Flood risk management is a devolved responsibility and this answer relates to England only. Changes in the way land is used can impact on the speed and volume of flood water run-off. However, deforestation is not a significant factor increasing flood risk in England.
There has been research on the impacts of woodlands and forestry on flood run-off. Mature forests can reduce the rate of run-off. New plantations can in fact increase it though this can depend on the nature of any drainage infrastructure installed in connection with them. Evidence to date suggests that, while there can be a significant impact on smaller flood events at the local scale, effects are likely to be much less for more extreme floods at the wider catchment level.
The developing cross-Government Flood and Coastal Erosion Risk Management Strategy, “Making Space for Water”, promotes a whole-catchment approach to flood alleviation, drawing on opportunities provided by rural land use and land management practices.