Analysis And Evaluation Of Irrigation Water Quality In Dujiangyan Irrigation

The global water is facing severe water shortage, and increasingly serious water pollution problem has become a global environmental problem. Dujiangyan Irrigation District is located in the western Sichuan Basin, Sichuan Province, the most developed industrial and agricultural production, the most economically prosperous region. However, the region per capita possession of water resources and water resources per mu occupancy were lower than the provincial and national average, but also sewage and water pollution in the hardest hit. In view of this, through surveys, monitoring, analysis the irrigation water quality of Dujiangyan Irrigation in different years and different seasons, to grasp the status and trends of agricultural irrigation water environment to explore the reasons caused by the irrigation district water quality change, and to provide a basis to improve the basic production conditions and ecological environment, improve the comprehensive agricultural production capacity and promote sustainable agricultural development.(1) The water quality of Dujiangyan Irrigation in winter was diffferent in different years. From October2008-October2010, it had a trend of decreasing. In October2008, October2009and October2010, the average water quality categories were Class Ⅱ, Class Ⅱ and Class Ⅲ, respectively. The conductivity, dissolved oxygen content, sulfate content, COD content and total nitrogen content was decreased respectively, but the nitrate content, ammonia nitrogen content showed a tendency to increase. In addition, the monitoring data of each monitoring site was greater than the same period from irrigation water sources Baopingkou, and the maxmum of water quality class up to Class V.(2) The water quality of Dujiangyan Irrigation in spring was diffferent in different years. From March2009-March2011, it showed a decreasing trend. In March2009, March2010and March2011, the average water quality categories were Class1, Class11and Class11, respectively. The nitrate content, sulfate content, COD content and total nitrogen content was decreased respectively, and the conductivity, dissolved oxygen content, ammonia nitrogen content showed a tendency to increase. In addition, the monitoring data of each monitoring site was greater than the same period from irrigation water sources Baopingkou, and the maxmum of water quality class up to Class V.(3) The water quality of Dujiangyan Irrigation was diffferent in different seasons. In July2011, October2011, March2012and June2012, the average water quality categories were Class Ⅲ, Class Ⅲ, Class III and Class Ⅲ, respectively. The nitrate content, sulfate content, hexavalent chromium content, copper content was up to the highest in the winter, the conductivity, ammonia nitrogen content was up to the highest in the spring, the dissolved oxygen content, the arsenic content, COD content, content of total phosphorus, total nitrogen content was up to the highest in the summer. In addition, the monitoring data of each monitoring site was greater than the same period from irrigation water sources Baopingkou, and the maxmum of water quality class up to Class Bad V.(4) The Comprehensive Pollution Index method derived from winter irrigation, spring irrigation and water quality in different seasons of Dujiangyan Irrigation. The average P values of them were all less than1, and the levels of contamination were uncontaminated.