Assessment of groundwater nitrate-nitrogen specific vulnerability and sensitivity analysis

The assessment index system and grading standard of groundwater nitrate-nitrogen specific vulnerability including water quality and quantity in the north coastal plain area are put forward in order to rationally exploit and protect groundwater in this paper. An ideal fuzzy matter-element model based on comprehensive weight is established to assess groundwater specific vulnerability, combining the subjective weight (AHP method) and the objective weight (improved entropy weight method) by the the game theory. The zoned map of groundwater specific vulnerability is created by the method coupled with GIS, taking the plain area of Longkou for an example. The most sensitive parameter is assessed through the single parameter sensitivity analysis. The results show that the low vulnerable zones are mainly located in the piedmont tableland of east and south part of the study area; the high vulnerable zones are mainly distributed along the Huangshuihe River and in the west region; and the middle vulnerable zones covers around 63.6% of the total area. The nitrogen fertilizer application is the biggest influencing factor of vulnerability. The high vulnerability region should be protected more carefully.