Assessment of the potential contribution of alternative water supply systems to urban water security [Case study : Sharm El-Sheikh, Egypt]

Sharm El-Sheikh (Sharm) is located in the southern rim of Sinai Peninsula where water scarcity is the severest in the world, precipitation ranges from 20 to 50 mm/year (A. Lamei et al., 2009). Tourism which requires significant amounts of water, is the main economic activity in the city. It attracted about 1.5 million tourists in 2016 (ETA, 2016). Sharm is the least populous city in Egypt. It has a population of about 85000 inhabitants (UNISDR, 2011). However, the population is growing rapidly as a result of the tourism industry. Together, the population and tourism sector are putting pressure on the existing water sources. Therefore, this research assessed the potential contribution of currently unexploited alternative water sources to urban water security in Sharm as well as, those in existence; and additionally, tested different levels of water demand based on varying trajectories of tourism and population growth by 2020. The coastal arid city basically relies on alternative water sources foremost, desalination of seawater and wastewater treatment; in addition, a slight contribution of rainwater harvested traditionally by local Nomads, as well as traditional water sources imported from groundwater in Al-Tor catchment (100 km far from Sharm). Each source contributes by 29.38, 18.98, 0.00073 and 0.36 Mm3/year to the existing water supply system respectively. On the other hand, water demand is confined on tourism activities, local residents, and green areas irrigation; each user requires around 7.75, 34.17 and 4.41 Mm3/year of water respectively. Tourism activities have achieved a water surplus of 8.11 Mm3/year due to tourism stagnation in 2016. However, water supply does not meet water demand of local population and green areas irrigation, which are experiencing water shortages of 4.65 and 1.67 Mm3/year respectively. The trends of population and tourism growth indicate an increasing water demand by 2020. Similarly, water supply is anticipated to increase around 14% of the existing volume as a consequence of increasing the current operating capacity of desalination plants and 20% of losses reduction from the public water network as well as, wastewater treatment. Consequently, the potential contribution of the existing water supply system is estimated to 55.66 Mm3/year by 2020. Likewise, water demand is expected to increase nearly 3.5% of the current volume by 2020, resulted from 14% increment in the number of tourists and 3.8% in the population. Thereby, existing gaps of water supply-demand regarding local people and irrigation will decrease to 3.88 and 0.69 Mm3/year respectively by 2020. Diversification of water supply systems by developing currently unexploited alternative water sources was seen an immediate solution that could tackle the problems of water shortage in the city of Sharm El-Sheikh. Rainwater harvesting and collection of flash floods were assessed using the spatial analysis tool ArcGIS, OpenStreetMap, and Curve Number method. The potential contribution of rainwater harvesting from rooftops of buildings in Sharm and collection of flash floods from the catchments of Wadi Kid, Al-Aat and, Um Adawi is estimated to 0.0072 and 5.86 Mm3/year respectively. Together, they could fill the existing gap of local inhabitants and decrease the gap of green areas irrigation from 1.67 to 0.46 Mm3/year. Although, Nomads in Sharm do not use desalinated seawater for drinking purpose, all the segments of society in Sharm confirmed the importance of rainwater for water supply augmentation. They see these two options can be used for several purposes including potable use after a proper treatment, thus; decreasing water demand on the existing water sources. ii Finally, different levels of water demand were tested based on different trajectories of population and tourism growth by 2020. The total anticipated water demand in the city of Sharm El-Sheikh is estimated to 52.31, 56.60 and 61.36 Mm3/year under low, medium and high growth scenarios respectively. Additionally, the two currently unexploited options could potentially add about 0.018 and 5.67 Mm3/year to the existing water supply system respectively by 2020. Together, the potential contribution of rainwater harvesting and collection of flash floods in conjunction with the potential contribution of the existing water supply system including improvements of the system efficiency by 2020 could fulfill the water demand under of all scenarios except high growth scenario, it will be facing a water deficit of 0.01 Mm3/year. In contrast, the low and medium growth scenarios will be achieving a water surplus of 9.04 and 5.29 Mm3/year respectively. Eventually, rainwater harvesting from rooftops of buildings in Sharm does not seem a feasible option in terms of quantity, the potential supply of this options seems relatively small compared to current water shortage of local people and green areas irrigation. Conversely, the contribution of flash floods could compensate the deficit and fulfill the water shortage of domestic population and more than 50% of irrigation