Water bodies include for example lakes, rivers, oceans, aquifers and groundwater. The Edwards Aquifer is one of the most prolific artesian aquifers in the world. Estimates of the groundwater stored in the principal aquifers are controversial. In the 1960s, more and more groundwater aquifers developed. Deliverability from salt caverns is, however, much higher than for either aquifers or depleted reservoirs. Memphis receives its water from artesian aquifers. Many aquifers, such as alluvial aquifers, occur entirely within regolith. The rainwater flows into lakes, rivers, or aquifers. The remaining freshwater is found in glaciers, lakes, rivers, wetlands, the soil, aquifers, and atmosphere. Such rivers are typically fed from chalk aquifers which recharge from winter rainfall. Using ground water from deep, confined aquifers provides more protection from surface water contamination. This may find applications in areas where the potable water is extracted from underground aquifers. The study of water flow in aquifers and the characterization of aquifers is called hydrogeology. The unconfined aquifers are tapped by dugwells. There are also baseflow contributions from the major aquifers in the catchment.