Work

Hydroclimatic Variability Shapes Long‐Term Water Balance

Year: 2026

Type: article

Abstract: Long‐term water availability is commonly interpreted through mean precipitation () and potential evapotranspiration (), yet hydroclimatic variability spans seasonal to event scales and may influence water partitioning beyond what mean climate alone captures. Although the aridity index () explains much of the spatial variability in evaporative fraction (), systematic departures from classical relationships suggest that additional modes of variability shape long‐term . Here, using large‐sample observations from catchments across the United States, Australia, and Brazil, we show that seasonal covariance, monthly variance, and event‐scale storm structure leave persistent, organized imprints on long‐term water balance. We introduce a hypothesis‐driven expansion of the aridity framework that incorporates these variability terms and demonstrates that sub‐annual climate organization can be explicitly embedded within long‐term water‐balance theory. This variability‐aware perspective provides a mechanistic pathway for assessing how shifts in climate variability, even under approximately stationary long‐term means, may propagate into future water yields.

Source: Geophysical Research Letters

DOI: 10.1029/2025gl121486

Authors: Antônio Alves Meira Neto, André S. Ballarin, Paulo Tarso S. Oliveira, Guo‐Yue Niu

Institutions: Colorado State University, Universidade de São Paulo, University of North Carolina at Charlotte, University of Arizona

Language: English

Topic: Hydrology and Watershed Management Studies

Subfield: Water Science and Technology

Field: Environmental Science

Domain: Physical Sciences

SDG: Climate action

Open Access status: gold

Estimated APC paid: $3,190