Desalination of Seawater using Geothermal Energy to Meet Future Fresh Water Demand of Saudi Arabia

The future economy of the Middle East countries (GDP growth) depends on the availability of fresh water for domestic and agricultural sectors. Saudi Arabia, for example, consumes 275 L/day per capita of water that is generated from desalination process using 134 x 10⁶ kWh of electricity. With 6 % population growth rate, demand for fresh water from fossil fuel based desalination plants will grow at an alarming rate. It has been reported that Saudi Arabia’s reliance on fossil fuels to generate electricity and generate fresh water through desalination using the same energy source is economically and politically unsustainable. This may lead to destabilisation of the global economy. However, Saudi Arabia has large geothermal resources along the Red Sea coast that can be developed to generate power and support the generation of fresh water through desalination. The cost of fresh water can be further lowered from the current US$ 0.03/m³. Among the gulf countries, Saudi Arabia can become the leader in controlling CO₂ emissions and mitigating the impact on climate change and agricultural production. This will enable the country to meet the growing demand of food and energy for the future population for several decades and to reduce food imports.     

Assessing the Potential for Rainwater Harvesting

Rainwater harvesting is one of the promising ways of supplementing the surface and underground scarce water resources in areas where existing water supply system is inadequate to meet demand. Rainwater harvesting is one of the measure for reducing impact of climate change on water supplies. Abeokuta has a mean annual rainfall of 1,156 mm which makes rainwater harvesting ideal. Intra annual variability lies betwen 0.7 and 1.0 while the inter annual variability was 0.2. Annually 74.0 m³ of rainwater can be harvested per household. Estimated annual water demand for flushing, laundry and flushing were 21.6 and 29.4 m³ respectively. Harvested rainwater in Abeokuta can satisfy household monthly water demand for WC flushing and laundry except for November, December, January and February. The excess rainwater stored in September and October is sufficient to supplement the short fall in the dry months provided there is adequate storage.Water savings potential is highest in June and September which is the two rainfall peak period in Southwest Nigeria.     

Assessment of Potable Water Savings in Office Buildings Considering Embodied Energy

The objective of this article is to assess the potential for potable water savings in office buildings located in Florianópolis, southern Brazil. The embodied energy of four alternatives to reduce potable water demand, i.e., rainwater harvesting, greywater reuse, dual-flush toilets and water-saving taps, was also assessed. The analyses took into account the potable water end-uses for ten buildings. The potential for potable water savings by using rainwater, as well as, the rainwater tank sizing were estimated using computer simulation. As for greywater reuse, it was considered that greywater from lavatory taps could be treated and reused to flush toilets. The potential for potable water savings by using water-saving plumbing fixtures was estimated by considering the replacement of toilets and taps. In order to estimate the embodied energy in the main components, each system was dimensioned and embodied energy indices were applied. The main result is that the potential for potable water savings by using dual-flush toilets ranges from 21.6 % to 57.4 %; by reusing greywater, it ranges from 6.8 % to 38.4 %; by using rainwater, it ranges from 6.1 % to 21.2 %; by using water-saving taps it ranges from 2.7 % to 15.4 %. However, by considering the embodied energy, the average for the ten buildings indicates that dual-flush toilets are the best choice as it is possible to obtain water savings of 5.50 m³/month per GJ of embodied energy, followed, respectively, by water-saving taps, greywater reuse and rainwater usage. The main conclusion is that the assessment of embodied energy should be considered when evaluating potable water savings in buildings as it helps to identify the best alternatives to save more water while causing less environmental impact.     

Analysis and Modelling of Stormwater Volume Control Performance of Rainwater Harvesting Systems in Four Climatic Zones of China

Rainwater harvesting has been widely used to alleviate urban water scarcity and waterlogging problems. In this study, a water balance model is developed to continuously simulate the long-term (57 to 65 years) stormwater capture efficiency of rainwater harvesting systems for three water demand scenarios at four cities across four climatic zones of China. The impacts of the “yield after spillage” (YAS) and “yield before spillage” (YBS) operating algorithms, climatic conditions, and storage and demand fractions on stormwater capture efficiency of rainwater harvesting systems are analyzed. The YAS algorithm, compared with the YBS, results in more conservative estimations of stormwater capture efficiency of rainwater harvesting systems with relatively small storage tanks (e.g., ≤50 m³). The difference between stormwater capture efficiency calculated using the YBS and YAS algorithms can be remedied by increasing storage capacity and reduced by decreasing water demand rates. Higher stormwater capture efficiency can be achieved for rainwater harvesting systems with higher storage and demand fractions and located in regions with less rainfall. However, the lager variations in annual rainfall in arid zones may lead to unstable stormwater management performance of rainwater harvesting systems. The impacts of storage and demand fractions on stormwater capture efficiency of rainwater harvesting systems are interactive and dependent on climatic conditions. Based on the relationships among storage capacity, contributing area, water demand, and stormwater capture efficiency of rainwater harvesting systems, easy-to-use equations are proposed for the hydrologic design of rainwater harvesting systems to meet specific stormwater control requirements at the four cities.     

Effectiveness of Rainwater Harvesting in Runoff Volume Reduction in a Planned Industrial Park,China

It is urgent to effectively mitigate flood disasters in humid mountainous areas in southeastern China for the increasing flood risk under urbanization and industrialization. In this study, a rural district with an area of 13.39 km² that planning to build an industrial park covering an area of 7.98 km² in Changting was selected to estimate the potential of collectable rainwater and the extent to which runoff volume can potentially be mitigated by rainwater harvesting. In addition, the optimum cistern capacity of a rainwater harvesting system in the planned industrial park was evaluated using daily water balance simulation and cost-efficiency analysis. The results showed that rainwater harvesting in the planned industrial park has great potential. The annually collectable rainwater is approximately 9.8?×?10⁶ m³ and the optimum cistern capacity is determined to be 0.9?×?10⁶ m³. With the optimum cistern capacity, the annual rainwater usage rate is 0.99, showing neither financial savings nor deficits. Rainwater harvesting can reduce 100 % of runoff volume in the cases of critical rainfall storm (50 mm) and annual average maximum daily rainfall (111.2 mm), and 58 % of runoff volume in the case of maximum daily rainfall (233.6 mm), respectively. All surface runoff can be collected and stored in the cisterns when rainfall amount is less than 135.5 mm in a rainstorm event.     

Parameters Influencing the Sizing of Rainwater Tanks for Use in Houses

Rainwater harvesting has been studied in different countries as a way of easing water availability problems and reducing potable water demand in buildings. The most important factor relating to the efficiency of a rainwater system is the correct sizing of the rainwater tank. Therefore, the objective of this article is to assess the influence of rainfall, roof area, number of residents, potable water demand and rainwater demand on rainwater tank sizing. The analysis was performed by using computer simulation and by considering daily rainfall data for three cities located in the state of São Paulo, Brazil. The roof areas considered were 50, 100, 200 and 400 m²; the potable water demands were 50, 100, 150, 200, 250 and 300 l per capita per day; the rainwater demands were taken as a percentage of the potable water demand, i.e., 10% to 100% at increments of 10%; and the number of residents was two and four. Results indicated a wide variation of rainwater tank sizes for each city and also for each parameter. The main conclusion that can be made from the study is that rainwater tank sizing for houses must be performed for each specific situation, i.e., considering local rainfall, roof area, potable water demand, rainwater demand and number of residents. Therefore, sizing rainwater tanks according to local tradition is not recommended as it may incur low efficiency.     

Stochastic Goal Programming Model for Optimal Blending of Desalinated Water with Groundwater

A stochastic goal programming (GP) model is developed in orderto determine the daily production of desalination plants to meet the requirements of water blending stations (WBS) for major cities in the Eastern Province of the Kingdom of SaudiArabia. The WBS is assumed to be a control point in the systemwhere water is blended to satisfy the desired water quality, downstream of the control point. The desalinated water is blended with brackish groundwater extracted from several groundwater wells. The objective of the model is to minimize the goal deviations from the following priority levels: demand for blended water, control of salinity levels, depletion of groundwater and maximize the use of brackish water, demand forbrackish water at WBS, and production of desalinated water. Anessential element of the model is the input data; unfortunately,available data are not accurate due to the inherent uncertaintyassociated with it. This uncertainty will generate uncertainty in the model output, which affects reliability and confidence associated with the decisions. Thus, reliable planning should consider uncertainties associated with model input parameters.The developed stochastic model shows how Goal Programming (GP)modeling can be used to plan the water resources in the EasternProvince of Saudi Arabia, assuming that both supply and demandare uncertain.     

Fog Water Collection Evaluation in Asir Region–Saudi Arabia

Based on the fact that water can be collected from fog under favorable topographical and atmospheric conditions. The small water droplets present in the fog precipitate when they come in contact with solid objects. The frequent fogs that occur in the southwestern region of Kingdom of Saudi Arabia have the potential to provide an alternative source of freshwater in this otherwise dry region if harvested through the use of simple and low-cost collection systems known as fog collectors. A fog collection project has been carried out in Asir region of Saudi Arabia. Three Standard Fog Collectors (SFC) were designed and manufactured with locally available materials and imported mesh. These SFCs were installed in April 2006. Three different sites were chosen based on topography and altitude and data from April 2006 to April 2007 were obtained. Measurements with the SFCs were made for regions with 2,260 to 3,200 m elevation. The results indicate that at highest altitudes (at Alsooda), it is feasible to obtain an average water production of 6.215 L/m² day over the studied period, and in the lower altitudes, which are in Abha city, it is possible to collect more than 3.3 L/m² day. The highest water collection was 24 L/m² day and recorded in Dec. 20, 2006 at Al-Sahab park station, and furthermore for the same site, the best average water production of 11.5 L/m² day was obtained in winter 3 months period namely (December, November and January). Data about the weather conditions has been collected for the studied region. An analysis of fog collection effectiveness was carried out and compared with international standards. The obtained results indicate that fog can be a useful source of water supply in the southwest region of Saudi Arabia.     

Comparative Evaluation Of Surface Water Availability,Wastewater Reuse And Desalination In Saudi Arabia

ABSRTACT

There is a growing concern in the Kingdom of Saudi Arabia to exploit water resources of acceptable quality to meet demands in domestic, industrial, and agricultural sectors. The agricultural water need, which constitutes approximately 84% of the total demand, was estimated to be 7430 million cubic meters in 1985. The annual domestic and other demands amounted to 1400 million cubic meters for 1985. Various alternative supplies to meet these demands are surface water, renewable groundwater resources, reclaimed wastewater, desalinated water, and non-renewable groundwater. Due to excessive withdrawal of water from deep aquifers, considerable drawdown has recently been noticed.

This paper reviews the existing and future trends in developing surface water resources, reclamation of waste-water from various towns and cities and its use, and the role of desalination plants in the coastal regions of the Arabian Gulf and Red Sea. These alternatives are evaluated and compared in economic terms. Cost-capacity relationships are developed for various alternatives which will be used in developing long-term plans for optimum allocation of available resources in different parts of the Kingdom.     

Rainwater Harvesting: An Alternative to Safe Water Supply in Nigerian Rural Communities

Rainwater harvesting (RWH) is an economical small-scale technology that has the potential to augment safe water supply with least disturbance to the environment, especially in the drier regions. In Nigeria, less than half of the population has reasonable access to reliable water supply. This study in northeastern Nigeria determined the rate of water consumption and current water sources before estimating the amount of rainwater that can potentially be harvested. A survey on 200 households in four villages namely, Gayama, Akate, Sidi and Sabongari established that more than half of them rely on sources that are susceptible to drought, i.e. shallow hand-dug wells and natural water bodies, while only 3% harvest rainwater. Taraba and Gombe states where the villages are located have a mean annual rainfall of 1,064 mm and 915 mm respectively. Annual RWH potential per household was estimated to be 63.35 m³ for Taraba state and 54.47 m³ for Gombe state. The amount could meet the water demand for the village of Gayama although the other three villages would have to supplement their rainwater with other sources. There is therefore sufficient rainwater to supplement the need of the rural communities if the existing mechanism and low involvement of the villagers in RWH activities could be improved.     

Water Quality Monitoring and Hydraulic Evaluation of a Household Roof Runoff Harvesting System in France

The quality of harvested rainwater used for toilet flushing in a private house in the south-west of France was assessed over a one-year period. Twenty-one physicochemical parameters were screened using standard analytical techniques. The microbiological quality of stored roof runoff was also investigated and total flora at 22°C and 36°C, total coliforms, Escherichia Coli, enteroccocci, Cryptospridium oocysts, Giardia cysts, Legionella species, Legionella pneumophila, Aeromonas, and Pseudomonas aeruginosa were analysed. Chemical and microbiological parameters fluctuated during the course of the study, with the highest levels of microbiological contamination observed in roof runoffs collected during the summer. Overall, the collected rainwater had a relatively good physicochemical quality but variable, and, did not meet the requirements for drinking water and a microbiological contamination of the water was observed. The water balance of a 4-people standard family rainwater harvesting system was also calculated in this case study. The following parameters were calculated: rainfall, toilets flushing demand, mains water, rainwater used and water saving efficiency. The experimental water saving efficiency was calculated as 87%. The collection of rainwater from roofs, its storage and subsequent use for toilet flushing can save 42 m³ of potable water per year for the studied system.     

Impact of El Niño and Climate Change on Rainwater Harvesting in a Caribbean State

The water situation of the Pusey district in St Catherine parish of Jamaica is acute because of the district’s hilly terrains which made connections to centralised public water supply difficult. Residents depend on rainwater harvesting (RWH) systems to meet potable needs, like many other catchments across Jamaica. Rainwater collecting practices and water use habits of the residents were surveyed and the present and future RWH capacity was evaluated using the available 18 years (1996 to 2013) rainfall data and downscaled PRECIS model A2 and B2 climate change scenarios. In addition, the effect of El Niño episodes on rainfall patterns was evaluated. The coefficients of variations for annual rainfall were found to be higher for the El Niño years than in normal years. In two of the El Niño years (1997 and 2009), rainwater harvesting capacity is negatively impacted as rainfall annual total is (42 % and 34 %) lesser than the average annual rainfall. The ability of RWH to meet potable needs in 2030s and 2050s will be reduced based on predicted shorter intense showers and frequent dry spells. A storage tank of 2.5 to 4.0 m³ per household (4 persons) is proposed to meet water demand during the maximum consecutive dry days, and January and February water shortage periods. Design of efficient RWH systems and provision of government subsidy on storage tanks will enable the residents to capture more rainwater to meet their daily domestic needs.     

Investment Needs and Privatization of Water Services in Saudi Arabia

The article outlines the dynamics of the privatization of water supply and sanitation services in Saudi Arabia. It also gives a summary of the projected requirements of desalination plants' capacity and the estimated capital investment needed for water supply and sanitation services. It gives a summary of public and private initiatives to privatize water services in Saudi Arabia.     

Preliminary Assessment of Rainwater Harvesting Potential in Nigeria: Focus on Flood Mitigation and Domestic Water Supply

This study was accomplished using 26 locations in the major ecological zones of Nigeria as well as different classes of residential buildings and different levels of water consumption. For each location, house dwelling class and level of water consumption, a water balance approach was used to assess the proportion of water demand that can be met by rainwater. Results obtained indicate that for all the locations in the rainforest zone and some parts in the guinea savanna zone, over eighty percent (80 %) of water demand of those living in bungalows can be met by rainwater. Rainwater harvesting potential was found to be a power function of rainfall coefficient of variation, with coefficient α and exponent β. High correlation coefficients (0.881?≤?R ² ?≤?1) were obtained between coefficient α and roof area per capita. Also, high correlation coefficients (0.847?≤?R ² ?≤?0.992) were obtained between exponent β and roof area per capita.     

Alternative Water Resources for Rural Residential Development in Western Australia

Rainwater collected from residential roofs and greywater generated from domestic uses except toilets are viewed as possible substitutes for high grade water sources which supply nonpotable indoor uses and irrigation in Australia. This paper searches for alternatives by adopting roofwater and greywater in residential envelope as per Australian water standards. A water balance model Aquacycle was applied to determine storage capacities and to evaluate the percentage reduction in water supplying, stormwater run-off and wastewater disposal, as well as volume of rainwater use and greywater reuse. This study provides the results of greywater recycling, which contributes to the greater saving of mains water supply than rainwater use, and which reduces more than half of the wastewater to receiving waters in the rural township of Cranbrook, Western Australia. The results of this study provide greywater usage (maximum reduction 32.5%) more significantly reduces scheme water supply than rainwater harvesting (maximum reduction 25.1%). Use of greywater on individual residential lots has the dramatic effect for drainage system by reduction approximately 54.1% or 88.1 m³/lot/year. The results of rainwater use analysis show explicitly that rainwater tanks are much more effective in intercepting roof runoff, with the maximum stormwater reduction 48.1% or 68.3 m³/lot/year. This research endeavours to offer a typical paradigm for an integrated water system in the rural residential sectors.     

The Role of Desalination in Meeting Water Supply Demands in Western Asia

Abstract

The increasing gap between the supply and demand for water in the Economic and Social Commission of Western Asia (ESCWA) member countries: Bahrain, Egypt, Iraq, Jordan, Kuwait, Lebanon, Oman, Palestine, Qatar, Saudi Arabia, United Arab Emirates, and Yemen) can be attributed to the limited availability of surface water, mining of fossil groundwater sources, and water pollution mainly of shallow aquifers, deficient institutional structure, poor management processes, and inapt allocation of financial resources. The non-sustainable use of natural water resources to meet the escalating water demand has also contributed to the depletion and deterioration of water quality and quantity. To meet water supply shortages in the domestic sector, water desalination has been entrenched as a viable option for the Gulf Cooperation Council (GCC), which includes the following countries: Bahrain, Kuwait, Oman, Qatar, Saudi Arabia, and United Arab Emirates. The objective of the paper is to investigate the role of water desalination in meeting the water demands in the ESCWA member countries. The significant role of desalination is highlighted with emphasis in evaluating not only its production trends, processes, and costs, but also its capacity in the provision of water demands. Water desalination has become a major and staunch water source for a number of large urban centers. For such countries such as Bahrain, Kuwait, and Qatar and the coastal zone areas of Oman, United Arab Emirates (UAE), and Saudi Arabia, desalination represents one of the most feasible and strategic alternative options for their current and future domestic water supply requirement. Given the high consumption rate from this source and its high production cost, fundamental efforts must be integrated and invested in both research and development programs to implement comprehensive conservation measures that would lead to a reduction in the consumption rates. Parallel to these achievements, efforts should be directed within the context of integrated management of water resources, to identify alternative potential water resources, to meet future water challenges.     

Urban Water Management in Developing Arid Countries

Urbanization, industrialization and rapid population growth in developing countries of the Arabian Peninsula are putting increasing pressure on local water authorities and water planners to satisfy the growing urban water and sanitation demands. In the Arabian Peninsula, water resources are limited, average rainfall is low and the seawater and brackish water desalination in addition to limited groundwater resources are the major water supply sources. The population increased from about 17.688 million in 1970 to 38.52 million in 1995 and is expected to reach 81.25 million in 2025. The urban population is expected to rise from 60% in 1995 to more than 80% in 2025. The domestic water demand is expected to rise from 2863 million cubic metres (MCM) in 1990 to about 4264 MCM in 2000 and 10580 MCM in 2025. In Saudi Arabia, the population increased by 143.6% between 1970 and 1995; and it is expected to reach about 40.426 million in 2025, with about 80% urban population. The domestic water demand in the Kingdom is expected to be about 2350 MCM in 2000 and 6450 MCM in 2025. Specialized agencies have been established for water production and distribution, and for wastewater collection, treatment and reuse. Special legislation has been introduced to manage water demands and to protect the interests of the community and its natural resources. Fifty-seven costly desalination plants have been constructed in the Peninsula on the Gulf and Red Sea coasts, as well as water transmission lines to transport the desalinated water to coastal and inland major cities. The seawater desalination unit cost is about US$0.70/m 3 for a large desalination plant with energy priced at world prices. More than $30 billion has been invested on water and sanitation projects. Present desalination production is about 46% of the total domestic demand, and the rest is pumped from deep and shallow aquifers. In general, fragmented legislation and institutional arrangements and low water charges have indirectly resulted in over-usage of domestic water, production of excessive quantities of wastewater, significant leakage, and enhancement of shallow water-table formation and rise in some cities. Facing the challenges of satisfying the growing urban water demands requires several essential measures such as: (a) introduction of new technologies to reduce water demands, and losses, and to enhance wastewater recycling and water conservation; (b) the updating of legislation to coordinate both responsibilities and actions among different water agencies; (c) the introduction of a strong and transparent regulatory framework to adopt different forms of water supply privatization, to reduce the costs of building, operation and maintenance of water and sanitation facilities, and to improve the level of services and billing, leakage and wastewater collection and treatment; (d) an increase in water tariffs to reflect the actual value of the water, and to enhance the awareness of public as to the value of water; and (e) development of short-term and long-term national water plans based on realistic water demand forecasting.     

Conjunctive use of Inter-Basin Transferred and Desalinated Water in a Multi-Source Water Supply System Based on Cost-Benefit Analysis

Water shortage has forced coastal cities to seek multi-source water supply with a focus on inter-basin water and desalinated seawater. The differences of water supply costs pose a challenge in the optimal use of multiple water resources. This paper aims to understand the impact of desalinated seawater’s variable costs on multi-source water supply through a cost-benefit analysis method based on a multi-objective optimization model, considering different combination scenarios of desalination yield, streamflow condition, seawater desalting plant (SDP) scheme, water shortage index and utilization ratio of the SDP. The application in the coastal city Tianjin, China shows that the desalination yield has an impact on the tradeoff between the water shortage index and the total water supply cost and an optimal desalination yield can be determined at a turning point. And where the turning point appears is influenced by the utilization ratio of the SDP and streamflow conditions of inter-basin water. Moreover, a single centralized SDP is found to have an overall lower water supply cost than several decentralized small-sized SDPs. Lower water shortage index leads to higher cost, and the unit decrease of shortage index will need more added cost when the shortage index is very low. This method is proven to be effective in identifying the best conjunctive use of inter-basin water and desalinated seawater, which can contribute to relieve urban water shortage.     

Water Resources Management in Saudi Arabia and Water Reuse

ABSRTACT

The potential for water reclamation and reuse in Saudi Arabia are assessed by considering relationships among the technical, social, economic, and environmental parameters. Generally, the planning process for water reuse has focused on specific technological processes, however water reuse should be analyzed as part of a total hydrologic system to ensure the efficient transfer of wastewater reuse technology

To bring relationships into better focus, the application is developed with reference to Saudi Arabia, which provides an excellent opportunity for practicing water reuse. In this region, a limited water supply is used to satisfy municipal, industrial, agricultural, recreational and other beneficial uses. The economic and social trends are toward continued industrial development and urbanization. In this setting, water recycling through reuse is becoming a more and more important means of expanding water supplies to meet the growing demands for water for virtually all social, economic and environmental uses

Saudi Arabia is an arid country with very limited water resources and about 10 million people. The country covers some 2.2 million km², four-fifths of the Arabian Peninsula. It is the largest country in the world without a river or a lake, and thus it represents the ultimate in its need to use the limited water supplies wisely.     

Water-saving strategies for irrigation agriculture in Saudi Arabia

Agriculture policy changes in Saudi Arabia are investigated by water footprint (WF) assessment. WF is calculated with the model SPARE:WATER for 3758 irrigated sites. The WF of agriculture areas (WF_area, km³ yr^?1) has decreased (–17%) since the year 2000 to 13.84 km³ yr^?1 (2011), which is mainly caused by the reduction of cropland by –33%. Nevertheless, water consumption per field has increased about 16%, which can be attributed to the cultivation of fodder crops (+12%). A scenario analysis revealed that a shifting cropping pattern towards less fodder crops reduces WF_area by –15%, and implementing improved irrigation technology leads to a combined reduction of up to 32%