An assessment of the impacts of multi-risk weather-related hazards in India from 1970 to 2025

Impact-based Forecasts and Warnings (IbFWs) are used to convey the likelihood of impacts associated with different hazardous weather conditions. Generally the appraisal of impacts is made on a hazard-by-hazard basis and does not always consider the interplay between different hazards, assets and societal groups, or the cascading risks that can occur. This has the potential to lead to inaccurate assessments of the risk associated with extreme weather events. Often the predicted impacts are underestimated because the multi-risks posed by multiple hazards occurring together or in quick succession, as well as the indirect impacts, are not accounted for. This work builds on international collaboration through the UK Met Office’s Weather and Climate Science for Services Partnership (WCSSP) India programme, which supports the development of improved impact-based forecasting capability for weather-related hazards.

The development, assessment and validation of multi-risk IbFWs is constrained by the lack of suitable impact data. In India, IbFWs have been developed, however, impact data for weather-related hazards are available from different and diverse sources, whilst the data vary in their intended end uses, formats and methods of collection. The Indian Meteorological Department’s (IMD) records of impacts from historical events are limited to single events, without recording multi-hazard contexts, making it challenging to relate impacts to multi-hazard events. Using global, open-access datasets such as the EM-DAT international disaster database (Lee, 2024) and the new MYRIAD Hazard Event Sets derived using an algorithm which identifies ‘clusters’ of natural hazards (Claassen et al, 2023), we assessed the bias in impact data and showed how combining diverse sources can significantly improve data quality. Using the guidelines from Smith (2015), impact data for multi-risk, weather-related hazards in India have been collated, reformatted and verified creating a robust impact dataset for developing, assessing and validating IbFWs. This new database records, for the period 1970 to 2025, the impacts of multi-hazard events in terms of:

• Primary impacts: Deaths, missing, injured, affected people, and economic losses;
• Secondary impacts: Displaced and evacuated people, buildings damaged and buildings destroyed;
• Tertiary impacts: Damage to critical infrastructure such as hospitals, schools, public buildings, roads, as well as to agriculture, and the costs of relief.

The database also records metadata such as event timeframe, location, GLobal unique disaster IDEntifier (GLIDE) number (if appropriate), hazard type and classification. This new resource enables assessments of biases in impact recording and identification of hazard combinations that cause the most severe damage.

Resources such as this database can provide essential knowledge of the type of multi-hazard events that are responsible for adverse impacts and can be instrumental in the development of risk assessments, emergency management response plans and mitigation policies.