FIFTY YEARS OF WATER RESOURCES PLANNING: LESSONS LEARNED IN THE CANARY ISLANDS

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1 FIFTY YEARS OF WATER RESOURCES PLANNING: LESSONS LEARNED IN THE CANARY ISLANDS MANUEL HERNÁNDEZ-SUÁREZ, Ph.D., M.Sc. Dipl. Ing. Director of the Canary Islands Water Center C/ Castillo 4-1º, 383 Santa Cruz de Tenerife, Spain. Tel: Fax: Key words: water resources planning, desalination, water research ABSTRACT An historical review of water resources planning from 195 until today, is presented. Initially, a free water market policy with limited planning was allowed to facilitate resources development with minimum official cost. This became unsustainable in early 197 s when exhaustion of groundwater reserves imposed severe water restrictions on population and farmers. Loomed scenarios were envisioned on hand of growing population and decreasing water availability. However, technical developments on desalination and water reuse created gradual changes and imposing almost a year by year revision of the water resource plans. Latest figures show up to 5% the water available on the islands come from these non-conventional resources. Research and development is making progress in providing answers to these new scenarios and examples are given. Coping with global warming and energy dependence appears to be the next challenge for the islands, as given data indicate. INTRODUCTION Advanced desalination technology is bringing cheap and affordable water to dry coastal zones such as the Canary Islands. This is a new fact. But, before we got here we have had to go thru numerous setbacks and long periods of uncertainties, as to where would the desired water come from. This paper summarizes the different phases of water resources planning (WRP) and development on the Canary Islands during the past fifty years. It also reports on some existing areas of concern. Finally, it describes areas of water research were progress has been made. WATER RESOURCES PLANNING UNDER EVOLVING CONDITIONS Before 196, with good reserves of groundwater, and a small population, concern for future demand was almost non-existent. With government consent, private initiative was providing water to towns and farms. Under those conditions government intervention was of minor importance, and WRP was not a matter of big concern (1) (see Fig.1). In the seventies, as groundwater reserves became depleted, interest arouse for more information on water resources management, as well as on hydrological data and statistics of water consumption. Many studies were made on basic hydrogeology and groundwater exploitation (2, 3, 4). Para ver esta película, debe disponer de QuickTime y de un descompresor Photo - JPEG. Fig. 1: The stream of Aguamansa, Tenerife, aprox (Ref. 1) Regarding WRP, researchers of those days had problems in getting information, as this was mostly in hands of private water right owners. They opposed government control and considered planning as another form of intervention. With diminishing water resources and a sensitive social environment, planners tried to evaluate possible solutions for water allocation, using linear programming and theoretical assumptions such as extraordinary population mobility and drastic changes in farm water use (5). What actually happened was that scarcity produced a change of habits in urban population and a strong decrease in water consumption. It also resulted in a significant number of farm closures Figure 2 shows the loom future that was envisioned in 1981 (6).

2 Meanwhile, desalination was making progress on the eastern islands. All of a sudden, the possibility of having a new water source different from the traditional ones became apparent. Fig 2: Prediction of water resources availability for the island of Gran Canaria in 1981 hm3/year Total water use Agricultural water use Thus, discussions that had been going on for almost two decades, on where the water should come from, concluded with the general understanding that desalination plants should be constructed, as soon as possible, to guaranty urban water supply. Therefore, in the 8 and 9 s, government action concentrated on building desalination plants. Also, water distribution systems and sewers had to be built. As it happened, urban water shortage was effectively surmounted by the mid 9 s. Under those new conditions, WRP allocated desalination plants in the coastal zones, reserving ground and surface water for higher altitudes. One of the WRP even recommends that the demands located below 3 meters a.s.l. should be provisioned only with desalinated water (7). Figure 3 shows the amount of desalinated water compared to total water consumption at the different islands in 22. N Desalinated water Total water use Fig. 3: Desalinated vs. total water use in 22

3 In the mid 9 s, having water supply in major cities guarantied, attention was focused on agriculture, which was quickly disappearing. Water reuse was presented as an option for providing much needed irrigation water, and new plans were drawn for transporting treated wastewater to agricultural zones (8,9). However, wastewater quality turned out to be extremely salty and some programs became a failure. Figure 4 shows the percentage of wastewater presently treated with secondary treatment on the different islands. Initially, electrodyalisis was used for desalinating treated wastewater. Later, microfiltration followed by reverse osmosis (RO) has been used. However, clogging has been a constant problem in these later plants. As a consequence, analysis has shown operational costs of these tertiary treatments plants to be above those of seawater desalination (1). The reason for this excessive clogging, has been related to poor performance of the wastewater treatment plants (WWTP). These receive BOD loads almost Fig. 4: Percentage of wastewater treated with secondary treatment double the normal values in the Canaries in 2. 8% found on the continent (11). These high loads are thought 7% to be related to consumer 6% habits and uncontrolled discharge of light industries. 5% To save existing tertiaries, WWTP are being upgraded. 4% 3% 2% 1% % EL HIERRO LA PALMA LA GOMERA TENERIFE GRAN CANARIA FUERTEVENTURA LANZAROTE Most recently, newly awarded WWTP have been designed with Membrane Biological Reactors (MBR) and ultrafiltration membranes. Future investigations will assess if these new WWTP coupled with RO provide the solution for an economical reuse of wastewater on the islands. Figure 5: Evolution of energy consumption per m 3 desalinated seawater kwh/m MSF MED RO RO+isobaric chambers RO+turbines In the past years, RO has made tremendous progress in reducing energy requirement. As shown on Figure 5 the energy requirement for seawater desalination has been reduced from 22 to 2 kwh/m 3 (12). Latest developments have made desalination of seawater even affordable to farmers. With the low costs of desalination, and as the high zones continue to dry-out, new water projects are now considering elevating desalinated water up 8 meters a.s.l. 2 About 5% of the cost of desalination is energy. Therefore an increase dependence of fossil fuels is developing. Wind energy accounts for only 7% of the total energy produced on the islands and other sources such as hydropower have been found useful solely for local applications. Figure 6 shows the evolution of population (13) and energy (14) and water consumption (15 and authors estimates for small desalination plants.) on the island of Lanzarote from 1965 to 22. As can be seen a good correlation can be drawn between the three parameters.

4 Population and water (m3/day) Fig. 6: Evolution of population, water consumption and energy consumption in Lanzarote Population Energy Water energy (Gw/year) Figure 7 shows the impact of desalination and economic activity on the energy consumption per capita for three different islands (13,14). Lanzarote, which show the higher values, depends totally on desalination and its economy is based mostly on tourism with almost no agriculture. Gran Canaria is about 6% dependent on desalination and has a mixed economy of tourism, agriculture and industry. In La Palma there are no desalination plants and the economy is based on agriculture, with limited tourism and industrial activity. GW per capita (including tourists) 6, 5, 4, 3, 2, 1, Fig. 7: Energy consumption per capita for Lanzarote, Gran Canaria and La Palma from 199 until 21. Lanzarote Gran Canaria La Palma Global warming is now affecting temperature and rainfall on the islands (16). Therefore new planning will have to take into account the effects of this new situation. Figure 8 shows the increase in temperature at the airport of Los Rodeos in Tenerife in the past 25 years. As can be seen, the average of the maximum temperatures for the month June has increased 3.ºC and the average about 2.6ºC. Similar increase have been monitored for other months. It is concluded from this, quick review, that a powerful demand has driven a constant search for new sources of water on the islands, certainly at a high cost. This has allowed for a considerable development in civil works, mining, and desalination. Still, uncertainties remain ahead, as other factors such as energy supply and global warming come under play.

5 Fig. 8: Evol uti on of Jun e«s temp erature in Lo sro deo s (Te ne rife) fro m 197 2to 2 1 ¼ C M xima Average M nima Fig. 8: Evol uti on of Jun e«s temp erature in Lo sro deo s (Te ne rife) fro m HOW FAR CAN WE PLAN AHEAD? At the present time water resources planning is carried out separately for each island. Strategies vary from one island to the next, as water availability and socio-economy differ EL HIERRO Fig.9: Urban water consumption per capita (L/person per day) LA PALMA LA GOMERA TENERIFE GRAN CANARIA FUERTEVENTURA necessary as they help to organize the projects within the different administrations. LANZAROTE On eastern more humid islands, with multiple and disperse sources of water, no single action solves the problem everywhere, but small actions are needed at various levels. The advantage of having to make many small actions has been a quick adaptation to new technologies. Consequently, planning has also been more flexible. Notwithstanding, it is our experience, in particular because of the very different conditions existing on the islands, that good master plans are most Furthermore, a regional master plan that integrates the plan for each island has been found useful, as it allows for benchmarking, as well as putting into perspective different goals (17). Figure 9 shows the average water consumption of urban population on the different islands. As can be seen the dry eastern islands such as Lanzarote and Fuerteventura account for the lowest water consumption. Prior to desalination these differences were much larger. Finally, it is our experience that powerful demands take only a few years to develop. As a consequence real values can deviate quickly up to 1% from predicted values. To avoid these deviations, updating, at least every 5 years, has been considered necessary.

6 INTERCOMMUNICATION The desire to involve stakeholders in the planning and decision making process resulted in 199 in a regional water law (18). This law institutionalized a system of water councils for each island. They became responsible for elaborating and executing the islands water resources plans. This branching of the administration into small bodies has lead to an intercommunication problem. Good and bad experiences are seldom transmitted outside each island. Consequently full potential of existing information and know-how is not fully used. As a result, decision-making process is sometimes impoverished and project yields end-up below its possibilities. The need for easy ways of intercommunicating between private and public bodies has been recognized, and efforts have been made in that regard, such the founding of the Canary Islands Water Center in Standard procedures for data and project reporting have also been proposed to improve communication. TECHNICAL DEVELOPMENT AND RESEARCH The evolution of waterworks from wells, dams and pipes to desalination and advanced membrane filtration systems has been very rapid, particularly in the past 1 years. Furthermore, problems have become very peculiar on the islands and very few references are sometimes available to assist professionals in finding adequate solutions. Thus, research and development has become increasingly necessary. For many years, hydrological research has been focused on evaluating the different parameters of the water cycle: rainfall, infiltration, surface runoff, evapotranspiration and groundwater recharge. Today the big numbers are agreed upon and considered adequate for water resources planning. Now, as indicated before, global warming appears to be affecting evapotranspiration and rainfall. Thus, new research will be required to evaluate its effect on the islands hydrological cycles. Special techniques have been developed for constructing geomembrane water reservoirs on top of volcanoes or over permeable lava soils (19). This new capability has had considerable impact on WRP, particularly on western islands to catch winter runoffs. Research on radiation and mechanical resistant of the geomembrane sheets has helped to identify most appropriate material and soldering techniques. Improvements in the design and construction of these types of reservoirs are still made. Electronic water meters for domestic use are becoming increasingly attractive to local water companies, as they allow for very efficient flow monitoring. Following this interest, trial studies are being conducted using these types of water meters and existing fiber optic as a carrier of information to the mainframe of the water company. Efficient desalination is a major point of interest for the islands. Initially, research was around vapor systems. Today, most of the work is carried out on RO plants. Research on the reduction of energy requirements and pretreatment for reducing membrane fouling, have brought considerable success (2,21,22). Most recently improving desalinated water quality has been investigated and new affordable remineralization techniques have been developed (23) Most of the research is carried out on existing commercial plants. CONCLUDING REMARKS Many scientists and engineers have studied in the past century water resources developments in the Canary Islands. Ground and surface water resources have been evaluated in detail, and the water balance of each island has been well described by different authors. Each of the eight islands has its own water resource scenario, based on its climate, geology, topography and socioeconomic development. hm 3 Fig. 1: Evolution of the origin of water in the Canaries Figure 1). desalinated groundwater reused reservoirs Having enjoyed fair economic growth and a powerful demand for many years, a vast experience has accumulated on water resources development and management. From an overexploitation of groundwater resources, to a severe water crisis in the 9 s, to a renaissance in the year 2, thanks to desalination (see From seen a catastrophic scenario forthcoming, to having an optimistic horizon. This big change has transformed the way we look at water resources planning and analysis today, as new possibilities for further progress emerge. As can be expected, this new situation will also bring new problems, which will also have to be resolved.

7 REFERENCES (1) Tomás Méndez Pérez, La Orotava, Cien años de blanco y Negro (1858, 1958), Editora de Temas Canarios, 22. (2) Fernández Caldas, E. y Pérez García, V. Características Químicas de las aguas subterráneas de las islas Canarias Occidentales, Centro de Edafología y Biología Aplicada de Tenerife, CSIC, (3) Custodio, E. Geohidrología de terrenos e isles volcánicas. Instituto de Hidrología, Centro de Estudios Hidrográficos del Ministerio de Obras Públicas, Madrid, (4) SPA-15, Estudio científico de los recursos de agua en las Islas Canarias. MOPU, Dirección General de Obras Hidráulicas, Madrid, 1975 (5) MAC-21, Proyecto de planificación y explotación de los recursos de agua de las Islas Canarias. MOPU, Dirección General de Obras Hidráulicas, 198. (6) Hernández Suárez, M. Estudio científico sobre los requerimientos de agua de los cultivos en Gran Canaria y la viabilidad del proyecto de planificación hidráulica MAC-21, Comisión Regional del Plátano (CREP), (7) Las Aguas del 2. Plan Hidrológico de Gran Canaria. Consejo Insular de Aguas. Cabildo Insular de Gran Canaria (8) Hernández Suárez, M. Manual Para la reutilización de agua de Santa Cruz de Tenerife, Area de Planificación Hidraúlica, Cabildo de Tenerife, (9) Marrero Domínguez, A. y Palacio Díaz, P. Depuración y reutilización de aguas en Gran Canaria. Generalidades. Consorcio Insular de Aprovechamiento de Aguas Depuradas de Gran Canaria (1) Hernández Suárez, M. y Santana Marrero, F. Estudio del funcionamiento de las plantas de microfiltración y osmosis en Gran Canaria. Dirección General de Aguas, Gobierno de Canarias, 23 (in print). (11) Hernández Suárez, M. Estudio del funcionamiento de la depuradora de Santa Cruz de Tenerife. Dirección General de Aguas, Gobierno de Canarias, Enero 23. (12) Hernández Suárez, M. Advances in environmental aspects of desalination: the Canary Islands experience Nato Experts Meeting. Department of Chemical Engineering, University of Oviedo, Sep. 21. (13) ISTAC, Population development in the Canary Islands, Gobierno de Canarias. (14) Endesa-Unelco, Datos de producción de energía en Canarias (15) Insular de Aguas de Lanzarote (INALSA). Datos de producción de agua desde 1965 hasta (16) Hernández Suárez, M. Evolución de la temperatura de los Rodeos en los últimos 3 años. El Manantial. Centro Canario del Agua, Num.12, Enero 22. (17) Hernández Suárez, M. Documento de trabajo para la elaboración del plan hidrológico de Canarias. Dirección General de Aguas, Gobierno de Canarias, 21. (18) Ley 12/199, de 26 julio, de Aguas del Gobierno de Canarias.. (19) Amigó, E y Aguiar. E. Manual para el diseño, construcción y explotación de embalses impermeabilizados con geomembranas. Consejería de Agricultura y Alimentación. Gobierno de Canarias, (2) Medanich, J. Energy recovery system (ERI) for reverse osmosis plants. Jornadas Técnicas Canagua, Las Palmas, 21 (21) Barreto, M. Cámaras Isobáricas. Nuevos sistemas de recuperación de energía de las salmueras de osmosis inversa. Congreso de AEDyR. Murcia, 2. (22) Drablos, Leif. Aqualing energy recovery system for RO, Jornadas Técnicas de Canagua, Las Palmas, 21. (23) Hernández Suárez, M. et al. La remineralización de agua desalada con carbonato cálcico, Congreso de AEDyR, Málaga, 22.