赤水河流域不同土地利用类型土壤侵蚀的137Cs法研究

Using ^(137)Cs Technique to Study Soil Erosion in Chishui River Region

本研究采用137Cs法对赤水河流域不同土地利用类型土壤侵蚀强度展开调查研究,以期为赤水河流域生态环境保护和实现流域的可持续发展提供基础数据。通过对赤水河中上游地区4种土地利用类型土壤剖面中137Cs含量的测定和分析,结果表明:坡耕地以侵蚀为主,平均坡度在11°~19°之间时,侵蚀模数介于3630~6776 t/(km2·a),其中,习水和叙永研究区坡耕地平均坡度均大于15°,土壤侵蚀强烈,侵蚀模数在6050~6776 t/(km2·a)之间;草地平均侵蚀模数为4235 t/(km2·a);(2)林地有微弱堆积,堆积模数为1331 t/(km2·a);水稻田堆积模数为3872 t/(km2·a)。可见,当平均坡度大于15°时,坡耕地土侵蚀强度较大,因地制宜的采取相应的水保措施是有效遏制水土流失的关键。

The Chishui River is the only unexplored tributary of the Upper Yangtze River, which should be protected. However, because of the complicated topography and soil type, the reliable data about soil erosion in this region are limited. A study was carried out to investigate soil intensities in different land use types by using the 137 Cs technique to provide fundamental data for ecological environment protection and sustainable development. In terms of the measured and analyzed 137 Cs contents in soils of four different land use types in the upstream, it is shown that in the case of the cultivated slope with the gradient varying between 11°-19°, the erosion modulus falls in between 3630-6776 t/（km2 ·a） and erosion intensity in Xishui is strongest. The average erosion modulus in lawn is 4235 t/（km2 .a）. The forest land is of mild accumulation and its accumulate modulus is 1331 t/（km2.a）. The accumulate modulus in the paddy field is 3872 t/（km2 .a）. The erosion intensity of slope cultivated land is strongest. It is a key source area of soil erosion. Therefore, returning the farmland to the forest and restoring vegetation is an effective way to prevent soil and water losses.