科尔沁沙地西部响水河悬移质泥沙粒度分析

目的]对科尔沁沙地西部响水河的悬移质泥沙粒度特征进行研究,以便更好地认识该河流泥沙特征及侵蚀产沙规律,为沙漠区河流—沙丘相互作用研究提供基础素材与例证。方法]通过野外实地考察,选择科尔沁沙地西部响水河3个典型河段对河水中的悬移质进行采样,然后进行室内激光粒度仪测试与分析。结果](1)在上游河段Ⅰ和下游河段Ⅲ处,河水侧蚀弯道凹岸流动沙丘基部,由其上游断面至下游断面泥沙粒径变细,分选变差。(2)河段Ⅱ河水侧蚀由Q_3河湖相地层构成的陡坡,弯道环流对凹岸的冲刷作用较明显,泥沙粒径由其上游断面向下游断面变粗,分选变好。(3)悬移质泥沙粒度呈现从上游至下游粒径显著变粗,分选变好的趋势。结论]该河的水源主要是其南侧石质残丘区泉水和河谷沿线流动沙丘或Q_3河湖相地层的侧向渗出水,随着沿途流动沙丘数量增加,集水面积扩大,流速和流量显著增加,河水的挟沙和冲刷能力随之增强;河流上、下游河段的悬移质主要来自被侵蚀的沙丘基部,中游河段的悬移质主要来自凹岸坍塌的Q_3地层砂。

Grain-size Characteristics of Suspended Load Sediments in Xiangshui River of Western Korqin Sandy Land

Objective] The grain-size characteristics of suspended load sediments of the Xiangshui River situated in the western Korqin sandy land were investigated in order to better understand the characteristics of sediments in desert river and erosion sediment regularities,and to provide basic information and examples for the study of the interaction between rivers and sand dunes in the desert area.Methods] Through field investigation,the suspended water samples of three typical sections in the Xiangshui River situated in the western Korqin sandy land were collected,and then the grain-size characteristics of sediments were studied in laboratory.Results] (1) At the river section Ⅰ and section Ⅲ,as laterally the mobile dunes on the concave bank of the curved river channel are eroded,the grain size of the sediments becomes thin,and sorting tends to be poorer.(2) At the section Ⅱ,as laterally the Q3 fluvio-lacustrine strata of the steep slope is eroded,the effect of bend circulation scouring the concave bank is obvious and the silt grain size becomes coarser and sorting.(3) From the upper reaches to the lower reaches of the river,the grain size of silts in the river is significantly coarser,and the sorting becomes better.Conclusion] The sources of the river derive mainly from the springs of the southern rocky denuded mountains and hills,and the lateral seepages of mobile dunes and Q3 sandy fluvio-lacustrine strata along the river valley.With the whole drainage area increases,flow velocity and flow flux are continuously augmenting and rive erosion and sand carrying capacity are enhancing due to the increasing number of mobile dunes along the stream.The sediments of the upper and lower reaches of the river coming from the base of the sand dunes are eroded by the water and the sediments of the middle reaches of the river derived from the Q3 fluvio-lacustrine strata in the collapse of the concave bank.