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DFO Flood Event: 2019-Malawi-4725

Causation

March 11, 2019: "The number of people killed in heavy rains and flooding in southern Malawi has risen to 30, while the number of people affected is now approaching 500,000 with an estimated 30,000 of them displaced. Meanwhile the same weather system has also caused flooding in regions of Mozambique, where over 30,000 people have been affected and 7 deaths reported. Mozambique is now facing the impact of Tropical Cyclone Idai which formed over the Northern Mozambique Channel on 09 March, 2019." From Flood List.

March 13, 2019: "Over the last 4 days models have been remarkably consistent in the forecast for this cyclone- Tropical Cyclone Idai. A surge is likely in coastal areas, and very heavy rains will likely hit Sofala and southern Zambezia. Below are images of the start of the heavy rainfall and the predicted storm track." DFO will include any flooding as part of event 4725. Kindly provided by Dr. Emily Niebuhr, who contributes as part of the GFP voluntary effort. On March 15, the storm was located as shown in image on right.

March 16, 2019: "Very heavy rains in Mozambique--over 500mm estimated by NASA IMERG over last three days focused in Pungwe River area west of Beira. Flooding estimated from GFMS as currently intense along Pungwe River and along Revue River a little to the south. from GFMS (see second figure for overview and third figure for 1 km inundation calculation. Flooding forecasts for the nest three days include a with maximum amount at 1000 mm." Kindly provided by Dr. Robert Adler (see next section below).

March 19, 2019: "Rain is continuing at moderate levels in Mozambique, but with more forecast over the next few days. Inundation still along Pungwe and Buzi River basins, but additional flooding now calculated toward Zambezi R. as rain has shifted toward north. Forecast rain over next 3 days indicates re-intensifying of flooding along Pungwe River.-GFMS tends to dissipate flooding conditions faster than observed, so some inundation and flooding shown for now and next few days could be underestimates". Kindly provided by Dr. Robert Adler (see next section below).

Modeling

1. Results from the NASA-supported Global Flood Monitoring System (GFMS) at ESSIC, University of Maryland. Date and UTC time is shown. This is inundation as modeled from input precipitation data.

2. Results from AER Flood Scan for Malawi at 90 m spatial resolution, March 16, 2019. Courtesy John Galantowicz, AER and African Risk Capacity. Data set version AFED V05r00. This is inundation modeled by comparison of current water-sensing microwave remote sensing of the ground surface and topographic data through a downscaling approach. Red is AFED-detected non-persistent water (March 3-23, 2019).

The ARC Flood Extent Depiction (AFED) data have been developed by Atmospheric Environmental Research, Inc. (AER) for the African Risk Capacity (ARC) Group. AFED data are downscaled from coarse resolution (22 km) microwave satellite data and, although depicted at ~90m resolution, will only detect large scale river flooding. Flooding in elevated areas and small tributaries usually is not detected. The data are provided to the public for information purposes only, and neither AER nor the ARC Group make any representation or warranty regarding the fitness of the data and information for any particular purpose. In no event shall AER nor the ARC Group be held liable with respect to any subject matter presented here.

 

Maximum Observed Flooding

Red is all mapped flooding from this event. Darker Red is mapped flooding from non-DFO sourcess (AER, see above, or Copernicus GIS data). Blue is a reference normal water extent. Light gray is all previously mapped flooding, since 1999. See also the DFO Web Map Server. Over the course of the event, remote sensing data are combined to show all flooded areas. GIS and other data are provided here. The date is for the last update. Remote sensing geographic coverage may not be complete due to cloud cover.

Click on colored dots for access to River Watch results.

Download Simplified Geotif version

 

Explanation

Event Numbers:

The Flood Observatory maintains a Global Active Archive of large flood events, 1985 to present. New major flood events are entered into this archive each week. A hand-drawn GIS polygon for each event outlines the region affected.

This event was selected for Observatory production of map and GIS data products.This web page and associated image and map (GIS) files become the permanent Flood Observatory record of the flood.

Intellectual Property:

As part of collaborations with other organizations, including GEO and the Global Flood Partnership, the Observatory's maps are made available here to the public. Geotif versions and GIS files are also available. With attribution, maps and data can be used freely for non-commercial purposes. With permission, they can be used for commercial purposes. Consult the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License and Robert.Brakenridge or Albert.Kettner (at Colorado.edu) if questions. Attribution for this map when Sentinel SAR data are used: "Dartmouth Flood Observatory at the University of Colorado, from satellite data provided by NASA and Copernicus/European Space Agency". When using GIS data (see below) provided to DFO from other sources, please acknowledge original source.

Image Data Sources:

NASA Landsat 8 and Copernicus/ESA Sentinel SAR data if used in this map were obtained from the the U.S. Geological Survey Hazards Data Distribution System. and the Sentinels Science Data hub, respectively. Landsat 8 is jointly managed by NASA and the United States Geological Survey. Copernicus is supported by the European Commission. MODIS data are obtained from the NASA NRT Global Flood Mapping facility (surface water extents) and from NASA Worldview (image files); SUOMI/VIIRS image data are also retrieved from NASA Worldview.

Obtain the GIS Data:

Flood extent files (Shp or Mapinfo) supporting this Flood Event Map are located here.

These files may include high spatial resolution mapping such as from Sentinel or Landsat, or lower resolution files from MODIS. File names commonly include the sensor source (e.g., S1 for Sentinel 1, LS8 for Landsat, MODIS for MODIS) and the image date.

Maximum water extent data from the Global Surface Water Explorer may be included as part of the light gray previously mapped surface water. It is based on Landsat images at a spatial resolution of 30 m (Pekel and others, Nature 540, 418-422, 2016). The NASA Shuttle Water Boundary Data (SWBD) surface water extent (90 m resolution), blue, is derived from NASA's 11-day February, 2000, SRTM mission and was corrected using Landsat data. These data are not provided in the GIS directories.

When used in the maps, Copernicus Emergency Management Service GIS data are imported and installed in a labeled "Copernicus" subdirectory. All flood extents not created here, including those from Copernicus, are shown in a darker red color on the map but are combined into one red layer on the simplified large geotif file (if provided).. Image data sources for Copernicus mapping results may include Sentinel SAR satellites and also Cosmo-SkyMed SAR satellites. Dissemination Policy: Under Copernicus and Commission Delegated Regulations, the information produced by the Copernicus Emergency Management Service shall be made available to the public on a full, open and free-of-charge basis. Attribution of the source is required: "Copernicus Emergency Management Service, Directorate Space, Security and Migration, European Commission Joint Research Centre (EC JRC). Accessed date. http://emergency.copernicus.eu/".

Funding, Data, and Institutional Support:

The NASA Earth Sciences Program, the Latin American Development Bank, the World Bank, the European Commission's Global Disaster Alert and Coordination System, GDACS, and Copernicus Emergency Management Service, the Google Earth Engine research awards program, the Committee on Earth Observation Satellites (CEOS) Disasters Working Group-Flood Pilot, the Japanese Space Agency, and the European Space Agency all have supported the Observatory's work via research grants and contracts or free satellite-derived data.

The Dartmouth Flood Observatory was founded in 1993 at Dartmouth College, Hanover, NH USA and moved to the University of Colorado, INSTAAR, CSDMS in 2010. Its operation depends on continued grant and project support. Gift contributions can be accepted. If your organization uses these data and maps, please consider becoming a partner and helping to sustain this effort. The institutional support of both universities is gratefully acknowledged.

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