Assessment Of Groundwater Intrinsic Vulnerability Using Gis-Based Drastic Method In Islamabad, Capital Teritory, Pakistan

Abstract

The UN included a target on clean water to its list of sustainable goals in response to the strain on the planet's freshwater resources. This goal aims to address the availability of clean water on a worldwide scale. Groundwater contamination was brought on by the widespread application of fertilizers and the use of wrong dumping sites in the Islamabad. The DRASTIC model, which is based on geographic information systems (GIS), was utilized in Islamabad to assess the groundwater's susceptibility. The vulnerability index of the DRASTIC model ranged from 275 to 900. The values near to 900 indicate more vulnerable zone while the values around 275 showed susceptibility toward the contamination. The area was classified into 5 zones in equal intervals. Among the zones are one with a very low vulnerability spanning 22 km2 or 2% of the entire research region and with a DRASTIC index between 275 and 400. The area covered by the low vulnerability zone index, which varied from 400 to 525, was 306 km2, or 28% of the total area. The moderate vulnerability zone index (525– 650) covered the greatest area, 500 km2, or 47% of the entire area. The high vulnerability index (650 - 775) covered 221 in km2 and 21 in percentage area and the very high vulnerability zone index (775 - 900) covered 26 km2 area indicating 2% of the study area. To verify the DRASTIC indices, a spatial distribution map of nitrate concentration was created. The results of the regression analysis indicate a weak relationship between groundwater vulnerability and the distribution of nitrates in area. It suggests that nitrate is not the contamination's vulnerability source in Islamabad; rather, the nitrate content was comparatively greater in the zone with very high DRASTIC results. Islamabad nitrate concentration ranged from 0 to 2.5 ppm. The index map will function as a foundational study for the establishment of safe zones for groundwater extraction and the control of the current environmental standards' deterioration in this region. The first task towards which should be handled in very high vulnerability areas should be the treatment of the stream from contaminations which are accumulating into the Rawal lake and the use of proper chemical which are not harmful for groundwater in NARC (National Agriculture and Research Center).