Source: Ryan Hignight/U.S. Army Corps of Engineers

 

A combination of saturated soil, snow, ice and heavier than usual spring rains led to vast flooding across the Midwestern U.S. over the last two weeks. Across many states including Iowa, Minnesota, Nebraska, South Dakota and Wisconsin, farms have been inundated with floodwaters as ice flows have damaged levees and dams and rivers breached their banks. Many farmers are now struggling to overcome the damage to their fields and livestock.

 

Using synthetic aperture radar (SAR), which utilizes microwave radiation that can ‘see’ through cloudy conditions and at night, PlanetWatchers performed an analysis of flooded areas on the border between Iowa, Nebraska and South Dakota, including a segment of the flooded Missouri River. Using SAR images from ESA’s Sentinel-1, images were acquired on March 5th and March 17th to implement our change detection algorithms on the impacted areas.

 

In this change detection analysis, PlanetWatchers calculated that in this single satellite footprint, 1,501,165 acres were lost or damaged due to flooding (see Image one). Much of this location is agricultural land and during most years this area is planted predominantly with corn and soybeans followed by large areas of grassland and alfalfa. As this is only a portion of the affected area, it is reasonable to assume the number of flooded acres is multiple times the acreage calculated here.

 

Image One: Areas impacted by flooding in the Midwest as of March 17th, 2019. Impacted areas are highlighted in red. This analysis shows the difference between March 5th and March 17th.

 

 

As it is still early in the growing season, crops have yet to be planted and the true toll of this flooding will not become clear until much later but early estimates put the total damage in the billions of dollars.

 

Image two and Image three show the process SAR images used in this analysis.

 

Image Two: SAR imagery from Sentinel-1 overlaid on an optical image. This radar image was acquired on March 5th, 2019.

 

 

Image Three: SAR imagery from Sentinel-1 overlaid on an optical image. This radar image was acquired on March 17th, 2019.

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