ICARDA CARAVAN 11

Flooding on a semi-arid steppe? It's just one of the irregular forces of nature that ICARDA scientists are seeking to manage for the benefit of a hard-pressed rural population.

ry areas are the focus of ICARDA's research and  development programs but work on water-use efficiency has its application well beyond most people's vision of a 'dry area.'
         Three major environments come within the scope of ICARDA's water specialists--drier environments such as steppe or badia, rainfed cropping environments and fully irrigated agricultural areas. Shortage of 'sweet' water is common to all such areas but the pressures and solutions have to be tailored to the immediate environment to obtain the highest crop yields from the most effective use of life-enhancing water.
         That's why it is vital to appreciate that the semi-arid steppe which suffers long periods of zero rainfall can be harmed irretrievably when scarce rainfall is so intensive that it leads to flash flooding and erosion of already-fragile soil. Invariably, however, it is more likely the case that the meager seasonal rainfall is so widespread that it is of little or no benefit to plants before it is lost through evaporation or simply dissipated uselessly in the soil.
          ICARDA is engaged in a number of projects relating to water harvesting in environments with either too little water or where it is uneconomic to grow crops with imported irrigation water. The underlying principle is the concentration of water from a large area on to a smaller area of land where the precious moisture can do the most good in nurturing either arable crops or trees. In fact, water harvesting isn't new. Systems based on technology devised several thousand years ago are still in use, and ICARDA is compiling details of indigenous systems in each of the countries where it operates.
          A major trans-national project in on-farm water husbandry takes in research projects in eight countries: Egypt, Iraq, Jordan, Libya, Morocco, Pakistan, Syria and Tunisia.
         Within the CGIAR System-wide Water Resources Management Program, ICARDA leads this ecoregional program in 'On-farm Water Husbandry in West Asia and North Africa' that links national program researchers in WANA. The research program addresses four main themes:
  • Description and analysis of indigenous systems, with particular focus on the human dimension;
  • Development of methods for appraisal of sites for water harvesting potential;
  • Optimizing the utilization of harvested water through devising proper methods and techniques; and
  • Disseminating new technologies to land users.
         Some of the richest experience gained so far has come from the Matrouh Resource Management Project centered on the town of Marsa Matrouh in northwest Egypt. ICARDA provides technical assistance for implementing this project within the Egyptian national program on "Research for Development." It has been financed since 1994 by the World Bank and the International Development Association. ICARDA is promoting the integration of water harvesting into watershed development plans appropriate for various ecosystems.
          Various techniques for water harvesting have been introduced or improved. Macrocatchment systems enable the concentration of water from large areas from which it can be stored in small reservoirs or in the soil for agricultural use. For water harvesting in wadi beds in Matrouh, stone walls are appropriately located and designed to cross the wadis, harnessing sufficient water to grow figs, olives and melons. Cisterns (large underground tanks) are also examples of macrocatchment and have been the only source of water for human and livestock consumption in this area for thousands of years. Many thousands of new cisterns are being constructed by the project to help farmers.
         ICARDA is working with the project on improving the efficiency of this indigenous system. The overall efficiency of these cisterns can be improved by firstly increasing collection efficiency and, subsequently, storage and utilization efficiency.
In Tunisia, other types of water harvesting are used, including mountain lakes constructed to supply supplemental irrigation water for crops much lower down. The famous jessour and misqat systems have supported figs and olives for hundreds of years in drier environments.
         At another extreme, microcatchment is proving exceptionally useful for small-scale agriculture--down to perhaps just one tree in some circumstances. The principle is the same as for some macrocatchment techniques --storing moisture in the soil. The catchment area may, however, be just 50 sq m, and the semi-circular bunds just a few meters long.
          Contour ridges created on the slopes are being used successfully in a number of countries to concentrate water in the required place particularly for improving shrubs and grasses for livestock. ICARDA has adopted simple methods to help farmers properly locate a contour ridging system. Using transparent plastic tubes filled with water and marked off for level, the task can be carried out quickly by just two people. In Pakistan, a father and son

working together planned 5 km of contours in one day using the tubes at 15 m spacing.
         Other microcatchment techniques found by ICARDA to be superior in the dry areas are the runoff strips for field crops such as barley, and small basins such as semicircular bunds and negarim (individual small basins) for shrubs and trees. A further alternative, particularly suitable for steppe areas where growing any crop is difficult for lack of moisture, is to alternate cultivated strips with bare water collection strips. Small gullies or depressions can be placed laterally in the crop rows to distribute water more evenly. Such a technique is useful for wheat, barley, lentil, chickpea and other field crops. It will not appeal to farmers who get sufficient rainfall to grow some sort of crop on all their land, but could make the difference between some crop production and none at all in more water-scarce areas.
           Plowing in strips separated by natural catchment areas supplies more water to barley which would normally suffer stress, and the technique substantially increases yield and reduces risk of crop failure. ICARDA has developed technologies to overcome the uniformity problems associated with this technique. ICARDA is also adapting a special ridger that can be towed by a normal tractor for large-scale mechanical implementation of the semicircular bunds. With this technology, shrub survival rate in the Syrian steppe pilot project was increased from 10% to 90%.
            Increasingly, remote sensing by satellite or other aerial photography, and geographical information systems (GIS), are being used to help determine suitable sites for water harvesting. For example, the Landsat sys

tem will give a 30 m by 30 m definition with which ICARDA scientists can plot areas with high potential for water harvesting. Once the site has been identified, fieldwork then takes place to determine factors such as run-off so the expected amount of water from the site can be estimated.
            Any of these techniques is useable in the drier environments where rainfall is not enough to support crops. It has to be remembered that while 100-250 mm of annual rainfall is very little indeed on an individual field or farm, it represents a great deal of water when spread over the vast extent of the dry areas. About 95% of that rainfall is lost through evaporation without any benefit. However, we can still make use of this rainfall by harvesting even where there are no rivers and no groundwater.
          Nor is it simply a case of producing more food by harnessing this moisture. Desertification is halted, wind and water erosion is prevented, and the environment maintained. By improving the potential returns from farming, male migration in search of city work is cut back.

Dr Theib Oweis is Water Management/Supplemental Irrigation Specialist at ICARDA.