摘要
198 9年以来三峡地区开展的侵蚀泥沙13 7Cs示踪的初步研究表明:三峡地区紫色土陡坡耕地侵蚀强烈,坡度>2 5°的坡耕地,侵蚀速率高达712 6 94 5 2t/(km2 ·a) ;黄壤质地粘重,抗蚀性好,坡度2 9°的陡坡耕地的侵蚀速率仅2 5 0 9t/(km2 ·a)。林草地侵蚀轻微,坡度2 5°林草地的侵蚀速率为30 6 6 88t/(km2 ·a) ,较坡耕地大致低一个数量级。上世纪6 0年代以来,开县小江河床上涨强烈,两岸滩地也有淤积发生,淤积厚度10 70cm不等,低滩地泥沙淤积厚度大于高滩地。开县春秋水库小流域输沙模数为15 6 0t/(km2 ·a) ,由于谷地泥沙淤积极为有限,此值基本可代表该流域的侵蚀模数。全国土壤侵蚀遥感普查公布的川东平行岭谷区侵蚀模数为30 0 0 5 0 0 0t/(km2 ·a)。
A study on erosion and sedimentation in the Yangtze Three Gorge Region by using the^(137)Cs technique, which has been carried out since 1989, provides valuable information on erosion and sedimentation severities in the region. Erosion is very severe on cultivated purple soils of steep slopes and the erosion rates on the slopes of>25° range between 7 126 t/(km^2·a) and 9 452 t/(km^2·a). However, erosion on cultivated yellow soils is not as severe as on the purple soils because of its clayey texture and high erosion resistance. The erosion rate on the slope of 29° is 2 509 t/(km^2·a). Erosion is slight on forest and grass slopes and erosion rates on the purple soil slopes of 25° ranges between 306 t/(km^2·a) and 688 t/(km^2·a), which are less than one tenth of the rates on the cultivated slopes. The channel bed of Xiaojiang River in the Kaixian County has risen significantly since 1960s. Sedimentation has also occurred on the flood plains and deposition thicknesses since 1960s range between 10 cm and 70 cm, and the thickness is greater on the lower flood plain than it on the higher plain. The specific sediment yield of the small Chunqu Gully Catchment is 1 560 t/(km^2·a), which may be representative of the average erosion rate over the catchment due to little deposition in the gully bottom. The erosion rates of 3 000~5 000 t/(km^2·a) for the Parallel Mountain Ridge and Valley Region in East Sichuan, announced by the state soil erosion survey using the remote sensing method, may be overestimated.
出处
《水土保持学报》
CSCD
北大核心
2005年第2期33-36,共4页
Journal of Soil and Water Conservation
基金
中科院知识创新项目 (KZCX3 -SW330
42 2 )
科技部 973项目 (2 0 0 3CB41 580 2 )
国家自然科学基金项目 (40 2 71 0 1 5)
国际原子能机构资助项目 (1 2 30 0 /RO)
