黄土高原小流域产沙性降雨标准分析
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摘要
为确定黄土高原小流域的产沙性降雨标准,提高小流域尺度降雨侵蚀力计算和侵蚀产沙预报精度,采用降雨量与产沙累积比例拟合的方法,拟定黄土高原20个小流域的产沙性降雨雨量标准,并探讨其对小流域下垫面特征的响应。结果表明:1)研究小流域产沙性降雨雨量标准变化范围为7. 48～33. 51 mm; 2)黄土丘陵沟壑区非治理、黄土丘陵沟壑区和黄土高塬沟壑区治理以及黄土高塬沟壑区林区小流域的产沙性降雨标准分别为7. 5～14. 0,14. 0～16. 8以及33. 5 mm; 3)治理小流域的产沙性降雨标准均大于与其对比的非治理小流域; 4)小流域的产沙性降雨标准随着下垫面特征的改变发生动态变化,治理程度越高,产沙性降雨标准越大。黄土高原不同小流域产沙性降雨标准差异较大,小流域水土流失治理是影响产沙性降雨标准的主要因素。本研究可以为小流域降雨侵蚀力计算和侵蚀产沙预报提供参考,并为小流域水土保持效益评价提供依据。
[Background] Soil erosion has been recognized as the most important environmental problems worldwide. Rainfall is acknowledged as the direct dynamic factor of soil erosion on the Loess Plateau. The obtainment of erosive rainfall standard is essential in calculating rainfall erosivity and predicting soil erosion. But not all of the sediment caused by rainfall will arrive the outlet section of small watershed( < 100 km2),thus the rainfall event under which sediment can reach to the outlet section of small watershed is called sediment generating rainfall of small watershed. There have been extensive studies on erosive rainfall standard on the Loess Plateau,but the research on the standard of sediment generating rainfall has been rarely reported. [Methods] On the basis of the observation of 20 small watersheds on the Loess Plateau,we determined the standards of sediment generating rainfall in small watersheds by fitting the regression relationship between rainfall amount calculated with area weighting factor method and the proportion of cumulative sediment yield to the total sediment yield at the inter-event timescale based on observations of not less than five years. The amount standards were obtained by the regression relationship when the proportion was given to 95%. Besides,the response of the standards of sediment generating rainfall to underlying surface conditions of small watersheds were also analyzed.[Results]1) The amount standards of sediment generating rainfall in 20 small watersheds ranged from7. 48 to 33. 51 mm. 2) In the Loess Hilly-gully Region,the amount standards of sediment generating rainfall in ungoverned watersheds and governed watersheds were 7. 5-14. 0 mm and 15. 6-16. 4 mm respectively. In the Loess Plateau-gully Region,the amount standards of sediment generating rainfall in governed and forested watersheds were 14. 1-16. 8 mm and 33. 5 mm respectively. 3) The amount standards of sediment generating rainfall in governed watersheds were all higher than those of their paired ungoverned watersheds. In small watersheds with larger area,the implementation of soil and water conservation such as check dams and reservoirs significantly increased the amount standards of sediment generating rainfall. While,in smaller watersheds,soil and water measures in slope( such as revegetation and terraces) also increased the amount standards of sediment generating rainfall. 4) The amount standard of sediment generating rainfall in one watershed was not a fixed value,varying dynamically with the modification of underlying surface conditions. [Conclusions] There is a large difference in the amount standards of sediment generating rainfall in different watersheds. In general, the amount standards of sediment generating rainfall will increase with the soil and water conservation in small watersheds. This study may provide valuable information for calculating rainfall erosivity and improve the prediction accuracy of sediment yield in small watershed scale. The results of this study can also provide a reference for the evaluation of soil and water conservation benefits on the Loess Plateau.
[Background] Soil erosion has been recognized as the most important environmental problems worldwide. Rainfall is acknowledged as the direct dynamic factor of soil erosion on the Loess Plateau. The obtainment of erosive rainfall standard is essential in calculating rainfall erosivity and predicting soil erosion. But not all of the sediment caused by rainfall will arrive the outlet section of small watershed( < 100 km2),thus the rainfall event under which sediment can reach to the outlet section of small watershed is called sediment generating rainfall of small watershed. There have been extensive studies on erosive rainfall standard on the Loess Plateau,but the research on the standard of sediment generating rainfall has been rarely reported. [Methods] On the basis of the observation of 20 small watersheds on the Loess Plateau,we determined the standards of sediment generating rainfall in small watersheds by fitting the regression relationship between rainfall amount calculated with area weighting factor method and the proportion of cumulative sediment yield to the total sediment yield at the inter-event timescale based on observations of not less than five years. The amount standards were obtained by the regression relationship when the proportion was given to 95%. Besides,the response of the standards of sediment generating rainfall to underlying surface conditions of small watersheds were also analyzed.[Results]1) The amount standards of sediment generating rainfall in 20 small watersheds ranged from7. 48 to 33. 51 mm. 2) In the Loess Hilly-gully Region,the amount standards of sediment generating rainfall in ungoverned watersheds and governed watersheds were 7. 5-14. 0 mm and 15. 6-16. 4 mm respectively. In the Loess Plateau-gully Region,the amount standards of sediment generating rainfall in governed and forested watersheds were 14. 1-16. 8 mm and 33. 5 mm respectively. 3) The amount standards of sediment generating rainfall in governed watersheds were all higher than those of their paired ungoverned watersheds. In small watersheds with larger area,the implementation of soil and water conservation such as check dams and reservoirs significantly increased the amount standards of sediment generating rainfall. While,in smaller watersheds,soil and water measures in slope( such as revegetation and terraces) also increased the amount standards of sediment generating rainfall. 4) The amount standard of sediment generating rainfall in one watershed was not a fixed value,varying dynamically with the modification of underlying surface conditions. [Conclusions] There is a large difference in the amount standards of sediment generating rainfall in different watersheds. In general, the amount standards of sediment generating rainfall will increase with the soil and water conservation in small watersheds. This study may provide valuable information for calculating rainfall erosivity and improve the prediction accuracy of sediment yield in small watershed scale. The results of this study can also provide a reference for the evaluation of soil and water conservation benefits on the Loess Plateau.
引文
[1]XIE Yun,LIU Baoyuan,NEARING M A.Practical thresholds for separating erosive and non-erosive storms[J].Transaction of the ASAE,2002,45(6):1843.
[2]魏天兴.黄土残塬沟壑区降雨侵蚀分析[J].水土保持学报,2001,15(4):47.WEI Tianxing.Study on rainfall and erosion inloess gulled-hilly area[J].Journal of Soil and Water Conservation,2001,15(4):47.
[3]王万忠.黄土地区降雨特性与土壤流失关系的研究Ⅲ:关于侵蚀性降雨的标准问题[J].水土保持通报,1984(2):58.WANG Wanzhong.Study on the relations between rainfall characteristics and loss of soil in loess region[J].Bulletin of Soil and Water Conservation,1984(2):58.
[4]汪邦稳,方少文,宋月君,等.赣北第四纪红壤区侵蚀性降雨强度与雨量标准的确定[J].农业工程学报,2013,29(11):100.WANG Bangwen,FANG Shaowen,SONG Yuejun,et al.Research for standard of erosive rainfall on Quaternary Red Soil area in north of Jiangxi province in China[J].Transactions of the CSAE,2013,29(11):100.
[5]刘和平,袁爱萍,路炳军,等.北京侵蚀性降雨标准研究[J].水土保持研究,2007,14(1):215.LIU Heping,YUAN Aiping,LU Bingjun,et al.Study on erosive rainfall standard of Beijing[J].Research of Soil and Water Conservation,2007,14(1):215.
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[8]FANG Haiyan,CHEN Hao,CAI Qiangguo,et al.Scale effect on sediment yield from sloping surfaces to basins in hilly loess region on the Loess Plateau in China[J].Environmental Geology,2007,52(4):753.
[9]ZHENG Mingguo,YANG Jishan,QI Deli,et al.Flow-sediment relationship as functions of spatial and temporal scales in hilly areas of the Chinese Loess Plateau[J].Catena,2012,98(17):29.
[10]毕彩霞.黄河中游皇甫川流域产沙性降雨及其对径流输沙的影响[D].陕西杨凌:中国科学院研究生院(教育部水土保持与生态环境研究中心),2013:29.BI Caixia.Study on watershed sediment yield rainfall and contributions of the watershed sediment yield rainfall to runoff and sediment in Huangfuchuan River Basin[D].Yangling,Shaanxi:Institute of Soil and Water Conservation,2013:29.
[11]刘元保.小流域降雨侵蚀力模拟[D].陕西杨凌:中国科学院水利部西北水土保持研究所,1990:15.LIU Yuanbao.Rainfall erosivity modeling of small watershed[D].Yangling,Shaanxi:Institute of soil and water conservation Chinese Academy of Sciences,1990:15.
[12]WEI Yanhong,HE Zhong,LI Yujin,et al.Sediment Yield Deduction from Check-dams Deposition in the Weathered Sandstone Watershed on the North Loess Plateau,China[J].Land Degradation&Develomment,2017,28(1):217.
[13]金建君,谢云,张科利.不同样本序列下侵蚀性雨量标准的研究[J].水土保持通报,2001,21(2):31.JIN Jianjun,XIE Yun,ZHANG Keli.A study on erosive rainfall standards based on different sample sizes[J].Bulletin of Soil and Water Conservation,2001,21(2):31.
[14]HUFF F A.Time distribution of rainfall in heavy storms[J].Water Resources Research,1967,3(4):1007.
[15]王万忠,焦菊英,郝小品.黄土高原暴雨空间分布的不均匀性及点面关系[J].水科学进展,1999,10(2):165.WANG Wanzhong,JIAO Juying,HAO Xiaopin.Non-uniform spatial distribution of rainfall and relationship between point rainfall and areal rainfall of different patterns of rainstorm on the Loess Plateau[J].Advances in Water Science,1999,10(2):165.
[16]HUANG Mingbin,GALLICHAND J,ZHANG Pingchang.Runoff and sediment responses to conservation practices:Loess Plateau of China[J].Journal of the American Water Resources Association,2003,39(5):1197.
[17]穆兴民,王文龙.黄土高塬沟壑区水土保持对小流域地表径流的影响[J].水利学报,1999(2):71.MU Xingmin,WANG Wenlong.The influence of the soil and water conservation on the surface runoff in the watersheds in the gully plateau region of the Loess Plateau[J].Journal of Hydraulic Engineering,1999(2):71.
[2]魏天兴.黄土残塬沟壑区降雨侵蚀分析[J].水土保持学报,2001,15(4):47.WEI Tianxing.Study on rainfall and erosion inloess gulled-hilly area[J].Journal of Soil and Water Conservation,2001,15(4):47.
[3]王万忠.黄土地区降雨特性与土壤流失关系的研究Ⅲ:关于侵蚀性降雨的标准问题[J].水土保持通报,1984(2):58.WANG Wanzhong.Study on the relations between rainfall characteristics and loss of soil in loess region[J].Bulletin of Soil and Water Conservation,1984(2):58.
[4]汪邦稳,方少文,宋月君,等.赣北第四纪红壤区侵蚀性降雨强度与雨量标准的确定[J].农业工程学报,2013,29(11):100.WANG Bangwen,FANG Shaowen,SONG Yuejun,et al.Research for standard of erosive rainfall on Quaternary Red Soil area in north of Jiangxi province in China[J].Transactions of the CSAE,2013,29(11):100.
[5]刘和平,袁爱萍,路炳军,等.北京侵蚀性降雨标准研究[J].水土保持研究,2007,14(1):215.LIU Heping,YUAN Aiping,LU Bingjun,et al.Study on erosive rainfall standard of Beijing[J].Research of Soil and Water Conservation,2007,14(1):215.
[6]WISCHMEIER W H,SMITH D D.Predicting rainfall erosion Losses:A guide to conservation planning.U.S.D.Agric[M].Handbook,1978,537.
[7]ZHENG Mingguo,QIN Fen,SUN Liying,et al.Spatial scale effects on sediment concentration in runoff during flood events for hilly areas of the Loess Plateau,China[J].Earth Surface Processes and Landforms,2011,36(11):1499.
[8]FANG Haiyan,CHEN Hao,CAI Qiangguo,et al.Scale effect on sediment yield from sloping surfaces to basins in hilly loess region on the Loess Plateau in China[J].Environmental Geology,2007,52(4):753.
[9]ZHENG Mingguo,YANG Jishan,QI Deli,et al.Flow-sediment relationship as functions of spatial and temporal scales in hilly areas of the Chinese Loess Plateau[J].Catena,2012,98(17):29.
[10]毕彩霞.黄河中游皇甫川流域产沙性降雨及其对径流输沙的影响[D].陕西杨凌:中国科学院研究生院(教育部水土保持与生态环境研究中心),2013:29.BI Caixia.Study on watershed sediment yield rainfall and contributions of the watershed sediment yield rainfall to runoff and sediment in Huangfuchuan River Basin[D].Yangling,Shaanxi:Institute of Soil and Water Conservation,2013:29.
[11]刘元保.小流域降雨侵蚀力模拟[D].陕西杨凌:中国科学院水利部西北水土保持研究所,1990:15.LIU Yuanbao.Rainfall erosivity modeling of small watershed[D].Yangling,Shaanxi:Institute of soil and water conservation Chinese Academy of Sciences,1990:15.
[12]WEI Yanhong,HE Zhong,LI Yujin,et al.Sediment Yield Deduction from Check-dams Deposition in the Weathered Sandstone Watershed on the North Loess Plateau,China[J].Land Degradation&Develomment,2017,28(1):217.
[13]金建君,谢云,张科利.不同样本序列下侵蚀性雨量标准的研究[J].水土保持通报,2001,21(2):31.JIN Jianjun,XIE Yun,ZHANG Keli.A study on erosive rainfall standards based on different sample sizes[J].Bulletin of Soil and Water Conservation,2001,21(2):31.
[14]HUFF F A.Time distribution of rainfall in heavy storms[J].Water Resources Research,1967,3(4):1007.
[15]王万忠,焦菊英,郝小品.黄土高原暴雨空间分布的不均匀性及点面关系[J].水科学进展,1999,10(2):165.WANG Wanzhong,JIAO Juying,HAO Xiaopin.Non-uniform spatial distribution of rainfall and relationship between point rainfall and areal rainfall of different patterns of rainstorm on the Loess Plateau[J].Advances in Water Science,1999,10(2):165.
[16]HUANG Mingbin,GALLICHAND J,ZHANG Pingchang.Runoff and sediment responses to conservation practices:Loess Plateau of China[J].Journal of the American Water Resources Association,2003,39(5):1197.
[17]穆兴民,王文龙.黄土高塬沟壑区水土保持对小流域地表径流的影响[J].水利学报,1999(2):71.MU Xingmin,WANG Wenlong.The influence of the soil and water conservation on the surface runoff in the watersheds in the gully plateau region of the Loess Plateau[J].Journal of Hydraulic Engineering,1999(2):71.