Science Events Audio

Leonard Konikow, Scientist, U.S. Geological Survey Abstract: Development of ground-water resources for agricultural, industrial, and municipal purposes greatly expanded during the 20th century, and economic gains from ground-water use have been dramatic. In many places, however, ground-water reserves have been depleted to the extent that well yields have decreased, pumping costs have increased, water quality has deteriorated, aquatic ecosystems have been damaged by reduced ground-water discharge, and land has irreversibly subsided. Some causes and effects of groundwater depletion, however, are neither obvious nor easy to assess. A surprisingly large fraction of ground water pumped from confined aquifers derives from storage losses in adjacent confining layers, but depletion in low-permeability layers is difficult to estimate, rarely monitored, and too often overlooked. A new simplified method for estimating depletion from confining layers was developed, tested, and applied. Results indicate that depletion