黄土丘陵区植物道路的产流产沙试验研究

Field Study on Biological Road Erosion in Loess Hilly Region

土质道路是当前黄土丘陵区农业生产与农村生活的主要道路,也是发生水土流失最严重的土地利用类型。若田间地块道路路面种植植物,则可以达到减少、控制道路水土流失的目的。在前人对生物道路实施的可行性、建造方法、实用性研究的基础上,在延安市燕沟小流域采用小区径流监测的方法,对12个不同处理植物路小区为期3a27场次产流降雨的产流产沙数据进行了分析。结果表明,植物道路侵蚀均发生在6—9月,其中降雨量10～25mm发生概率最高,最小产流雨为5.7mm。降雨量与降雨强度对道路侵蚀影响显著,为此将降雨量划分为5级,分析了各级降雨下的侵蚀强度,同时给出了侵蚀强度随降雨侵蚀力变化的模拟模型。同时,分析坡度对道路产流、产沙的影响表明,5°～10°坡的侵蚀强度是3°～5°坡的3.7倍、0°～1°坡的6.5倍;5°～10°坡的径流深是3°～5°坡的2.44倍、0°～1°坡的3.66倍。试验道路3a平均侵蚀模数2825t·km-2·a-1,远低于当地土路5～10万t·km-2·a-1的侵蚀模数。

The earth road bears the agro-productive activity and villagers＇ daily life in the Loess hilly region. It is also the most erosive land use in this region. Planting grasses on the earth road had been suggested and put into use in some areas to control the soil and water loss from road surface. In this paper, some experiments were conducted in Yan＇ gou watershed to study the rainfall erosion of biological road. The experiments lasted 3 years and obtained scientific data from 27 times rainfall-erosion events and 12 plots of biological road. The research showed that all road erosion happened from June to September during 2003 to 2005, among those the event rainfall within 10-25 mm had the highest probability and the minimum rainfall was 5.7 mm for road erosion to come about. Rainfall amount and its intensity had significant effects on the road erosion. The rainfall amount was sorted into 5 classes and road erosion intensity of every rainfall classes was analyzed. The study also established the simulation model to show how the road erosion was affected by rainfall erosive force. The road slope did affect the runoff and also silt loss of biology road. As to the erosion intensity, the erosion modulus in roads of 5°- 10° was 3.7 times that of 3°-5°, 6.5 times that of 0°-1°. The runoff modulus of 5°-10° road was 2.44 times that of 30°-5°, 3.66 times of that 0°-1°. During the experiment period the average erosion modulus was 2 825 t·km^-2·a^-1, much less than that of road without grass cover.