Analysis of water quality change trends and causes of the Wei River

The Wei River has played an important role in the economic development of the Guanzhong-Tianshui economic zone. Sustainability of the Guanzhong-Tianshui economic zone has currently impeded by the over exploitation and severe environmental pollution. In order to provide the scientific support for the water pollution control and management of the Wei river, the change trend of the water quality of the Wei river and the resultant reasons are discussed based on the data of the main control sections of the Wei river over the period from 2000 to 2008. A series of the analytic methods are employed in the paper involving the integrated index of organic pollution, the Daniel trend test technology, Spearman rank correlation coefficient. The following results can be drawn. (1) The marked drop trend of the integrated index of organic pollution occurs at the Wolongsi control section, while there is weak decline trend of the integrated index of organic pollution at the other main control sections of the Wei river. (2) The holistic water quality of the Wei River has ameliorated, which can be evidenced by the monitoring data at the main control sections of the Wei river. (3) The improvement of the water quality of the Wei river is the result of a series of reasons. One of the reasons can be the apparent cut of the pollutants discharging from the industrial point sources, which leads to the decrease of the pollutants entering the water body. The effective control of the pollution from the daily life is another cause. In addition, the betterment of the management system definitely contributes to the improvement of the water quality of the Wei river.