Improving coastal flood forecasting services of the Environment Agency

摘要

Preventive flood works are susceptible to overtopping and therefore associated with a residual risk of flooding, during which prime objectives are to save life, minimise damage, reduce disruption to communication lines, mitigate trauma and restore normality. Residual flood risks are managed by provision of information through flood forecasting and warning (FF&W) services for the population at risk of flooding. Lead-time plays a crucial role in the effective delivery of this service. Currently the lead-time is a minimum of 2-hours in England and 1-hour in Wales and the Environment Agency (the Agency) for England and Wales has the lead to provide FF&W services where cost-effective and technically feasible. This paper outlines a review of the Agency's capability on coastal flood forecasting (CFF) and the potentials for improving the lead-time of warning messages. It reports that existing CFF capabilities have normally been based on judgement and empirical approaches, signifying that these services have largely been reactive. An ongoing R&D project is integrating the modelling capability developed by coastal scientists with the wealth of experience gained by the fluvial forecasting community. A potential outcome is a new capability to improve lead-time by detecting the impending incidents, not from the water level at the coastlines alone but, with an insight into the whole processes of the sea-state. This paper outlines best practice in terms of the following elements: 1. Modularisation of the service into separate processes with well defined interfaces. 2. Seeking generic definitions for accuracy, timeliness and reliability. 3. Categorisation of modelling techniques and physical systems. 4. A risk-based and defensible approach to selecting a modelling solution. 5. Integrating FF&W services to other flood management measures.