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Accueil du site → Master → Pays Bas → 2006 → Development of design criteria for the construction of retention dams in Wadi far’a, West Bank

UNESCO-IHE Institute for Water Education, Delft (2006)

Development of design criteria for the construction of retention dams in Wadi far’a, West Bank

Basaruddin A.B.M.J.

Titre : Development of design criteria for the construction of retention dams in Wadi far’a, West Bank

Auteur : Basaruddin A.B.M.J.

Université de soutenance : UNESCO-IHE Institute for Water Education, Delft

Grade : Master of Science 2006

This study is carried out in order to conserve water resources in the arid region of the Fara basin, West Bank. The Fara basin stretches along the northeastern part of the West Bank and it is completely contained within the Eastern Aquifer Basin (EAB). The total catchment area of the Fara basin is about 320 km2, comprising three sub-catchments which are Al-Fara, Al-Badan and Al-Malaqi with an area of 64 km2, 53.4 km2 and 216 km2 respectively. The study focuses on Al-Fara and Al-Badan subcatchments.Daily rainfall data of five stations in the area were available since 1967, although for some of the stations data are missing for large periods. These data were analysed for consistency and then used to compute daily values for each subcatchment. Annual extremes of the areal rainfall series were also analysed for consistency and the occurrence of trends or change points. Subsequently the annual daily extreme k-day rainfall for return periods of 2, 10, 25, 50 and 100 years were obtained from Gumbel distributions. The runoff coefficient for each subcatchment was computed from the large storm event recorded in the winter of 2004-2005. Large differences were observed between the two neighbouring catchments which can be attributed to differences in the topography and geological formations.An attempt was made to relate the runoff coefficient to rainfall intensity in order to estimate runoff volumes for extreme rainfall events (for return periods T = 2 and T= 10 years). For the design of the size of the spillway, the peak discharge for T = 50 is required. For this purpose simple conceptual models (e.g. the Nash model) were used to derive the unit hydrograph. Since these models require as input effective precipitation, the loss rate for each storm had to be determined. A simple model for estimating the losses was developed with the help of the NAM model. The 50-year flood for Al-Badan subcatchment (58 m3/s) appeared larger than the design capacity of the Parshall flume (58 m3/s). Analyzing the efficiency of constructing the retention dams for a return period 2 years, it was found that about 90 % of the storm water runoff could be used for artificial recharge.

Mots clés : dam design criteria ; dam construction ; West Bank ; water conservation dam ; artificial recharge ; Palestine


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