Bongaigaon district is situated in eastern most part of Assam and on the southern bank of Brahmaputra. Bongaigaon district of Assam covers a geographical area of 1093 sq. km and lies between 26˚ 09΄ 52˝ and 26˚ 30΄ 03˝ N. Latitudes and 92˚ 22΄ 47˝ East longitudes. The district is bounded on the North by Chriang and North West by Kokrajhar district on the East by Barpeta district on the South west by Dhubri district. The Brahmaputra River flows through the southern boundary of the district. Bongaigaon has been subdivided into five 3 administrative development blocks namely Dangtol, Boitamari, Manikpur, Srijangram, Tappatary. Study area represents two distinct physiographic division viz. (a) flood plains of Brhamaputra River and (b) Denudational hills of Archean age. Bongaigaon district is a part of the northern extremity of the Shillong Plateau. The present area of study forms part of the vast alluvial plains with gentle rolling to pography of the Brahmaputra basin. It is bounded by Brahmaputra River in the south to the north the piedmont zone and to the southwest pediment inselberg complex. It has been observed that the aquifer disposition changes from north to south of the district. In the north eastern and northern fringe of the district exploratory tube wells drilled down to the depth of 100 m shows mono aquifer system. The granular zones comprising of fine to coarse sand associated with gravels occurs at the depth varying from 10 to 100m explora tory tube wells drilled in the younger alluvium at Gerukabari, Aolaguri, Bongaigaon refin ery shows the dominance of coarse sand and gravel zones .