Hydrology & Hydraulic Modelling
River Rea Flood Mapping Study
Keywords: Flood Risk Urban Flooding.
River Rea Flood Mapping Study
Client, & Other Organisations
Scott Wilson
Birmingham City Council
Environment Agency
Description
Edenvale Young Associates Ltd. were commissioned to prepare a Flood Risk Mapping Study in accordance with relevant guidelines for a proposed mixed use development off Deritend High Street, Digbeth, Birmingham. The overall and original aim of this study was to evaluate the flood risks and prepare updated flood risk maps for the site in the vicinity of Connaught Square, Birmingham.
The catchment for the River Rea is a heavily urbanised catchment, with many surface water sewers discharging into the river. The river bed and the embankments are man-made structures, consisting of concrete and brick channels and walls. There are 48 structures in approximately 7 km long river reach.
The project includied convertion of an existing HEC-RAS model into ISIS. The results of these models showed significant differences in the water levels between the two programmes.The level differences reached almost 5 metres downstream of the site and around 4 metres in the site location for the 1,000 year return period. The primary reason reason for the levels overestimation in HEC-RAS was in the high density and schemetasiation of the structures. The structures were reconfigured in ISIS to assess the risk of flooding to the development and it was concluded that there will be no flooding to the roads adjacent to the development for the 1:100, 1:100 plus climate change allowance and 1:1000 year return periods.