湘江沟头地表和深部地质约束的水系侵蚀能力差异及袭夺预测分析

Analysis on difference of erosion capacity and river capture prediction in the head of the Xiangjiang tributary constrainted by surface and deep geological information

基于地表基础地质调研、GIS流域分析与深部地球物理相结合的综合方法,选取长江支流湘江沟头的两条具有共同溯源侵蚀点(矮塘村)的水系作为研究对象,对比两条水系程江和注江相同河长流经区的地形地貌、水位高程、地层、构造背景以及深部电阻率数据,综合分析两者的侵蚀能力的差异性。其中,注江流域的基岩易于被侵蚀,节理较为发育,使得其下蚀作用和溯源侵蚀能力较强。预测两条水系的演化趋势会在矮塘村周边发生河流袭夺现象,从而影响到程江下游的鲤鱼塘镇的城市居民生活用水和工农业生产。此外,注江的持续下蚀作用会加强对基岩白垩系红层的侵蚀作用,推测其流域未来可呈现更为壮观的丹霞地貌。

Based on the comprehensive method of basic surface geological investigation,GIS watershed analysis and deep geophysical analysis,the difference in retrogressive erosion along the Xiangjiang tributary is compared.Two drainage areas in the head of the Xiangjiang tributary,the Chengjiang and Zhujiang Rivers,are selected as subjects with the same source of erosion at Aitang Village.Under comparison with topography,water level elevation,lithology of bedrock strata,tectonic setting and deep geophysical data,the Zhujiang River has greater erosion ability and stronger headward erosion,with easily eroded bedrock and well-developed joints.It is predicted that river capture could occur around Aitang village.The evolution trend may lead to a decrease in water volume of Liyu town in the lower reaches of the Chengjiang River,which will affect urban domestic water and industrial and agricultural production.In addition,the continuous strengthening of retrogressive erosion can cause downcutting erosion of the Cretaceous red layer and the watershed will present a more spectacular Danxia landscape.