Fresh Water Provision Techniques in Arid Regions - Term Paper Example

A Feasibility Report on Fresh Water Provision Techniques in Arid Regions Presented Table of Contents Table of Contents 2 0 Introduction 3 2.0 Fresh water provision techniques 3 2.1 Ground Water Drilling Technique 4 2.2 Desalination 6 3.0 Conclusion 7 4.0 List of references 9 Fresh Water Provision Techniques in Arid Regions 1.0 Introduction Though an estimated 70% of the world comprises of water mass, most regions continue to experience water scarcity most of the times. As a result, policy makers are faced with a challenging task of ensuring adequate supply of quality drinking water in water scarce areas (Ahmad Abstract, 1986). The water scarce regions are often referred to as arid and semi arid lands (ASALs). Generally defined, arid regions have limited natural water resources, precipitation and high variability of runoff over time and space (Wheater, Mathias and Li 2010, 1).Water situation is becoming more severe in these water scarce regions as global warming continues to affect the frequency and quantity of precipitation received. To make matters worse, the little water received in these areas is usually not safe for domestic, agriculture and commercial use and there an urgent need to provide fresh water. To do so, policy makers explore various fresh water provision techniques as discussed in subsequent sections of this report. 2.0 Fresh water provision techniques In endeavors to provide fresh water to the arid regions of the world, different techniques are employed that include ground water drilling, desalinization and piping techniques. These techniques often vary from those employed in areas where precipitation is high. Therefore, climatic conditions in arid regions dictate to a large extent what technique(s) is most appropriate. Key issues in water provision and water resource management which dictate appropriate techniques will include availability of adequate supply, conservation measures, cost effectiveness, pricing and sustainability. 2.1 Ground Water Drilling Technique Ground water is normally obtained from aquifers through drilling and piping the water to the surface for various uses. This technique involves identification of areas in arid regions that have sufficient and quality underground water for agriculture, domestic and commercial use. The technique is more preferred to its low cost of establishment compared to other techniques like desalination. To ensure sustainable use of underground water, policy makers and regulatory authorities establishes water databases through registration of wells and their yields, documenting water composition, control of drilling in all phases and regular monitoring of water table and changes in salinity. However, the challenge with this technique is that over time demand for fresh water has increased both socially and economically requiring more wells to be dug. For example, over the last 3 decades, demand for water within the United Arab Emirates and other Gulf states which are often classified as arid regions, was estimated to increase from 4,250Mm3/ year in 1980 to 35,395Mm3/ year by 2010 (Alsharhan et al 2001, 277). Therefore, this means that governments in arid regions have to drill more wells or explore alternative fresh water supply techniques. This water supply technique faces various challenges relating to quality and sustainability. One, underground water may contain dissolved solid substances whose value is above the established norm. Establishing these levels require sophisticated technology which is costly and often not at the disposal of most governments in arid regions. Where levels are higher than the benchmark standard, such wells have to be closed or alternative technologies to reduce the hazardous effects of these particles employed (California Environmental Protection Agency 1995, 5). For example, high fluoride levels are common in arid regions where fluoride levels have to be reduced to the World Health Organization (WHO) to reduce effects of tooth decay and bone weakening. In addition, underground water also faces contamination from various pollutions sources. Effluents from industries and raw sewerage get to the porous rocks and contaminate underground water. The hazardous chemicals make such water unsuitable for drinking. For example, over 70% of New Delhi population is dependent on underground water where a third of it is contaminated with nitrates and fluorides originating from fertilizers, industrial wastes and domestic sewerages (Chaudhary, Jacks and Gustafsson 2002, 180). Three, underground water potential and its recharge is influenced by rainfall patterns, geological formations, nature of aquifer bodies, hydrological properties and ground water flow characteristics. As a result, some areas will have higher recharge capacity and storage than others and therefore more underground water potential. In most cases, arid regions where the aquifer is shallow may have limited water supply especially if rainfall is erratic and insufficient. This causes problems on the sustainable use of such water sources. The above underground water crisis has increased over time for a number of reasons including; uncontrolled use of borehole technology resulting into over exploitation at higher rates than rate of water recharge; pollution of water resources; lack efficient water usage; in adequate legal framework on water conservation, underground water recharge and ecosystem sustainability. Alsharhan et al (2001, 278) noted that within the Gulf states over pumping has led to notable decline in water quality, rise in total dissolved solids and increasing salinity. Addressing these issues will ensure enhanced availability and sustainable given that underground water is an important part of the hydrological cycle and is valuable source of water supply. 2.2 Desalination Given that ground water is finite, governments are nowadays dedicating more effort to increased production of desalinated water. Various studies indicate that desalinating water is economically viable for certain localities. Desalination involves construction of a desalination plant where sea water is treated lowering the salinity levels making it safe for domestic, commercial and agricultural use. Two main processes are often used in water desalination, that is, the multi-stage flash process and the reverse osmosis process (Alsharhan et al 2001, 278). The reverse-osmosis desalination process involves passing sea water through a desalination plant. Seawater is fed into the plant through a low water pump into a pre-treatment chamber for removal of suspended material, bacterial and organics carried out by sand filtration followed by media filtration. Present residual chlorine is removed with active carbon filters or by injection of sodium bisulfate solution. Energy recovery unit is then used to concentrate disposal before water is pumped through high pressure pump into membranes where conversion takes place. Water conversion could be anywhere between 70-95% recovery for brackish water and 35-50% for sea water. Recovered water is cooled and stored in a tank ready for use. Quality of water under this process is influenced by water temperature, membrane rejection properties together with degree of water recovery and system design. Low rejections of boric acid through the membranes, small organic compounds dissolved in the feed water are some of the challenges of using these techniques (Drioli and Giorno 2009, 227). Though the reverse-osmosis membrane process is regarded as the most promising technology for brackish and seawater desalination, there are drawbacks. For example, installation/ investment and energy costs are high, both accounting for 60-80% of the total project costs. In addition, water from such plants is also expensive and best suited for urban population, industries and large irrigation farms. Exploring alternative low energy sources and good practice in pre-treatment helps to reduce energy and membrane replacement costs. On the other hand, multi stage flash (MSF) distillation is also a proven method of desalting since 1950s. In fact, 60% of desalting capacity comes from MSF plants due to its operational simplicity, proven performance and availability of standard designs (International Atomic Energy Agency, 2011). Desalination plants can be operated independently (single purpose) or linked to power stations (dual purpose). MSF distillation is a method whereby seawater is spontaneously boiled through a series of chambers at progressively low pressures allowing water to boil at low temperatures. This hastens the process of obtaining pure water. Water vapor from the boiling water is condensed into pure water at a series of chambers. Seawater moves from one chamber to another at a lower pressure, process that is repeated until the seawater leaves all the chambers. Condensed pure water is stored in tanks ready for use (Chen et al, 2011, 534). The MSF distillation process has a better water recovery ratio as design studies have shown that about one-tenth of a square foot of condensing surface is required to produce one gallon of fresh water per day (Ahmad Abstract, 1986). However, the cost of establishing a MSF distillation plant runs into millions where out of the total project cost, 33% of the money is spent on capital goods for the plant, 21% on operating costs and the remaining 26% on power. Although the cost has relatively decreased due to competition and improved technological efficiency, costs of new plant and upgrading costs still remains high. 3.0 Conclusion People need to understand that water is a finite economic resource and demand for fresh water will continue to outstrip supply and should therefore be used efficiently and sustainably. Proper legal framework and clear monitoring and evaluation of water utilization in arid regions should be put in place to ensure proper ecosystem management and recharge of underground water. Key stakeholders should be involved in solution search and recommendations on ways of overcoming challenges in water provision incorporated in governments’ strategic planning process (Shakweer 2007, Abstract) 4.0 List of references Ahmad, A. 1986, development of new materials for desalination. Anti-corrosion Methods and Materials, 33 (1), 4-13. Alsharhan, A.S., Rizk, Z.A., Nairn, A.E.M, Bakhit, D.W. and Alhajari, S.A. 2001, Hydrology of arid region: The Arabian Gulf and adjourning areas. Amsterdam: Elsevier science B.V. California Environmental Protection Agency, 1995.Drilling, coring, sampling and logging at hazardous substance release sites: Guidance manual for ground water investigations. CEPA. http://www.dtsc.ca.gov/SiteCleanup/upload/SMP_Drilling_Coring_Sampling_Logging.pdf. [Accessed 28th Nov. 2011]. Chaudhary, V., Jacks, G., and Gustafsson, J 2002, An analysis of groundwater vulnerability and water policy reform in India. Environmental Management and Health, 13 (2), 175-193. Chen, J.P., Wang, L.K., Hung, Y., and Shammas, N.K. 2011, Membrane and desalination technologies. New York: Humana Press. Drioli, E. and Giorno, L 2009, Membrane operations: Innovative separations and transformations. Rende: Wiley-VCH Shakweer, A. and Youssef, R. 2007, Futures studies in Egypt: Water foresight 2025, Foresight, 9 (4), 22-32. Wheater, H. S., Mathias, S. A., and Li, X 2010, Ground water modeling in arid and semi arid areas. New York: Cambridge University Press. Read More