HIMALAYAN WASTE MANAGEMENT: SEA-LEVEL RESPONSES TO SEDIMENT EROSION AND DEPOSITION IN THE INDUS RIVER BASIN AND THE NORTHEASTERN ARABIAN SEA

Sea level is of wide interest because it is a sensitive recorder of interactions between climate, tectonics, and surface processes, and because changes in sea level are instrumental in driving Earth’s topographic evolution. On thousand-year timescales, sea-level variations are strongly affected by spatial and temporal variations in surface loads, including the redistribution of sediment from continents to the seafloor. In this work, we use a gravitationally self-consistent sea level model to compute sea level responses to sediment erosion and deposition from 122 ka to the present in the region surrounding the Indus River, which has one of the highest fluvial sediment fluxes on Earth. The model requires input histories of ice and sediment loads, and it calculates sea level responses from the resulting deformational, gravitational, and rotational perturbations in the Earth’s form. Our modeling suggests that sediment erosion and deposition in and around the Indus basin are capable of producing meter-scale changes in sea level near the Indus delta over timescales as short as a few thousand years, and that these responses grow larger over time as sediment transfer continues. Perturbations of this size are significant in the context of studies of ice sheet stability, given that the modern Greenland and West Antarctic ice volumes hold the equivalent of about 8 and 5 m of global mean sea level change, respectively. This implies that any existing paleo-sea level markers older than a few thousand years near the Indus delta will be significantly warped by sediment transfer, and that such deformation will need to be corrected for in studies that use local paleo-sea level markers from this region to infer paleo-ice sheet volumes. This analysis highlights the role that fluvial sediment fluxes can play in driving sea-level changes over millennial timescales from the Indus River, and, by implication, from other rivers with large sediment fluxes.