Intensification of irrigated agriculture and precipitation explain rising evapotranspiration in the Snake River Basin despite declining atmospheric demand
4 affiliations
- 1University of Idaho - Boise Campus, United States Of America; Corresponding author.
- 2University of Idaho - Boise Campus, United States Of America
- 3University of Idaho, United States of America
- 4Idaho Water Resources Research Institute, United States of America
Abstract
Evapotranspiration (ET) is the dominant water outflux in irrigated semi-arid basins, yet its long-term trends and drivers remain poorly quantified at management-relevant scales. In intensively irrigated systems operating under prior appropriation, detecting and attributing changes in consumptive water use is essential for sustainable water governance. Here we show, using OpenET ensemble estimates across 53 HUC-8 watersheds of the Snake River Plain over 2000–2023, corroborated by GRACE-derived water balance and Landsat net primary productivity, that ET increased significantly in 25 of 53 watersheds at a basin-wide median rate of 1.7 mm yr⁻¹ , driven primarily by irrigated area expansion (contributing to 54% of ET trend) and secondarily by precipitation (contributing to19% of ET trend), while declining atmospheric evaporative demand partially offset these gains. The region underwent a significant basin-wide shift toward dairy forage production, with alfalfa, other hay, and corn collectively increasing their share of cropland at the expense of small grains, indicating crop compositional intensification. Reliance on individual OpenET models had significant control on attribution inferences, with the irrigated fraction contribution to ET trends ranging from 11% (geeSEBAL) to 60% (SSEBop) across models compared to 54% for the ensemble. These findings demonstrate that land use intensification can override climatically driven declines in atmospheric evaporative demand. Additionally, inter-model uncertainty in remote sensing ET products is sufficiently large to alter water management conclusions.
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BibTeX
@article{kukal2026intensification,
title = {{Intensification of irrigated agriculture and precipitation explain rising evapotranspiration in the Snake River Basin despite declining atmospheric demand}},
author = {Meetpal Singh Kukal and Dinesh Gulati and Meng Zhao and Alex Maas and Kendra E. Kaiser},
journal = {Journal of Hydrology: Regional Studies},
year = {2026},
month = oct,
doi = {10.1016/j.ejrh.2026.104078},
url = {https://doi.org/10.1016/j.ejrh.2026.104078},
note = {CC BY},
}
RIS
TY - JOUR
TI - Intensification of irrigated agriculture and precipitation explain rising evapotranspiration in the Snake River Basin despite declining atmospheric demand
AU - Meetpal Singh Kukal
AU - Dinesh Gulati
AU - Meng Zhao
AU - Alex Maas
AU - Kendra E. Kaiser
PY - 2026
DA - 2026/10/30
JO - Journal of Hydrology: Regional Studies
DO - 10.1016/j.ejrh.2026.104078
UR - https://doi.org/10.1016/j.ejrh.2026.104078
AB - Evapotranspiration (ET) is the dominant water outflux in irrigated semi-arid basins, yet its long-term trends and drivers remain poorly quantified at management-relevant scales. In intensively irrigated systems operating under prior appropriation, detecting and attributing changes in consumptive water use is essential for sustainable water governance. Here we show, using OpenET ensemble estimates across 53 HUC-8 watersheds of the Snake River Plain over 2000–2023, corroborated by GRACE-derived water balance and Landsat net primary productivity, that ET increased significantly in 25 of 53 watersheds at a basin-wide median rate of 1.7 mm yr⁻¹ , driven primarily by irrigated area expansion (contributing to 54% of ET trend) and secondarily by precipitation (contributing to19% of ET trend), while declining atmospheric evaporative demand partially offset these gains. The region underwent a significant basin-wide shift toward dairy forage production, with alfalfa, other hay, and corn collectively increasing their share of cropland at the expense of small grains, indicating crop compositional intensification. Reliance on individual OpenET models had significant control on attribution inferences, with the irrigated fraction contribution to ET trends ranging from 11% (geeSEBAL) to 60% (SSEBop) across models compared to 54% for the ensemble. These findings demonstrate that land use intensification can override climatically driven declines in atmospheric evaporative demand. Additionally, inter-model uncertainty in remote sensing ET products is sufficiently large to alter water management conclusions.
SN - 2214-5818
ER -