HESS Opinions: Beyond the Long-term Water Balance: Evolving Budyko's Legacy for the Anthropocene towards a Global Synthesis of Land-surface Fluxes under Natural and Human-altered Watersheds

Abstract. Global hydroclimatic conditions have been significantly altered over the past century by anthropogenic influences that arise from the warming global climate and also from local/regional anthropogenic disturbances. Traditionally, studies have used coupling of multiple models to understand how land-surface fluxes vary due to changes in global climatic patterns and local land-use changes. We argue that Budyko's framework that relies on the supply and demand concept could be effectively adapted and extended to quantify the role of drivers – both changing climate and local human disturbances – in altering the land-surface response across the globe. We review the Budyko framework along with potential extensions with an intent to further the applicability of the framework to emerging hydrologic questions. Challenges in extending the Budyko framework over various spatio-temporal scales and evaluating the water balance at these various scales with global data sets are also discussed.