Evidence of higher evapotranspiration in croplands than in forestlands in four Mississippi watersheds over the past decade

Historically, forestlands have been widely recognized to lose more water through evapotranspiration (ET) than croplands. Using remote sensing data from MODIS (Moderate Resolution Imaging Spectroradiometer) with an 8-day temporal and 500 m spatial resolution, we compared the annual ET between croplands and forestlands in the Yazoo River Basin (YRB), a humid subtropical region in Mississippi, USA, over a 21-year period from 2001 to 2021. Based on the Mann-Kendall test, there were significant increasing trends in annual ET for the croplands (τ > 0.44, p < 0.01) but not for forestland over the 21-year period. According to Pettitt’s test, there was an abrupt change (or turning point) in annual ET starting in 2011 for the croplands. Using the time at this turning point (i.e., 2011) along with the Kolmogorov-Smirnov test, we found that there was a very significant difference (α = 0.05) in annual ET between croplands and forestlands with 19 % higher ET in the croplands over the 11-year period from 2011 to 2021. This occurred because of increasing irrigated cropland areas in the YRB during this period, providing more water for ET. Our finding on croplands lost more water than forestlands through ET challenge the traditional concept on how forestlands and croplands influence ET. •Estimate evapotranspiration (ET) in croplands and forestlands using remote sensing data.•Cropland has larger ET than forestlands in Mississippi watersheds in recent 10 years.•Significant increasing trend of ET in croplands but not in forestlands in recent 20 years.•Findings change traditional visions on how forests and crops affect ET.