沙漠季节性河流风沙、水沙交替传输过程研究——以毛不拉孔兑为例

The study of aeolian-fluvial sediment interactive (alternative) transport processes in ephemeral rivers is an important research content in the field of soil erosion and sediment dynamics. Researches indicate that the studies about only one of the processes of aeolian or fluvial are difficult to determine the sediment transition and transport relationships between deserts and rivers, and the effects for evolution of erosion and deposition in rivers caused by aeolian sediment. Therefore, this project prepare carry out the study of aeolian-fluvial sediment interactive transport in the Maobula Gully of Inner Mongolia. According to the field observation and wind tunnel experiments of aeolian sediment feed into gully, the model of aeolian sediment feeding into gullies will built. Using the sediment and flow observation system and 3-D laser scanner, we will observe the processes of aeolian sediment is eroded and carried by hyperconcentrated flow. And the flume experiments were used to simulate the erosion and transport processes of the hyperconcentrated flow in a desert channel of the Maobula Gully. Using the field observed and experimental data of flow and sediment, and the data collected from Tugerige Hydrometic Station, we would calibrate the 1-D nonuniform flow and sediment model. Integrating the calibrated 1-D nonuniform flow and sediment model and aeolian sediment feeding gully model, a model of aelian-fluvial sediment interactive transport in desert ephemeral rivers would built. Using this model, we will reveal the spatio-temporal variation rules of aelian-fluvial sediment interactive transport in desert ephemeral rivers. The results of this project have important theoretical and practical meanings respectively for further understanding aeolian-fluvial sediment dynamical processes in desert ephemeral rivers, and relieving the silting problem of the reach between Sanhuhekou to Toudaoguai of the Yellow River.

沙漠季节性河流的风沙、水沙交互（交替）传输过程是土壤侵蚀与泥沙动力学研究的重要内容之一。研究表明，单纯研究沙漠季节性河流的风沙或水沙过程，不易理解河流与沙漠之间泥沙的转换与传输关系，以及风沙对河道冲淤演变的影响。因此，本项目拟在沙漠季节性河流毛不拉孔兑开展风沙、水沙交替传输过程的研究。通过风沙入孔兑过程的野外观测与风洞实验，构建风沙入孔兑模型。利用泥位、流速监测系统和三维激光扫描仪，实地观测风沙被高含沙水流的侵蚀与搬运过程。通过水槽实验，模拟高含沙水流在沙漠河段的侵蚀与输移过程。根据实测与实验获得的水沙数据，结合图格日格水文站数据，率定一维非恒定流水沙输移模型。整合风沙入孔兑模型，构建风沙、水沙交替输移模型，揭示沙漠季节性河流风沙、水沙交替输移的时空变化规律。其研究结果对深入理解沙漠季节性河流风沙、水沙动力过程，及缓解黄河三湖河口至头道拐的淤积问题有一定的理论与实践意义。

沙漠季节性河流的风沙、水沙交互传输过程是土壤侵蚀与泥沙动力学研究的重要内容之一，研究风沙、水沙交互过程对于理解河流与沙漠之间泥沙的转换关系以及河道的冲淤演变过程具有重要的意义。本项目通过野外观测、粒度分析、地形扫描、泥位观测、模型模拟等手段，对典型沙漠季节性河流——毛不拉孔兑的风沙、水沙交替传输过程进行了研究。结果显示：毛不拉孔兑中游沙漠段是上游粗泥沙与中游风成沙的交互河段。1982-2012年之间，风沙对河道的年均补给量约457331.1 t/y，且呈显著逐年下降趋势。风沙进入河道能够显著影响河床的粗糙度，并最终影响河道的水沙传输。毛不拉孔兑洪水传输过程中其泥沙含量主要由流量和产水量控制，洪水的产沙量与风沙补给量的相关关系在0.356-0.51之间，呈中等相关。耦合风沙输移模型和非恒定流水沙输移模型，构建了风沙-水沙一体化传输模型，利用模型对毛不拉孔兑典型水沙过程进行了模拟，结果显示产沙量的相对误差均在30%以下，输沙率峰值在33%以下，说明模型能够较好的模拟沙漠季节性河流的风沙、水沙交互传输过程。改项目的研究结果对深入理解沙漠季节性河流风沙、水沙动力过程，及缓解黄河三湖河口至头道拐的淤积问题有一定的理论与实践意义。