青藏公路路堤边坡水土保持措施及效益分析

EFFECTIVENESS OF EROSION CONTROL MEASURES ON QINGHAI-TIBET HIGHWAY SLOPES

公路建设加速了区域的原有侵蚀,为了摸清公路边坡的侵蚀特征,寻找有效的防治措施,在青藏公路边坡布设不同水土保持措施的径流观测小区,进行了两年的观测(2003年和2004年),结果表明:(1)工程措施具有较好的水土保持效益,其减流(减沙)效益在第一年和第二年分别达到38.83%(81.89%)和48.72%(95.81%),其中截排水措施的水土保持效益一方面说明公路路面来水也是边坡侵蚀的重要动力,有效拦截路面来水将会极大地减少径流和泥沙,另一方面也说明要提高公路边坡土壤侵蚀的预测能力,应该将路面来水作为重要的驱动力之一;(2)植被措施可以起到一定的减流减沙效果,其中人工植被措施有很大的潜力,其减蚀效益都在50%以上;(3)综合措施表现出了极好的水土保持效益(减流在40%以上,减沙在97%以上),尤其土工格室+植被措施,兼具水土保持与景观双重效益。该研究可以为青藏高原地区的水土保持设计和生态环境保护规划提供数据支持。

To understand the characteristics of road erosion and find effective control measures, runoff plots were set up on Qinghai-Tibet roadside slopes （fillslope）. After two-year study （2003 and 2004） ,it is found that （1） It is obvious for engineering measures to control runoff and soil loss. The reduction percent of runoff （soil loss） was 38.83%（81.89%）and 48.72%（95.81%）,respectively in 2003 and 2004. The effects of drain water from road surface showed that road surface water was also an important driving force for erosion on roadside slopes. To predict soil loss more accurately,runoff from road surface should be considered in building erosion prediction model. In addition,controlling road surface runoff would efficiently minimize soil erosion on roadside slopes. （2） Grass measures only showed some effects in controlling erosion; however, the effects of natural grass proved that planted grass would have great potential effects on soil erosion control if they were well established. （3） Engineering control measures could intercept runoff and sediment at initial stage just after construction,keeping water and nutrient and promoting vegetation growth, which would increase the capacity of vegetation in intercepting runoff and sediment. So the combination of two measures is the most effective way to control runoff and soil loss,all combined measures could reduce more than 40% of runoff and more than 97% of soil loss.