基于USLE模型的重庆仙鱼小流域土壤流失减少比例评价

Evaluation on Soil Loss Reduced Ratio Based on USLE Model in Xianyu Small Watershed in Chongqing

以仙鱼小流域为例,通过对各项措施图斑的平均坡度、坡长、保土措施、植被覆盖度、土地利用方式等调查,采用USLE方程的各参数因子,计算土壤流失减少比例.仙鱼小流域通过治理后,水土流失减少比例为28.19%,水土流失防治达到目标要求;通过对不同措施图斑水土流失减少比例分析,水土流失减少比例随着坡度或坡长的增加而增加,以25°坡度、70 m坡长作为变化的分界点,当坡度在25°以下或坡长小于70 m时土壤流失减少比例变化趋势较缓,当坡度在25°以上或坡长大于70 m时土壤流失减少比例增长趋势较快;各项水土保持措施中,以石坎坡改梯防治水土流失的效果最好,坡面水系工程措施可有效提高坡耕地抵御季节性干旱的能力.该研究结果可为今后开展小流域综合治理提供实践经验.

Soil loss reduce ratio（SLRR） is an important indicator in the evaluation of various measures to reduce soil erosion in small watersheds.Taking the Xianyu small watershed in Chongqing city for example and using various parameters of the USLE（universal soil loss equation） model,this paper calculates the proportion of soil erosion reduction through various measures（average slope,slope length,soil conservation measures,vegetation coverage and land-use）.The treatment of this small watershed proved to have attained its expected objectives,with an SLRR of 28.19%.An analysis of different measures of SLRR indicated that SLRR increased with the slope or slope length,with a slope cut-off point of change at a gradient of 25° and a slope length of 70 m.When the gradient was ≤25° and the slope length was 70 m,the slope soil erosion reduction proportion tended to change slowly.When the gradient was 25° and the slope length was 70 m,the slope soil erosion reduction proportion tended to change quickly.Of all the soil and water conservation measures,stone-faced terracing gave the best results.Slope water system engineering measures could effectively improve the ability to withstand seasonal drought in sloping land.