Extending the codebase

Floods

Global Floods Database

For flood data we have event (observations) across times, where each time frame we have the rasterfiles and corresponding precipitation data and Population Exposed Per Country Per Event.

Crucial points:

  • On website top right (“About the data”) hand corner are 2 summary csv files from top right

    • Flood event with a measure of intensity (1, 1.5, 2), persons dead and displaced, by country and by country X year.

  • We can find the description of the data from here: data description

  • We can now easily relate all the weather data, particularly the flood data by index or date (YYYYMMDD).

  • We can read the raster (map) images.

Summary about the data:

The Global Flood Database is a project backed by several institutions, with primary collaboration between Cloud to Street and The Flood Observatory (DFO). The project provides valuable information on flood occurrences and their impacts.

  1. Data Source and Methods: The database uses NASA MODIS Aqua and Terra satellites for its data, which provide daily images at a 250-m resolution. The data includes flood maps dating back to the year 1. These maps represent significant events documented by the DFO. The selection of areas to map is done by intersecting a polygon from the DFO flood database with global HydroSHEDS watersheds.

  2. Population Exposure and Precipitation Estimates: The database estimates population exposure by overlaying flood maps with the Global Human Settlement Layer (GHSL) population data. It uses the PERSIANN-CDR dataset for daily precipitation estimates, calculated by the 95th percentile of rainfall accumulation in the mapped watersheds.

  3. Using the Website: The database website allows users to select a country and then choose a specific event by its start date. Data can be added to the map by selecting the desired layer from the toolbar. It is noted that events are mapped over watersheds, which may overlap multiple countries. Therefore, selecting a country will display all events intersecting with it, even if it is not the primary coverage. Users can download the map as a GeoTIFF file, which comes with a metadata document. The GeoTIFF contains five bands: flooded, duration, clear_views, clear_perc, and jrc_perm_water.

  4. Downloadable Data: Users can download the precipitation data displayed on the website. They can also download population-exposed estimates for all events, either for the entire event or by country. These estimates have been filtered to remove noise and isolated pixels.

  5. Exposed and Displaced Populations: The number of exposed people is calculated by intersecting the observed inundated area with population data. The number of displaced people is taken from the DFO event catalogue and is often reported by the media or the government of the affected country. The numbers of exposed and displaced people can differ significantly for a variety of reasons, and some flood events lack data on displaced persons.

  6. Casualties and Causes: The database also includes data on casualties and causes of flood events, as reported in the media or by government agencies, recorded in the Dartmouth Flood Observatory Catalogue.

International Disasters Database

The International Disasters Database is a database of natural disasters. According to it, the these three highest impact flooding events in Nigeria in last decade are 2012-0366-NGA , 2018-0365-NGA, 2010-0509-NGA. These can records can also be integrated into the codebase.