POST FLOOD DRINKING WATER QUALITY ASSESSMENT IN CHARSADDA DISTRICT USING GEOGRAPHIC INFORMATION TECHNOLOGIES

Abstract

Flooding is a regular event in Khyber Pa.khtunkhwa, especially the areas settled along the Rivers. During and after the flood, the main issue is the availability of clean drinking water to the affected community. The floods of 2010 adversely affected the infrastructure, water resources and the population of Charsadda District. Vast majority of flood affected population had no access to clean drinking water and were forced to rely on unsecure and contaminated sources. Keeping in view the severe situation of drinking water quality, a study was developed with the objectives to (a) analyze/map pre & post flood drinking water quality parameters (pH, alkalinity, total hardness, electric conductivity, chlorides, sodium, sulphates, potassium, TDS, total plate count and Coliform Bacteria) and identify suitable drinking water sites/sources. For this purpose, pre and post event satellite remote sensing data (Landsat ETM+ 2001 and GeoEye-1 2010) and DEM were used to map and extract flood extent, land covers and topographic information of the study area. Similarly, post event water samples were collected from various sources within and outside the flooded area. Lab tests were performed and water quality parameters were compared with Pakistan Council for Scientific & Industrial Research (PCSIR) standards. Department of Environment (DOE) classification was used for developing the Water Quality Indices. These results were compared with the pre:.event lab results for the same points in the study area and analyzed with PCSIR standards. Water Quality Index based on the chemical parameters revealed no change for alkalinity, chlorides, hardness and sulphates. Sodium and pH shows an improve condition, but the rating of potassium, TDS, total plate count and coliform bacteria have deteriorated. Comparison with the PCSIR standards reveals that the water becomes totally unfit for drinking purposes due to plate count and Coliform bacteria in part of Charsadda District. These parameters were overlaid on flood extent map showing that not all the contamination was due to flood water but samples outside flood plain also had values exceeding the permissible limits. Water quality maps were generated showing classes as most suitable, moderately suitable and unfit for drinking, as well as for suitable sites for clean drinking water.