Streamflow elasticity as a function of aridity

Abstract

Relating variations in annual streamflow to a climate anomaly, commonly referred to as streamflow elasticity to climate, is central for a rapid assessment of the impact of climate change on water resources. This elasticity is classically estimated via a multiple linear regression between anomalies in streamflow and climate variables. However, this approach does not explicitly account for the fact that elasticity depends on aridity as suggested by “Budykotype” water balance formulas. Using a large dataset of 4122 catchments from four continents, we first verify empirically the link between elasticity and aridity. Then, we propose a method to constrain elasticity coefficients with derivatives from a “Budyko-type” water balance formula, that allows introducing an explicit dependency between elasticity and aridity. We show that adding this dependency produces a regionalized elasticity formula with physically-realistic elasticity coefficients.