Study On Water Quality Evolution And Ecological Water Requirement In Tarim Rivre Basin

Over the past 50 years,the degradation of the ecological environment in the watershed has become more and more serious,which has had a tremendous impact on human production and life.The Tahe basin,which is located in the inland arid area,has become the focus of many scholars.The scale of agriculture in the Tahe basin is expanding,and the development and utilization of water resources is becoming more and more strong.Many water environment problems are unavoidable.At present,the water quality of the Tahe River Basin has been deteriorating,especially the water quality mineralization.Based on the water quality data and hydrological data of 1982-2014 years,this paper uses Mann-Kendall trend analysis and cumulative anomaly analysis to reveal the temporal and spatial evolution law of water quality in the Tahe River Basin,and uses the improved Tennant method to calculate the ecological water requirement in the "four sources one dry" river.The main conclusions are as follows:(1)The concentrations of CODMn and NH3-N in the mainstream of Tarim River increase significantly,and the salinity is not a significant downward trend.The mutation time of CODMn and ammonia nitrogen concentration was in early 1990 s,and the abrupt time of mineralization was in early twenty-first Century.In space,CODMn and salinity decreased along with the increase of ammonia nitrogen.(2)The concentrations of CODMn and salinity in Akesu River increased significantly,and ammonia nitrogen did not decrease significantly.In the past five years,three indicators were not significantly decreased.The mutation time of CODMn was in the beginning of 1990 s,while the mutation time of mineralization was in early twenty-first Century,and there was no mutation in ammonia nitrogen.CODMn,ammonia nitrogen and salinity all increased along the way.(3)The CODMn and ammonia nitrogen in Hetian River are fluctuating,and there is a decreasing trend in the whole,and the salinity is a relatively significant upward trend.The mutation time of CODMn concentration was in early twenty-first Century,ammonia nitrogen was in the middle of 1980 s,and the mineralization degree was at the end of 1990 s.Both CODMn and salinity increased along the path,and the concentration of ammonia nitrogen was higher than that of upstream and downstream.(4)The concentrations of CODMn,ammonia nitrogen and salinity in the Ye Qiang River increased significantly.The mutation time of CODMn was about 1994,and there was no mutation of ammonia nitrogen,and the mutation time of mineralization was around 2000.In the space,ammonia nitrogen and salinity decreased first and then increased,and CODMn showed a weak downward trend.(5)The CODMn and salinity of the Kai Du Peacock River show a significant upward trend,and ammonia nitrogen is not significantly fluctuating.At the end of 1990 s,the CODMn mutation time did not change abrupt,and the mutation time of mineralization was in early twenty-first Century.The concentrations of CODMn,NH3-N and salinity in the space increase from upstream to middle reaches,and from middle to lower reaches.(6)The main reasons for the change of water quality are the increase of social population and the increase of production scale,the increasing of pollution sources,such as industrial pollution sources,domestic sewage and farmland drainage,resulting in the decline of water quality.Geography,climate and factors that led to water quality change.(7)the ecological water requirement of river water in the "four sources and one dry" general water use period and peak water consumption period was determined.At present,the study of river water volume can ensure the health of the river ecosystem.