with increasing runoff rate after runoff generation stabilization and gradually approached unity.This research further improves our understanding of the hydrological and erosional mechanisms of meltwater and the generation of flooding in frozen soil conditions.
基金This research was supported by the National Natural Science Foundation of China(51779204,51879281,5207910)Program for Science&Technology Innovation Research Team of Shaanxi Province(2018TD-037)the Research Fund of the State Key Laboratory of Eco-hydraulics in Northwest Arid Region,Xi'an University of Technology(Grant No.2018KFKT-1).
文摘As an important soil and water conservation engineering measure,more than 100,000 check dams are constructed across the Loess Plateau;these dams play a vital role in reducing floods and sediment in the region.However,the effects of check dams on hydrologic process are still unclear,particularly when they are deployed as a system for watershed soil and water management.This study examined the watershed hydrologic process modulated by the check dam system in a typical Loess Plateau catchment.By simulating scenarios with various numbers of check dams using a distributed physically-based hydro-logical model,the effects of the number of check dams on runoff generation and concentration were analyzed for the study catchment.The results showed that the presence of check dams reduced the peak discharge and the flood volume and extended the flood duration;the reduction effect on peak discharge was most significant among the three factors.The system of check dams substantially decreased the runoff coefficient,and the runoff coefficient reduction rate was greater for rainstorms with shorter return periods than for rainstorms with longer return periods.The check dams increased the capacity of the catchment regulating and storing floods and extended the average runoff concentration time in the catchment that flattened the instantaneous unit hydrograph.This study reveals the influencing mech-anism of check dam system on the watershed hydrological process under heavy rainstorm conditions and provides a theoretical basis for evaluating the effects of numerous check dams on regional hydrology and water resources on the Loess Plateau.
