Water Quality Assessment And Trend Analysis In The Black River Basin

With the rapid development of social economy,the constant enlargement of the human production scale,and wanton discharge of sewage which come from industrial,agricultural and life,make a lot of harmful substances discharged into water body and caused physical and chemical changes in surrounding water environment. Evaluating regional water environment need to use a reasonable method of water quality assessment,according to the evaluate results to analyze water quality change trend,for the current problems of water environment,to take the effective protection measures to improve the water environment,provide powerful guarantee for the sustainable development of water environment.The Black River is the second largest inland river in the northwestern region,with an average annual runoff of the river for Yingluoxia station is15.8×109m3. Over the years,there is the irrigated agriculture area of top ten commodity grain base and important defense military place-Jiuquan Satellite Launch Center.With the rapid development of population and economic,overexploitation and utilization of water resources,serious environmental problems have become increasingly important in the Black River Basin,water quality problems began to restrict the economic development of the Black River Basin.Water quality assessment and trends analysis has become rational use and protection of water environment in Heihe River Basin as a basic work.In this study,base on the actual situation of the Black River Basin water quality,firstly under conditions of natural geographical and hydrogeological of investigative Basin,using water quality monitoring data from2007to2011years of the Black River Basin to undertake water quality evaluation and section comprehensive evaluation,and secondly use the PWQTrend software to analyze water quality trends for the Black River Basin.Finally,according to the results of final evaluation and water quality trends,made some protective measures and rationalization proposals to the water Environment of the Black River Basin.(1) It is the principal component projection method based on index transform value that is applied to water assessment of the Black River Basin,through take the index transformation value of each calculated water quality as the weighting sets,the evaluation results showed that:the water quality level of Zhamashenke, Yingluoxia, Gaoai, Zhengyixia, Sunan, Shandan bridge were Ⅱ,Ⅱ,Ⅲ,Ⅱ,Ⅱ,Ⅴ respectively,the water quality which is from good to bad is that Sunan, Zhamashenke, Yingluoxia, Zhengyixia, Gaoai, Shandan bridge in sequence in these six monitoring sections.(2) The results of Black River water quality trends after PWQTrend software examination show that the water quality of the Black River overall demonstrate a good trend.In the trend test of NH3-N for many years,the unconspicuous trend occupy66.7%,and the downward trend occupy33.3%,while rising trend occupy37.5%,thereinto,the biggest concentration change trend are Gaoai,Zhengyixia and Shandan bridge.In the trend test of CODmn for many years,the section with rising trend occupy16.7%,the section with decline trend occupy16.7%,the unconspicuous trend occupy50%,thereinto,the biggest concentration change trend of in the are Zhengyixia and Gaoai.(3) In view of the problem of heihe river basin, such as serious shortage of water resources、the imbalance of supply and demand、 unreasonable structure of supply water、 water management is not perfect and etc.For this the following measures should be adopted in the heihe river basin:strengthen the protection of drinking water intake, developing ecological agriculture, adjusting the unreasonable industrial layout, strengthen the law about water resources and water environment (gauge) construction, increase the propaganda of environmental protection knowledge, establish and improve the heihe river basin water environment monitoring and supervision system,strengthen the management of industrial pollution sources and the environment.