Variation trends analysis of eco-hydrological factors in lower reaches of the Yellow River during the past 50 years

The change of the river eco-hydrological process has an intensely responding with its corresponding ecological environment. Thus carrying out researching on variation trends of river eco-hydrological factors is contributory to find out evolution law and mechanism of the river ecological system. The paper firstly studied on the elements statistical characteristics on runoff, flood, river sediment and fluvial geomorphology in order to revealing the longterm evolution rule, mutation characteristics of different ecological indexes. Furthermore, it analyzed the ecological system response mechanism initiated by the changed elements and tapped the critical factors impacting river eco-hydrological system evolution.It may provide the support to research water cycle health and ecological patterns safety. The results show that the factors occurring strongly change included numbers of large floods, average water depth, annual runoff, intra-annual distribution, minimum and maximum flow occurring time and so on. Climate change and human activities such as reservoir operation and drawing water, led to eco-hydrological elements strongly impacted in the downstream Yellow River, some of which elements had be broken as numbers of large floods and average water depth. The damage could be brought out by reservoirs accumulative action and the unreasonable water-drawing permit system.