Study on the risk assessment and forewarning model of groundwater pollution

In the purview of groundwater pollution, a rational exploitation, utilization, protection, and risk assessment of groundwater has become an important means of groundwater management and pollution prevention. Xiashan Economic Zone of Weifang City which is located in the central region of the Shandong Peninsula, China, has been chosen to investigate the risk assessment of pollution by heavy metals (Pb, Cr, Cd, and Hg) permeating into groundwater periodically through the soil layers or the vadose zone. This study deals with the risk assessment and forewarning model of groundwater pollution by the use of comprehensive risk index method along with GIS overlay analysis and groundwater pollution forewarning system. Soil samples (n = 988) and water samples (n = 327) from groundwater resources of Xiashan Economic Zone and eight major factors, i.e., runoff factor, overburden strata factor, atmospheric precipitation factor, pollutant source type, pollutant generation quantity, pollutant release possibility, water yield from aquifers, and groundwater conservation district, have been thoroughly studied. Based on data analysis and study, groundwater pollution risk assessment zonation map and groundwater forewarning distribution map were established. The results show that the distribution area accounting for 3.07% of the total area is of medium warning with high risk of pollution. Mainly spread on both banks of the river, the serious warning zone is covering 26.80% of the total area for groundwater, and the groundwater is distressed with a risk of moderate pollution. While the tremendous warning area for groundwater pollution is distributed in over 70.13% of the total area, thus, putting in a state of high-risk pollution. The warning degree of groundwater pollution in typical water source areas was identified, and the possible alarming warning instance can be forecast. Based on the warning degree, the governance protection area and key protection area were divided. The corresponding prevention and control measures were put forward after formulating the prevention and control plan of groundwater pollution based on this kind of study.