贵州鹅项水库沉积物特征及其土壤侵蚀的意义

CHARCTERISTICS OF SEDIMENTS FROM E-XIANG RESERVIOR,GUIZHOU,AND THEIR IMPLICATIONS FOR SOIL EROSION

对位于贵州西南部非喀斯特丘原区的鹅项水库中取得的一沉积物样芯（EX-1）做了137Cs,TOC,C/N和粒度分析以及矿物磁性测量。通过对这些分析和测量结果进行解译,推测了在过去的45年（1960~2005年）中这一水库的汇水流域内土壤侵蚀强度的相对变化。在这45年中,鹅项水库流域的土壤侵蚀经历了由弱到强再持续减弱的一个过程。将这一推测结果与流域内降水数据和土地利用/覆被变化资料数据相结合,探究了该流域土壤侵蚀强度变化的原因。与贵州西南部典型喀斯特流域的情况相比,在鹅项流域内,土地利用/覆被变化情况对土壤侵蚀强度的影响相对次要,而降水对土壤侵蚀强度变化的影响则更为重要。这可能主要因为与典型喀斯特流域相比,鹅项流域的土层较厚、植被覆盖较好。

A sediment core（ EX-1 ） was retrieved from E-xiang Reservoir at the non-karst hilly-plain region in Southwest of Guizhou. Analyses of 137Cs, particle-size,TOC, and C/Nand measurement of mineral-magnetism were performed for EX-1. By interpreting results of these analyses and measurements,relative changes in intensity of soil-erosion of the last 45 years（ 1960 - 2005） were inferred for the catchment of this reservoir. During the last 45 years, soil erosion was first slight, then intensive and has subsequently again weakened. Main factors controlling the soil erosion has been explored by combining the inferred results with data on both precipitation and LUCC （Land Use and Cover Change） for the catchment of this reservoir. Compared to those in typical karst catchments of Guizhou,the impacts of LUCC on soil-erosion are relatively minor while changes in precipitation have relatively major influences on soilerosion in E-xiang catchment. This is probably due to the thicker soils and denser vegetation in E-xiang catchment than in the typical karst catchments.