Research Program

United Kingdom Node:

This node is based at the National Oceanography Centre, Southampton (NOCS). NOCS is a collaboration between the University of Southampton’s School of Ocean and Earth Science and the Southampton-based branch of the Natural Environment Research Council’s National Oceanography Centre.

The focus will be on coastal flooding driven by sea level extremes and how flooding probabilities may change over coming decades as global sea level continues to increase and the intensity of storms may change. Coastal flooding is a major risk threatening the coastal zone. As flooding is caused by the combined action of tides, storm surges and waves in overtopping coastal defenses, an understanding of the modification of each of these parameters as well as their interactions is needed to obtain reasonable estimates for engineering and environmental purposes. Change in mean sea level is an additional varying parameter that increases the risks and will make overtopping more probable and probably longer lasting. The mean sea level changes will most probably be dominated by mass addition from melting ice sheets and steric expansion but both these processes are expected to be spatially variable and linked with changes in oceanic circulation and the associated currents. Obtaining reasonable estimates of future changes requires an understanding of the uncertainties in the predictions of mass and steric contributions over coming decades. Even where climate change does not cause intensification of storms, shifting weather patterns are likely to lead to measurable changes in extremes.

The Channel Coastal Observatory (CCO), based at the NOC, operates a network of shallow water wave buoys and maintains an extensive archive of coastal monitoring data for southern England, much of which is highly managed and vulnerable to coastal flooding. The CCO operates on behalf of the maritime authorities responsible for management of coastal flooding and erosion and, hence, are primary end users for the results of this type of research. The observations include long-term records of beach change and incidents of coastal overtopping and flooding; they can be used both for calibration and validation of coastal surge models.

The UK node will focus on the following aspects of the coastal flooding problem. It will assess the impact on the skill of surge forecasts made using forecast winds from new coupled models being developed by the Canadian and Australian nodes. This will be done using a coastal surge model driven by wind forecasts from the coupled models. In the case of the Canadian model, ensembles of forecasts will be used. The research will focus on two sensitive areas (although the methodologies developed will be applicable to other areas). The first area will be the south coast of the UK and the work will be carried out in collaboration with the CCO and the Canadian node (ensemble weather forecasts); the second area will focus on the coastline of China with the collaboration of the Australian node (e.g., tropical cyclone forecasting).

The uncertainties in flooding events due to changes in the intensity and trajectories of storms will further be elaborated by combining it with various scenarios of climate change reflected in different sea level rise, as well as possible alterations of the tidal signal (a potentially significant effect). Thus we will establish comprehensive range of the risk faced by the coastal areas, taking into account tidal changes, sea level rise and changes in local storm surges. The development of the appropriate methodology is also an important product of this process.

Professor Michael (Mikis) Tsimplis is the leader of this node. Professor Tsimplis holds a joint appointment at the School of Law of the University of Southampton and also the National Oceanography Centre at Southampton.