Water Provision Techniques in Semi-Arid Regions, Desalination of Seawater - Case Study Example

A Report on Water Provision Techniques in Semi-arid Regions 1.0 Introduction Semi-arid regions lack enough water, and there is a need for policymakers to come up with the best techniques that can be used to help solve the problem. There are various semi-arid regions in the world; for example, Israel, Northern parts of Nigeria and others. These areas are characterised by high population growth rate and low amounts of rainfall annually (Bermingham, 2000). This report gives a critical analysis of two water provision techniques that can be used to help curb water shortage problems in developing countries which have semi-arid regions. Rainwater harvesting and seawater desalination were compared according to cost, output, social, and environmental impacts. 2. Comparison of Seawater Desalination and Rainwater harvesting Techniques 2.1 Desalination of seawater Desalination refers to the process of removing salts and minerals from seawater so that the water can be fit for domestic and industrial uses (Campling, et al. 2010). Desalination of sea water has helped to solve water shortage problem in Israel since the inception of the first desalination plant in 2005 (Zaide, 2009). 2.1.1 Cost Although this method was not used in the past because it was viewed as a high-cost project, recent improvements in technologies have made it possible to use cheaper methods in the desalination process (Zaide, 2009). The use of new membrane technology reduces energy use by 25-40%, and economies of scale associated with large-scale production enable the production of quality drinking water at $0.52/m3 (Zaide, 2009). This low cost makes it viable to desalinate the water for both domestic as well as commercial use. The level of energy used mainly depends on the level of water salinity. This, therefore, means that the lower the level of salinity the lower the cost of energy used. Energy requirement level also depends on the efficiency of the pump used as well as the process design (Zaide, 2009). This is method is more expensive than rainwater harvesting. 2.1.2 Output Desalination of sea water helps to increase water supply in semi-arid regions, in Israel, for example, it accounts for about 5% of total water supply (Zaide, 2009). Some semi-arid regions such as Israel, which has low rainfall benefit from seawater desalination because rainwater cannot sustain water needs in the country. Research has it that a single-stage plant, which is highly efficient, requires about 4kWh/m3 and around 0.5-2.5 kWh/m3 to produce 1m3 of quality water from the sea or salty groundwater (Elimelech and Philip, 2011). In Israel, for example, Build-Operate-Transfer (BOT), which uses Sea Water Reverse Osmosis (SWRO) technology, guarantees the production of about 100 MCM/year, which is about 5% of Israel’s total water supply. BOT, which is the largest and most advanced SWRO plant in the world, continues to offer technological and economically feasible water treatment (Zaide, 2009). Projections made by researchers show that by 2025, desalinated water will compose about 54% of both domestic and industrial water use in Israel (Zaide, 2009). Policy makers should ensure that they desalinated seawater that has a low saline level, as this will ensure low cost. 2.1.3 Social and Environmental Impacts Desalination of seawater has predominantly positive social and environmental effects. High-quality water that is produced offers the people in semi-arid regions a chance to carry out agriculture. It improves their standards of living because they earn income from the agricultural produce (Campling, et al. 2010). Desalination is also beneficial to the environment because some harmful concentrates are removed from seawater (ibid.). For instance, in Israel, the desalination plants incorporate boron treatment. The process is 92% efficient because it reduces the level of boron to 0.4 mg/l thus, solving the problem that farmers face in the use of treated wastewater which has high boron levels (Zaide, 2009). However, it needs to be pointed out that some negative environmental issues arise from desalination process as well. For example, harmful concentrated brine is discharged into the seawater (Tal, 2006), and apart from that, high energy levels are also used thus affecting the environment. Policymakers should promote the use of natural gases because they are more energy efficient. 2.2 Rainwater harvesting This refers to collection of rainwater from the surfaces that rain falls on, it is then filtered and stored for later use (Campling, et al. 2010). This technique has been used to collect water for domestic and industrial uses in Mexico and in other parts of the world (Jennings). 2.2.1 Cost Rainwater harvesting is one of the most effective tools for water provision in the semi-arid regions. This method is highly preferred around the world because it is cheaper compared to seawater desalination, which requires capital resources that might not be available in some semi-arid areas (Campling, et al. 2010). This is because a domestic user just needs to connect the tank with well-fitted water collection system such as gutters. Rainwater harvesting projects vary from building a tank for one home to large-scale projects that aim at providing water for the whole community. Rainwater should be treated to remove impurities and pathogens. Water used for agriculture can be filtered by use of a cartridge filter whereas water meant for drinking uses sand filters, which can be made from cheap locally available materials (Jennings). This method is cheaper because storage facilities depend on the use and the location of the catchment area. Large storage facilities are required if the water harvested will be used by many people. 2.2.2 Output Rainwater harvesting is an effective method because it is possible to determine the amount of rainfall that will be experienced. Proper harvesting requires prior analysis of the topography, prevailing winds, legal restrictions, the microclimates and weather among others. For instance, studying the weather will show the mega and seasonal patterns that will help in determining how much water can be harvested and when it can be harvested (Cheng, Hu, and Zhao, 2009). It is an effective method because people can collect water from their house’s roofs. It can be carried by people and governments in all countries unlike seawater desalination, which can only be done in countries with large water bodies. It is also beneficial to communities living in semi-arid regions because water can be collected from other regions that have high amounts of rainfall and then supplying it to the semi-arid regions (Jennings, n.d.). 2.2.3 Social and Environmental impacts Rainwater harvesting is important to the environment because it helps in the reduction of damages that would have been caused by floods during heavy rains (Mathew, 2002). After harvested water is used, the grey water from washing and other household uses should be reused in farms and in other uses. Grey water is beneficial to the environment because it has organic compounds from hair and skin, which are foods to organisms that live in the soil (Jennings). Also, NPK an important component in fertilizers is also found in varying degrees in the grey water. Rainwater harvesting also enables the locals to carry out irrigation in the semi-arid areas, which enables them to earn income thus, improving their standards of living (Mathew, 2002). There are some substances found in grey water that are harmful to the environment for example sodium and chlorine. Grey water users should be careful when using it so that they can ensure that they use it at the right time and in the right amount (Jennings). Most homes in Mexico and China use roofs made of tar and gravel roof because they are cheaper than other roofs (Deng, Shan, Zhang and Turner, 2006). These roofs have chemical leachates that make the harvested water unfit for human consumption, and if a person uses it, he might have health complications. People should ensure that they use roofs that do not contaminate rainwater. 3.0 Recommendations Rainwater harvesting is the best water provision technique in semi-arid areas because it is cheaper than seawater desalination. It is possible for a person to harvest water and store it in large scale during the rainy season for use in the dry season but it is not feasible for an individual to desalinate seawater alone because it is expensive. Although desalination of seawater has benefited countries such as Israel, the technologies required are very costly and most developing countries, which have semi-arid regions, cannot afford these technologies. Therefore, people and governments should invest in water storage facilities so that they can collect enough water during the rainy season (Thomas and Ford, 2005). The only way that people can benefit from rainwater harvesting is by ensuring that they maximise water use through recycling. Policymakers should encourage farmers to switch to recycled water so that they can maximise its use (Li, Gong and Wei, 2000). Urban developments, development of heavy industries and the use of fertilisers and pesticides contribute to water shortage through degradation of the little available water in these regions (Gratzfeld, 2000). Policymakers should ensure that they put in measures that prevent contamination of natural water sources as well as ensuring that all polluted sources are treated. Rainwater harvesting should be adopted because it helps in the reduction of environmental hazards, such as flooding which leads to loss of life and destruction of properties. Dams should be built in areas that receive high levels of rainfall so that the water can be piped to the semi-arid regions. Policy makers should also advise the people on the best roofs that they should use so that they can collect rainwater that is free of harmful chemicals. 4.0 Conclusion Policymakers in semi-arid regions need to adopt a water provision technique that will be beneficial to the people living in these areas. Rainwater harvesting should be adopted because it is cheaper compared to desalination of seawater. It helps in the reduction of environmental hazards such as flooding which leads to massive destruction of properties and in extreme cases, it leads to loss of life. Seawater desalination requires a lot of energy, which leads to depletion of energy resources in these areas, and therefore, it is not feasible for most developing countries, which have low energy resources. Desalination of seawater is not possible in countries that do not have seas or other large water bodies. People should also be encouraged to fully utilise the water they have through recycling. 5.0 References Bermingham, S., 2000. Changing Environments. Oxford: Heinemann Campling, P., Nocker, L.D., Schiettecatte, W., Iacovides, A.I., Dworak, T. and Arenas, M.Á., 2008. Assessment of the risks and impacts of four alternative water supply options. European commission–DG environment Cheng, H., Hu, Y. and Zhao, J., 2009. Meeting China’s water shortage crisis: current practices and challenges. Environmental science & technology. Elimelech, M. and Phillip, W.A., 2011. The future of seawater desalination: energy, technology, and the environment. Science. Deng, X.P., Shan, L., Zhang, H. and Turner, N.C., 2006. Improving agricultural water use efficiency in arid and semiarid areas of China. Agricultural water management. Gratzfeld, J., 2003. Extractive industries in arid and semi-arid zones: environmental planning and management. IUCN. Jennings. R., Water Harvesting and Management In Semi-Arid Regions. http://www.eng.warwick.ac.uk/ircsa/pdf/11th/Jennings.pdf Li, X.Y., Gong, J.D. and Wei, X.H., 2000. In-situ rainwater harvesting and gravel mulch combination for corn production in the dry semi-arid region of China. Journal of Arid Environments. Mathew, M., (2002) Nigeria: Current Issues and Historical Background. New York: Nova Publishers. Tal, A., 2006. Seeking sustainability: Israel's evolving water management strategy. Science. Thomas, D., and Ford, R. (2005) The Crisis of Innovation in Water and Waste Water. Cheltenham: Edward Elgar Publishing. Zaide, M., 2009. Drought and arid land water management. United Nations Commission on Sustainable Development (CSD)-16/17 National Report Israel. Read More