青藏公路路堤边坡产流产沙与降雨特征关系

道路侵蚀是区域土壤侵蚀的重要组成部分,为了摸清公路边坡侵蚀规律,在青藏公路路堤边坡布设自然径流观测小区,进行定位观测,实验结果表明:(1)研究区内的降雨特征是:以次降雨量5～10mm和平均降雨强度小于5mm/h的降雨为主,在观测期内的降雨量分别为52.89mm,61.31mm,分别占总量的56.72%和65.76%。(2)降雨量和平均降雨强度的乘积与侵蚀模数、径流深有较好的线性相关关系,其相关系数分别为0.6576和0.7982,这与通用土壤流失方程较为吻合,降雨量(降雨动能)与平均降雨强度的组合可以作为路堤坡面侵蚀预测的重要因子。(3)对径流深与侵蚀模数分别取自然对数,两者拟合结果表明有较好的线性相关(相关系数R=0.8633),随着径流深度的增加侵蚀模数也在增加。路堤边坡的径流系数主要集中在0.1～0.4之间,平均0.29,表明边坡的入渗能力较强。

Relations Between Rain Characters and Sediment Yielding and Runoff on Embankment Slope of Qinghai-Tibet Road

Road erosion is one of soil erosion types in regions. To grasp the mechanism of road erosion, runoff plots were used to make observations, and results show that :(1)Characters of rains in study area: the rainfall and rain intensity are mainly 5~10 mm and <5 mm/h respectively in most rain events, and they brought 52.89 mm and 61.31 mm rainfall respectively, which getting to 56.72%,65.76% of whole rainfall respectively.(2)There are well linear relationships between the product of rainfall and rain intensity,sediment concentration and runoff depth, and their correlation coefficient are 0.657 6 and 0.798 2 respectively. These are well accordance to USLE, so the integration of rainfall and rainfall intensity can be an important factor to predict soil losses from road embankment slope. (3) Natural logarithms of sediment concentration and that of runoff depth are well linear (correlation coefficient R=0.863 3), sediment concentration is increased with runoff depth increasing.Mean runoff coefficients is 0.29, of which show that there are large infiltration capacity in the embankment slope.