Study On The Water Quality Analysis And Evaluation Of The Heihe River Basin In Hohhot

With the continuous development of economic society, industrialization and urbanization, water environment pollution problem becomes more and more severe. There are many problems about the pollution of the environment and this phenomenon becomes the restrictive factor of economic development. Therefore, it is in urgent need of water pollution control. Heihe river, which flows with the Yellow River in the Hekou country, is one of the tributaries from the Midwest into north shore of the Yellow River in Inner Mongolia’s largest. This Heihe river is carrying almost all sewage of Hohhot. As the second stages of "introducing water of Yellow River into Hohhot", The amount of water taking from Yellow River reaches forty thousand tun per day, which is accounting for more than sixty percent of urban water consumption. Estuary of Heihe for "introducing water of Yellow River into Hohhot" is less than ten kilometers in the downstream. The quality of Heihe is directly affect the water security for the whole city.In order to understand the present situation of the Heihe river quality in Hohhot more accurately,15 monitoring points were set and in accordance with the 《surface water environment quality standard》 (GB3838-2002),23 fundamental analysis projects, electrical conductivity, soluble total 25 items for testing analysis were made by The environmental protection agency to investigate the water environmental quality of the Heihe river basin. According to the monitoring results the status of water quality analysis and evaluation were made to each point and the all river. The Heihe river basin was present the V class and the pollution degrees were different. The entry section was mild polluted, the cross-section of the Yellow River was moderate polluted and the rest of the cross sections were severe polluted or worse. The main pollutants were total nitrogen, ammonia nitrogen, CODCr, BOD5, total phosphorus and dissolved oxygen. The author monitored the river quality of the Heihe river to analysis the change trend of water quality in recent years. Based on the river, the annual variation tendencies of pollution index in each points of Heihe river was obtained. The individual pollution index, the composite pollution index and contributing degree of pollution index were used to research the main pollution factors of Heihe river.Based on the hydrological data and the investigation for the sources of pollution along the river, it further clarified that the water quality of the Heihe river basin is present the V class. The people’s livelihood drainage monitoring section is mild polluted and the main pollutant is total nitrogen. The cross-section of the Yellow River is moderate polluted and the main pollutant for total nitrogen. The rest of the cross sections were severe and major pollutants are total nitrogen, ammonia nitrogen, CODCr, BOD5 and total phosphorus. There are no large-scale livestock and poultry breeding and farming in Hohhot, town life source is the primary cause of water quality deterioration and the second pollution cause is industry.