Past and future evolution in the Thames Estuary

Abstract

In order to manage estuaries effectively, it is important to be able to predict how they are likely to change in the future, both to natural and anthropogenic forcing. This paper looks at historical morphological development of the Thames Estuary, taking into account the effect of human intervention, and uses the ASMITA morphological model to predict the long-term evolution of the estuary into the future, assuming either historic rates of sea-level rise or accelerated sea-level rise. The historical sediment budget for the Thames Estuary was examined and source and sink terms, including fluvial sediment supply and historical dredging rates, were included in the ASMITA model. ASMITA predictions showed good overall agreement with the historical data, highlighting the benefits of detailed historical review and the inclusion of anthropogenic effects in the model. Future ASMITA predictions for the period 2000 to 2100 suggest that, under both historical and accelerated sea-level rise scenarios, the estuary will experience accretion, but, for the accelerated sea-level rise scenario, accretion will be at a slower rate than sea level rise. With accelerated sea-level rise, intertidal profiles were predicted to be up to 0.5 m lower with respect to high water.