梯田建设和淤地坝淤积对土壤侵蚀影响的定量分析

Influences of Terrace Construction and Check Dam Silting-up on Soil Erosion

为了研究梯田建设和淤地坝淤积对流域土壤侵蚀的影响,本文首先建立了包含梯田、坡耕地、陡坡草地以及坝地在内的黄土高原丘陵沟壑区流域简化模型,并定义了流域的先锋期、过渡期以及顶级期三个状态,使用修正通用土壤流失方程(RUSLE)分析了不同时期的流域土壤侵蚀模数。结果显示:先锋期与顶级期是流域水土保持治理的极限状态,先锋期峁边线上部土壤侵蚀模数为299.56t×hm-2×a-1,下部土壤侵蚀模数为136.64t×hm-2×a-1,平均侵蚀模数为229.74t×hm-2×a-1;顶级期峁边线上部土壤侵蚀模数为39.10t×hm-2×a-1,下部土壤侵蚀模数为1.10t×hm-2×a-1,平均侵蚀模数为22.81t×hm-2×a-1;在过渡期,随着梯田面积比例的增加,峁边线上部土壤侵蚀模数呈指数减少,而随着淤积高度的增加,峁边线下部土壤侵蚀模数呈线性减少,文章最后对这一结论进行了实证分析。

To research the terrace construction and check dam silting-up soil erosion effects, this paper firstly established a generalized model consisting of terrace, slope land, steep slope grassland, and check dam land in hilly and gully region of Loess Plateau, defined the pioneer phase, transitional phase and climax phase. Then it used the revised universal soil loss equation （RUSLE） to analyze soil erosion modulus in different periods. The results showed that pioneer phase and climax phase are the limit state of soil and water conservation. In pioneer phase, soil erosion modulus is 299.56 t×hm^-2×a^-1 and 136.64 t×hm^-2×a^-1 in the upper and lower parts of demarcation of hill and gully slope, respectively, and the average erosion modulus is 229.74 t×hm^-2×a^-1. In climax phase, soil erosion modulus is 39. 10 t×hm^-2×a^-1 and 1.10 t×hm^-2×a^-1 in the upper and lower parts, and the average erosion modulus is 22.81 t×hm^-2×a^-1. In the transitional phase, with the increase of the ratio of the terrace, soil erosion modulus index is reduced at upper Mao sideline; with the increase of the sedimentation of the height, soil erosion modulus shows a linear decrease at lower Mao sideline.