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FAO Near-East & North Africa Land & Water Days, Amman, 15 – 18 Dec. 2013 Techn. Session 5 „Rainfed Agriculture: Financing Smart Agriculture Projects“

Water Harvesting and Supplemental Irrigation - MENA Case Study 1 - Water Productivity Enhancement

Prof. Dr. Dieter Prinz, Karlsruhe, SW-Germany (prof.prinz@t-online.de)

EXECUTIVE SUMMARY

Water Harvesting: The collection and concentration of rainfall and its use for the irrigation of crops, pastures, trees, for domestic and livestock consumption. Climate Smart Practices: (a) Fitting to the local climatic conditions; (b) Well suited for future climatic conditions (Climate Change Adaptation) Efficient Practices: (a) Catching the rain optimally, (b) High water-use efficiency / Water Conservation; (c) High economic / financial efficiency (‘Water Productivity’)

Case Study 1.A: Increasing Water Use Efficiency of Stored Wadi Water in Jordan’s Badia

Innovations (1) Highest water use efficiency was obtained, when the stored water was used in winter and the reser-voirs emptied as often as possible. (2) Further-on, sediment removal did not only extend the lifetime of the reservoirs, but the extracted sediments contributed to an improved soil fertility. Literature: Oweis, T. & Taimeh, A. (2002). Farm Water Reservoirs: Issues of Planning and Management in Dry Areas. In: Adeel, Z. (ed.) Integrated Land Management in Dry Areas. United Nations University, Tokyo, p. 165-182

Case Study 1.B: Using Groundwater Dams for Subterranean Water Storage

Issue The use of floodwater flowing in wadis is well established, but the benefits of constructing ground-water dams are not as well known. To establish such a dam, a trench is dug into the wadi sediment across a wadi bed, down to the bedrock. The dam itself is built from stone or con-crete; the work can be done by manpower or largely mechanized. Alternatives to groundwater dams are sand dams, which are constructed in steps, generating accumulation of coarse sand upstream of the structure.

Issue Large parts of the Jordan’s ‘Badia’ are suffering from low, erratic winter rainfall, high evaporation (> 2000 mm/a) and low soil fertility. Surface crusts cause low infiltration and high runoff with subsequent soil erosion. Vegetative cover is therefore generally poor. ICARDA established, in cooperation with the University of Jordan, a research site in a typical ‚badia‘ area (in Muaqqar) to investigate improved management options of small farm reser-voirs. Three small earth dams were constructed across the up-stream part of a wadi, creating farm reservoirs of 25,000 to 40,000 m3 volume. The stored water is used to irrigate field crops and trees (Supplemental Irrigation), aiming at a high WUE. Challenges Main questions are: (1) Is the productivity of water used for sup-plemental irrigation of winter crops higher than that used for full irrigation in summer? (2) Is the emptying of a reservoir as soon as it is filled more efficient than leaving it filled for later use?

Flooded wadi and a reservoir

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In Niger a groundwater dam was constructed by local communities under guidance and financed by an interna-tional NGO. The dam was 120 m long and 2 meters high. After a single flood, about 25,000 m3 of water had been accumulated (over a wadi length of 300 m). The water is used for irrigation and domestic purposes. Challenges The above-surface flow in wadis lasts for hours or days, whereas the groundwater flow within the wadi bed lasts for weeks. The dams can be extended above the sediment level at time of construction to serve the purpose of slowing down the runoff flow and to facilitate infiltration. These dams offer numerous advantages of water storage e.g. very low evaporation, hardly any pollution, no breeding of mosquitoes. However, a precondition is that the wadi bed consists mainly of coarse sand (35 % water content), not of fine sand (5% water content), silt or clay. There are numerous groundwater dams in the Near and Middle East, e.g. in the Negev, where the extracted water is stored in large ponds for irrigation. Innovations In spite of being a very ancient technique, the potential of groundwater and sand dams is largely un-

tapped. The (material) costs are generally low (500 Euro). There are modern tools available to identify

suitable wadis (e.g. radar satellite images), the location of most suitable sites for a ground-water or sand

dam (e.g. using Google Earth), the size of the catchment (by DEM and Google Earth). Literature: van Waes, B., Bouman, D. & Worm, J. (2007). Smart Water Harvesting Solutions. Examples of innovative, low-cost technologies for

rain, fog, runoff water and groundwater. Netherlands Water Partnership, http://publications.cta.int/en/publications/publication/1394/

Case Study 1.C: Rooftop Water Harvesting in Greenhouse Production in Lebanon Mountains

Issue Due to the high demand for vegetables and cut flowers in the densely populated coastal areas, green-house production in the Lebanese mountains flourishes. To optimize the use of available water resources, a ‘Green Plan’ project was started; its special features are (1) Rainwater is harvested from the tops of plastic greenhouses and directed into a pond, which is lined with PVC sheets and geotextiles. (2) The pond water is flowing by gravity into other greenhouses and is used there for drip irrigation of ornamental plants (roses, stocks etc.). The location is NE of Jounieh, Central Lebanon, 300 – 350 m asl, precipitation as well as evaporation are about 1000 mm/year. Challenges As there are no springs in the area, there is the need for rainwa-ter harvesting; greenhouse rooftops offer unpolluted, good quality water, well suited for crop production within the green-houses. Karstic underground asks for sealing of ponds to store the water. The rainwater storage needs expertise and funds; the lifetime of a pond is limited to max. 10 years. A high water use efficiency can be achieved by applying drip irrigation in the greenhouses. Innovations The ‘Green Plan’ agency is an autochthonous authority under the Lebanese Ministry of Agriculture, par-tially financed by international donors. Green Plan experts develop together with interested farmers technical and financial development plans for their enterprise. Farmers receive soft loans and subsidies; the progress is documented. Literature: Republic of Lebanon (2012). Hilly Areas Sustainable Agriculture Development (HASAD). Project Design Report. Prepared by IFAD (International Fund for Agricultural Development) Updated for Supplementary Financing. Beirut, Lebanon