EVALUATION OF DYKES AS WATER HARVESTING SYSTEM IN WADI SHEBITY WEST MERSA MATROUH, NORTHWESTERN COASTAL ZONE – EGYPT.

M, El Kady,; N, Hassan,; H, El Kassas,; Noha, S, Donia,; M, Wassif,

doi:10.21608/jes.2018.30844

EVALUATION OF DYKES AS WATER HARVESTING SYSTEM IN WADI SHEBITY WEST MERSA MATROUH, NORTHWESTERN COASTAL ZONE – EGYPT.

Document Type : Review Article

Authors

¹ Soil Conservation Department, Desert Research Center

² Irrigation and Drainage Department, Faculty of Engineering, Ain Shams University

³ Institute of Environmental Studies and Research, Ain Shams University

10.21608/jes.2018.30844

Abstract

The main objective of this research is evaluating dykes as rain water harvesting activities to maximize rainwater utilizing in drainage basins in the northwestern coast of Egypt which receive amount of water and have a population growth and agricultural activities. Wadi bed cultivation is the water harvesting system in the chosen wadi. It is usually done through construction of stone dykes to store surface runoff coming from tableland in the south, the main problems associated with this type of water harvesting are unequal water distribution through the wadi, where less runoff water reaches the wadi beds in downstream, with the result that downstream crops become increasingly water-stressed, moreover storing volume of water higher than fig water requirement the results in delaying agricultural development. To maximize rainwater use, 50 stone dykes of 50 cm spillway height were evaluated in term of water distribution efficiency and the percentage of stored water volume to plant water volume requirement/season. And depending on the storage capacity of dykes, fig water requirement and the runoff volume of the average season of rainfall data for 17 years from October to march (one season) estimated by Soil Conservation Service (SCS) method and Geographical information system (GIS)
The results of the present study show that wadi Shebity watershed receives average annual rainfall volume of 435217 m³, 121922 m³ from it by percentage of 28 % run on ground while the residue percentage of 72 % distribute among evaporation and infiltration in soil, 118590 m³ of surface run off by percentage of 97 % stored by dykes by water distribution efficiency of 3, 12, 100 % for rainfall of 12, 20 and 53 mm respectively, and 3332 m³ by percentage of 3 % is lost in the sea. The percentage of the stored water volume to the cultivated areas water volume requirements is 118 % with difference of 18168m³. The study reveals that the end of wadi shibty is in safe from flood hazard, where the runoff coming from the table land at the south is stored completely by dykes even with the maximum rainfall of 53 mm. The spillway height of 50 cm is not suitable to distribute surface runoff through the wadi for low and medium rainfall which is more frequency, moreover stores water volume higher than the fig water requirement with 18168 m³. Further the methodology followed in this study can be applied in all other wadis watersheds but designing new or modification of the existing water harvesting system of dykes will depend on its watershed area and its physical Characteristics, rainfall, the cultivated land area and crop/fruit type. The present study reaches out for some recommendations to maximize rainwater utilizing

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