WATER RESOURCES DEVELOPMENT AND MANAGEMENT RED SEA STAT

Abstract

ABSTRACT This Ph.D. thesis integrates geological. remote sensing. geophysical, climatological and hydrogeological studies, to investigate the hydrogeological situation in the central Red Sea State. This area is considered to be one ofthe most gro\ving areas in Sudan, in which the two main ports ol“Sudan are situated. Port- Sudan and Sawakin. The geological studies are concerned with the rock types, of both basement and sedimentary origin, and their related structures such as faults, fractures and joints which affect the amount and quality ofground\vater. The geological studies. done by use feld measurements, rock sample analysis and mapping. For remote sensing studies the land-sat TM and MSS were used to detect target areas for \vater exploitation projects. by determining the geological setting, topographical features and drainage pattern. lt is evident that these integrated study techniques are useful reconnaissance method for \vater resources studies. The geophysical investigation method applied in this study is the electromagnetic method (EM). which gave good results in determining sediments thickness and the basement conliguration at the target areas. including the Lower, Middle and Upper Gates of Khor Arbaat and at the proposed dam sides at Khor Mog and Khor Salalab. The climatological and hydrological studies included the collection ofdata on elements. precipitation, evaporation, humidity. temperature and stream runoff, which effect the \vater budget. From these studies the total annual precipitation in the study area is found to be ofabout 900 million cubic metres. where the average annual precipitation in the study area is about I20 mm. Most ofthis amount of \vater lost by evaporation which is calculated in average to be of M00 mm/year. Other loss ofthis amount of \vater is found to be due to surface runoff. the groundwater storage in fractures and weathering zones or in Alluvial sediments. ' The hydrogcological studies were done only in the Alluvial sediments ofthe Khor due to the lack ofthe boreholes in the other lithological units for pumping test. The variation in hydraulic conductivity and storage capacity is due to the heterogeneity ofscdiment types, which is range from 2.60xl0'3 m/s to 2.35xl0'1 m/s in Khor Arbaat, from 6.52xl0'4 m/s to 3.06.\l0" m/s in Khor Saloum and ofabout 2.70xlO'3 m/s in average in the Coastal Area. The water level fluctuated due to the recharge and discharge in the basin, the water table rises during the summer and winter rains in the study area, \vhere it reached the lo\vest value in the dry period during June and .luly. The storage capacity of Khor Arbaat calculated to be of about 22 million cubic meters, the annual recharge by the flood is ofabout l2 million cubic meters. The groundwater recharge as underground flow at the Upper-Gate is of about 365 x103 m3/year. The total annual discharge as underground flow at the Lower-Gate is 455xl03m]/year. the discharge due to pumping from Khor Arbaat basin ofabout 4.5x IO“ m3/year in average. The total needs for potable water estimated by Water Authority at Port- Sudan to\vn is 60.000 mi/day. The available water supply is 30.000 ma/day from Khor Arbaat (l5.000 ml/day from surface-\vater and 15.000 m3/day from groundwater). Additional \vater supply can be possible: where of about 30,000 m3/day can pump liom the groundwater resources in Khor Arbaat instead of l5.000

,/_ m3/day. Of about 30.000 m3/day can pump from Khor Saloum in case that the groundwater resources 01' Khor Saloum used only lbr domestic purposes. By surface- water harvesting can safe considerable a mount of potable \vater for human needs. using local l-lafirs and earth dams. From the \vater chemistry the ions of Na“, Cl", SO4'2 are the dominant ions. The amount of these ions in water and the total salinity increases toward the Sea. which indicate the mixing of Sea water at the coastal area. From the rock geochemical analysis recognised that the source of salinity is mainly due to the transportation ol'chemical ions by the \vind from the Sea Coast to the recharge areas, and not due to the rock weathering in the drainage basins. ' . According, to the TDS values in water, water resources can be classified in to ls‘. Class water type of TDS< 1000 ppm. Used as drinking water, 2"“ Class water type ofTDS value from I000 to I500 ppm. use for agricultural purposes and 3'“ Class water type of TDS > I500 ppm. use for other purposes such as flushing. cooling. etc.