Study of the Morphometric Characteristics of Wadi Gaza and Water Harvest Its Upper Course Using Geographical Information Systems (GIS)

This study aimed at using GIS in studying the morphometric characteristics of Wadi Gaza basin. A Digital Elevation Model (DEM) with 30 m resolution (pixel size) was used for topographic analysis. ArcGIS 10.1 with it extentions, and Google Earth were used for some morphometric analysis. The maximum altitude of the basin is 1020m above the mean sea level in the northwestern part of it, while the minimum altitude is -5m below the mean sea level in the lower basin in the west. The highest rank of the wadi is 7 which indicates that the basin lived a long period of its erosion cycle. The total number of wadi attributes for all ranks is 3788, and their total length is 4782 km. The shape of the basin is closer to the rectangular shape, and this reduces the dangers of floods. The difference of altitude between the upper basin and the lower one is 1025m along 132km distance. This proves that the basin of Wadi Gaza is mountainous and rough. Water resources in the upper basin of Gaza basin were divided into two parts: Precipitation and groundwater. Annual precipitation in the southern area is 200 mm, where that of the northern part reached 600 mm. There are 4 wells and 9 springs with limited amount of production. The study suggested 8 sites for constructing dams, and other 6 sites as alternatives, according to a number of parameters derived from Model Builder maps and field work. The runoff of the area is around 15 m m³, and storage capacity is around 7.4 m m³, and this amount of water can develop uncultivated lands in the area.