A STRATEGIC APPROACH TO SCALE-UP SAFE WATER ACCESS CONSIDERING HYDROGEOLOGICAL SUITABILITY AND USING SOCIAL ASPECTS IN MATLAB, SOUTHEASTERN BANGLADESH

Despite a significant progress in our understanding of the source and distribution of arsenic (As), its mobilization through sediment-water interactions, there has been limited success in mitigation attempts in Bangladesh. A social survey conducted by the KTH initiated project on Sustainable Arsenic Mitigation (SASMIT) during 2009-2011 in 96 villages in Matlab revealed that only 18% of total tubewells provide safe water. Among these, the safe water access also varied widely (between 0 and 90 percent) due to placement of wells with inadequate knowledge of local hydrogeology and unplanned development. This study has developed a method for safe tubewell installation considering hydrogeological suitability, safe water access and other relevant social information.

Piezometers installed at 15 locations over an area of 410 km², using local boring techniques allowed to delineate the hydrostratigraphy, characterize the aquifers in terms of sedimentary properties and water chemistry, hydraulic head distribution, which ultimately led to the identification of the aquifers suitable for tapping safe groundwater using local technology. The piezometer locations with safe drinking water quality were then targeted and considering safe buffer distances, clusters of villages (mauzas) were intervened for safe tubewell installation. Social mapping of all the villages within the mauzas were done using GIS to evaluate the availability of safe water options for all clusters of households (bari). For safe well installations, priority was given to the baris with no/poor safe water access, greater number of beneficiaries especially poor households, and easy access to the tubewell site from all households of the respective cluster. Following this method, it was thus possible to make 95% of the newly installed wells As-safe and scaled up the safe water access in some mauzas even from 0 to 40 percent.

As a strategy to improve safe water access, this study recommends investigating the hydrogeological suitability through installation of a few piezometers with a minimum effort and based on the results the implementation plan can be made using GIS based social mappings for relatively uniform distribution and to maximize the safe water access.