Preliminary Study About The Effect On The Ecological Environment Of Estuary Of Yellow River And Its Adjacent Area Caused By The Change Of Yellow River Runoff

Yellow River is the main river in northern China, which exports large amount of nutrients to the Bohai Sea annually. The estuary of Yellow River and its adjacent area, a major fishery and spawning grounds of the Bohai Sea, have abundant species. But in recent years, the Yellow River runoff showed a significantly downward trend, severely affecting the ecological environment of the estuary and its adjacent area. According to the marine investigations and data from historical literature, large amount of survey data were collected. Combining it with the runoff data in Lijin Hydrological Station of Yellow River, the change trend of the ecological environment of the estuary and its relationship to the runoff are studied. The results showed that:Based on the data collected from Lijin Hydrological Station since 1950, the annual average flow and silt of the Yellow River gradually declined, and their change trends are obviously correlative. The main character of Yellow River runoff is that the water and silt distributed unevenly from year to year. Dry year and flood year happened alternately. And from 1970s, the phenomenon of cutoff happened frequently. The distribution of the runoff and silt in a year is also uneven and mainly concentrated in July to October.The investigated data of two cruises in 2004 indicate that the ecological indicators in Estuary of Yellow River and its adjacent area are significantly different in flood season and dry season. The difference of the Yellow River runoff is the major reason that causes the differences of environmental indicators in these two cruises. And the pollutants from the Xiaoqinghe River contribute a lot to the concentration of nitrate and ammonium.Based on the data collected from the literature, Estuary of Yellow River and its adjacent area is divided into 7 square-areas, the change of water ecological...