Authors: M. Jamaluddin Ahmed1, Sayeda Halima Begum2, Didarul Alam Chowdhury3, Newton Mandal4 M. Zahedur Rahman Chowdhury5
Abstract: Chittagong is one of the major emergent cities in Bangladesh which its area is rapidly increasing as neighboring districts like Rangamati, Khagrachari, Bandarban and Cox’s Bazar. Most of the people are using the groundwater as a prime source for their domestic needs. Assessing the quality of ground water is an essential concern in this new era. The work has been conceded by traveling to the sampling site, collection of required water samples, and estimation of water discharge and determination of basic parameters of the site. The water samples have been analyzed for physicochemical parameters as prescribed by APHA*, using standard techniques and compared with WHO (2014-2015) drinking water quality standards. The ground water quality information maps of the entire study area were prepared by GIS Inverse Distance Weighting (IDW) technique for 26 parameters. GIS technology proved to be very useful for enhancing the accuracy. We obtained the location of the well by using the GPS and Arc GIS software. The IDW was applied to find out the spatial distribution of groundwater quality. In interpolation with the spatial analyst method of IDW, a weight is attributed to the point to be measured. The amount of this weight is dependent on the distance of the point to another unknown point. These weights are controlled on the bases of power of ten. With increase of power of ten, the effect of the points that are farther diminishes. Lesser power distributes the weights more uniformly between neighboring points. In this method the distance between the points count, so the points of equal distance have equal weights. The advantage of IDW is that it is intuitive and efficient. This interpolation works best with evenly distributed points. Similar to the SPLINE functions, IDW is sensitive to outliers. Furthermore, unevenly distributed data clusters result in introduced errors. The results obtained in this study with the spatial database established in GIS was helpful for monitoring and managing groundwater quality and its pollution in the study area of greater Chittagong region and other neighboring districts.
Keywords: Ground water, spatial distribution, physicochemical parameters, drinking water quality, GIS, inverse distance weighing technique
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