CHANGE AND TREND OF DEVELOPMENT OF STREAMFLOW AND SEDIMENT IN THE REACH BETWEEN HEKOUZHEN AND LONGMEN OF THE YELLOW RIVER
Zhang Shengli(Institute of Hydrauranlic Research,Yellow River Conservancy Commission)
The reach between Hekouzhen and Longmen of the Yellow River is the source area of high and coarse sediment of the YeJlow River and its amount of streamflow and sediment on the siltation of the lower Yellow River are very important.In this paper, the change of streamflow and sediment of that reach in recent years is analysed, the reasons of change are studied,the trend of development in the future is predicted.In recent years, runoff and sediment in the studied reach are reduced ob -riously, and the ratio of reduction in the flood period is bigger.The main reason is the reduction of the amount and intensity of the rainfall. Comprehensive controlling measures have intercepted role. Drawing off water and sediment, deposited on the streambed have also some effects.In the future, the change of streamflow and sediment regime in the reach between. Hekouzhen and Longmen will be "polarization" further, i.e., the streamflow and sediment in the common years will be reducted, if rainstorm occurs, the flood and the sediment may be greatly increased, and the change depends on different combination of such factors.