Assessing the hydrogeological potential of shallow coastal cheniers in Suriname.

Cheniers are sandy or shelly sediment ridges that are formed, often parallel to the shore, on silty and clay-rich coastlines. We will investigate Chenier plains in Suriname’s low-lying coastal region to quantify their hydrogeological potential to function as a medium for sustainable drinking water supply and irrigation in rural areas, where people lack access to reliable water supply for now and in the future.

In the study area, the cheniers are of Quaternary age and occur as elongated sandy depositions surrounded by clayey swamps and tidal deposits (Augustinus, 1989; Groen 2000,2002). Substantial research has been conducted on the depositional environments, formation processes, and internal structure of cheniers, but large knowledge gaps remain regarding their hydro(geo)logical potential. Previous hydro(geo) logical investigations indicate that the saline groundwater originally entrapped during deposition, has been completely flushed out through sustained recharge from abundant precipitation. This study will therefore focus on understanding the hydro(geo)logy of the cheniers in the study area. We will investigate to what extend cheniers interact with underlaying stratigraphy and surrounding sedimentary layers, the relationship between the geomorphology and their water bearing capacity, and the current groundwater quality.  Additionally, we will determine the impact of climate variability, climate change and groundwater extraction on chenier groundwater availability and quality.   

We will use hydrogeological and geophysical methods (electrical resistivity and electromagnetic methods) to characterize the subsurface by understanding their hydrogeology and groundwater occurrence in relation with geology and depositional environment. We will install piezometers to monitor groundwater levels and hydraulic heads variations and to assess the impact of seasonal changing weather conditions on recharge and groundwater levels, while water samples will be collected to assess water quality and determination of the chemical composition of major ions and stable isotopes. In addition, we will take chenier sediment samples  to determine hydraulic parameters together with pumping test analysis.

We will use the field data acquired to develop conceptual and numerical models for the study area mimicking groundwater flow and salinity patterns within and around the cheniers. We will make projections of groundwater availability and quality under future groundwater extractions, sea level rise and climate change scenarios. The variable-density groundwater flow and salt transport model will also be used to evaluate different management scenarios in order determine management practices for protection and sustainable groundwater use of the cheniers containing freshwater lenses.