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运用137Cs技术研究了威宁草海沙河小流域不同土地利用方式和地貌部位的土壤侵蚀特征。结果表明:研究区137Cs的背景值为879Bq·m2;农耕地土壤剖面中137Cs中呈均匀分布,非农耕地土壤剖面中呈指数递减分布;不同土地利用方式下,137Cs的面积活度值从大到小为灌丛地>人工草地>农耕地,土壤侵蚀模数值为农耕地>草地>灌丛地;不同地貌部位土壤中,137Cs面积活度值从大到小为下坡>中坡>上坡,侵蚀模数值变化为上坡>中坡>下坡。小流域年均侵蚀模数为:1254.9t·(km2·a)-1,灌丛地侵蚀模数为462.6t·(km2·a)-1,人工草地为630.4t·(km2·a)-1,农耕地为3311.8t·(km2·a)-1。因此,在小流域水土流失综合治理过程中,农耕地是治理的重点。
The 137Cs technique was used to study the soil erosion characteristics of different land use patterns and topographic features in the Haisha Small Watershed of Weining Causa. The results showed that the background value of 137Cs in the study area was 879Bq · m2. The distribution of 137Cs in the soil profile of farmland was uniform and the distribution of 137Cs in non-agricultural land decreased exponentially. Under different land use patterns, The soil erosion modulus values of agricultural land> grassland> shrub land in the areas of small grassland> artificial grassland> agricultural land. In the different landforms, the activity of 137Cs decreased from large to small downhill> medium slope> Uphill, erosion modulus changes as uphill> mid-slope> downhill. The average erosion modulus of small watershed was 1254.9t · km2 · a-1, the erosion modulus of shrubs was 462.6t · km2 · a-1 and that of artificial grassland was 630.4t · km2 · a- 1, 3311.8t · (km2 · a) -1 for farmland. Therefore, in the comprehensive management of soil and water loss in small watershed, agricultural land is the focus of governance.