GEOL 100 Chapter Notes - Chapter 17: Groundwater Recharge, Saltwater Intrusion, Vadose Zone
Document Summary
Groundwater is viewed as a way to acquire additional supplies of freshwater. Small wells pull out little groundwater, water table remains as it has. Larger wells extract larger volumes of water, pumping so rapidly that groundwater recharge is not fast enough. Forms a funnel shaped cone of depression around the well. Direction of groundwater flow changes dramatically across the entire area. Instead of flowing in one direction, it flows toward the large well and into the cone of depression from all directions. Change in flow causes safety issues since waste disposal sites (landfills) are planned with the original groundwater flow direction. Change in flow can bring contaminated water into previously fresh wells. Original small well dries up because it no longer reaches the water table. Most water is pumped from the sediment filled basin and used by people in the valleys. Bedrock has some permeability, but much lower overall porosity and water than sediment in the basin.
