This paper builds on the ‘Flooding from Other Sources’ project (HA4a), funded as part of Defra's Making Space for Water strategy. The HA4a study concluded that flood risk mapping is feasible for many of the sources of flooding that were investigated, which are not currently covered by the Environment Agency Flood Map, using existing flow modelling and GIS tools. However, there are some major constraints in terms of the need to undertake extensive data collection to allow the generation of useful flood maps that are not dominated by modelling uncertainties. The project anticipated that different levels of data collection and modelling might be needed for different purposes, given the hierarchical nature of UK flood risk assessment and management in the United Kingdom under PPS25 and the EC Floods Directive. This paper compares and contrasts three different approaches to urban flood modelling using topographic analysis, blanket extreme rainfall and semi‐coupled sewer/overland routing. The UK summer floods 2007 have highlighted the pressing need for mapping the risk from urban flash flooding, and the Pitt Review has recommended that areas at high risk from surface waters should be urgently identified. This can be done now at some level of detail, and we can be guided as to what level, from our increasing knowledge of vulnerable populations, from records of historical flooding and by using some of the screening methods described herein.

This paper describes two projects requiring production of national floodplain maps for England and Wales -some 80,000 km of river. The novel solutions developed have brought together a national Digital Elevation Model (DEM), automatically-generated peak flow estimates at intervals along the watercourses and two alternative methods of calculating the outlines: normal depth calculation; and a purpose-built 2-dimensional raster-based floodplain model, JFLOW. The DEM was derived using Interferometric Synthetic Aperture Radar (IFSAR) techniques and has a vertical precision of ±0.5 m-1.0 m (RMSE) and a 5 m horizontal resolution. The flow estimates were derived by automating Flood Estimation Handbook (FEH) techniques. The normal depth calculations are applied at a number of discrete cross-sections with linear interpolation between to form a 3-dimensional water surface. This is overlain on the DEM to produce the flood outline. Careful manual checking is required at a number of stages. The JFLOW model is based on a discretised form of the 2-dimensional diffusive wave equation and directly simulates the flood outline in a series of overlapping short (1 km) reaches. Flood outlines from the overlapping reaches are merged to produce the overall flood envelope. The model has been written to work as a screen-saver, allowing distributed processing across all computers in an office and manual intervention is minimal. In simple valley situations both methods give similar results, but show differences in more complex areas. Each has advantages and disadvantages, but both have been shown to be a practicable solution to allow production of 160,000 km of flood outline in 12 months.

This paper discusses the effects of climatic change on plant diseases, which include altered geographical distribution of host and pathogens and changes in physiology of host-pathogen interaction due to elevated CO2 and increased ozone and ultraviolet B. Modelling approaches used to determine the effects of weather factors and/or varying atmospheric composition on the physiology of host-pathogen interaction are mentioned.

A novel approach to consider local‐scale defence infrastructure in an urban environment, coupled with a broadscale hydraulic model framework, is applied to the capital city of Kuala Lumpur, Malaysia. Broadscale hydraulic modelling frameworks are often able to employ more complex models, but are typically limited to homogenous decision‐making to ensure standardised outputs across large regions. Conversely, small‐scale hydraulic modelling frameworks tend to better integrate local‐scale features but can be computationally expensive to scale up beyond a regional view. Improvements to the broadscale hydraulic model framework through the incorporation of defence systems yield a more accurate representation of fluvial flood risk. This study incorporates defences in Kuala Lumpur, yielding a reduction in our estimates of fluvial flood extent by around 40%. The results of this study are validated against a set of high‐quality observations, demonstrating the capability of the model framework in capturing flood risk in more than 95% of known flood risk zones in the city. Incorporating defence infrastructure using data‐driven decision making and existing functionality in the hydraulic model could be automated in future model builds. This new approach bridges the gap between local‐scale model frameworks and the broadscale, homogenous 2D hydraulic modelling studies.

Flood defences play a central role in the quantification of flood risk. JBA Risk Management produces undefended hazard maps that are supplemented with defence information to provide risk practitioners with the most flexible view of risk. This requires knowledge of the locations of river defences so that they can be removed from the digital terrain models prior to flood modelling. We report on work to develop a predictive model for identifying river defences. This model was created using the U-Net deep neural network for image segmentation. The model was developed over a series of iterations, where the prediction outputs were refined and used to retrain the model. We have used this model to produce national maps of defences for a range of countries.