CLIMATE CHANGE AND ITS IMPACTS ON WATER RESOURCES IN THE MAGHREB REGION Abdelhamid Ben Abdelfadel1 and Fatima Driouech2 1 Secrétariat d’Etat chargé de l’Eau et de l’Environnement/ Direction de la Recherche et de la Planification de l’Eau, Morocco. 2 Secrétariat d’Etat chargé de l’Eau et de l’Environnement/ Direction de la Météorologie Nationale, Morocco. I - TENDANCE ET CHANGEMENT CLIMATIQUES DANS LES PAYS DU MAGHREB Climate change and its impacts represent a big challenge for the entire world. The Maghreb region, located in the extreme north of Africa, is one of the vulnerable regions to climate change impacts thought his low green house gases emissions. Climate change could have negative impacts on several socioeconomic sectors of the region like water resources. An important part of water resources in the Maghreb region has as origin the precipitation. Any changes in precipitation characteristics may affect water resources of this region already under water scarcity conditions. Precipitations in the Maghreb region are highly variable both in space and time. For example, in Morocco, where the most part of the country don’t receive more than 400 mm annually (the extreme north of the country and the high altitudes exceeds 800 mm per year), the coefficient of variability for extended-winter (October-March) totals ranges between 30% near the Atlantic coast to over 70% in the south (Ouarzazate). The Maghreb countries have experienced different drought episodes with variable impacts on economy and water resources. However Morocco has experienced the most serious ones (1980-1985, 1994-1995). Climate historical data of the region show that the drought seems to be increasing and the annual rainfall amounts to be decreasing over time. The first signs of changes already appear in this region through both the temperatures and the precipitation evolutions. Temperatures have increased by 1 to 2 °C during the twentieth century. Fig. 1 : Annual mean temperature in Oran ES-SENIA station (Algeria) for the period 1926- 2006. Source: Mahi Tabet-Aoul (les notes d’alerte du CIHEAM, N° 48 – 4 juin 2008). An increasing trend is apparent. Rainfall amounts registered, for example in Morocco, show a negative trend at national and regional scales. Nationally, spring rainfall has declined by over 40% since the 1960s. The drought seems to become more persistent over time. The maximum dry-spell length is found to be increasing during the rainy season, significantly so during the end of this season (February-April) where it has increased by 15 days since the 1960s. At the same time, the total number of wet days shows a negative trend revealing an increase in the annual dry day number. Many regions became more arid (According to the aridity index of De Martonne) between 1961-1985 and 1986-2005: namely Oujda, Taza, Kenitra, Rabat, Meknès. Annual total number of cold days (days with maximum temperature below 15 °C) shows a negative trend as well as cold wave durations. The observed changes in rainfall and temperature in the Maghreb have already negative impacts on water resources of the region which is projected to experience more impacts in the future. Tendance des indices annuels relatifs aux jours humides et à la sécheresse Période: 1960-2005 R1mm: Total de jours 0,8 humides cdd: Période maximale de sécheresse 0,6 0,4 0,2 Tendance 0 ir e tra fi t s ca h er s a ba an Fè nè d Sa ec ad ng an uj ni Ra Ifr k ék Ag O Ké Ta bl ra M sa ar M Ca -0,2 -0,4 -0,6 Fig. 2 : Trends of the total number of wet days (blue bares) and the maximum dry-spell length (yellow bares) in different Moroccan meteorological stations. The trends are calculated for the period 1960-2005. One can see the quasi-general trend toward less number of wet days and more persistent droughts. A wet day is a day with at least 1mm total amount of rainfall. In terms of future projections, mean temperatures are projected to increase by 0,5 to 1,5°C for the period 2020-2029 and by 2,5°C to 5,5°C for the end of the century (2090-2099), according to the scenarios and places and comparatively with the base period 1980-1999. The temperature increase is projected to be more important as far we go away from the coasts towards the internal lands. Annual rainfall is expected to decrease generally in the region with a large consensus of the models for Morocco where the decrease is projected to reach 20% by the end of the century. In addition, drought is expected to become more persistent. Projected changes in temperature and precipitation in the Maghreb are expected to have important impacts on water resources of the region. II - IMPACTS OF WATER SCARCITY AND THE CLIMATIC CHANGES ON WATER RESOURCES IN MAGHREB COUNTRIES In Maghreb countries, the water has a vital character, because the climatic and hydrological contexts are extremely fragile. The spatial and temporal irregularity of the water availability, the impact of the droughts and flooding and the pressure of the demand of water are in continual increasing facing limited resources. There are many factors that had direct impact on the abundance of water resources. OVERVIEW ON WATER RESOURCES IN MAGHREB COUNTRIES OVERVIEW ON WATER RESOURCES IN MAGHREB COUNTRIES Morocco The regime of rainfall is characterized by a strong irregularity. The mean of the high annual rainfall vary from more than 1000 mm per year in the mountains zones in the North to unless 300 mm in the East and the South basins of the country. This irregularity is marked again more to the level of the outflow of surface and underground water. Indeed, water resources vary per capita from a zone of the country to the other; of near 2 000 m3/hab/an to the level of rich water basins in the Northwest to close to 150 m3/hab/an on very poor water basins of the Southeast. The potential of renewable water resources is valued to 22 Billions m3 per year of which 18 Billions m3 come from the outflows of surface water. On this potential 77% are mobilizable in the present economic conditions. On this mobilizable potential the 2/3 are mobilized currently and are used to height of 88% in the irrigation and 12% in supplying drinking water. During the last three decades, an important effort has been agreed for the mobilization of water resources for the development of this sector and to succeed the following objectives: - The satisfaction of the needs in drinking water and industrial water supply; - The development of irrigated agriculture and the hydropower production; - The promotion of development of the poor regions and the interregional solidarity concerning access to water. Currently Morocco has a heritage of hydraulic infrastructures composed of 128 big dams, with a total capacity of approximately 17 Billions m3 and 13 infrastructure of transfer (1100km, and 210 m3/s) and an important network of boring . Mauritania The hydrological regime of Mauritania is characterised by the weakness of the outflows. The north is very dry and arid with middle contributions of 100 Mm3 per year, the south benefits from the contribution of the Senegal stream, situated at the border with 7 Billion m3 per year. The underground waters are largely non renewable (only 300 Mm3/year are renewable). Algeria The potential water of resources in Algeria is of 17 Billion of m3 (surface water 10 Billion of m3, underground water 7 Billion of m3 mainly in the Sahara) Algeria has 57 dams with a storage capacity of water 5.7 Billions of m3. The program of development of small and middle hydraulic has permitted to put 1000 small dams in place, located in mountains with a storage capacity of 120 Mm3 (the half of this infrastructure has been deteriorated under the effect of the floods and the silting up). The underground aquifers situated to the north of the country are exploited to 90%, with 1.9 Billion of m3 per year. Some aquifers are becoming overexploited. In the Sahara region the extracted volume is valued to 1.7 Billion of m3 . Tunisia The potential of water resources is valued to 4.8 Billions of m3, with 2.7 Billion of m3 of surface water and 2.1 Billions of m3 of underground water. The 60% of resources are situated notably to the north of the country to the level of the Mijrada basin. Mobilized water Resources are of 4.1 Billion m3 per year by 26 big dams and infrastructure of transfer, 880 small dams and 5500 network of boring. Libya The major part of the territory of Libya is arid and dry, with rare out-flows, except in the mountains with the contribution of 200 Mm3 per year. 16 small dams of water storage have been achieved with a total capacity of 60 Mm3. Underground water Resources are of 600Mm3 in the north zone of the country. In the south zone of the country (Merzouga, Srire, Koufra) the most water is old. The exploited volume is 4.4 Billion m3 per year. IMPACTS OF WATER SCARCITY AND THE CLIMATIC CHANGES ON WATER IMPACTS OF WATER SCARCITY AND THE CLIMATIC CHANGES ON WATER RESOURCES IN MAGHREB COUNTRIES RESOURCES IN MAGHREB COUNTRIES The main prominent effects of the hydrological regime during the last years in Maghreb countries can be to summarize as follows: Frequent Droughts During the last decades the Maghreb regions knew frequent droughts as the years 1982- 1983, 1994-1995,1998-2000,2006-2007 and the successions of dry years 1980-85, 1991- 1995 and 1998-2001. As the outflows are bound closely to the precipitations, these droughts have been accompanied by decreases in the contributions of the rivers. the mean of the runoff of 35 last years in part from 15 to 25% and according to the regions compared to the average of the long set of the contributions (to see graphic below of Morocco and Algeria). Evolution of the water contributions in the basin of centre Algeria Evolution of the water contributions in dams of Morocco In order to face the severity of the droughts lived; some countries adopted programs of restriction. In Morocco, for examples, thanks to the politics of the dams, water supply have been assured normally. Frequent Flooding If the problems of water are especially felt through the droughts, the countries of Maghreb notably Morocco, Algeria and Tunisia, in spite of their semi-arid or arid character, are submitted, like all countries of the periphery Mediterranean, to important flooding that can be as well very prejudicial for the public or private infrastructures that for agriculture, and to cause numerous victims among the population. The phenomenon of the flooding is not recent in these zones, but it began to be felt more strongly during the last decade, because of a part, the demographic growth, the economic boom and the urban, agricultural, industrial and tourist development that encourage an increasing occupation of the vulnerable zones, and on the other hand, of the increase of the occurrence of strong storms localized at the origin of fast and violent flash flood. The catastrophic floorings like the Ourika in 1995, Mohammadia in 2007, Alger in 2001, Tunis in 2007 and others are always present to the mind. Overexploitation of the groundwater The situation of the groundwater in Maghreb countries, has been marked by continuous decreases of water level in the quasi-totality of the aquifers reaching alarming values. This decrease caused by the conjugated effects of the drought, the climatic changes and socio economic development that all countries of the region know. It had for consequence, the overexploitation of the water reserves, the reduction of the of basis outflows of the rivers, drying some springs and see intrusion. The graph below, shows the evolution of the level table of the Souss aquifer in Morocco (decrease of 40 m during the last ten years), Mitidja in Algeria (decreases of 20 m during the last ten years) and Merguellil in Tunisia. Decrease of the level of aquifer of Souss m -10 -20 -30 -40 -50 -60 -70 -80 1982 1985 1988 1991 1994 1997 2000 2003 2006 Decrease of the level of aquifer of Mitidja Decrease of the level of aquifer Merguellil (Tunisie centrale) The aquifers System of the Sahara Septentrional, shared between Libya, Algeria and Tunisia, is influenced by the effects of droughts and the intensification of the withdrawals. The graph. below shows the fast growth of the withdrawals from 1970. Deterioration of water quality With the frequency of the droughts and the decrease of the basis debits of the rivers, the power of self purification of the rivers is reduced. What induce the deterioration of the water quality particularly marked in the places of dismissals of the industrial and domestic worn-out waters. Therefore, an increase of the pollution indicators has been recorded in particular during the drought years (1994-1995; 2000-2001 and 2001-2002) with the increase of the contents in biodegradable organic matters (appreciated by the DBO5) downstream the main domestic and industrial dismissals. What entailed a consumption of all the oxygen dissolved in water in some cases. This deterioration of the water quality had such consequences: - The disruption of drinking water production stations; - The development of the phenomenon of the eutrophisation and the deterioration of the water quality in the deep layers - Mortality of fish in some dams III - ACTIONS OF ATTENUATION OF THE EFFECTS OF THE SCARCITY AND THE CLIMATIC CHANGES The scarcity, the increasing demand, the effect of the climatic changes, the pollution, are among the future challenges of water resources for the future generations. To face, it is necessary to have an integrated and versatile strategy. This strategy must permit to increase the offer, to manage the demand, to encourage the efficient allowance of water resources and to reduce the pressures exercised on these. The main axes and plans of actions of attenuation of the scarcity and the effects of climatic changes can be summarized like follows: Mobilization of water resources: - Big dams for the storage of surface water : The hydrological regime in Maghreb countries is marked by the alternation of dry and humid periods. The contributions of the humid years occur in some days. Therefore the storage of water during the humid years in order to use it during the dry years imposes itself. The dams of bigger sizes should be encouraged to take into account the impact of the climatic changes. - Small and middle dams for the farming development : To bring to the farming population the key factor that assures him in addition to the subsistence, the valorisation notably of his/her/its agricultural resources, the construction of small dams destined to procure several services (drink water supply, irrigation, livestock……) is a solution to adopt there or the conditions lend themselves of it well. Water Transfer from the excess regions toward the regions showing a deficit The first objective is to avoid the losses of water toward the sea and the second is to reduce the territorial disparities and to sustain the socioeconomic development of the regions already advanced that risk to be in shortage for lack of water in the futur. Safeguard and protection of groundwater resources The Groundwater constitutes an important part of the hydraulic heritage of Maghreb countries. To assure their safeguard and their protection for the future generations and for the difficult moments, it is necessary to undertake the following actions: - To control the withdrawals of underground waters in order to protect them against the overexploitation; - To institute a dissuasive pricing; - To generalize the economy of water for all users; - To suppress the subsidies encouraging the overexploitation of the aquifers; - To reinforce the integrated management of water resources ; - To reinforce water policy; - Rational and participative management of the underground water in return for the establishment of the conventions settings (contracts of aquifers) for the management of the underground water; - Resort to resources in water of substitution to relieve the aquifers; - Sensitization of the users, the local actors, the local decision-makers and the agents of authority to the constraints of water scarcity and to the risk of draining of underground waters; Artificial Recharge and exploration of the deep aquifers To protect against the effects of the climatic changes, the artificial refill of the aquifers and the exploration of the deep waters play a vital role in the zones that know some frequent shortages of water and those destitute of surface water resources. Preservation of the water quality In the context of the scarcity, the quality of the superficial and underground waters is threatened by numerous pollutions. It is important to undertake all to improve and to preserve the quality of in water resources and the protection of the environment. Development of non conventional water resources The possibilities of growth of the conventional water offer, to satisfy the demand in water with the country in perpetual growth, are limited and become more and more expensive. The growth therefore of the availabilities in water as having resorts to non conventional water resources must be also among the priorities. It is about the reuse of worn out waters after treatment, the demineralization of the brackish underground waters, of the desalination of the sea water, as soon as the costs justify this use, and rain water harvesting. Protection against the extreme phenomena: Floodings - Droughts - To put a plan in place of struggle in against the Flooding, - To put modern tools in place of forecasting and prevention against the flooding in different basins and in the flooding sites, - Establishment of cards of droughts vulnerable zones and flooding zones. Management of demand of water With the scarcity, the increasing of the demand, mobilized water resources must be valorised sufficiently. The mobilization of surface waters and the underground waters, the transfers of inter-regions water, the struggle against the pollution, the use of the non conventional waters is as many actions that could not bring their fruits if so much that water resources endure wastes and losses. Thus, it is imperative to : - Improve the output of worn out waters used while resorting notably to methods and techniques saving of water in the sector of the irrigation; - Increase the productivity of the cultures while introducing some varieties to faster maturation, less consumers of water and giving a bigger output; - Reduce the losses of the networks of irrigation and distribution of the drinking water; - Fight against waste and to warn the pollutions permanent and accidental of resources in water; - Treat the worn-out waters and to reuse them for ends less exigentes in quality; - Put in place of structures them tariff encouraging the utilisation efficacy of resources in water; - Undertake actions of communication and sensitization to the set of the users. Sensitization and communication - Sensitization of the population to the economy of water and on the value water, - Sensitization of the population on the zones to risk - Backing of the coordination between the different partners of the sector of water. Encourage the scientific research - Backing of follow-up of resources in water: development and modernization of the networks, study and modelisation …etc, - Development of the research for the forecasting of the drought.
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