Major Dam Types Used to Control Groundwater - Essay Example

Name: University: Course: Tutor: Date: Major Dam types used to control groundwater Introduction Underground water is being stored in aquifers which are pockets of water massed beneath the ground in the earth crust. Due to climatic changes which have caused depletion of forest cover in water catchment areas and high temperatures that are causing high rate of evaporation the ground water masses are under threat which is not exceptional to underground water. Most municipalities in the world are harvesting underground water to meet the supply demand of its customers (Diaba, Et al. 2004). Therefore, underground water is being depleted at a higher rate and there is need to control it by use of dams. The dams will used to hold water stationary at the same place hence being able to percolate to the underground aquifers which would be drained from there. According to Donald Routledge Hill, (2001) the dams would also be handy during dry spells as its water would also be drained for use. Dam Categories The dams are meant to replenish underground water aquifers and increase their storage therefore they are used as means on controlling the ground water (Fearnside, 2006). There are two major categories of dams which are used to replenish underground water; underground ground dams and subsurface dams. The surface water resources are becoming scarce especially in Arid and Semi Arid areas and the only option is groundwater as it’s the only resource which is not fully exploited. But expatriates are giving warning on over harvesting of the underground water without replenishing it as the resources would also be depleted (Hut Et al. 2008). Over with draw of water from the earth crust lives empty spaces init which makes the earth crust unstable hence increases chances of earth movement as it tries to fill in the void spaces. According to Hilborn & Ludwig, 2003 there is great concern on the management of ground water for it to be sustainable and be able to serve the increasing needs of water. Therefore use of underground water should be done in a sustainable manner to be used in an indefinite time without causing unacceptable economic, environmental and social consequences (Horwitz, 2002). These should be enhanced because in the coming decades rapid shift on independence of underground water will be inevitable. To be able to able to generate additional water resources underground there is need to enhance creation of both underground dams and surface dams which will be used to harvest water to raise the groundwater levels and ensure loss of water due to evaporation (Yilmaz, & Onder, 2005). The level of underground water has been deepening over the years hence there is need to raise it to make the water easily accessible to those who will drill wells. Ground water Dams Ground water dams are structures which are built to obstruct natural flow of the water underground to ensure that it is stored beneath the ground surface. According to Megphed, (2008) the ground water dams are of two types; sand storage dams and subsurface dams. Subsurface dams Subsurface dams are mainly constructed below ground levels to be able to arrest flow of water in the natural aquifer. The dam is built in a very simple manner, by digging a trench a cross a valley. A wall which is impermeable is then the trench is filled with the materials which were excavated initially. These reservoir dams are meant to hold water during rainy seasons by withholding the water which would be flowing down the valley. This type of reservoir will hold water which would be used during the wet season or even the dry season. Much of the water will also be able to percolate in to the earth crust hence replenishing the underground water therefore raising the water table. The percolation is made much easy as the water is held still for long therefore the ground is able to sip through easily unlike if it would be allowed to flow down stream to the rivers, lakes or even ocean (Ren21, 2004). The appropriate materials to construct such dams will mainly depend on the locally available materials. The dams would either be built using reinforced concrete, plastics, steel sheets, reinforced concrete, clay or even masonry stones. Injection screen would be used to make the wall impermeable (Nilsson, 2006). Availability of such materials will also be determined by the cost of materials, skilled labor available and ease of construction. Heights of the dam differ but the preferred range should be 2-6 Meters. Source: http://www.ewra.net/ew/pdf/EW_2005_11-12_05.pdf Sand storage dams Sand storage dams are constructed across stream bed, a wall is built at the stream bad and it is filled with sand while some sand deposits are also swept down the stream and it is trapped by the wall built (Svec, & Halek, 2002). When rains water is held by the wall and accurate up stream and its being held in the sand which has been put in the dam. These types of dam are built in arid and semiarid areas where temperatures are high and evaporation rate is very high. By use of sand it prevents the water to evaporate as it would have evaporated if the dam water is open (Singh & Prinz 2007). Such type of dam is able to hold water for long which makes them much more effective in replenishing underground water as the water is held stationary for long hence being able to percolate with ease in the earth crust where they find their way to the aquifers deposits underground. The water held underground is used mainly during dry spells when there is no rain and the streams have dried up (Yilmaz, 2006). Once the stream dries up water deposits are held in the sand, people who need to fetch the water held in the dam needs to dig in the sand to get access to the water deposits. If the hole which is dug is deep they would use a pump to bring the water on the earth surface (Sommer, 2005). The water would also be drawn from the dam by use of a drain at the bottom of the reservoir at the upstream side of the dam. It is advisable to protect sand dams against erosion along its banks which would carry the sand down stream. Source: http://www.ewra.net/ew/pdf/EW_2005_11-12_05.pdf Diaphragm Earth Dams Diaphragm Earth Dams are made up of semipervious and pervious embankment which is reinforced with an impermeable barrier mainly made up of a thin wall or membrane. The diaphragm is placed at the upstream face of the embankment, the embankment is the one which determines the quality of the dam and would be made up of a steel plate, asphaltic concrete or cement concrete. Stonewall Earth Wall The dams are constructed using rubble masonry with earth filling walls. Most of them a wall is built down stream which retains water when it rains and in some cases a wall is also built up stream to be able to hold water at one place (Commission on Engineering and Technical Systems, 2006). This method of building dams is quite old it is more than 100 years old and has proved to work on well but its main disadvantage compared with sand dam is the increased rate of evaporation which makes it loss a lot of water. According to Benetin, Et al. 2003 the main aim of building a dam is to hold water at a place for use during the dry season and some to percolate in the earth crust to replenish underground water. Therefore, although the dam is able to hold for water a lot of it wasted to evaporation and hence it is not preferable to use such dams in regions whose temperatures are very high. Conclusions Ease accessibility of water was the main contributor of development and settlement during early civilizations. People used to settle along river banks and large water masses such as lakes where cities were developed (Bazza, 2001). But with the increased population and settlement in other areas which do done have ease access to water has resulted to dependence on underground water. Therefore, it is essential to ensure underground water is maintained and controlled to be sustainable by building dams which will replenish water underground. According to Upmanu, (2009) if the water will not be replenished there are possibilities of running into water crisis which has already begun in most part of the world which are arid and semi arid areas. References Bazza, M, 2001. Water Resources & Irrigation Management, Available from: http://www.fao.org/world/Regional/RNE/morelinks/Publications/English/HYSTORY-OF-WATER-RESOURCES.pdf Benetin, J., Radcenko, I & Halek, V, 2003, Methods Used In the Prediction And Control Of The Groundwater Regime In Basins Adjacent To Large Rivers. Available from: http://iahs.info/redbooks/a136/iahs_136_0009.pdf Commission on Engineering and Technical Systems, 2006, Safety of Existing Dams: Evaluation and Improvement. New York, McGraw-Hill Diaba, M., Himidaa, H & Saleha, M, 2004, The Impact of the High Dam on the Quality of Groundwater. Studies in Environmental Science. Vol. 17, No. 7, pp. 95-99 Donald Routledge Hill, 2001, Engineering in Medieval & Classical Times, New York, Routledge Fearnside, M, 2006, Hydroelectric Dams in Brazilian Amazon, Environmental Conservation Journal, Vol. 22, No. 1 pp. 17-29 Hut, R., Ertsen, M & Joeman, N & Vergeer, N, 2008, Effects of sand storage dams on groundwater levels. Physics and Chemistry of the Earth, Vol. 33, No. 45, pp. 56-66 Hilborn, D & Ludwig, D, 2003, Resource Exploitation, Uncertainty and Conservation, Science Journal, Vol. 91, No. 12, pp. 27-41 Horwitz, M, 2002, Interactions between surface water & groundwater, Hydrogeology Journal, Vol. 13, No. 6, pp. 21-37 Megphed, 2008, Ground Water Recharge Of Coastal Areas. Available from: http://megphed.gov.in/knowledge/RainwaterHarvest/Chap11.pdf Nilsson, H, 2006, Small Scale water supply groundwater, London, IT Publications Ren21, 2004, Renewable Global Status Report 2006 Update, Available From: http://www.ren21.net/globalstatusreport/download/RE_GSR_2006_Update.pdf Sommer, H, 2005, Macro Invertebrate response and Water Quality, Marine & Freshwater Research, Vol. 71, No. 15, pp. 930-62. Singh, A & Prinz, D, 2007, Improvement of Water Harvesting, cape town, World commission on Dams. Svec, J & Halek, V, 2002, Groundwater Hydraulics, Praha, Academia, Upmanu, L, 2009, Water Matters: A Tale of Prosperity and Decline. Available from: http://blogs.ei.columbia.edu/water/2009/07/28/punjab-a-tale-of-prosperity-and-decline/ Yilmaz, M, 2006, Control of Groundwater by Underground Dams, Ankara, Metu Yilmaz, M & Onder, H, 2005, Underground Dams: A tool of sustainability Management & Development of Groundwater Resources. Available from: http://www.ewra.net/ew/pdf/EW_2005_11-12_05.pdf Read More