黄土丘陵区降雨坡面再分配规律研究

Study of Rainfall Redistribution on Slope in Loess Hilly Region

采用野外定位监测方法 ,以在安塞进行的降雨坡面再分配试验结果为依据 ,系统地分析了坡面降雨 -径流-入渗的转化规律 ,降雨在坡面上的水文行为强度、方向等。研究结果表明 :降雨的土壤入渗量受坡长、土地利用方式等因素影响 ,长坡能够接收较多雨量 ,试验年份 (旱年 )坡长每增加 2 0 m,草地约增加入渗 0 .77m m,灌木地增加0 .92 mm。不同土地利用方式下其降雨入渗量为灌木林地 >草地 >农地。长坡沙棘地较农坡地减少径流 4 .91m m,较长坡草地减少 4 .10 m m。相当于灌木地减流 5 6 .5 2 % ,草地减流 4 7.16 %。雨水转化土壤水的转化系数

Based on field study of rainfall redistribution on slope, authors put forward that the transition of rainfall to soil water is affected by slope length, land use form, etc.in both intensity and orientation. The results showed that soil could get more rainfall with slope length increasing from top to bottom . With a 20 m increase of slope length, the increase of incepted rainfall is 0.77 mm in grassland or 0.92 mm in shrub land. In the trial study, the 60 m slope length of shrub (or grassland) could reduce 4.91 mm (or 4.1 mm) of runoff compared with that of slope farmland, which accounts for 56.52% (47.16% )of runoff cut rate. K a representatives rate of water incepted from rainfall, was also in the same way. Forestry land had higher K a than that of grassland.It is also stated that the subsoil water movement is the main cause of slope soil water difference.