Monthly crop water requirements of irrigated crops in the United States
from 1981-2019
Abstract
Irrigated agriculture depends on surface water and groundwater, but we
do not have a clear picture of how much water is consumed from these
sources by different crops across the US over time. Current estimates of
crop water requirements are insufficient in providing the spatial
granularity and temporal depth required for comprehensive long-term
analysis. To fill this data gap, we utilized crop growth models to
quantify the monthly crop water consumption - distinguishing between
rainwater, surface water, and groundwater - of the 30 most widely
irrigated crops in the US from 1981 to 2019 at 2.5 arc minutes. These 30
crops represent approximately 95% of US irrigated cropland. We found
that the average annual total crop water consumption for these 30
irrigated crops in the US was 154.2 km3, 70% of which was from
irrigation. Corn and alfalfa accounted for approximately 16.7 km3 and
24.8 km3 of average annual blue crop water consumption, respectively,
which is nearly two-fifths of the blue crop water consumed in the US.
Surface water consumption decreased by 41.2%, while groundwater
consumption increased by 6.8%, resulting in a 17.3% decline in blue
water consumption between 1981 and 2019. We find good agreement between
our results and existing modeled evapotranspiration (ET) products,
remotely sensed ET estimates (OpenET), and water use data from the US
Geological Survey and US Department of Agriculture. Our dataset and
model can help assess the impact of irrigation practices and water
scarcity on crop production and sustainability.