为对比分析HEC-HMS模型三种降雨损失方法在沁河流域的适用性。借助Morris筛选法识别降雨损失方法的关键参数,选用流域内5场雨洪资料进行参数率定和模拟精度分析。结果表明:(1)SCS CN值曲线法、Green-Ampt法、Initial and Uniform法主要...为对比分析HEC-HMS模型三种降雨损失方法在沁河流域的适用性。借助Morris筛选法识别降雨损失方法的关键参数,选用流域内5场雨洪资料进行参数率定和模拟精度分析。结果表明:(1)SCS CN值曲线法、Green-Ampt法、Initial and Uniform法主要敏感性参数分别为CN值、土壤饱和导水率、恒定损失率。(2)选取洪峰流量、洪水总量、峰现时刻误差以及Nash系数对模型模拟精度进行评价,SCS CN值曲线法和Initial and Uniform法模拟结果达到乙等精度,Green-Ampt法模拟结果达到丙等精度。研究成果可为半湿润地区中小流域降雨损失方法的选择提供参考。展开更多
Understanding the relationship between hillslope soil loss with ephemeral gully and rainfall regime is important for soil loss prediction and erosion control. Based on 12-year field observation data, this paper quanti...Understanding the relationship between hillslope soil loss with ephemeral gully and rainfall regime is important for soil loss prediction and erosion control. Based on 12-year field observation data, this paper quantified the rainfall regime impacts on soil loss at loessial hillslope with ephemeral gully. According to three rainfall parameters including precipitation （P）, rainfall duration （t）, and maximum 30-minute rainfall intensity （I30）, 115 rainfall events were classified by using K-mean clustering method and Discriminant Analysis. The results showed that 115 rainfall events could be divided into three rainfall regimes. Rainfall Regime 1 （RR1） had large I30 values with low precipitation and short duration, while the three rainfall parameters of Rainfall Regime 3 （RR3） were inversely different compared with those of RR1; for Rainfall Regime 2 （RR2）, the precipitation, duration and Iso values were all between those of RR1 and RR3. Compared with RR2 and RR3, RR1 was the dominant rainfall regime for causing soil loss at the loessial hillslope with ephemeral gully, especially for causing extreme soil loss events. PI30 （Product of P and Izo） was selected as the key index of rainfall characteristics to fit soil loss equations. Two sets of linear regression equations between soil loss and Plzo with and without rainfall regime classification were fitted. Compared with the equation without rainfall regime classification, the cross validation results of the equations with rainfall regime classification was satisfactory. These results indicated that rainfall regime classification could not only depict rainfall characteristics precisely, but also improve soil loss equation prediction accuracy at loessial hillslope with ephemeral gully.展开更多
Erosion agents and patterns profoundly affect hillslope soil loss characteristics. However, few attempts have been made to analyze the effects of rainfall and inflow on soil erosion for hillslopes dominated by sheet e...Erosion agents and patterns profoundly affect hillslope soil loss characteristics. However, few attempts have been made to analyze the effects of rainfall and inflow on soil erosion for hillslopes dominated by sheet erosion or rill erosion in the Chinese Mollisol region. The objective of this study was to discuss the erosive agent(rainfall or inflow), hillslope erosion pattern(sheet erosion or rill erosion) and slope gradient effects on runoff and soil losses. Two soil pans(2.0 m long, 0.5 m wide and 0.5 m deep) with 5° and 10° slopes were subjected to rainfall(0 and 70 mm h–1) and inflow(0 and 70 mm h–1) experiments. Three experimental combinations of rainfall intensity(RI) and inflow rate(IR) were tested using the same water supply of 70 mm by controllingthe run time. A flat soil surface and a soil bed with a straight initial rill were prepared manually, and represented hillslopes dominated by sheet erosion and rill erosion, respectively. The results showed that soil losses had greater differences among treatments than total runoff. Soil losses decreased in the order of RI70+IR70 > RI70+IR0 > RI0+IR70. Additionally, soil losses for hillslopes dominated by rill erosion were 1.7-2.2 times greater at 5° and 2.5-6.9 times greater at 10° than those for hillslopes dominated by sheet erosion. The loss of <0.25 mm soil particles and aggregates varying from 47.72%-99.60% of the total soil loss played a dominant role in the sediment. Compared with sheet erosion hillslopes, rill erosion hillslopes selectively transported more microaggregates under a relatively stable rill development stage, but rills transported increasinglymore macroaggregates under an active rill development stage. In conclusion, eliminating raindrop impact on relatively gentle hillslopes and preventing rill development on relatively steep hillslopes would be useful measures to decrease soil erosion and soil degradation in the Mollisol region of northeastern China.展开更多
Soil erosion affects soil productivity and environmental quality.A laboratory research experiment under simulated heavy rainfall with tap water was conducted to investigate the effects of anionic polyacrylamide(PAM) a...Soil erosion affects soil productivity and environmental quality.A laboratory research experiment under simulated heavy rainfall with tap water was conducted to investigate the effects of anionic polyacrylamide(PAM) application rates(0,0.5,1.0,and 2.0 g m-2) and molecular weights(12 and 18 Mg mol-1) on runoff,soil erosion,and soil nutrient loss at a slope of 5°.The results showed the two lower rates of PAM application decreased runoff while the highest rate increased runoff as compared with the control.Sediment concentration and soil mass loss increased significantly with the increasing PAM application rate.Compared with the control,PAM application decreased K+,NH4+,and NO3-concentrations in sediment and K+ and NH+4 concentrations in runoff,but significantly increased the mass losses of K+,NH4+,and NO-3 over soil surface except for the NH4+ at PAM application rate lower than 1.0 g m-2.PAM application decreased the proportion of K+ loss with runoff to its total mass loss over soil surface from 60.1% to 16.4%.However,it did not affect the NH4+ and NO3-losses with runoff,and more than 86% of them were lost with runoff.A higher PAM molecular weight resulted in less soil erosion and K+ mass loss but had little effect on runoff and NH+4 and NO3-losses.PAM application did not prevent soil erosion and the mass losses of K+ and NO3-under experimental conditions.展开更多
文摘为对比分析HEC-HMS模型三种降雨损失方法在沁河流域的适用性。借助Morris筛选法识别降雨损失方法的关键参数,选用流域内5场雨洪资料进行参数率定和模拟精度分析。结果表明:(1)SCS CN值曲线法、Green-Ampt法、Initial and Uniform法主要敏感性参数分别为CN值、土壤饱和导水率、恒定损失率。(2)选取洪峰流量、洪水总量、峰现时刻误差以及Nash系数对模型模拟精度进行评价,SCS CN值曲线法和Initial and Uniform法模拟结果达到乙等精度,Green-Ampt法模拟结果达到丙等精度。研究成果可为半湿润地区中小流域降雨损失方法的选择提供参考。
基金supported by the National Natural Science Foundation of China(Grant No.41271299)by the Opening Fund of MWR Laboratory of Soil and Water Loss Process and Control in the Loess Plateau of China(Grant NO.2017001)
文摘Understanding the relationship between hillslope soil loss with ephemeral gully and rainfall regime is important for soil loss prediction and erosion control. Based on 12-year field observation data, this paper quantified the rainfall regime impacts on soil loss at loessial hillslope with ephemeral gully. According to three rainfall parameters including precipitation （P）, rainfall duration （t）, and maximum 30-minute rainfall intensity （I30）, 115 rainfall events were classified by using K-mean clustering method and Discriminant Analysis. The results showed that 115 rainfall events could be divided into three rainfall regimes. Rainfall Regime 1 （RR1） had large I30 values with low precipitation and short duration, while the three rainfall parameters of Rainfall Regime 3 （RR3） were inversely different compared with those of RR1; for Rainfall Regime 2 （RR2）, the precipitation, duration and Iso values were all between those of RR1 and RR3. Compared with RR2 and RR3, RR1 was the dominant rainfall regime for causing soil loss at the loessial hillslope with ephemeral gully, especially for causing extreme soil loss events. PI30 （Product of P and Izo） was selected as the key index of rainfall characteristics to fit soil loss equations. Two sets of linear regression equations between soil loss and Plzo with and without rainfall regime classification were fitted. Compared with the equation without rainfall regime classification, the cross validation results of the equations with rainfall regime classification was satisfactory. These results indicated that rainfall regime classification could not only depict rainfall characteristics precisely, but also improve soil loss equation prediction accuracy at loessial hillslope with ephemeral gully.
基金funded by the National Natural Science Foundation of China(Grant Nos.41601281,41701313)the National Key R&D Program of China(Grant No.2016YFE0202900)
文摘Erosion agents and patterns profoundly affect hillslope soil loss characteristics. However, few attempts have been made to analyze the effects of rainfall and inflow on soil erosion for hillslopes dominated by sheet erosion or rill erosion in the Chinese Mollisol region. The objective of this study was to discuss the erosive agent(rainfall or inflow), hillslope erosion pattern(sheet erosion or rill erosion) and slope gradient effects on runoff and soil losses. Two soil pans(2.0 m long, 0.5 m wide and 0.5 m deep) with 5° and 10° slopes were subjected to rainfall(0 and 70 mm h–1) and inflow(0 and 70 mm h–1) experiments. Three experimental combinations of rainfall intensity(RI) and inflow rate(IR) were tested using the same water supply of 70 mm by controllingthe run time. A flat soil surface and a soil bed with a straight initial rill were prepared manually, and represented hillslopes dominated by sheet erosion and rill erosion, respectively. The results showed that soil losses had greater differences among treatments than total runoff. Soil losses decreased in the order of RI70+IR70 > RI70+IR0 > RI0+IR70. Additionally, soil losses for hillslopes dominated by rill erosion were 1.7-2.2 times greater at 5° and 2.5-6.9 times greater at 10° than those for hillslopes dominated by sheet erosion. The loss of <0.25 mm soil particles and aggregates varying from 47.72%-99.60% of the total soil loss played a dominant role in the sediment. Compared with sheet erosion hillslopes, rill erosion hillslopes selectively transported more microaggregates under a relatively stable rill development stage, but rills transported increasinglymore macroaggregates under an active rill development stage. In conclusion, eliminating raindrop impact on relatively gentle hillslopes and preventing rill development on relatively steep hillslopes would be useful measures to decrease soil erosion and soil degradation in the Mollisol region of northeastern China.
基金Supported by the National Natural Science Foundation of China (No.40635027)the Fund of State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau,China (No.10501-169)
文摘Soil erosion affects soil productivity and environmental quality.A laboratory research experiment under simulated heavy rainfall with tap water was conducted to investigate the effects of anionic polyacrylamide(PAM) application rates(0,0.5,1.0,and 2.0 g m-2) and molecular weights(12 and 18 Mg mol-1) on runoff,soil erosion,and soil nutrient loss at a slope of 5°.The results showed the two lower rates of PAM application decreased runoff while the highest rate increased runoff as compared with the control.Sediment concentration and soil mass loss increased significantly with the increasing PAM application rate.Compared with the control,PAM application decreased K+,NH4+,and NO3-concentrations in sediment and K+ and NH+4 concentrations in runoff,but significantly increased the mass losses of K+,NH4+,and NO-3 over soil surface except for the NH4+ at PAM application rate lower than 1.0 g m-2.PAM application decreased the proportion of K+ loss with runoff to its total mass loss over soil surface from 60.1% to 16.4%.However,it did not affect the NH4+ and NO3-losses with runoff,and more than 86% of them were lost with runoff.A higher PAM molecular weight resulted in less soil erosion and K+ mass loss but had little effect on runoff and NH+4 and NO3-losses.PAM application did not prevent soil erosion and the mass losses of K+ and NO3-under experimental conditions.
