半干旱区微集水系统土壤水分调控效果研究

分析了定西市安定区以隔坡水平阶为主体的径流调控工程和梯田(对照)的土壤水分与植被生长状况及11a累积土壤水分水量平衡特征。结果表明，隔坡水平阶工程保存完好，产流区(25m²)年均产流0.3m³，产沙3.96kg，被蓄水区全部拦蓄，有效控制了水土流失，增加了水资源量，缓解了林草植被水分供应不足状况。2m土层含水量与植被生长成反比。梯田土壤含水率最高，但农作物受旱减产最大；隔坡水平阶产流区土壤含水率较低，紫花苜蓿减产较大，蓄水区土壤含水率最低，但侧柏林生长旺盛。隔坡水平阶(林草带状混交)年均蒸散量为428.6mm，较梯田高2.2mm。

Regulation and Control Effects of Soil Moisture for Micro-catchment Water Harvesting System in semiarid Area

Soil moisture and vegetation growth,as well as the balance of accumulated soil moisture over eleven years,were analyzed for runoff regulation and control projects on level terrace with slope and the terrace as contrast in Anding District,Dingxi City.Results indicated that the level terrace with slope was preserved perfectly,where annual average runoff and sediment yields in runoff generating area(25 m₂)were 0.3 m₃ and 3.96 kg,respectively.Runoff and sediment were totally retained by impounding area,which effectively controlled soil and water loss,increased water resources,and relieved the water shortage for tree and grass water demands.Soil water content in the 2 m layer varied inversely with vegetation growth.In the terrace as contrast,soil water content was highest,but the reduction of crop yield by drought reached the maximum.In the level terrace with slope,soil water content was lower and alfalfa yield was reduced greater in runoff generating area.In impounding area,however,soil water content was the lowest,while the growth of platycladus orientalis was strong.Annual average evapotranspiration for the level terrace with slope(forests and grass mixed by belts) was 428.6 and 2.2 mm higher than that for the terrace as contrast.