WATER SUPPLY MANAGEMENT APPROACHES USING RES IN RHODES ISLAND, GREECE E. Manoli, D. Assimacopoulos1 and C. A. Karavitis2 National Technical University of Athens, Chemical Engineering Department, Process Analysis and Plant Design Section, 9 Heroon Polytechniou, Zografou Campus, GR-15780, Athens, Greece ABSTRACT: Desalination powered by Renewable Energy Sources (RES) is presented in order to augment the water supply in the semi-arid region of Rhodes island.. The island of Rhodes was chosen as a case study as it relies mostly on the exploitation of groundwater resources and faces serious water shortage problems due to the aquifers depletion. Alternatives are discussed and compared in contrast to the construction of storage dams so as to meet the urban demand up to the year 2040. Results may indicate that by using also financial incentives and management approaches, desalination powered by RES could be an attractive and environmentally friendly option in an effort to solve problems related to water quantity and quality in semi-arid regions with adequate Renewable Energy potential. 1. INTRODUCTION resources problems. The whole scheme should be incorporated in an overall management framework in an In the South Mediterranean region water is used in an effort to ensure the long term sustainability of the region. unsustainable manner. The South European Mediterranean landscape, as a whole, is ecologically fragile and seriously endangered by prevailing social and economic trends. In 2. THE ISLAND OF RHODES this regard, the future of the region may be threatened by increasing coastal area stress, by expanding differences 2.1 Physiography, Social and Economic Profile between tourist areas and the rural hinterlands, and by the sensitivity between the water and soil equilibrium. Most of The island of Rhodes is located in the SE corner of the the population is concentrated in the coastal zone, and Greece and is one of the largest and most populated of the increasing tourism causes a strong, seasonal water demand. Aegean Islands, with an area of 1400 km2. Thus uneven water demands in both space and time greatly The permanent population of the island was 98,181 increase the cost of making water accessible [1]. A most inhabitants (NSCG, 1991). The most densely populated illustrating example of the above is the island of Rhodes. and urbanized area is the north of the island around the Desalination, compared to more conventional water municipality of Rhodes per se and its coastal suburbs. The supply related interventions, can take an advantageous remaining of the island is mainly rural with decreasing position in terms of economic costs and environmental population density from the north to the south. impacts. Amongst the various desalination techniques, The predominant economic activity is tourism. Reverse Osmosis (RO) has been widely used during the Approximately half of the labour force is occupied with last years. The recent technology advances in the field of tourism related activities, thus strongly contributing to the energy recovery have managed to reduce the specific coastal development schemes and the accompanying energy consumption at 2.0 kWh/m3 for seawater intensive use of water resources. The rural hinterland, desalination [2]. The low energy requirements are expected which has been affected by tourism development to a far to render the particular desalination technology more lesser degree relies still on agriculture and confronts competitive compared to other desalination techniques and serious depopulation problems [3]. conventional interventions. Under these conditions, wind- Despite the fact that agriculture is the second most powered RO desalination units could offer an effective, important economic activity, the local market demand is economic and environmentally friendly solution in water not satisfied, and agricultural products have to be imported stressed areas where adequate wind potential exists. from the mainland. The reasons for such a case as well as The island of Rhodes, presents a unique challenge of a the corresponding declining future trend may be attributed semi-arid region, where shoddy water resources to the lack of capital investments, to the ageing of the rural management and uncontrolled development have led to population and to the shift towards the service sector. severe water shortages and environmental stresses. The island with an excellent wind potential seems ideal for the 2.2 Water Resources Issues implementation of Desalination powered by Renewable Energy Sources in order to confront proliferating water 1 Corresponding author, email: [email protected], Fax: +301-7723155 2 Faculty affiliate, Water Resources Planning of Management. Dep. of Civil Engineering, Colorado State University, Fort Collins, Co.; U.S.A. The average annual precipitation for the whole island is 586 mm resulting in 753 x 106 m3 of potential water volume from which about 70% is lost to evapotranspiration. From the remaining volume, 108 x 106 m3 (14.4%) and 120 x 106 m3 (15.9%) constitute the infiltration and the surface runoff respectively [5]. Other estimates produce an overall annual average rainfall of 712 mm and a surface runoff coefficient of 0.20 [3]. Urban water supplies in Rhodes are still, solely, obtained from groundwater resources and in most cases do not require treatment other than chlorination to meet the urban water supply sanitation requirements. Water Demand (2000) (MCM) 5.84 to 5.85 2.79 to 5.84 1.46 to 2.79 0.7 to 1.46 , RODOS 0.03 to 0.7 TRIANTA PARADEISION, , Water Demand Distribution , 7.1 , DAMATRIA, , KOSKINOU , THEOLOGOS, MARITSA , Χ Χ Χ , FANAI , KALYTHIAI , KALAVARDA Χ , PSINTHOS Irr igation Salakos Springs , Domes tic needs , AFANTOU SALAKOS , DIMYLIA Χ , ARCHIPOLIS , APOLONAΧ , PLATANIA , KRITINIA Χ Figure 2. Water Demand Distribution (2000) , EMPONAS , ARCHANGELOS Χ , MALON Χ Following a moderate scenario for the permanent and AGIOSΧ ISIDOROS, LAERMA , , MASARI , SIANA seasonal population increase, which assumes small and Χ , KALATHOS Χ Χ , MONOLITHOS Χ decreasing growth rates for the highly developed areas, , ISTRIOS , PYLON Apolakia Dam , PROFILIA Χ , , LINDOS ! LARDOS urban water demand is expected to reach 25.15 MCM. by Χ , ASKLIPIEION , APOLAKKIA , ARNITHA , VATION the year 2020 and 32.45 MCM by the year 2040, which , GENNADION accounts for almost 70% of the total water demand (46.23 Settlements/Towns , MESANAGROS , Boreholes MCM). Water demand growth and the need for , Χ Springs LACHANIA sustainability of the water resources point towards the , KATTAVIA ! Dams Water Network Main Water Transfer Pipe necessity for the application of water supply policy Sea Intrusion Front alternatives in an effort to ensure the island’s future economic and social growth. Figure 1. Water Supply Sources 2.3 Water resources management approaches Water supply for irrigation is similarly dependent on groundwater except for the case of the southwest part of In order to delineate alternatives confronting the severe the island where the possibility exists for the use of surface water supply problems in Rhodes island, it is important to water impounded from the Apolakkia storage dam and understand the broader context of Greek water resources reservoir (7.3 MCM/yr). management . The most pressing issue is the existence of The strong dependence on groundwater resources many government departments dealing with water along with the large urban population concentration and problems with compartmentalized and not well- tourist development in the northern part of the island has coordinated activities. Added to this is a water law system led to the depletion and overexploitation of the adjacent which is not responsive to modern issues of an urbanized mostly coastal aquifers. From Figure 1, it can be deduced society and widely scattered, thus permitting overlapping that safe yield has been exceeded in most aquifers in the functions, multiple advisory bodies and insufficiently northern part of the island and in the southern irrigated decentralized management responsibilities through areas. In addition, the sea intrusion front is advancing or regional organizations [4]. The most striking element so as seriously threatening the groundwater resources. A to describe the state of water resources management foreseeable increase in water demand and the further options in Rhodes, is that a crisis seems imminent development of the tourist sector are expected to aggravate regarding water supplies and their usage. Such a crisis, the situation and they are strongly eliciting the need for the present also in other similar parts of the world, may be implementation of integrated water resources management demarcated by the following: (a) the annual fluctuation of efforts. water supply exacerbated by periodic droughts or floods; The total water demand for the year 2000 has been (b) the rapid water consumption increase and highly estimated at 32.66 MCM of which 80% is attributed to the consumptive water demands, especially as a result of highly urbanized northern part and the tourist coastal zone dramatic shifts from the rural areas to urban developments; [3]. The remaining 20% refers to the irrigation demand, (c) the trend towards more intensive irrigation needs in the mainly concentrated in the rural southern and central parts remaining agricultural sector; (d) the deterioration of the of the island (Figure 2). water quality, as a result of both water intensive life styles and tourist uses; (e) the decreasing groundwater availability joint