Hydrology Research In Press, Uncorrected Proof © IWA Publishing 2012  |  doi:10.2166/nh.2012.018

Setting design inflows to hydrodynamic flood models using a dependence model

Duncan Faulkner, Caroline Keef and John Martin

JBA Consulting, South Barn, Broughton Hall, Skipton, UK. E-mail: duncan.faulkner@jbaconsulting.co.uk
Office of Public Works, Jonathon Swift Street, Trim, Co. Meath, Ireland

First received 21 January 2011; accepted in revised form 24 October 2011. Available online 9 May 2012

In setting design inflows to hydrodynamic models of flood flow along rivers, there can be a conflict between site-specific hydrological estimates of flow for a given return period and what the river model calculates as it routes flood hydrographs. This paper describes research carried out as part of the Flood Studies Update programme in Ireland, aimed at developing guidance on how to divide up-river models and set the magnitude and timing of their inflows so that conditions in the model reach correspond to the expected design flood return period. A model for the joint distribution of flood peaks at pairs of catchments has been developed. The relationship between flood return periods is linked to physical differences between catchments. The model thus allows estimation of the statistical distribution of the flood return period expected at one site during a flood of specified return period elsewhere. A separate regression model predicts the relative timings of flood peaks on pairs of rivers. A summary of the resulting practitioner guidance is given, along with an overview of the testing of the method. The paper concludes with a discussion of the potential for application of the spatial dependence model to other problems in hydrology.

Keywords: design event; flood modelling; spatial dependence

Full Text PDF