Abstract:

The large area nitrate pollution in unconfined water is very serious in Guanzhong basin,and “three nitrogen”  is main contaminant, the concept of groundwater special vulnerability and its influence factors such as groundwater intrinsic factor, artificial factor, and specific factor about contaminant were analyzed. From these factors, 13 parameters were chosen to assess groundwater special vulnerability. The simulating results of “three nitrogen” transport and transformation were coupled to the special vulnerability evaluation model so that the process models were cupled with evaluation model, together with GIS technology, the special vulnerability of groundwater was evaluated. It is shown that the areas in which groundwater is polluted by “three nitrogen” easily are the alluvial plain which located at middle and lower Weihe River, low loess tableland, and the loess tableland that the thickness is less than 20 m near Xi’an at the south bank of Weihe River. The assessment results are accorded with the actual groundwater nitrogen pollution distribution in the year 2001, the concentration of nitrate in groundwater in these areas have exceed criterion in a large region.

Key words: groundwater special vulnerability, process model coupled with evaluating model, “three nitrogen”pollution, Guanzhong basin, groundwater