This project will employ LiDAR and CASI image analysis to determine the structural properties of woody vegetation on floodplains, in order to develop physical parameterizations of flow resistance by vegetation. This approach will offer improved spatial characterization of floodplain friction for the new generation of distributed hydraulic models, allowing enhanced estimation of inundation area, velocity and depth of floodwater. LiDAR is an important source of information for floodplain studies and has recently been applied to map floodplain roughness using simple object height models. This project aims to progress this, using dual-pulse altimetry and morphological filtering to identify individual trees, determine their height, canopy diameter and stand density. Allometric and fractal models will then be used estimate trunk diameter and vertical physiology, enabling the identification of transfer functions to predict frontal area and spatial drag coefficients. CASI data analysis will be used to classify plant species, allowing different transfer functions to be developed for different functional physiologies. Sensitivity analysis using 2d finite element and raster hydraulic models will then be used to evaluate different model structures. The project will develop an existing collaboration with experts at Toulouse and Clermont and will study sites on the Garonne and Allier rivers that have an unrivalled data context.