半干旱黄土丘陵区水平阶整地规格与降雨量的关系

Relationship Between Specification of Level-terrace Preparation and Rainfall in Semiarid Loess Hilly Region

以半干旱区甘肃省榆中县孙家岔流域5种不同下垫面条件下的径流小区为研究对象，对小区6a的自然降雨产流观测资料进行了分析，研究了半干旱黄土丘陵区水平阶整地规格与降雨量的关系。研究结果表明，刈割草地较荒坡地的径流量增加了9．77％～24．87％；灌木措施（甘蒙柽柳小区、柠条小区）径流量较荒坡地可减少8．28％～60．57％和12．24％～78．41％；次降雨的产流深（草灌小区）与降雨强度具有很好的线性关系；水平阶则可以完全拦蓄降雨。在15°～25°坡地上配套水平阶的设计宜按5年一遇最大6h降雨进行，此时若埂高为0．1m，其允许最大坡长为3．9～8．2m。适当加高水平阶埂高，可提高防御标准和防护面积。

The runoff in five different surfaces was observed in Sunjiacha basin of Yuzhong County in Gansu Province, and the relationship between specification of level-terrace preparation and rainfall in semiarid loess hilly region was studied. The results showed that the runoff in mowing grass plot was 9.77%-24.87% higher than that in original barren slope plot. In comparison with barren slope plot, Tarnarix mongolica plot and Caragana microphylla plot were capable of decreasing the runoff for 8.28%-60.57% and 12.24%- 78.41%, respectively. The depth of runoff after individual rainfall had a great linear relationship with rain- fall intensity. The level terraces were definitely able to increase the rainfall conversation. The configuration of level terraces should be under the consideration of maximum 6 h rainfall within five years. In this case, the level terraces ridge should be 0.1 rn, with the slope length of 3.9-8.2 m. Heightening the ridge properly will raise the efficiency and protection area of level terraces.