Modeling the effect of climate change on suspended sediment load and sediment resuspension in an urban river

Suspended sediment remains a major challenge for environmental system modeling due to its non-point source feature and complicated transport regime and it has rarely been investigated under the climate change context. This study uses a watershed hydrology and sediment yield model (GWLF) and a hydrodynamic and sediment transport model (WASP) to estimate suspended sediment load and bed material resuspension for the Aberjona River, MA and predict changes in response to variations in future climate. Depending on climate scenario, mean annual suspended load change between -2% to 19% from current level (1950-1999) is found for the Mid-century (2030-2059) and -8% to 18% for the end of the century (2070-2099) while mean annual sediment resuspension is projected to increase by 8% to 52% in the Mid-century and 2% to 89% by the end of the century. Mean monthly suspended load is modeled to change by -87% to 140% for the Mid-century and by -87% to 164% for the end of the century. Change in monthly resuspension varies from -99% to 237% and -100% to 342% for the two scenario periods respectively. The increase of suspended sediment load corresponds to the increase of surface runoff due to more rainfall but higher evapotranspiration caused by warming trend counteracts it. Sediment resuspension is significantly intensified under more frequent occurrence of extreme high flow condition.