Water Quality Evaluation of Tianjin Main Blowdown River Based on Comprehensive Evaluation Method

In order to study the situation of the Tianjin main blowdown rivers'water contamination,we used comprehensive evaluation method to evaluate the water quality of five main blowdown rivers in Tianjin,Jinhe River,South Canal,Haihe River,North canal and Ziya River.In 2009,we processed the monitoring and evaluation for water quality data.The results showed that:judging from single pollution index,Haihe Rivers'pollution index was in the order of total phosphorusammonia nitrogentotal nitrogenchemical oxygen demandfluoride1,indicating that the eutrophication in Haihe Rivers was severe;The comprehensive pollution index of Haihe River was 12.15,which indices in Jin River and South canal were lower 2.76 and 2.37,respectively than in Haihe River,the rate of pollution contribution,the total nitrogen of Haihe River was 16.62%.Finally water pollution degree(P) analysis shows that,P0.5 in Haihe River belongs to moderate pollution and P0.5 in other four rivers belongs to light pollution.