Fig. 1
From: Classification of drought severity in contiguous USA during the past 21 years using fractal geometry
US Drought Monitor Category (left: 2010-08-24) and (right: 2021-08-24) taken from US Drought Monitor (USDM). The maps use five classifications: abnormally dry (D0), showing areas that may be going into or are coming out of drought, and four levels of drought: moderate (D1), severe (D2), extreme (D3), and exceptional (D4). Map of the USA painted with blobs of yellow, orange, and red, https://droughtmonitor.unl.edu/CurrentMap/StateDroughtMonitor.aspx?conus. Source(s): National Drought Mitigation Center (NDMC), the US Department of Agriculture (USDA), and the National Oceanic and Atmospheric Administration (NOAA)