Past, Present, and Future of Flooding-induced Crop Loss in U.S. Midwest

Despite the overall positive trend in crop yield worldwide, the food system remains fragile and can be significantly disrupted by extreme weather. From January - May 2019, the U.S. Midwest experienced unprecedented flooding, which overwhelmed flood defense infrastructure. Such extreme floods result from an accumulation of factors and pose significant threats to food security. Although individual extreme events are extensively studied, the cascading events and their compounding effects, in which several climatic events work in tandem to overwhelm human capacity and cause disasters, are not well-understood.

Here, we present results from an interdisciplinary study of the 2019 U.S. Midwest flood and subsequent crop loss, which incorporates maps of the flood extent at 60 m resolution from 558 Sentinel-1A/B Synthetic Aperture Radar (SAR) satellites, maps of crop green-up at 1 km resolution based on Moderate Resolution Imaging Spectroradiometer (MODIS) observations, and data from 3128 stream gage stations. We find that counties along the main river networks and higher latitudes are most affected by flooding. In addition, croplands experienced a delayed greenup of up to 60 days on average in 2019. We find that over the past ~70 years, there is ~43% correlation between historical crop decline and spring excess discharge and that in the future, the frequency and magnitude of spring flooding are likely to increase across the U.S. Midwest. Thus, we conclude that flood events, in particular those that occur near and during the planting season, have a significant impact on crop loss across the U.S. Midwest. This crop loss is not limited to the 2019 event—it has been prevalent in the past and is likely to continue in the future as climate warming accelerates.

The datasets presented here provide a detailed understanding of the past and present relationship between human activities and climate events. Future work is required to understand better the time-dependence of cascading events, their impact on crop conditions, and to constrain the compound effects on land cover and land-use change.