Land subsidence

Another potential problem, particularly if geothermal water is not returned to its source, is land subsidence. For example, there has been significant subsidence at the Wanaker field in New Zealand. Finally, an annoying difficulty with geothermal heat has been the noise produced by escaping steam and water. The shriek of the high-pressure fluids is intolerable, and is usually dissipated in towers in which the fluids are... 

A rise in sea level would further accelerate the rate of land loss in coastal Louisiana. Even a 50-centimeter rise in sea level (in combination with land subsidence) would inundate almost aU of the delta and would leave New Orleans, most of which is below sea level and only protected with earthen levees, vulnerable to a hurricane. 

Dunrud, C. R. 1984. Coal mine subsidence - western United States. In Holzer, T. L. (ed) Man-Induced Land Subsidence. Geological Society of America, Boulder, Reviews in Engineering Geology, VI, 151-194. 

Prakash, A., Fielding. E. J., Gens, R., van Genderen, J. L. Evans, D. L. 2001. Data fusion for investigating land subsidence and coal fire hazards in a coal mining area. International Journal of Remote Sensing, 22, 921-932. 

Another limited resource required for farming is fresh water. In regions where rainfall is insufficient to support large crops, water is either channeled into fields from lakes, rivers, and streams or else pumped up from the ground. In many areas, groundwater is the primary source of fresh water, but excessive use of groundwater can lead to land subsidence, illustrated in Figure 15.26. 

Probably the most well-known example of land subsidence is the Leaning Tower of Pisa in Italy, shown in Figure 16.3. Over the years, as groundwater has been withdrawn to supply the growing city, the tilt of the tower has increased. 

The RSLR consists of two components the eustatic rise caused by an increase in the water volume of the sea (due to changes in the ratio between the input and output components of the water balance of the sea) and the land subsidence. In many river mouths, the effect of the second factor prevails. 

Land subsidence in deltas can be associated with two factors (1) tectonic subsidence of the seabed and its peripheral parts and (2) gradual thickening (and dehydration) of young deltaic deposits under the pressure of their own weight. Extraction of groundwater and gas can also cause the subsidence of deltaic deposits. Worldwide, river deltas are the main areas of land subsidence. It can reach 10 mm year 1 (the Mississippi River mouth) and more [3]. 

The rate of the RSLR in the Black Sea and the Sea of Azov and at their river mouths (Table 3) varies over a wide range [3,8,24-26]. These data show that actual eustatic sea level rise increased with time and by the beginning of the 21st century reached in the Black Sea 4 mm year x. Besides, these data confirm the assumption that the land subsidence plays very important role in the RSLR in river mouth areas and can reach 3-6 and even 12 mm year-1. The most values of the RSLR and subsidence are typical of the coastal parts of the Danube and Rioni deltas (Table 4). 

The land use problems in cave and karst areas are legion. These include water quality, flooding, and land subsidence. Such problems have attracted significant... 

More often than not, once a peat swamp was established on a coastal plain or delta and later covered by sediments due to land subsidence, a second swamp was established in the same region by cyclic changes in sea level and re-establishment of swamp-type vegetation. In this way, multiple layers of peat and subsequently of coal were formed. 

Duan Y. 1998. Research status on land subsidence and sustainable development in the 21 century of China. Chinese J. of Geological Hazard and Control, 9(2), pp. 1-5. 

Gong S. 1997. Forecast of Shanghai land subsidence. Forecast, Vol. 2, pp. 33-35. 

Ran Q and Gu X. 1998b. A coupled model for land subsidence computation with consideration of rheological property. Chinese J. of Geological Hazards and Prevention, 9(2), pp. 99-103. 

Wei J, Cui Y and Shao J. 2000. 3-D Finite Element method simulation of ground water and land subsidence in Jining City. J. of Changchun Univ. of Sci. Tech.,3(X4), pp. 376-381... 

A series of environmental problems, such as mining collapse, karst collapse, ground fissure, land subsidence and water pollution, are produced by coal exploitation in the subsidence area of the south lake, Tangshan city, which seriously affect the people s daily life and production. 

Xixin Zheng Qiang Wu, et al. 2002. Urabn land subsidence research progress and trends [J]. Geology Review 48(6) 612-618 (in Chinese). 

Plateau Land subsidence, ground fissures, water loss and soil erosion, water and soil pollution... 

Allen, A.S. 1984. Types of land subsidence. In Guidebook to Studies of Land Subsidence Due to Ground-Water Withdrawal, Poland, J.R, ed.. International Hydrological Programme, Working Group 8.4, United Nations Educational, Scientific and Cultural Organization, Paris, France, pp. 133-142. 

Allen, D.R., and Mayuga, M.N. 1969. The mechanics of compaction and rebound, Wilmington Oil Field, Long Beach, California, USA. In International Symposium on Land Subsidence, Tison, L.J., ed.. International Association of Hydrological Sciences, Tokyo, Japan, pp. 410 22. 

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