京津水源区坡耕地土壤侵蚀特征分析

坡耕地是保障粮食安全与经济发展的重要资源.本文利用承德市南山径流场资料对不同坡长下径流深、含沙量及侵蚀量进行对比分析,结果显示:坡长和降雨强度都对土壤侵蚀有影响,随着坡长变化,导致土壤侵蚀量变化的两个主导因素不断变换.雨强小于0.25 mm/min时,坡面土壤侵蚀模数随坡长的增加而增大;雨强大于0.25mm/min时,随坡长的增加先增大后减小,最大侵蚀量总是出现在22 m坡长范围内.径流深均值与侵蚀量增量随坡长变化趋势一致,含沙量均值变化与雨强关系密切.所以治理京津水源区坡耕地水土流失,应在22 m坡长以内采取等高植物篱等措施,既可降低工程投入,又减少坡面土壤流失,提高土地生产力.

Analysis of characteristics of soil erosion on slope land in the water source areas of Beijing and Tianjin

Slope land is a kind of important resource which canensure food security and economic development. Data of Nanshan runoff plots in Chengde was used to study how slope length influenced soil erosion, sediment concentra-tion and runoff depth in different length of plots. The results showed that both the slope length and rainfall intensity had influence on soil erosion. And the two factors changed with the slope length. When I₁₀ was less than 0.25 mm min, with the increase of slope length, soil erosion modulus decreased; when I₁₀ was more than 0.25 mm min, with the increase of slope length, soil erosion modulus increased at first and then decreased, and reached a maximum of 22 m. The change of mean runoff depth against slope length was identical to that of the volume of soil erosion; and the average runoff sediment was changed by rain intensity. So contour hedgerows or other measures can be used to reduce project investment and slope soil erosion and to improve land productivity.