川中紫色土区小流域土地利用与土壤流失关系

Soil loss of different land use type in central hill region of the Sichuan Basin

根据长江上游水土流失重点防治工程总结报告,建立小流域土壤流失量、轻度以上侵蚀土地面积与农地、林地、荒地、其他用地面积无截距多元回归模型,以及小流域土壤流失量与不同侵蚀强度土地面积无截距多元回归模型,分析不同类型土地的侵蚀模数、土壤流失率、土壤流失比、土壤流失面积比,不同侵蚀强度土地侵蚀模数、土壤流失比。结果表明:(1)农地、林地、荒地、其他用地的土壤侵蚀模数分别为2353、2319、12162、-2750t/km2·a;前三者的土壤流失比分别为56%、25%、19%,水土流失的首要用地类型是农地,但在个别小流域,林地或荒地也会是产生土壤流失的首要用地类型,其他用地对土壤流失起到抑制作用;(2)农地、林地、荒地的土壤流失率分别为52%、34%、100%,土壤流失面积比分别为72%、16%、12%,农地流失面积比远高于其他用地类型,但在个别小流域,林地流失面积比大于农地;(3)无明显侵蚀、轻度侵蚀、中度侵蚀、强度以上侵蚀土地土壤侵蚀模数分别为-481、2500、484、8068t/km2·a;轻度侵蚀、中度侵蚀、强度以上侵蚀土地土壤流失比分别为8%、33%、59%,强度侵蚀土地是水土流失的主要来源。

According to the report of Water and Soil Conservation in Upper and Middle Reaches of the Yangtze River,relationship between land use type and erosion was studied.Three models were constructed using data of soil erosion modulus,percentage of land area of erode land and percentage of land area of different land use type.The results show that：（1） soil erosion modulus reached 2 353,2 319,12 162t/km2·a and-2 750t/km2·a at cultivated land,forest land,wild land and other land,respectively;soil loss percentage of former three land use types reached 56%,25% and 19% separately,and slope cultivated land is the main land use type of soil loss;（2） soil loss area percentage of cultivated land,forest land and wild land reached 52%,34% and 100%,soil loss area ratio reached 72%,16% and 12%;（3）soil erosion modulus reached-481,2 500,4 849t/km2·a and 8 068t/km2·a at slight erosion land,light erosion land,moderate erosion land and above strong erosion land,the soil erosion percentage of latter three kinds of land type reached 8%,33% and 59%.The strong erosion land is the main source of soil loss.