基于遥感和137Cs方法的半干旱草原区土壤侵蚀量估算

结合遥感地学分析方法和地球化学放射性同位素——137Cs示踪技术对青藏高原东北部共和盆地塔拉滩草原地区的土壤风蚀量进行估算。利用遥感数据获取研究区土壤侵蚀强度相对等级图斑,在不同等级侵蚀空间信息中选取137Cs样品采集点,并测定土壤样品中的137Cs含量,以此确定不同等级侵蚀类型的土壤侵蚀量。结果表明,在本研究区发生的风力侵蚀强度不大,主要属于微度侵蚀和轻度侵蚀类型,分别占研究区总面积的47.12%和35.58%,二者占研究区总面积的82.70%,侵蚀模数介于220.28~580.13 t·km-2·a-1之间;只有极小区域发生了强烈以上侵蚀,面积为22.14 km2。在本区还发生强烈的堆积过程,出现大面积的风沙堆积区域,面积约322.67 km2,占研究区总面积的11.78%。本区年均土壤总侵蚀量约为87~115万t,总堆积量约为55~78万t,平均每年由塔拉滩向龙羊峡水库输入的土壤量约为32~37万t。此方法可以对干旱环境中土壤风力侵蚀进行快速的较为客观的估算,具有一定的应用前景。

Estimation of Soil Erosion Quantity in Semi-arid Steppe Region with Remote Sensing Technologies and 137Cs Measurements

Soil wind erosion is the most important course of earth surface change in semi-arid area. The soil erosion quantity of a experimental region in Talatan of Gonghe basin, Qinghai province, is estimated with integrated technologies of remote sensing and geochemistry radioactivity isotope. The results show that the soil wind erosion is not intensive in this region; most belong to the very light and light types, accounting for 47.12% and 35.58% of the study total area respectively, and the erosion modulus is about 220.28~580.13 t·km-2·a-1; only small area of near 22.14 km2 belong to severe erosion and very severe erosion types. Also, there is intense deposition course in this region, its area is 322.67 km2, accounting for 11.78% of the study area. For the whole study area the total soil erosion per year is 870 000 to 1 150 000 ton, and the deposition is 550 000 to 780 000 ton. The transportation of soil from Talatan to Longyangxia reservoir per year is about 320 000~370 000 ton.