云南干热河谷不同坡面整地方式强化降雨入渗的效益

通过对云南元谋干热河谷典型坡面上改造于2001年的水平台、水平沟及对照自然坡面的土壤水分进行动态监测,分析计算不同坡面整地方式在集中降雨条件下湿润峰运移情况、土壤水分通量及土壤持水量,结果表明:集中降雨后,缓坡上水平台整地在0—200 cm土层范围内湿润峰运移较明显;陡坡上的水平沟整地在0—100 cm土层范围内湿润峰运移较快,由于侧渗损失较大,100 cm以下土壤水分改善不明显;自然坡面在降雨前后只有0—40 cm土层范围内土壤水分有明显变化,40 cm土层以下湿润峰下移趋势不明显。实施水平台和水平沟整地后,强化了天然降雨入渗,分别能将89%和83%的降雨转化为土壤水分,在时空上对降雨重新进行了分配,而自然坡面只有22%的天然降雨能转化为土壤水分。水平沟和水平台整地能将拦截入渗的降雨转化为0—200 cm土层土壤水分,0—200 cm土层持水量最大增幅分别可达57.67、56.93 mm,并能使入渗的水分长时间蓄存在土壤中。

Benefits of Enforced Rainfall Infiltration through Different Ways of Sloped Land Preparation of Dry-hot Valley in Yunnan

It analyzes and calculates the humid peak transfer,soil moisture flux and soil retention of different sloped land preparation under the conditions of concentrated rainfall,through dynamic monitoring of soil moisture of tableland,contour trench and checking with natural slopes that were rebuilt on typical slopes of dry-hot valley in Yuanmou of Yunnan in 2001.The outcomes show that after concentrated rainfall,the humid peak within 0-200 cm layer of tableland preparation on gentle slopes transfers obviously;the humid peak within 0-100 cm layer of contour trench preparation on steep slopes transfers faster and the improvement of soil moisture beneath 100 cm is not remarkable due to greater loss of lateral seepage;the variations of soil moisture only within 0-40 cm layer of natural slopes before and after rainfall is greater and the tendency of downward transfer beneath 40 cm is not remarkable.The implementation of contour trench and tableland preparation has strengthened rainfall infiltration,turned 89% and 83% rainfall into soil moisture respectively and redistributed rainfall spatially and temporally while only 22% of natural rainfall of natural slopes can be turned into soil moisture.The contour trench and tableland preparation can change the intercepted rainfall into 0-200 cm layer soil moisture;the maximum increase of water retaining capacity of 0-200 cm layer can reach to 57.67 mm and 56.93 mm respectively,while the infiltrated water can be stored in soil for a long time.