From oil to water

Providing drilling services and geological interpretations from diverse environments is one of the joys of a career in geosciences. From marginal marine Permian rocks, Cretaceous Chalks, Paleogene – Neogene clastics and Holocene Delta sediments a story unfolds with every sample analysed.

My recent work in the southwest of Bangladesh has been focusing on the risks faced by local communities from increasing salinisation of water resources in the region. The residents of the delta, faced with poor quality drinking water, turned to groundwater – only to be confronted by problems with arsenic and in some regions elevated salt content in the water.

Whilst arsenic screening of groundwater is a priority in the region, the local population now face the threat of increasing salinity in both groundwater and surface waters. Salinisation is driven by a complex set of environmental processes including sea-level rise, decreasing river discharge and the occurrence of cyclone induced storm surges – which force saline water from coastal regions further inland and in extreme cases cause widespread flooding.

Human activities, designed to improve the stability of the delta and enhance wellbeing and quality of life, frequently result in undesirable side-effects. The mighty rivers are cut off from the plains which require the sediments, deposited during the annual floods, to replenish nutrients, maintain elevation and flush excess salts from the rich floodplain soils. Embankments constructed to prevent catastrophic flooding now funnel high tides further inland, bringing more brackish and saline water further into the delta.

The result is less freshwater availability, lower crop yields, increased health risks, higher internal migration and a switch from agriculture to aquaculture. Working with a local team we are investigating the dynamic process of salinisation to provide the scientific basis for policy development.

Local percussion drilling techniques enable wells to be sunk to over 140′