In this study, laboratory rainfall simulation experiments were conducted to investigate the regulatory effects of grass coverage on rainfallrunoff processes. A total of 80 grass blocks planted with well-grown manilagr...In this study, laboratory rainfall simulation experiments were conducted to investigate the regulatory effects of grass coverage on rainfallrunoff processes. A total of 80 grass blocks planted with well-grown manilagrass, together with their root systems, were sampled from an eastern suburban area of Xi'an City in the northwest arid area of China and sent to a laboratory for rainfall simulation experiments. The runoff and infiltration processes of a slope with different grass coverage ratios and vegetation patterns were analyzed. The results show that the runoff coefficient decreases with the increase of the grass coverage ratio, and the influence of grass coverage on the reduction of runoff shows a high degree of spatial variation. At a constant grass coverage ratio, as the area of grass coverage moves downward, the runoff coefficient, total runoff,and flood peak discharge gradually decrease, and the flood peak occurs later. With the increase of the grass coverage ratio, the flood peak discharge gradually decreases, and the flood peak occurs later as well. In conclusion, a high grass coverage ratio with the area of grass coverage located at the lower part of the slope will lead to satisfactory regulatory effects on rainfall-induced runoff.展开更多
Though being considered strategically important in matters of national defense based on its abundance of natural resources,Northwest China is one of the most ecologically vulnerable areas in the country. As one of the...Though being considered strategically important in matters of national defense based on its abundance of natural resources,Northwest China is one of the most ecologically vulnerable areas in the country. As one of the region's important water sources,glaciers have gone through major changes due to climate change. An analysis of research results over the past 60 years reveals that the glaciers have been retreating in general to some degree in large river basins in Northwest China,but the rate of retreating varied largely among different regions,ranging from 0. 01% ·a^(-1) to 0. 75% ·a^(-1). Specifically,glaciers around the Lantsang River Basin and the Altay Mountains have been retreating fastest. The retreat of glaciers has already caused an increase in runoff in mountainous areas of Northwest China. Meanwhile,increases in the frequency of glacial flash floods and in the flood discharge will further enhance the probability of glacial lake outburst floods and ensuing disasters.展开更多
Assessing the effects of vegetation on water and soil conversation is the key basis for research and management of ecological restoration on water-eroded areas.In this study,the runoff depth,soil loss and correspondin...Assessing the effects of vegetation on water and soil conversation is the key basis for research and management of ecological restoration on water-eroded areas.In this study,the runoff depth,soil loss and corresponding precipitation of five plots planted respectively with Pueraria lobata,Lespedeza bicolor Turcz,Manglietia yuyuanensis Law,Paspalum natatu Fliigge,Paspalum wettsteinii Hackel and one control plot were observed monthly from 2003 to 2010 in Hetian Town of Changting County,Fujian Province,a typical water-eroded area in southern China.Then the effects of different vegetation on water/soil conversation(RE/SE)were determined using the ratios of runoff depth/soil loss between vegetated plots to the control plot.Meanwhile,the effect of precipitation on the water and soil loss was also analyzed.The results showed that,both the water and soil conservation effects of Pueraria lobata and Manglietia yuyuanensis Law are better than Lespedeza bicolor Turcz and Paspalum natatu,while Paspalum wettsteinii Hackel are the worst.The differences of effects of water conservation are more significantly than those of soil conversation between five kinds of vegetations.The runoff depth is mainly affected by precipitation,the determination coefficients(R2)of linear regression models between precipitation and runoff depth of all planted plots are all greater than 0.9,whereas the determination coefficients of the linear regression models between precipitation and soil loss vary form 0.3 to 0.8 for different vegetated plots.These results provide a reference for vegetation reconstruction in the current and similar areas.展开更多
The identification of runoff generating areas (RGAs) within a watershed is a difficult task because of their temporal and spatial behavior. A watershed was selected to investigate the RGAs to determine the factors aff...The identification of runoff generating areas (RGAs) within a watershed is a difficult task because of their temporal and spatial behavior. A watershed was selected to investigate the RGAs to determine the factors affecting spatio-temporally in southern Ontario. The watershed was divided into 8 fields having a Wireless System Network (WSN) and a V-notch weir for flow and soil moisture measurements. The results show that surface runoff is generated by the infiltration excess mechanism in summer and fall, and the saturation excess mechanism in spring. The statistical analysis suggested that the amount of rainfall and rainfall intensity for summer (R2 = 0.63, 0.82) and fall (R2 = 0.74, 0.80), respectively, affected the RGAs. The analysis showed that 15% area generated 85% of surface runoff in summer, 100% of runoff in fall, and 40% of runoff in spring. The methodology developed has potential for identifying RGAs for protecting Ontario’s water resources.展开更多
基于气象、水文观测及NCEP/NCAR(National Center for Environmental Prediction/National Center for Atmospheric Research)再分析数据对黄河上游主要汇流区夏季复合干热事件变化特征及其成因以及对径流的影响进行了分析与探讨。结果...基于气象、水文观测及NCEP/NCAR(National Center for Environmental Prediction/National Center for Atmospheric Research)再分析数据对黄河上游主要汇流区夏季复合干热事件变化特征及其成因以及对径流的影响进行了分析与探讨。结果表明,在平均空间分布上,黄河上游主要汇流区夏季高温日数从西南到东北逐渐增多,而夏季降水量正好相反;从时空分布看,1961年以来黄河上游主要汇流区夏季高温日数呈一致增多趋势;夏季降水从长期趋势看呈一致波动变化,但2000年以后呈一致增加趋势;复合干热事件本世纪以来显著增多。在多时间尺度变化上,黄河上游主要汇流区夏季复合干热事件主要以年际和趋势变化为主。环流影响因子方面,黄河上游主要汇流区夏季复合干热事件变化受多环流因子共同影响,但在不同时间尺度上影响因子差异较大,年际尺度上西风环流、东亚夏季风、南亚夏季风、高原夏季风及北风环流的影响程度均较弱,年代际尺度上主要受高原夏季风环流影响,多年代际尺度上同时受西风环流、东亚夏季风、南亚夏季风、高原夏季风及北风环流共同影响。大尺度环流背景场上,西太平洋副热带高压偏西偏强、缺少异常的西南水汽输送及垂直场上异常的下沉运动是本世纪以来黄河上游主要汇流区夏季复合干热事件增多的主要原因。黄河上游主要汇流区夏季复合干热事件的增加会使得流域兰州站的径流量减少,而1998年以来黄河兰州段径流量的增加主要原因是降水增加。展开更多
基于SWMM(Storm Water Management Model)对歙县古关组团的暴雨径流过程进行系统分析,揭示了坡度较大的小汇水区域在暴雨初期的显著冲刷效应。研究发现,在1~10 a重现期的暴雨事件中,初雨径流(占总径流的20%)所携带的以总悬浮固体(TSS)...基于SWMM(Storm Water Management Model)对歙县古关组团的暴雨径流过程进行系统分析,揭示了坡度较大的小汇水区域在暴雨初期的显著冲刷效应。研究发现,在1~10 a重现期的暴雨事件中,初雨径流(占总径流的20%)所携带的以总悬浮固体(TSS)计的污染物占比高达44.5%~83.9%,表明该区域存在明显的初雨冲刷现象。进一步分析表明,当采用容积为5 a一遇暴雨,20%初雨径流量的滞留池时,各重现期TSS的拦截率可达到67.4%~78.7%,拦截效果较为理想。该结论为类似坡度较大的小汇水区域末端滞留池的设计与建设提供了科学依据,可有效减少城市的面源污染。展开更多
基金supported by the National Natural Science Foundation of China(Grant No.51609196)
文摘In this study, laboratory rainfall simulation experiments were conducted to investigate the regulatory effects of grass coverage on rainfallrunoff processes. A total of 80 grass blocks planted with well-grown manilagrass, together with their root systems, were sampled from an eastern suburban area of Xi'an City in the northwest arid area of China and sent to a laboratory for rainfall simulation experiments. The runoff and infiltration processes of a slope with different grass coverage ratios and vegetation patterns were analyzed. The results show that the runoff coefficient decreases with the increase of the grass coverage ratio, and the influence of grass coverage on the reduction of runoff shows a high degree of spatial variation. At a constant grass coverage ratio, as the area of grass coverage moves downward, the runoff coefficient, total runoff,and flood peak discharge gradually decrease, and the flood peak occurs later. With the increase of the grass coverage ratio, the flood peak discharge gradually decreases, and the flood peak occurs later as well. In conclusion, a high grass coverage ratio with the area of grass coverage located at the lower part of the slope will lead to satisfactory regulatory effects on rainfall-induced runoff.
基金Supported by the China National Natural Science Foundation(41401084,41471060)the International Partnership Program of Chinese Academy of Sciences(131C11KYSB20160061)
文摘Though being considered strategically important in matters of national defense based on its abundance of natural resources,Northwest China is one of the most ecologically vulnerable areas in the country. As one of the region's important water sources,glaciers have gone through major changes due to climate change. An analysis of research results over the past 60 years reveals that the glaciers have been retreating in general to some degree in large river basins in Northwest China,but the rate of retreating varied largely among different regions,ranging from 0. 01% ·a^(-1) to 0. 75% ·a^(-1). Specifically,glaciers around the Lantsang River Basin and the Altay Mountains have been retreating fastest. The retreat of glaciers has already caused an increase in runoff in mountainous areas of Northwest China. Meanwhile,increases in the frequency of glacial flash floods and in the flood discharge will further enhance the probability of glacial lake outburst floods and ensuing disasters.
基金Supported by National Natural Science Foundation of China(41071281)
文摘Assessing the effects of vegetation on water and soil conversation is the key basis for research and management of ecological restoration on water-eroded areas.In this study,the runoff depth,soil loss and corresponding precipitation of five plots planted respectively with Pueraria lobata,Lespedeza bicolor Turcz,Manglietia yuyuanensis Law,Paspalum natatu Fliigge,Paspalum wettsteinii Hackel and one control plot were observed monthly from 2003 to 2010 in Hetian Town of Changting County,Fujian Province,a typical water-eroded area in southern China.Then the effects of different vegetation on water/soil conversation(RE/SE)were determined using the ratios of runoff depth/soil loss between vegetated plots to the control plot.Meanwhile,the effect of precipitation on the water and soil loss was also analyzed.The results showed that,both the water and soil conservation effects of Pueraria lobata and Manglietia yuyuanensis Law are better than Lespedeza bicolor Turcz and Paspalum natatu,while Paspalum wettsteinii Hackel are the worst.The differences of effects of water conservation are more significantly than those of soil conversation between five kinds of vegetations.The runoff depth is mainly affected by precipitation,the determination coefficients(R2)of linear regression models between precipitation and runoff depth of all planted plots are all greater than 0.9,whereas the determination coefficients of the linear regression models between precipitation and soil loss vary form 0.3 to 0.8 for different vegetated plots.These results provide a reference for vegetation reconstruction in the current and similar areas.
文摘The identification of runoff generating areas (RGAs) within a watershed is a difficult task because of their temporal and spatial behavior. A watershed was selected to investigate the RGAs to determine the factors affecting spatio-temporally in southern Ontario. The watershed was divided into 8 fields having a Wireless System Network (WSN) and a V-notch weir for flow and soil moisture measurements. The results show that surface runoff is generated by the infiltration excess mechanism in summer and fall, and the saturation excess mechanism in spring. The statistical analysis suggested that the amount of rainfall and rainfall intensity for summer (R2 = 0.63, 0.82) and fall (R2 = 0.74, 0.80), respectively, affected the RGAs. The analysis showed that 15% area generated 85% of surface runoff in summer, 100% of runoff in fall, and 40% of runoff in spring. The methodology developed has potential for identifying RGAs for protecting Ontario’s water resources.
文摘基于气象、水文观测及NCEP/NCAR(National Center for Environmental Prediction/National Center for Atmospheric Research)再分析数据对黄河上游主要汇流区夏季复合干热事件变化特征及其成因以及对径流的影响进行了分析与探讨。结果表明,在平均空间分布上,黄河上游主要汇流区夏季高温日数从西南到东北逐渐增多,而夏季降水量正好相反;从时空分布看,1961年以来黄河上游主要汇流区夏季高温日数呈一致增多趋势;夏季降水从长期趋势看呈一致波动变化,但2000年以后呈一致增加趋势;复合干热事件本世纪以来显著增多。在多时间尺度变化上,黄河上游主要汇流区夏季复合干热事件主要以年际和趋势变化为主。环流影响因子方面,黄河上游主要汇流区夏季复合干热事件变化受多环流因子共同影响,但在不同时间尺度上影响因子差异较大,年际尺度上西风环流、东亚夏季风、南亚夏季风、高原夏季风及北风环流的影响程度均较弱,年代际尺度上主要受高原夏季风环流影响,多年代际尺度上同时受西风环流、东亚夏季风、南亚夏季风、高原夏季风及北风环流共同影响。大尺度环流背景场上,西太平洋副热带高压偏西偏强、缺少异常的西南水汽输送及垂直场上异常的下沉运动是本世纪以来黄河上游主要汇流区夏季复合干热事件增多的主要原因。黄河上游主要汇流区夏季复合干热事件的增加会使得流域兰州站的径流量减少,而1998年以来黄河兰州段径流量的增加主要原因是降水增加。
