British Mandate: A Survey of Palestine: Volume I - Page 398

CHAPTER X.

tigations into the question of the amount and dependability of winter storm water likely to be available for storage, a system of measurements of the discharge of all perennial and non-,Perennial rivers has been carried out by the Water Commissioner's staff. A considerable amount of material in incomplete form had been collected by touring officers and observers measuring the flow of springs and streams and the discharge of flood waters in the wadis after rain. Measures were taken to complete the computation by the engagement of additional staff, but unfortunately, owing to war-time exigencies, it has not yet been possible to have these records and other technical papers printed. The results indicate that the average 'run-off over a number of years is in many cases less than 10% of the rainfall in the respective catchment area. For the study of the winter storm water flow in the non-perennial rivers and the connected problem of storage of the winter floods, the number of observation stations was increased. Regular measurements are now made at 33 sites. Information is also received from the Water Research Bureau of the Jewish Agency, the Palestine Electric Corporation, the Palestine Water Company and other bodies in respect of another 14 stations. Regular measurements of the discharge of the more important rivers, springs and perennial streams are made at 160 stations.

investigation INTO THE POSSIBILITY OF DAMS FOR FLOOD-CONTROL AND RESERVOIRS FOR IRRIGATION PURPOSES.

36. Conditions in Palestine for the storage of large quantities of water from winter to summer are prima facie unfavourable : adequate investigations have not yet been completed and it has not yet been found possible to make any real use of this means of obtaining or conserving water. An experimental reservoir was made in the Abu Samara Wadi in 1934 : in that case 93% of the rain which fell in the catchment area was absorbed into the soil, and of the 7 % that reached the "reservoir" only a small percentage was available for use. Jewish settlers in the Asluj Wadi are now trying another experiment of a similar nature. Both these experiments tend to show that, without costly water proofing, it will be difficult to store storm water from winter to summer, although it may be practicable to impound it for short periods.

37. Some night storage reservoirs have been made and used to good advantage for impounding water pumped from wells, or flowing from springs during the night, so that it can be used for irrigation in the day-light. The use of this kind of reservoir is increasing though there are a few cultivators who prefer to irrigate during the cool of the night when there is less evaporation.

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