Floodplain Morphology And Relation To The Spatial Distribution Of Arsenic In The Aquifers Of Matlab, Southeastern Bangladesh

Landforms comprising the older and younger flood plains (OFP & YFP) in Meghna basin surrounding Matlab, southeastern Bangladesh have been identified through the visual interpretation of Google Earth images. The interpretation reveals that the visually identified OFP and YFP are characterized by different geomorphic components. The fluvial geomorphology shows a close relation with the distribution of arsenic (As), manganese (Mn) and iron (Fe) in groundwater from the aquifers. It was interpreted that the fluvial processes which results the landforms in the active floodplain influence the groundwater As occurrences. Less active processes in the stable and well developed OFP decreases the risk of elevated As in groundwater. The off-white and white sand aquifers of the OFP are contended with low levels of As (<50 mu g/L) but high levels of Mn and Fe, whereas the off-white aquifers of YFP are contended with high levels of As (>50 mu g/L) and Fe but low levels of Mn. Thus, the landforms can be taken into consideration before installing tubewells in a floodplain area.