Hydro-meteorological risk assessment methods and management by nature-based solutions

Hydro-meteorological risk (HMR)management involves a range ofmethods, such asmonitoring of uncertain climate, planning and prevention by technical countermeasures, risk assessment, preparedness for risk by earlywarnings, spreading knowledge and awareness, response and recovery. To executeHMR management by risk assessment, manymodels and tools, ranging fromconceptual to sophisticated/numerical methods are currently in use. However, there is still a gap in systematically classifying and documenting them in the field of disaster risk management. This paper discusses various methods used for HMR assessment and itsmanagement via potential nature-based solutions (NBS), which are actually lessons learnt from nature. We focused on three hydrometeorological hazards (HMHs), floods, droughts and heatwaves, and their management by relevant NBS. Differentmethodologies related to the chosen HMHs are consideredwith respect to exposure, vulnerability and adaptation interaction of the elements at risk. Two widely used methods for flood risk assessment are fuzzy logic (e.g. fuzzy analytic hierarchy process) and probabilistic methodology (e.g. univariate andmultivariate probability distributions). Different kinds of indices have been described in the literature to define drought risk, depending upon the type of drought and the purpose of evaluation. For heatwave risk estimation, mapping of the vulnerable property and population-based on geographical information system is awidely usedmethodology in addition to a number of computational, mathematical and statistical methods, such as principal component analysis, extreme value theorem, functional data analysis, the Ornstein–Uhlenbeck process and meta-analysis. NBS (blue, green and hybrid infrastructures) are promoted for HMR management. For example, marshes and wetlands in place of dams for flood and drought risk reduction, and green infrastructure for urban cooling and combating heatwaves, are potential NBS. More research is needed into risk assessment and management through NBS, to enhance its wider significance for sustainable living, building adaptations and resilience.