Author(s): Sun Yan Evans; Don Moore; Patrick Butcher
Linked Author(s):
Keywords: LIDAR; GIS; Floodplain; Modelling; Flood risk mapping
Abstract: Floods are natural, sometimes disastrous, events that can threaten life, damage property and disrupt communications. Over 10% of the total land area of England and Wales is at risk from extreme flood events. Even where there are defences, flooding can still occur due, for example, culverts becoming blocked and defences being breached. Section 105 of the UK Water Resources Act 1991 and Department of Environment (Do E) /MAFF joint circular 30/92 (Circular, 1992) seeks to limit development and/or settlement in ‘flood risk zones’. The new Planning Policy Guidance Note 25 (PPG25) (DTLR, 2001) for England and the Technical Advice Note 15 (TAN 15) (Welsh office, 1998) for Wales on Development and Flood Risk require the Environment Agency to provide information to local authorities about the extent of floodplain and other information for assessing flood risk. This ensures that the Environment Agency is brought into the consultative process for any proposed developments within or impacting on floodplains. The Environment Agency has established a programme to produce flood risk maps for England and Wales. These maps are being used to help curb inappropriate development in flood risk areas, and to help reduce the risk to life and damage to property from a flood event. Web-based indicative flood risk maps covering England and Wales are now available to help property owners assess their vulnerability to flooding. The floodplain extents are presented against a backdrop of Ordnance Survey maps at a scale of 1:10,000. A backdrop of Ordnance Survey maps at1:50,000 scale is being made available to the general public. The site uses postcodes to identify specific areas. These are the first flood outlines published anywhere in the world to offer this level of detail with complete coverage for England and Wales. This paper gives the background to, and details of, flood risk mapping and means of controlling development affecting floodplains in England and Wales. It describes the relevant techniques used in acquiring topographic data. In particular, the application of remote sensing techniques in acquiring large scale detailed topographic data is discussed. Tools, techniques and procedures used in estimating flood levels, generating flood risk maps and flooding databases, particularly the application of GIS techniques are described. Mott Mac Donald is one of the consultants responsible for the production and delivery of flood risk maps and associated hydrodynamic models linked to cartographic bases under a three year framework agreement with the Environment Agency of England and Wales.
Year: 2002