GEOL 104 Lecture Notes - Lecture 33: Ice Shelf, Glacier Terminus, San Joaquin Valley

• School: Queen's University
• Department: Geological Sciences and Geological Engineering
• Course: GEOL 104
• Professor: Daniel Layton- Matthews

Document Summary

Environmental problems: mining groundwater, subsidence, saltwater contamination. In many places, the water available to recharge the aquifer is significantly short of amount being withdrawn. More being taken out than can replenish. The ground sinks when water is pumped from wells faster than natural recharge processes can replace it i. e. san joaquin valley in california, land level has dropped 9m since 1925 due to heavy pumping. Excessive groundwater withdrawal causes saltwater to be drawn into wells, thus contaminating the freshwater supply. Can correct the problem with recharge wells. Freshwater is less dense that saltwater, it floats on the saltwater and forms a lens-shaped body that may extend to considerable depths below sea level. If excessive pumping lowers the water table, the base of the saltwater zone will rise 40 times that amount. Results mat be saltwater contamination of wells. Extremely permeable aquifers (course gravel) have such large openings that groundwater may travel long distances without being cleaned.