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Jordan University of Science and Technology (JUST) 2006

Evaluation of using sand ditches water harvesting system in rainfed agricultural areas

عبدالله محمود محمد التميمي

Titre : Evaluation of using sand ditches water harvesting system in rainfed agricultural areas

Auteur : عبدالله محمود محمد التميمي

Université de soutenance : Jordan University of Science and Technology (JUST)

Grade : Master of Science (MS) 2006

The increase in water shortage is regarded one of the most difficult problem in many parts of the world. In many arid and semiarid regions, pumped ground water and the water from streams, rivers and reservoirs is no longer sufficient to cover the ever increasing water demand. Therefore, increasing water resources from floodwater harvesting is necessary and gained lots of interest in recent years. Rainfall harvesting can significantly supplement water demand for agricultural production. Because soil moisture can be lost through evaporation, runoff, and percolation down in a manner that the plant can not benefit from it, new techniques are needed to store water for long period in the soil profile for plant use under drought conditions. Using sand ditches may help in solving the problem, it decreases the need for irrigation and increases the period of irrigation interval during drought periods, through decreasing surface runoff and maximizing amount of rainfall storage. Other methods of collecting rainfall include ; the use of terraces, runoff strips and contour ridges. The efficiency of these methods is limited by the type of soil. Since northern Jordan is predominantly clay soils, which have low infiltration rates, water will remain at soil surface and eventually lost to evaporation. Constructing sand ditches would decrease water loss to evaporation and increase soil moisture content by permitting water to infiltrate through the sand ditch which has higher infiltration rate than the surrounding clay. Installation of sand ditches would intercept rainwater and conserve it for plant survival under stress conditions. The water intercepted by sand ditches will slowly infiltrate through sand layer and then redistributed to the surrounding clay soil. The movement of water from sand to the clay soil is due to high water potential of sand compared to the clay soil which has low water potential. Four different soil treatments were selected and randomly distributed over twelve plots, four sand ditch treatment, two compacted treatment, two plots were covered by plastic mulch, and two plots as controls. each plot was 10m long and 2m wide. Soil moisture content was monitored for all plots using TDR device. Storage tanks were installed in the lowest end part of each runoff plot for measuring runoff water. Also, erosion was measured through weight sediments in the storage tank. The results showed that sand ditches intercepted runoff by 43%, 59% and 81% compared to control, compacted and mulch treatments, respectively. Consequently sand ditch increased the amount of infiltrated water by 178.4 mm compared to control and compacted treatment which were 154.9 mm and 134 mm, respectively. Sand ditches decreased sediments by 61% compared to control and 81% compared to compacted treatment. Using sand ditch increased vegetation cover by 72% compared to control and compacted treatment which were 44% and 19%, respectively. Sand ditch increased biomass by 3115 kg/ha compared to control and compacted treatment which were 2087 kg/ha and 507 kg/ha, respectively. Using sand ditch is recommended in arid lands like Jordan, due to its high rainfall harvesting efficiency, low runoff, reduced soil loss from erosion, and it is relatively easy to design and do not interfere with agriculture operation.


Page publiée le 26 décembre 2019