Flood risk management

Chapter 3. Globally, floods are the most common of all natural disasters. They lead to loss of life, extensive disruption and major economic impacts. Flood risk is expected to increase in the future because of changes in extreme weather patterns caused by long-term climate change. According to the UN Office for Disaster Risk Reduction, India has experienced an average of 17 floods per year over the period 2000 to 2019, affecting approximately 345 million people (UNDRR 2020). Estimating the risk and severity of floods both now and in the future is vital for the design and management of infrastructure such as flood management schemes, dams, hydropower projects and irrigation systems. Flood frequency estimates are also a key source of information for flood risk maps and insurance applications. The key challenge is closing the gap between research and practice in design flood estimation in India. This chapter introduces new statistical and modelling techniques for generating spatially consistent flood frequency estimates, moving away from simple regional equations. These new techniques are flexible, robust, and can easily be applied to local data. A particular advantage of the combined approach is that it has the potential to incorporate projected changes in climate, and thus to establish the likely effects of these changes on flood frequency. Here, the application of these methods to river catchments in the State of Maharashtra is shared, but the approach has the potential for national application in hydrological design and flood risk assessment throughout India.