The Arab world is facing one of the severest water scarcities in the world.

Transcription

1 Water Harvesting Techniques in the Arab Region By Abdelaziz Zaki UNESCO Cairo Office

2 Water Resources in the Arab region The Arab world is facing one of the severest water scarcities in the world. According to WWDR, most of the Arab Countries fall under the lower end of the water availability list as well as the quality list. Factors contributing to water resources vulnerability in the Arab Region. aridity, low rainfall, high evaporation, uneven distribution ib ti of water resources, complexity of the hydro-political conditions, the rapidly growing human population, the deterioration of water quality; and the accelerated demand for water

3 Rainfall Distribution There is a severe spatial rainfall distribution over the Arab region.

4 Rainfall Distribution The total average annual volume of rainfall is about 2, billion m 3. Only 2.66 million Km 2 receives 1,488 billion m 3 constituting 19% of the total area of the Arab region, while 406 billion m 3 of rain fall on 15% of the total area. Two thirds of the Arab region is arid and hyper arid deserts (9.24 million Km 2 ) and receives 344 billion m 3 of rainfall.

5 Renewable Water Resources The estimated renewable water resources in the Arab region range from 246 to 441Billion m 3 with an average of 340 Billion m 3 (Salih 2002). The total average annual volume of rainfall is about 2, billion m 3 contributing tib ti only 180 billion m 3 of renewable surface and groundwater resources. Additionally, the region receives 160 billion m 3 of surface water from catchments outside the Arab region. The average annual recharge to groundwater is estimated at 45 Billion m 3, whereas 135 Billion m 3 is available in wadi system.

6 Water Harvesting Systems There are different water harvesting techniques practiced in the Arab region. They can be grouped into two categories: i. Water harvesting and storage systems; and ii. Water harvesting and spreading systems; Survey of traditional water harvesting systems has revealed that some 11 systems are used in the Arab region.

7 Distribution of traditional water system in the Arab States, after UNESCO Cairo (1995) Category Wat ter harv vesting and storage syste ems g and ms ater harvesting reading system Wa spr Name of system Jor rdan Un- -Arab Em mirates Bah hrein Tun nisi Alg geria Sau udi Arabia Sud dan Cisterns x x x x x x x x x Small dams x x x x x x x x x x x x x x Hafirs x x x x x x x x x x Tree trunks x Koroum / Ghadirs Terraces / Masateh Irrigation diversion i dams Water spreading dykes Miskat x x Artificial recharge Check dams x x Syr ria x x x x x x x Ira aq x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x Om man Qat tar Ku uwait Leb banon Lib bya Egy ypt Mor rocco Mau uretania Yem men

8 Terracing Water Harvesting in the Arab Region: Overview and Examples Terracing is successfully used for rainfall utilization and soil conservation in the mountainous areas of south western Saudi Arabia and Oman. Terracing is widely used in Yemen as one of the effective conservation techniques Different forms of terracing are available depending on its purpose such as soil conservation and water use. Rained agriculture is practiced on terraces in many communities, more 1.5 million hectares have been regularly cultivated.

9 Spate Irrigation (flood irrigation) It mainly counts on water spreading where the flood water is diverted from the wadi course to an immediately adjacent cultivated area. Agricultural land is graded and divided into basin for storing enough water to allow enough water to be stored for the season. Therefore, soils should be with sufficient water holding capacity. In large wadis with high discharges, a temporary earth dams created in order to retard the flow and receive the first wave of flood Spate irrigation is practiced in Sudan, Yemen, Oman, Tunisia, Algeria and Saudi Arabia. Spate Irrigated areas versus total irrigated areas in some Arab countries (FAO, 1999) Country Year of Irrigation data Spate irrigation area (ha) Total irrigation area (ha) % of spate irrigation coverage Yemen 1987/ , , Algeria , , Morocco ,000 1,258,200, 13 Tunisia , ,000 8 Sudan ,200 1,946,

10 Meskat The Miskat System is one of the ancient methods employed in harvesting rainwater. They are used in the Arab Maghreb specially in Tunisia, Morocco and the north west of Libya in Nafousa mountain.

11 Dams and Reservoirs Dams of various sizes were constructed in most Arab countries for the purposes of irrigation, flood control and groundwater recharge. Dams assist in reducing flood damage downstream by reduce the magnitude of peak discharge. Sediment which carried by floods is trapped upstream dams creating good soil for agriculture. Most of the dams built in Saudi Arabia, the United Arab Emirates and Oman were for the purpose of recharge to depleted aquifer systems. Few large dams in Saudi Arabia, Egypt, Tunisia, Sudan and Jordan have multi-purposes. These dams have been built either at the head waters of catchments in the mountainous regions or in the downstream portions of catchments as in Saudi Arabia, Sudan, Egypt, Tunisia, Jordan, Yemen, the United Arab Emirates, and Oman.

12 Water harvesting projects in two major wadis in Egypt: Case Studies Multi-purpose water harvesting projects in W. Ghuweiba and W. Wateir in Egypt. Studies were carried out by the Water Resources Research Institute of Egypt. Cairo W. Ghuweiba W. Watier

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17 Wadi Ghuweiba Project Wadi Ghuweiba area is about 2500 km 2 and its main stream length is 130 km. The Wadi has strong slopes range between 10 and 28 m/km and elevations between 1300 m to about 100 m. Industrial zone is constructed in its delta. Field geoelectrical survey was conducted in Wadi Ghuweiba comprising i 16 vertical Electrical l Sounding (VES).

18 An artificial recharge system was suggested to increase the rate of recharge to the Quaternary aquifer. Six locations were employed to induce infiltration into the Quaternary aquifer. Dams heights ranged between 3 and 7 meters with capacities ranged between 60 to 6500 thousands m 3.

19 Stored water lasts for 2-3 weeks according its volume Evaporation rate ranges from 8-12 mm/day AA Recharged water to different aquifers (1000 m3) Subbasin s Name Average Return periods (years) 5-yr 10-yr 25-yr 50-yr 100-yr Shona Khafory Esaimer Abiad AA Noot

20 Wadi Watier Project Wadi Watier (about 3600 km2) in southeastern Sinai, Egypt The catchment area is covered by basement rocks, mainly granites which are highly fractured. The international road between Egypt and Jordan and several tourist villages are seasonally subjected to the flash floods of Wadi Watier. Basin Boundary Town

21 For the purpose of water resources development of the area and to minimize i i the harmful destruction effects of Wadi Wateir flash foods, seventeen detention dams and five storage dams were proposed. p For economic reasons, the probable floods of 25- years were selected to design the different kinds of control works. Wadi Watier Project

22 Dams locations were selected upon field investigations according to the most practical and suitable sites taking into consideration the construction process and transportation of the equipments and materials. Two types of dams were proposed, the detention and the storage dams, according to the amount of runoff volume from each subbasin.

23 Reuse of recharging water for groundwater aquifers, as indirect contribution, can cover the requirements of about 3000 feddans/year. Another positive impact is the creation of a good agriculture-land land upstream the proposed structures amount to about 500 feddans. Dam s Type Reservoir Capacity Detention Storage (1000m 3 ) D1 147 D2 199 S1 900 D3 147 S2 7,810 D4 230 D5 87 S3 1,125 D6 145 D7 200 D8 204 D9 180 D D S4 3,400 D D13 55 D D S D D17 4.5

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25 Water Harvesting Constraints in the Arab Region Rainfall and runoff data availability (short records) Un-gauged Catchment conditions Financial support for establishing monitoring systems Up-scaling problems from experimental catchments (if exist) to water harvesting scale Suitable hydrological techniques for arid conditions Socio-Economic i aspects High cost of water harvesting constructions in the Arab region in relation to its immediate use. Maintenance

26 UNESCO Cairo Office activities in the Field of Water Harvesting Enhance capacity building through the organization of WH training workshops (ex.: Sudan, 2004 and Jordan 2005) Foster networking and experience exchange through the Arab Wadi Hydrology Network (AWHN) coordinated by ACSAD Organization of the International Conference on Wadi Hydrology (every 2 years) Egypt, 2000, Jordan 2003 and Yemen in The next conference will be in Oman during Preparation of technical publication within the AWHN. Rainfall water Management in the Arab Region (state of the Art) edited by A. Salih, Khouri, J, and Amer A. Water Harvesting training Manual edited by O. Remawi and A. Kharabsha. Recent publication is under-preparation. First draft is available.

27 Concluding Remarks 1. Strengthening the existing hydrological monitoring systems in the Arab region 2. Establishing more new experimental basins in the Arab region for more understanding of the hydrological characteristic of the region. 3. Establishing regional database and strengthening the existing ones in the Arab region. 4. Encouraging more joint research activities in arid zone hydrology. 5. Enhancing capacity building and fostering networking in the field of water harvesting in the Arab region. 6. Raising public awareness for increasing the water use efficiency with special focus on the ethical dimension.

28 Concluding Remarks 7. Encouraging the involvement of the stakeholders, NGOs and communities in the maintenance of the water harvesting construction. 8. Enhancing the coordination among the scientific institutes in the Arab region for more experience exchange in the field of water harvesting techniques.

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