Philip E. LaMoreaux

Catastrophic subsidence: An environmental hazard, shelby county, Alabama

Induced sinkholes (catastrophic subsidence) are those caused or accelerated by human activities These sinkholes commonly result from a water level decline due to pumpage Construction activities in a cone of depression greatly increases the likelihood of sinkhole occurrence Almost all occur where cavities develop in unconsolidated deposits overlying solution openings in carbonate rocks. Triggering mechanisms resulting from water level declines are (1) loss of buoyant support of the water, (2) increased gradient and water velocity, (3) water-level fluctuations, and (4) induced recharge Construction activities triggering sinkhole development include ditching, removing overburden, drilling, movement of heavy equipment, blasting and the diversion and impoundment of drainage Triggering mechanisms include piping, saturation, and loadingInduced sinkholes resulting from human water development/management activities are most predictable in a youthful karst area impacted by groundwater withdrawals Shape, depth, and timing of catastrophic subsidence can be predicted in general termsRemote sensing techniques are used in prediction of locations of catastrophic subsidence. This provides a basis for design and relocation of structures such as a gas pipeline, dam, or building Utilization of techniques and a case history of the relocation of a pipeline are described

Groundwater development, Kharga Oases, Western Desert of Egypt: A long-term environmental concern

AbstractThe groundwater reserves in Kharga Oases have been studied for the long-term socioeconomic development in the area. The Nubian Sandstone, which consists of a thick sequence of coarse clastic sediments of sandstone, sandy clay interbedded with shale, and clay beds, forms a complex aquifer system. The Nubian Aquifer has been providing water to artesian wells and springs in the Kharga Oases for several thousand years.Groundwater in the Kharga Oases is withdrawn from springs and shallow and deep artesian wells Nearly all the wells originally flowed, but with the exploitation of ground-water from deep wells for irrigation beginning about 1959. the natural flows declined as more and more closely spaced deep wells were drilled By 1975 many deep wells had ceased to flow The water demand in the area has been met by pumping both shallow and deep wells The total annual extraction from deep wells has fluctuated over the year, however, the annual withdrawal from deep wells has exceeded extraction from shallow wells About 17 billion m3 of water was withdrawn from the combination of shallow and deep wells during the period 1960–1980The Nubian complex aquifer in the Kharga Oases has a very large groundwater potential that could be exploited and beneficially used for a long-term agricultural development in the area, provided proper well spacing and management are implementedOther major environmental considerations for which precise hydrogeologic data are needed include1Determination of the long-term yield available from properly constructed and producing artesian wells that will support a planned migration of population from the overcrowded Nile delta and flood plain areas2Development of an effective management program and adequate staff to maintain groundwater production over an extended period of years3The impact on climate caused by extensive irrigation in the oases of the Western Desert of Egypt4Protection against water logging of soils from irrigation practices5Protection against salinization of soils from irrigation practices6Development of effective surface and subsurface drainage practices7The impact of farming and pest control practices on the shallow groundwater of the oases8Determination of the long-term development of the artesian water on the quality of the water from the aquiter systems in the Western Desert This paper addresses items 1, 2 and 8.