ROLE OF WATER REUSE IN THE INTEGRATED MANAGEMENT OF INSULAR WATER RESOURCES: THE CASE OF THE AUTONOMOUS REGION OF MADEIRA AND THE CANARY ISLANDS

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1 ROLE OF WATER REUSE IN THE INTEGRATED MANAGEMENT OF INSULAR WATER RESOURCES: THE CASE OF THE AUTONOMOUS REGION OF MADEIRA AND THE CANARY ISLANDS S. DELGADO*,1 ; F. DÍAZ*; M. ÁLVAREZ*; J. RODRÍGUEZ*; A. YANES**; B. PEÑATE**; L. RODRÍGUEZ**; F. OLIVEIRA*** * Dpt. Chemical Engineering. University of La Laguna. Av. Astrof. Fco. Sánchez S/N. 382 La Laguna, Spain. Tel: Fax: ** Technological Institute of the Canary Islands (ITC). Playa de Pozo Izquierdo S/N Santa Lucía,. Plaza Sixto Machado, S/C, Spain. *** Agência Regional da Energia e Ambiente da Região Autónoma da Madeira (AREAM). Edifício Madeira Tecnopolo Funchal. Madeira. Portugal. 1 Contact person: S. Delgado. sdelgado@ull.es KEYWORDS integrated water management; islands; water reuse ABSTRACT The integrated management of water resources has taken a great importance in recent years, since all parts of the water cycle has been found to be closely linked to each other: water supply, wastewater collection, treatment and reuse. This aspect reveals a great importance in insular environments as the Canary Islands and the Autonomous Region of Madeira, which share geological, environmental and economic characteristics. The traditional water supply of these archipelagos has been groundwater. Nowadays, due to over-exploitation of aquifers, most islands cannot meet their water demand with the traditional water resources. Under circumstances of water scarcity the obligation for communities is the establishment of conservation measures, being water reuse one of them. Nowadays there are water reuse schemes operating in, and (Canary Islands) and in Porto Santo (Region of Madeira). The main reuse applications are landscape and crop irrigation. In this paper the role of water reuse in the management of water resources in insular environments as the Canary Islands and the Region of Madeirais is analyzed. The present situation of water resources and consumption is discussed, as well as the status and perspective of water reuse as a part of the integrated water management. INTRODUCTION The integrated management of water resources is taking a major relevance in recent years, since every part of the water cycle has been found to be closely linked to the other ones: water supply, wastewater collection, treatment and reuse (Bahri, 1999; Lazarova et al., 2; Okun, 22). This aspect reveals a great importance in insular environments as the Canary Islands and the Autonomous Region of Madeira. These regions present some specific problems concerning water supply, and as a consequence of the isolation and distance, the integrated water resources management results more necessary than in any other case. The Canary Islands and Madeira are two archipelagos situated in the Atlantic Ocean, off the north-west coast of Africa, sharing geological, environmental and economic characteristics (Figure 1). The Canary Islands comprises seven major inhabited islands, with a surface of 7,447 km 2, and an estimated population of 1,7, inhabitants in 2. The 85% of the Canarian population settles in only two islands: and, each one with more than 7, inhabitants. The Region of Madeira is composed by two inhabited islands, Madeira and, and the Desertas and Selvagens islets, with a surface of 796 km 2, and an estimated population of 242, inhabitants in 2. Madeira is the main island, with 238, inhabitants, which is the 98% of the region population. The main economic activity of both archipelagos is the tertiary sector, which represents more than 7% of the regional income of both archipelagos. However, agriculture is a still quite relevant sector when it comes to water consumption, being more than 5% of water consumption in both regions, as well.

2 Figure 1. Location of the Autonomous Region of Madeira and the Canary Islands on the Atlantic Ocean. The objective of this communication is to analyze the role of water reuse in the management of water resources in insular environments as the Canary Islands and the Region of Madeira. The present situation of water resources and consumption will be discussed, as well as the status and perspective of water reuse as a part of the integrated water management. DISCUSSION Water supply The traditional water supply of the Canary Islands and the Autonomous Region of Madeira has been groundwater, constituted mainly by galerias (horizontal water tunnels) and vertical wells. Surface water has been very limited in the Canary Islands, where no rivers exist. In the island of Madeira surface water resources are quite significant, but have been very little utilized. The development of irrigation in agriculture and the accelerated population growth during the last century, together with the consolidation of the tourist trade in the last decades has led to the over-exploitation of aquifers in some islands, such as and Gran Canaria, the most populated and economically active of the Canaries. Other islands have been chronically suffering from water scarcity, as and, in the Canary Islands, and in the Region of Madeira, and seawater desalination has been used for years. Due to less availability of groundwater and over-exploitation of aquifers, the amount of water from the catchments has decreased and water quality has become in some cases unsuitable for human consumption and some crops. In Figure 2 water consumption and traditional water resources in the Autonomous Region of Madeira and the Canary Islands are presented. It is remarkable the situation of islands as and, where conventional water resources are almost negligible nowadays. In Figure 3 water consumption for the different uses (agriculture, industry, domestic and tourist trade) in each island of both archipelagos is presented. The considerable amount corresponding to agriculture must be remarked, exceeding the domestic and touristic demand in most islands, although agriculture represents less than 5% of regional income in both regions. Traditionally, groundwater has supplied the totality of water for agriculture.

3 Conventional resources Total consumption Madeira* Figure 2. Conventional resources and total water consumption in the Autonomous Region of Madeira and the Canary Islands in 2 (in Madeira Island only the groundwater resources have been considered) (Source: Water Plan of the Canary Islands, 21; AREAM, 21). Agricultural Domestic and touristic Industrial Madeira Figure 3. Water consumption by sectors in the Autonomous Region of Madeira and the Canary Islands in 2 (Source: Water Plan of the Canary Islands, 21; AREAM, 21). Under these circumstances of water scarcity, it results compulsory to take conservation measures in order to preserve the available groundwater (water of high quality) for the human supply. Most of the water used in urban areas and for irrigation does not require water of potable quality. Wastewater reuse appears as a key factor in the sustainable management of water resources (Shelef and Azov, 1996; Lazarova et al., 2, 21), especially in insular environments. Water reuse Present situation A preliminary comparison between agricultural water demand and reclaimed water availability could be useful in order to make an initial approach to the possibilities of water reuse in the different islands under study. Hence, in Figure 4 the production of raw wastewater, reclaimed wastewater, and reused water in every

4 island are presented. The agricultural water demand is presented, as well, since crop and landscape irrigation is the most feasible application of water reuse in the Canaries and the Region of Madeira, and recent researches have revealed that in other insular environments, wastewater reclamation and reuse for crop irrigation has been found as the most cost-effective solution to water shortages and the protection of the environment (Xu et al., 21). Agricultural demand Raw wastewater Reclaimed wastewater Reused water Madeira Figure 4. Agricultural water demand, production of raw wastewater, reclaimed water and reused water in the Autonomous Region of Madeira and the Canary Islands in 2 (Source: Water Plan of the Canary Islands, 21; AREAM, 21). Nowadays there are water reuse schemes operating in, and (Canary Islands) and in (Region of Madeira). In all cases reuse applications are crop and landscape (parks & gardens and golf courses) irrigation. Water quality must be suitable for the appropiate purpose and, for which a tertiary treatment is often required, after which a disinfection is applied (usually chlorination). and have centralized water reuse schemes, in which several treatment plants (2 in, and 3 in ) supply reclaimed water to a unique reuse scheme. Both schemes include separate water transportation systems, storage reservoirs, advanced treatment facilities (disinfection), and water distribution networks for the reuse of water. The scheme was put into operation in 1993, in which water from the metropolitan area (Santa Cruz-La Laguna) and the main touristic area (Adeje-Arona) treatment facilities is reused in the South of the island, in crop (banana plantations) and golf courses irrigation. Water reuse in started more recently, and applications are crop and lanscape irrigation (parks and gardens, and golf courses). In there are 19 treatment plants whose water is reused, mainly in the surrounding areas, in crop and lanscape irrigation. Nevertheless, it must be noted that the 83% of the water reused corresponds only to 4 treatment plants located along the East and South side of the island, where main cities and touristic resorts are. In, reclaimed water destined to be reused undergoes an advanced treatment, such as microfiltration or reverse osmosis, and disinfection. There are two main reclaimed water transportation networks (on the North side, and on the East-South side of the island). In, in the Autonomous Region of Madeira, an infrastructure for reclaimed water reuse exists (including advanced treatment, disinfection, storage, and distribution network). However, due to the low agricultural activity in the island, just a few farmers are nowadays using the reclaimed water from the reuse system. Actually, the most appropriate application of water reuse in would be parks and gardens irrigation and a projected golf course. Nowadays, a part of the reclaimed water is already reused in parks and gardens irrigation.

5 Although water reuse has been considered in the water plans of all the islands, in the island of Madeira,, and the reuse of water has not been implemented yet, for two reasons. Firstly, these islands, especially Madeira Island, and, have abundance of water resources. Water consumption is far below the conventional water resources. Even, Madeira Island has plenty of surface resources which are not utilized. Secondly, these islands have very low developed systems of wastewater collection and treatment, with very small amounts of water to be reused available. This is the case of, where, in inspite of lacking water resources for ages, water reuse is still in its first stages, due to the recent implementation of wastewater collection and treatment facilities in the island. Water management Water reuse has started to be considered a part of the water resources management recently, and the responsibility of it must lie on the corresponding insular water management authorities. Each Canary Island has its own Insular Water Councils in charge of the island s water management. This authority develops the island s water plan, which takes into account the specific hydrological characterisctics of each island. Hence, water reuse is considered differently depending on the island s water abundance. In the region of Madeira water resources are managed by similar organizations: in Madeira Island the water supply is managed by IGA (Investimentos e Gestão da Água, S.A.) and wastewater treatment and disposal by the Regional Authority of Sewerage (DRSB, Direcção Regional do Saneamento Básico); in, both water supply and wastewater treatment, disposal and reuse is managed by IGA. What is clear is that the islands are very limited territories where all elements of the water cycle must be taken into account in order to efficiently manage the water resources. Traditionally, water supply systems are separate from the sewerage systems, with separate management utilities. When water reuse turns up, a new link must be taken into account, since reclaimed wastewater which will be supplied for crop irrigation (water supply authority) will come from a wastewater treatment plant (sewerage authority). It sounds clear that both water and sewerage authorities need to plan together and define their respective role in the water reuse management in islands. In most of the Canary Islands the respective water management authorities (Insular Water Councils) are in charge of reclaimed water reuse management. In a third water-related utility was created (a reclaimed water service), which is in charge of the reclaimed wastewater transportation, storage and reuse. In the island of Madeira the Regional Authority of Sewerage (DRSB) is the authority in charge of wastewater management. In, as said before, it is IGA which manages both water supply and wastewater treatment, disposal and reuse. Future perspectives. Depending on the agricultural water demand and the wastewater production (Figure 5) 3 different cases can be found among the islands of the Madeira and Canarian Regions: 1) and, characterized by a high agricultural water demand and a significant and concentrated urban wastewater production; 2) Madeira Island, and, with a fairly low wastewater production, and both considerable high agricultural water demand and groundwater resources; and 3), and, with a wastewater production higher than the agricultural water demand. The island of El Hierro does not fit in any of these categories, since in spite of lacking water resources, it has a low wastewater production due to a small and disseminated population. 1) and. Considering the water demand from agriculture and the production of raw wastewater in the main urban areas of and, it can be inferred that a significant part of the groundwater destined to agriculture could be conserved in case of treating this wastewater until the suitable quality for agriculture and reusing it (Figure 4). In these two islands, if wastewater from urban and touristic areas were treated and reused a significant part of the traditional resources would then be conserved. Anyway, it is necessary to state the uneven distribution of wastewater production sites and agricultural areas where water would be reused. And, at the same time, it should be taken into account the quality of the reclaimed wastewater obtained, which could require additional advanced treatments. With all this, it results necessary to talk about reclaimed water that could be feasibly reused in crop and landscape irrigation; that is, which could be cost effectively reused. At this point it turns up evident the need to examine other non potable reuse applications. The concrete case of water from touristic areas brings on some inconveniences when its later reuse for crop and lanscape

6 irrigation is intended, due to the often unsuitable quality of these effluents, caused by the additives used by some touristic resorts activities (laundry, swimming pools water treatment, etc). Taking into account the difficulty of reusing touristic wastewaters, grey water reuse and the dual systems should be considered in the future, since the adaptation of resorts and settlements that have recently been developed to the dual systems is much easier than the old inhabited areas. In some islands the proportion of touristic wastewater is quite important, such as in,, and, as it can be seen in Figure 5. domestic and touristic domestic touristic Madeira Figure 5. Domestic and touristic raw wastewater production in the Autonomous Region of Madeira and the Canary Islands in 2 (Source: Water Plan of the Canary Islands, 21; AREAM, 21). In, there are 3 areas which produce the 75% of the whole raw wastewater of the island: Santa Cruz-La Laguna metropolitan area (36%), Adeje-Arona (25%) and the Orotava Valley (14%). Nowadays Santa Cruz-La Laguna metropolitan area and Adeje-Arona have both large treatment plants, taking part in the South Reuse Scheme. The treatment plant for the Orotava Valley will be in operation soon, and a project for the reuse of the reclaimed water from this plant on the North side of the island is planned. There are other two reuse schemes projected in other parts of the island for the future (Fernández and Aguiar, 21). In 4 municipalities produce the 61% of island s wastewater. The concentration of reclaimed water in few prodution sites makes easier its later reuse. As a consequence, the 4 treatment plants of these municipalities produce the 83% of reused water of. Trends in involve the implementation of a transportation and distribution network among the main treatment plants and final users, as crop fields, golf courses and municipal parks and gardens, as well as the upgrading of water to be reused by means of advanced treatments. 2) Madeira Island, and. In these islands, an increase in the amount of wastewater collected and treated is expected in the future, by the development of the sewerage and treatment infrastructure. In spite of this, in these islands water reuse should be considered more as an environment conservation measure than a water conservation measure, since the amount of groundwater saved by the application of reclaimed water in agriculture would be low (see Figure 4). In the Canary Islands and the Region of Madeira the coastal environment preservation is a very important issue to take into account, since the tourist trade is main economy sector, and the preservation of the environment is more than ever necessary. 3), and. As it can be seen in Figure 4, in these islands the production of wastewater is higher than the agricultural water demand. This is due to the small role of agriculture in these islands ecomomy, which have become almost completely tertiary in last decades. In case of having reclaimed water of suitable quality for crops, the agricultural water demand could be met with the island s reclaimed wastewater. Taking into account the role of tourist trade in these islands, as well as in touristic

7 areas of and, where more than a half of wastewater is produced in seaside resorts (Figure 5), other non potable uses, as grey water reuse, through the adoption of dual distribution systems, is an option that needs to be considered, where new settlements, as tourist resorts and residential areas, are developing. While dual distribution systems might seem at first glance to be costly, several factors common to many cities have made them economically attractive (Okun, 22). CONCLUSIONS The integrated management of water resources is of major relevance in insular environments, since every part of the water cycle has been found to be closely linked to the other ones: water supply, wastewater collection, treatment and reuse. In insular environments it results compulsory to reuse water in those applications where suitable, as a conservation measure in order to preserve the available groundwater (water of high quality) for the human supply. Even in environments with a surplus of water resources, water reuse should be considered as a conservation measure (coastal environment preservation). Although wastewater reuse for crop irrigation has been found as the most cost-effective solution to water shortages in insular environments, other non potable uses, as grey water reuse, by the adoption of dual distribution systems, is an option to be considered, in touristic areas where new settlements are developing. ACKNOWLEDGEMENTS This work was funded by the INTERREG IIC project AQUATLAN EA-D2E-nº4.7 from the EU, between the Technological Institute of the Canary Islands (I.T.C.), the Agência Regional da Energia e Ambiente da Região Autónoma da Madeira (AREAM), and the Dpt. of Chemical Engineering of the University of La Laguna. Financial support has also been provided by the Ministery of Economy of Spain and the Government of the Canary Islands, and by the Direcção-Geral do Desenvolvimento Regional of Portugal and Governo Regional da Madeira. As well, we express our gratitude to the the Canarian Water Councils, and all the public and private water organizations for their collaboration in the project. REFERENCES AREAM (21). Gestão de águas residuais na Região Autónoma da Madeira. Report for AQUATLAN Project. Bahri, A. (1999). Agricultural reuse of wastewater and global water management. Wat. Sci. Tech., 4(4-5), Fernández, J. and Aguiar, E. (21). Use of reclaimed wastewater for irrigation in (in Spanish). Seminar on water reuse in the Canary Islands and Madeira. Present situation and new trends. Pozo Izquierdo (), october 21. Lazarova, V.; Cirelli, G.; Jeffrey, P.; Salgot, M.; Icekson, N. and Brissaud, F. (2). Enhancement of integrated water management and water reuse in Europe and the Middle East. Wat. Sci. Tech., 42(1-2), Lazarova, V.; Levine, B.; Sack, J.; Cirelli, G.; Jeffrey, P.; Muntau, H.; Salgot, M. and Brissaud, F. (21). Role of water reuse for enhancing integrated water management in Europe and Mediterranean countries. Wat. Sci. Tech., 43(1), Okun, D.A. (22). Water reuse introduces the need to integrate both water supply and wastewater management at local and regulatory levels. Wat. Sci. Tech., 46(6-7), Shelef, G. And Azov, Y. (1996). The coming era of intensive wastewater reuse in the Mediterranean region. Wat. Sci. Tech., 33(1-11), Water Plan of the Canary Islands, Prov. Doc. (21). Water and Public Works Department. Autonomous Government of the Canary Islands. Xu, P.; Valette, F.; Brissaud, F.; Fazio, A. and Lazarova, V. (21). Technical-economic modelling of integrated water management: wastewater reuse in a French island. Wat. Sci. Tech., 43(1),