and you can link to an engineering geology users manual from Ontario (OFR5288) and other handbooks from USACE and USBR.
Also useful are papers related to groundwater-surface water interaction. One good reference USGS Circular 1139) can be downloaded at the following website:
Fundamentals of Groundwater by Zhang and Schwartz. One of the best books about groundwater. It has a chapter specifically about Groundwater Quality that might give you some insight about that topic you asked.
My dear groundwater quality briefly is affected by rainfall intensity, geochemistry of considered formation, capillary action, local streams, weather conditions (temp., humidity, wind speed, sunshine).
A continuous interaction between surface and groundwater produces sometime good and bad effects on both system. In most cases rainfall has good consequences on groundwater when bio-chemistry of vadous zone is good.