Analysis on Impact Factors of Shallow Groundwater Quality in Semi-Arid Region

As an example of semi-arid region in western part of Jilin Province, the hydro-chemical data of 48 shallow wells for more than 20 years were collected to study. The results showed that TDS increased continually which illustrated deterioration of groundwater quality. With the aim to protect groundwater resources, the influence factors of groundwater quality changes are the key points to be studied. Grey relational grade (GRG) analysis, a useful technique for dealing with dynamic data, was applied to find out the main characteristic components affected groundwater quality. Results indicated that groundwater quality was mainly affected by the changes of concentration of SiO₂, HCO₃^-, total hardness and Ca²⁺. It means that groundwater temperature, groundwater table depth and rainfall are the main factors because these are the key causes dominate the characteristic components. Studies also explained man-made pollution has little influence on regional shallow groundwater quality.