Non-renewable groundwater resources: a ... - unesdoc - Unesco

CHAPTER 5 ■ REGIONAL CASESTable 1 shows the calculated storage capacity of the total Nubian Aquifer System (NAS) inboth its unconfined and confined parts, within the four sharing countries, exceeding520,000 km 3 . The groundwater resources of the Nubian Aquifer System are not all fresh groundwater.The water quality, as measured by its total dissolved solid content, changes from excellent(500 ppm) in the southern part of the system to hyper saline in the Northern part (CEDARE,2002). Eliminating this hyper saline water, the total volume of fresh groundwater in storage isapproximately 373,000 km 3 .Table 1. Total recoverable fresh groundwater volumesfrom the Nubian Sandstone Aquifer System (NSAS)AQUIFER UNCONFINED PARTArea Saturated thckness Volume in storageREGION (km 2 )(m)(km 3 )Egypt 311,861.87 838.5 52,299.24Libya 350,732.68 1786.4 125,309.77Chad 232,977.04 1026 47,806.89Sudan 373,102.44 454 33,877.70Total — — 259,293.60AQUIFER CONFINED PARTAll occurrencePart with saline waterREGIONArea(km 2 )Saturatedthickness(m)Water *volumein storage(km 3 )Area(km 2 )Saturatedthickness(m)Water *volumein storage(km 3 )Volumeoffresh waterin storage(km 3 )Egypt 503,813.93 1,498.8 151,023.26 128,793 1,887 48,606.48 102,416.78Libya 403,356.88 1,407.48 113,543.35 350,835.24 1,458 102,303.56 11,239.79Chad — — — — — —Sudan — — — — — —Total — — 264,566.61 — — 150,910.04 113,656.57* Based on average formation bulk porosity of 20%REGION Egypt Libya Chad Sudan TotalTotal volume of fresh waterin storage (km 3 )*154,716.02 136,549.56 47,806.89 33,877.7 372,950.17* Total volume of fresh water in storage is equal to the sum of the fresh water in the aquifer confinedand unconfined parts.77