Water Quality Evolvement And Forecasting Of The Well-field At The Middle-low Reach Of Dagu River

The water quality of Dagu River, which is one of the most important well-fields atQingdao city, is closely relative to the each aspect of social development and people'sdaily life. In recent years, with the fast development of industry and agricultureproduction in Dagu River basin, the water condition is strongly disturbed. In this paper,the status and reasons of water pollution, which include surface water and groundwater inthe scope of Dagu River well-field, is analyzed based on hydrogeological investigationand GIS technology; through ascertaining the groundwater supply, runoff and drainageconditions of the well-field, groundwater quality mathematical model is built; thegroundwater pollution trends are predicted by the MODFLOW software, and suitableprevention and cure methods are brought forward.First, surface water quality general situations of Dagu River and its chief branchesare analyzed, and the distributing situations of point sources and face sources areascertained. Groundwater level and quality dynamic curves are made by the groundwaterdynamic monitor management software based on the observation data from 1992 to 2003,with which the dynamic rules of groundwater quality change at different areas and thecorrelation between groundwater and surface pollution sources are analyzed.Contour charts of chief contaminations in groundwater are made by MAPGIS basedon the data of 1995 and 2003, groundwater quality evolutive trend and interferencedegree with groundwater at different human activity zone are analyzed by contrasting thecontour charts.After that, the hydrogeological conditions are found out and the hydrogeologicalconcept model is generalized. Next, through analyzing systematically the rainfall,evaporation, runoff, exploitation and water level data of the groundwater, allhydrogeological parameters of this area is defined, then mathematical model ofgroundwater of Dagu River is built.Last, using the MODFLOW, water quality evolutive trend of Dagu River is predictedfrom 2003 to 2012, and prevention and cure methods are brought forward. The results areas following: the water quality is generally becoming better, but some areas where arenear to pollution source are becoming worse. Nitrogen concentration do not obviouslydecline, further more, it has the trend to be worse in special years, and the nitrogenconcentration in the west area of Dagu River that is mostly agriculture production isgenerally higher than the east area, and rainfall seep play chief rule to supplyinggroundwater, local pollution source have great effect on groundwater.