淤地坝坝控流域土地利用类型空间优化配置研究

Spatial optimal allocation of land use pattern in dam-controlled area of check dam

以小河沟流域的花梁淤地坝坝控流域为研究对象,收集坝控流域的土地利用类型资料,在分析原有土地利用结构及其土壤侵蚀强度的基础上,基于RUSLE模型对坝控流域内不同土地利用空间优化配置进行研究.结果表明:不同土地利用类型下土壤侵蚀强度不同,不合理的土地利用结构是造成该流域土壤侵蚀严重的主要原因.梯田能够有效地控制土壤侵蚀,在水土保持效益中具有不可替代的作用;花梁坝坝控流域水土保持措施的最优配置方案为:3°以内的平坦地作为耕地,草地分布在3°~7°的缓坡地,7°~25°的坡地作为梯田,其余坡地作为林地;在最优配置下,多年平均侵蚀模数为6.102 8×10~5 kg/(km^2·a),淤积年限内各年份的土壤侵蚀模数都有很大程度的下降,最大减蚀比为93.48%(1980年),最小减蚀比达到47.52%(1976年).研究结果可为黄土高原淤地坝坝控流域水土保持措施的合理配置提供参考.

We choose Hualiang check dam, which is a typical check dam in the Xiaohegou watershed as our study area. Based on the analysis of the former land use structure and soil erosion intensity, land use are allocated in the basin controlled by the check dam. The results showed that irrational way of-land-use is the main incentive for serious erosion in the area. Different land-use types lead to different soil erosion intensity. Terraces, which can effectively control soil erosion, has an irreplaceable role in soil and water conservation measures. After comparing all configuration schemes we found the optimum configuration scheme in Hualiang check dam is： the smooth ground within 3° as cultivated land, grass land distributed in the gentle slope between 3° to 7°, the slope between 7° to 25° as terrace and the rest of the slope as forest land. In this situation, the annual average of soil erosion modulus in check dam is 6.102 8× 10^5 kg/（km^2· a）. Soil erosion modulus of each year in the sedimentation has decreased obviously as the maximum erosion reduction ratio is of 93.48%,which appears in 1980 with the minimum erosion reduction ratio, 47.52% appearing in 1976. The research achievement can provide useful reference for the adjustment of land use structure of other check darns in the Loess Plateau.