Calculating Methods for Quantifying Environmental Flows in Estuaries: A Case Study of Haihe River Basin, China

This paper developed a new method for quantifying environmental flows in estuaries. Three types of water requirements were included in calculations: the water cycle, the biological cycle, and the habitat. Three estuaries of the Haihe River Basin in China were presented as case studies for verifying the applicability and practicability of the proposed method. The results indicated that the minimum annual environmental flow requirements for the Haihe. Luanhe and Zhangweixin Estuaries were 5.97 x 10(8), 6.80 x 10(8) and 4.96 x 10(8) m(3) respectively. For the Luanhe Estuary, the annual freshwater inflow was sufficient for achieving the ecological objectives. The estuarine ecosystems in the Haihe and zhangweixin estuaries have degenerated significantly over the past decades and could not be rehabilitated naturally. The spatial variations in the environmental flows were related to the differences between the local climate conditions and the fluvial flow regimes of the estuaries. The temporal variations were influenced by the climatic conditions. Sediment transport was affected directly by reductions of river discharge. and so was the balance of salinity.