Advances and prospects of ecological water demands in the Yellow River Estuary

Ecological water demands of the Yellow River estuary include river ecological water demand, wetland ecological water demand and offshore ecological water demand. In this paper, the target, content and calculation results of the ecological water demands in the estuary of the Yellow River in the past 20 years are systematically summarized. Based on the evolvement feature of the Yellow River Estuary, the key points and main research directions of ecological water demand are put forward. For the river ecological water demand, it is mainly to meet the habitat of important fishery species, focusing on the response process of the indicating species to natural runoff rhythm and quantifying the hydrologic and ecological response relationship to restore ecological function of the natural hydrological situation to a certain extent. For the wetland ecological water demand, vegetation, soil, water-salt balance and evapotranspiration law should be studied in depth, and the ecosystem structure should be built from the rational design of vegetation and birds niche and the maintenance of biodiversity, so as to determine the reasonable scale of wetland. For the offshore ecological water demand, it is necessary to study the mechanism of shaping and maintaining the spawning grounds of low salinity fishery species by flushing fresh water into the sea, and study the habits of important fishery species, appropriate nutrient levels and phosphate transport and diffusion mechanism. Since the operation of Xiaolangdi reservoir, the proportion of years in which the runoff of Lijin section meets the requirements of existing ecological water runoff results is 37% ~ 58%, and there is often lack of flow pulse in spring. Primary analysis shows the annual ecological water demand of wetland, river fish and offshore fish is 8.6 billion m3, and the runoff process needs periodic floods. It is suggested to optimize and adjust the multi-year operation scheme of the Xiaolangdi reservoir, giving consideration to the shaping of spring discharge pulse, which may meet the ecological needs of the estuary on a much larger scale. © 2020, China Water Power Press. All right reserved.