The Assessment And Trend Analysis Of The Groundwater Quality In Urban And Suburb Area Of Beijing

Water resource is one of the most basic material conditions which men have to depend on for their survival and development. With the development of economy and the rapid increase of the population, human beings are consuming groundwater resource at the speed and scale they have never met before. In Beijing, the production volume of the groundwater meets 2/3 of the water totally supplied. Because the over-rapid development of the city, the relative lag of the city arrangement and the construction of municipal facilities, the irrationality of the industry structure and the yearly increasing of the city-life wastes, the discharge amount of the city waste is far beyond that the environment can self-purify. So a series of groundwater pollution problems appeared .The water-supplying safety of some water plants and the drinking water sanitation of city residents was badly effected. This has become one of the most important problems that limit the economic development of Beijing. .The aims of this survey and research are to assess the groundwater quality of the aquifers in Beijing suburb, to analyze the main factor that effect the groundwater, to study its changing trend and to forecast the status of the groundwater in the next ten years.1. the brief conditions of topography, meteorology and hydrology in the study areaThe Beijing city is located in the northwest of the North Plain of China and borders upon Hebei province and Tianjin city. The width from east to west is about 160 kilometers and the length from south to north is about 170 kilometers. The area in its northwest is higher than its southeast. In its west and north there are continuous mountain groups, and in its northwest there is plain extended to the Bo sea. from the northwest to the southeast , the characteristic of topography changes from erosive construction mountains to alluvial plain.Beijing city belongs to the zone of the continental monsoon climate.It's droughty and windy in spring, hot and rainy in summer, cool and moist in fall, cold and dry in winter. The over-years average rainfall is about 630 mm, the over-years water-surface evaporate is above 1000 mm.Beijing city is in Haihe valley in which there are many river networks. From the east to the west there are Juhe in Jiyunhe system, Chaohe> Baihe and Huaihe in Chaobaihe system, Wuyuhe in Beiyunhe system, Yongdinghe and its branch(Weishuihe) in Yongdinghe system and the Jumahe in Daqinghe system.The Beijing plain was formed by the alluvial function of the most important rivers that include Yongdinghe Chaobaihe Juhe Wenyuhe Jumahe etc. The main aquifer is composed of sand-scree, sand-gravel and sand. The deposit thickness of Quaternary changes unequally from a few meters to hundreds of meters. The aquifer has one to many layers which are composed of sand-scree, gravel and sand, and its total thickness is generally 10-50 m, individually more than 70 m, but all of layers is less than 150 m in which It's very convenience to exploit the groundwater, so they are the main layers of exploiting groundwater in Beijing.2. the assessment targetBecause one of the most important functions of the groundwater in Beijing city now is for drinking, we select total hardness, chloride, sulfate, nitrate nitrogen, nitrite nitrogen, ammonia nitrogen, total dissolved solid(TDS), chemical oxygen demand(COD), As, Hg, Cr6+, volatile phenols and cyanide as the assessment index.3. the assessment standardThe assessment standard adopted in this detection is The Underground Water Quality Standard GB/T14848-93. The indices of the groundwater is sorted into five categories. We refer to the superior limits of the third category as the standard we use to access the groundwater quality.The assessment standard of the organic compounds adopted in this detection is some rules in The Groundwater Environment Quality Standard GB/T3838-2002, 4.The assessment method:we adopt the assessment ways of comprehensive assessment andremark recommended by the national Groundwater Quality Standard.5.the method for prediction:Time Series Model ca...