目前关于河道内环境需水量研究多集中于水资源短 缺性河流，而关于水量比较充足河流的环境需水量的研究报道较少。依据长江下游生态环境 特点提出并概算了长江下游干流河道内最小环境需水量。计算结果表明 ，长江下游干流河 道内最小环境需水量约为 2 069.2亿m3。在丰水年枯水期该环境流量对长江口的生态 环境影响不大，但在枯水年枯水期将会产生严重的生态环境问题。 

At present, the study of environmental water demands is focused on the rivers for lack of water resources, but attention is paid little to the rivers of rich water. The paper puts forward and calculates the lowest environmental water demand in river course of stem stream according to the features of ecosystem and environment of lower reach of Yangtze River. The result shows the lowest environmental water demand is about 2 069.2×10 8m3. There is few impact on the ecosystem and environment of the Yangtze Estuary in dry se ason of high flow year, but will cause a serious ecosystem and environment probl ems in dry season of dry year.