Hydrological Studies and Groundwater Potential of Islamabad Region.
Third South Asia Geological Congress Lahore, Pakistan.

Islamabad is the capital city of Pakistan situated between latitude 33 29 and 33 49 N and longitude 72 50 to 72 24E bordered by Rawalpindi city in the South and Southeast, Margalla hills in the North and Murree hills in the Northeast. Climatically the area lies in sub-humid region. Annual average rainfall is about 925 mm. temperature ranges between 3 to 40 C. Access to the city is through Grand Trunk Road and Motorway, connected with Peshawar and Lahore. The area is generally an uneven landform covered with alluvial deposits and bedrock outcrops of Miocene Rawalpindi Group (Murree Formation) skirted by Eocene Margalla Hill limestone in the North. The northern mountainous area rises abruptly and appears as Himalayan foothill extension. The area is drained by many perennial streams out of which Korang river, Gumrah Kas, Tanawala Kas, Bedarwali Kas and Lei Nala are the major constituents of drainage system. During rainy season the velocity of water is very fast and these hill torrents due to high relief and slope of the area.

Hydrogeologically, the area lies in Soan River catchment basin in Potwar Plateau formed as part of Indo-Gangetic synclinorium of Tertiary and Pre-Tertiary sediments. Consolidated and unconsolidated deposits exposed in the area are of sedimentary origin and belong to Eocene to Recent in age. The consolidated deposits are mainly composed of limestone, sandstone, clay, shale and conglomerates. These deposits do not serve as aquifer and water travels through joints, cracks and fissures only. Unconsolidated deposits of recent age are found as terrace gravel and alluvial fill.

Groundwater in Islamabad area occurs in alluvial deposits and hardrock deposits. The transmitting capacity of consolidated deposits is very low. Therefore, it can be considered only for small yields for requirement at the places of acute local shortage of water availability. Nevertheless alluvial aquifers are suitable for large scale groundwater development.

In order to locate the sites feasible for exploitation of groundwater, hydrogeological and geophysical surveys were carried out in 1979-80 referred to Hydrogeology Directorate, WAPDA by Capital Development Authority to overcome the acute shortage of drinking water in the capital city. The work was conducted to locate prospective sites by spot investigation in different sectors selected on priority bases fixed by Capital Development Authority. The work was completed in two phases, phase-I included sectors F-10, F-11, G-9, G-10, G-11, H-9 and National Park area and phase-II covered sectors F-8 and I-9. Based on the findings of reconnaissance and geophysical survey test drilling and water sampling from various subsurface horizons at 21 locations were carried out. An aquifer test was also conducted to determine the aquifer parameters. Groundwater samples collected during survey and test drilling were got analyzed from WAPDA laboratory. The groundwater quality is good and suitable for drinking, agriculture and domestic uses. Findings of these studies are summarized in this paper.  

Sajid Rashid
Institute of Geology, Punjab University, Lahore, Pakistan.

Abdul Quddos Khan and Khalid Asghar
Hydrogeology Directorate of WAPDA, Lahore, Pakistan.