黄土丘陵区水平梯田保水保土效益分析

Analysis on the Benefits of Level Terrace on Soil and Water Conservation in Loess Hilly Areas

水平梯田是防止水土流失的一种有效方式。在韭园沟流域的支沟——王茂沟流域分别选取梯田和坡耕地进行土壤采样,测定土壤含水量,结合137Cs示踪,对比分析了梯田长期的保水保土效益。结果表明:梯田土壤水分变化分为土壤水分剧变层(0—20cm)、土壤水分活跃层(20—30cm)和土壤水分调节层(30cm以下);梯田不同深度土壤含水量均表现为内侧(第一级)>中部>外侧(第五级);坡向对梯田土壤水分的影响并不是十分显著;梯田0—20cm土壤蓄水量高于坡耕地7.2%;0—40cm平均土壤蓄水量高出坡耕地1.8mm;研究流域坡耕地与梯田侵蚀程度分别属于极强度侵蚀和强度侵蚀,梯田平均水土保持效益为53%。建议在该地区修建梯田时,提高梯田的设计标准,对梯田田面、田埂认真维护,实现梯田长期的水土保持效益。

Level terrace is an effective way to prevent soil and water loss. A parcel of terrace and slope land in Wangmaogou watershed in Suide was chosen and soil samples were collected. The soil water moisture and ^137 Cs contents were measured to study the benefits on soil and water conservation of level terrace. The results showed that the change of soil moisture of level terrace can be divided into 3 layers, changing drastically in 0--20 cm layer, changing actively in 20--30 cm layer and changing regulatively below 30 cm depth. The soil moisture content from each layer showed the inner which is the first ladder is a little higher than the middle, and the middle higher than the outer. The soil moisture content is slightly influenced by slope aspect. The water storage of terrace in 0--20 cm layer is 7.2% higher than slopeland and is 1.8 mm higher in 0--40 cm layer. The erosion degrees are extremelY intensive erosion on slope land and intensive erosion on terrace. The average soil and water conservation benefit of terrace is 53 %. The suggestions of improving the design stand- ard of terrace and maintaining carefully for farm surface and ridge were put out to realize the long-term bene- fits for soil and water conservation of terrace.