Shallow aquifers in the densely-populated areas of the Indo-Gangetic plain are severely polluted with arsenic (As). The occurrence of As and its spatial concentration variability are conditioned by the geomorphological setting of the Holocene floodplain, with the highest concentrations in elevated point-bar surrounded by clay-filled oxbow lakes (clay plugs). The work hypothesis is that the As is locally derived from the clay plugs. In this study, the potential As volume in the clay plugs is calculated, and the migration process of arsenic from clay plug to adjacent point bar is studied. Satellite data in combination with a side-scan sonar survey in present-day oxbow lakes, and As concentrations in sediment from a well were used to calculate the sediment volume of the clay plug, the potential volume of As, and the contact area between the clay plug and adjacent point bar, and to estimate the initial diffusion flux of dissolved As from clay plug to the adjacent point bar.