Purpose of the database
The main objective of the database is to establish the frequency and geographical spread of extreme weather events in India and to quantify the loss and damage due to them. It is based on publicly available data sourced from government sources and media reports.
It has quantified the number of extreme weather event days and not the number of extreme weather events. Loss and damage, however, have been quantified month-wise because of the unavailability of data. Loss and damage are also calculated state-wise and not event-wise. This was done because a state has reported two extreme weather events on many days, but the associated loss and damage information is not consistently available.
Process and assumptions
The primary datasheets have been sourced from two government organisations—the IMD and the Disaster Management Division. Media reports have been screened for: a) additional information and b) to ascertain human deaths and cropped area affected.
The database has classified extreme weather events into seven broad types, based on the classifications used in various government documents. They are heavy rains, floods and landslides; lightning and storms, cyclones, snowfall, cloudbursts, cold days/cold waves and heatwaves.
In the heavy rains, floods and landslides category, the report considers heavy rainfall events (64.5 to 115.5 mm in 24 hours) only if they had associated deaths or damage. All, very heavy (115.6 to 204.4 mm in 24 hours) and extremely heavy rainfall (>204.4 mm) events have been considered. The lightning and storms category includes thunderstorms, hailstorms, dust storms, and gales. The cold day/cold wave category includes cold days, severe cold days, cold waves and severe cold waves. The heatwave category includes heatwaves and severe heatwaves.
Loss and damage
Loss and damage have been assessed under four categories: human deaths, crop area affected, houses destroyed, and animal deaths. While media, IMD and Disaster Management Division reports have been used to ascertain human deaths and crop area affected, the remaining two is sourced only from Disaster Management Division reports, which are available only for the monsoon months. As a result, the data for the two parameters for Jan-May is not included in the report.
In cases where different sources give varying loss and damage numbers for the same day, the source with the highest numbers has been considered.
In India, state disaster management authorities collect and collate data on damage due to disasters. These agencies then feed the information to the central agencies. Some of the state disaster management authorities, such as Assam and Himachal Pradesh, regularly release their own data. This report has not considered them to avoid double counting and data gaps.