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Geology topics

T.L. Holzer

Publications and source records attributed to T.L. Holzer.

22 records · Page 2Linked to original sources

Land subsidence caused by ground water withdrawal in urban areas

At least eight urban areas in the world have encountered significant economic impact from land subsidence caused by pumping of ground water from unconsolidated sediment. The areas, most of which are coastal, include Bangkok, Houston, Mexico City, Osaka, San Jose, Shanghai, Tokyo, and Venice. Flooding related to decreased ground elevation is the principal adverse effect of the subsidence. Lesser effects include regional tilting, well-casing failures, "rising" buildings, and ground failure or rupture. Subsidence of most of these urban areas began before the phenomenon was discovered and understood. Thus, the subsidence problems were unanticipated. Methods to arrest subsidence typically have included control of ground water pumping and development of surface water to offset the reductions of ground water pumping. Ground water recharge has also been practiced. Areas threatened by flooding have been protected by extensive networks of dikes and sea walls, locks, and pumping stations to remove storm runoff. ?? 1985 D. Reidel Publishing Company.

GeoJournal

Elastic expansion of the lithosphere caused by groundwater withdrawal in south-central Arizona

Relative crustal uplift observed from 1948–1949 to 1967 in the Lower Santa Cruz River Basin in south-central Arizona is attributed at least in part to elastic expansion of the lithosphere induced by the removal, and subsequent loss by evapo transpiration, of 4.35 × 10 13 kg of groundwater from alluvium. The area of unloading is approximately 8070 km 2 . Uplift, relative to an apparently stable area west of the unloaded area, was observed in two areas near Casa Grande and Florence where crystalline bedrock is either close to the land surface or crops out through alluvium from which groundwater was withdrawn. The magnitudes of uplift were approximately 6.3 and 7.5 cm respectively. The observations are based on first-order leveling. The observations are significant at three standard deviations for random surveying errors, and are not believed to be affected by systematic errors. However, the 7.5-cm uplift observed at Florence may be from 1 to 2 cm in excess of the actual uplift because of the possibility of subsidence of a tie point due to groundwater pumping during the leveling in 1948–1949. Uplift is attributed to groundwater withdrawal on three bases. First, the observed uplift is consistent with a theoretical evaluation of elastic expansion based on linear elasticity theory. For the observed distribution of unloading and uplift and a Poisson's ratio of 0.25, a Young's modulus for the lithosphere of approximately 0.68 Mbar is implied. This value is comparable to values of the lithosphere reported elsewhere. Second, the magnitude of uplift compares favorably with the magnitude of elastic depression caused by the formation of Lake Mead, Arizona—Nevada, 430 km northwest of the study area, when allowance is made for the different magnitudes and areal distributions of surface (un)loading. And third, in the area near Casa Grande, a reversal in the sense of bedrock displacement form subsidence of tectonic origin to uplift approximately coincided with the beginning of large groundwater overdraft. The uplift from 1948 to 1967 near Casa Grande was preceded from 1905 to 1948 by 7–8 cm of tectonic subsidence; no precise data for the area near Florence are available before 1948.

Arizona