Contaminant transport in deltaic aquifers: The impact of surface-to-subsurface connectivity
Abstract
Deltaic aquifers are complex systems with highly heterogeneous surface networks and subsurface architecture. Sand-rich subsurface channels in the aquifer are the preserved result of dynamic deposition and evolution of surface river channels. Thus, the subsurface structure may reflect a vertical stacking of multiple channel networks over geologic time which successively translated from the surface network. This spatial geologic connectedness is critical to understanding vulnerability of groundwater resources to contamination. In this study, deltaic systems are generated by numerical modeling (DeltaRCM) to incorporate different rates of sea-level rise and sediment input sand fraction. The aim is to investigate the vulnerability of various aquifers from different types of contamination mechanisms, considering the impact of sedimentary connectivity and depositional environment. Three cases of contamination are considered that are representative of contamination scenarios in the Bengal Basin. In the first case, saline water intrudes into the surface river channels and salt is drawn into the aquifer by surface water-groundwater exchange. In the second case, saline water intrudes laterally from the seaside in the subsurface. Lastly, arsenic transport is considered from shallower to deeper aquifer. By comparing Case 1 to Case 2, we investigate the influence of surface to subsurface connectivity on the vertical and lateral contaminant movement. The comparison of Case 1 to Case 3 focuses on the effect of the surface network on vertical contaminant transport. The results can help researchers better understand the vulnerability of deltaic groundwater systems.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMEP21D2237X
- Keywords:
-
- 1824 Geomorphology: general;
- HYDROLOGY;
- 1825 Geomorphology: fluvial;
- HYDROLOGY;
- 1861 Sedimentation;
- HYDROLOGY;
- 1862 Sediment transport;
- HYDROLOGY