Water Use in Agroecosystems: An Extended Budyko Framework

Climate change and human activities are rapidly altering watershed dynamics, with agricultural management being a key protagonist in modifying water partitioning within watersheds. The Budyko framework relates precipitation partitioning to climatic conditions through fundamental constraints of water and energy availability. However, managed watersheds deviate from the natural Budyko curve due to their modified water balance, particularly through irrigation inputs.
This study develops a process-based extension of the Budyko framework by explicitly incorporating irrigation into the water balance equations. Our approach accounts for both stochastic rainfall and irrigation inputs, considering different management methods, climatic conditions, and crop parameters. This allows us to predict and explain the shifts in water partitioning observed in managed watersheds within the Budyko space.
We validate our theoretical predictions using real-world basins that span diverse climates and management practices - from rainfed to fully irrigated agriculture. The framework successfully captures the transitions between different agricultural strategies through their modified evaporative patterns, showing good agreement with observed data across various irrigation methods and crop types, demonstrating how these interventions have altered hydrological patterns on a global scale.
This framework advances our understanding of agricultural feedbacks on the water cycle through modified evapotranspiration patterns. The ability to characterize these changes using minimal parameters makes it valuable for improving hydrological models and detecting irrigation practices through their distinctive signatures in the Budyko space.