Developing GIS tool to indentify critical areas for drinking water supply during dry season in Dinajpur district

Abstract

Huge drawdovm of the groundwater tahle is one of the environmental hazards due to large scale groundwater withdrawal during dry period. Hand tube wens (HTWs) and shallow tube wells (STWs) operated under gra~itational foree, arc the main supplier of drinking water in rural area~ may be dry out due to excessive drawdown, This worst condition of drinking water supply in rural areas has been found in the northwest part of Rangladesh, namely in Dinajpur dismet. Therefore, this study was conducted to identify the areas within Oinajpur district where groundwater goes under a certain level of safe yield from which water cannot be withdrawn with hand tube wells. A maximwn of 6m depth to groundwater table from ground surface has been considered us the safe yield limit to ensure the drinking water supply in the study area through HTWs and STWs with full operational eft1eiency. The existing groundwater table of the study area has been analyzed from different groundwater observation wells of BWDR Jur the last available nine years' data. Three interpolation methods available in GIS namely, inverse distance weighted (lOW), rhin-plate Spline and Kriging have been tested \0 construct groundwdter level surface from the observation well data. Among this three interpolation methods, Kriging with ordinary linear semi-variance model has given the most accurate result when a few number of groundwater observation well data available. "lhis study showed that the most of the critical areas lie in Biral, Dinajpur Sadar, Kaharole and Khansama upazilus of Dinajpur dismct where armual groundwater level fluctuation is in the range of 4.0m to Il.Om. Rochagonj, Birganj and Chirirbandar upazilas of Dinajpur district have been found us negligible "Titical areas where annual groundwater level fluctuation varies from 1.5m to 6.5m. This ~tudy also developed some customized tools using Avenue scripts (built in object-oriented programming language) in ESRl's ArcView CIS 3.2 !\Oflware ""ith Spatial Analyst 2.0 exten~ion to make tbe delineation of water scarce areas easy for different time on the basis of available data.