Water runoff harvesting for olive plantations in Syria through annually reconstructed V-shaped micro-catchments, enhanced by downslope ploughing
Farmers create furrows around their olive trees in V-shaped or fishbone-shaped micro-catchments. Using only a hoe and some stones, farmers manually construct V-shaped earthen bunds (small dykes) around each tree. The furrows then divert the runoff systematically to the micro-catchments where it concentrates in basins around the trees. This operation is repeated every year, and if the structure is damaged after a heavy storm, farmers repair it. This is a low-cost way of retaining rainwater for olive production.
The Khanasser Valley is situated in north-western Syria. The annual rainfall average is around 220 mm. Because of the low productivity of the soil, the foot slopes of degraded hills are traditionally used for extensive grazing or barley cultivation. These areas are generally considered as too dry for olive cultivation, but farmers have attempted nonetheless to achieve self-sufficiency through olive oil production, and have developed olive orchards in this area.
Facing the twin problem of topsoil loss and climate hazard (drought and wind erosion), the old ways of tilling orchard are inadequate. Traditionally, farmers prefer to till their orchards by tractor in order to keep them weed-free. As this tillage operation is usually practiced up and down the slope, the resulting furrows stimulate runoff and erosion. Since 2002, agricultural advisors have suggested the V-shaped micro-catchments as a water-harvesting measure.
Farmers create furrows around their olive trees in V-shaped or fishbone-shaped micro-catchments. They aim first to keep their orchard weed-free, without stimulating runoff and erosion caused by tillage operation practiced up and down the slope. The furrows then divert runoff systematically to the micro-catchments, where it concentrates in small basins around the trees.
This water-harvesting technique is mainly applied by “agriculturalists”. This term refers to a type of farmers where the livelihood of the whole household depends mainly on agriculture. Farmers with more interest in off-farm labour or sheep rearing are less interested, but they are also starting to apply this practice gradually.
Two supporting technologies are used to optimise the results of this practice, namely:
- mulching the area around each tree with locally available stones (limestone and/or basalt); and
- sometimes planting the catchment areas between the trees with low water-demanding winter crops (lentils, vetch, barley etc.), especially when the trees are young.
The first practice reduces soil temperature and surface evaporation during the summer, while assisting with water infiltration. The labour input for establishment and maintenance is low, the technology is easy and cheap to maintain, and there is enough local skill to sustain and expand the system. The second practice helps to reduce surface erosion.
On top of the positive ecological impacts (erosion control, reduced runoff, lower need for irrigation), this practice also improves olive productivity. Nevertheless, as the orchards have been developed to achieve self-sufficiency in olive oil production, we cannot formally confirm the extent to which this practice is a source of well-being or financial gain.
The cost of this practice is considered as low and does not require additional external inputs. To achieve water preservation and reduce summer irrigation needs, it is advisable as an accompanying measure to change the irrigation system. The use of localised irrigation, especially drip irrigation or other improvements, are recommended, because if traditional surface irrigation is applied, then the potential savings offered by water harvesting may not be fully realised.
- Lower need for irrigation water
- More efficient utilisation of rainwater
- Reduced soil loss due to erosion
- Increased yield of olives
*The actual number of trees or hectares of land converted for runoff harvesting is not available.
- Training of farmers (based on knowledge of agricultural advisors)
- Low cost of implementation
- Adoption of the practice by 100% of farmers in Harbakiyeh and Habs, Khanasser Valley
100 percent of land-user families have implemented the technology voluntarily. Based mainly on workforce availability, this practice could be easily applied in other areas where water is in short supply.
- Around USD 88 per hectare. Only runoff-harvesting technology is considered in the total cost per hectare (annual activities of ploughing and water-harvesting structure establishment and maintenance). The planting of olive trees and their maintenance are not included in this cost.
Francis Turkelboom, ICARDA Francis Turkelboom: F.Turkelboom@cigar.org
ICARDA, Aleppo, Syria: www.icarda.org
- Tubeileh, A. and Turkelboom, F. (2004). “Participatory research on water and soil management with olive growers in the Khanasser Valley”. KVIRS project, ICARDA, Syria.
- Tubeileh, A., Bruggeman, A., Turkelboom, F. (2004). “Growing olive and other tree species in marginal dry environments”. ICARDA, Aleppo, Syria.