05 Dec 2022
05 Dec 2022
Status: this preprint is currently under review for the journal ESurf.

Impacts of Human Modifications on Material Transport in Deltas

Jayaram Hariharan, Kyle Wright, Andrew Moodie, Nelson Tull, and Paola Passalacqua Jayaram Hariharan et al.
  • Department of Civil, Architectural and Environmental Engineering, Center for Water and the Environment, University of Texas at Austin, Austin, Texas, USA

Abstract. As humans continue to inhabit and modify river deltas, the natural processes governing material transport through these landscapes are altered. Two common engineering projects undertaken on deltas are the dredging of channels to enable shipping and the construction of embankments to reduce flooding. While the impact of these topographic modifications has been studied at a local-level for specific sites, there is a gap in our generalized understanding of how these landscape modifications impact material transport. To narrow this gap, we conduct exploratory numerical modeling to develop deltaic landscapes with different input sediment compositions, modify their topography to mimic dredging and embankments, simulate different flow conditions, and then model the transport of passive particles. We find that human modification of topography lowers hydrological connectivity by reducing the area visited by fluvial inputs. The amount of time particles spend within the delta is reduced by the construction of polders and is lengthened by dredging. Material buoyancy has a greater impact on nourishment areas and exposure times than flow regime or topographic modification, with positively-buoyant particles spending longer and visiting a greater area of the delta than neutral and negatively-buoyant material. The results of this study can help guide the design of future engineering projects by providing estimates of their likely impact on transport processes.

Jayaram Hariharan et al.

Status: open (until 16 Feb 2023)

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Jayaram Hariharan et al.

Jayaram Hariharan et al.


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Short summary
We simulate the transport of material through numerically simulated river deltas under natural and human-modified (embankment construction and channel dredging) scenarios to understand their impacts on material transport. Human modifications reduce the total area visited by passive particles, and alter the amount of time spent within the delta relative to natural conditions. This work can help us understand how future construction may impact land building or ecosystem restoration projects.