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A simple framework for relating variations in runoff to variations in climatic conditions and catchment properties
Author(s) -
Roderick Michael L.,
Farquhar Graham D.
Publication year - 2011
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/2010wr009826
Subject(s) - evapotranspiration , surface runoff , drainage basin , environmental science , precipitation , climate change , potential evaporation , vegetation (pathology) , hydrology (agriculture) , runoff curve number , climatology , meteorology , geography , ecology , geology , cartography , geotechnical engineering , biology , medicine , pathology
We use the Budyko framework to calculate catchment‐scale evapotranspiration ( E ) and runoff ( Q ) as a function of two climatic factors, precipitation ( P ) and evaporative demand ( E o = 0.75 times the pan evaporation rate), and a third parameter that encodes the catchment properties ( n ) and modifies how P is partitioned between E and Q . This simple theory accurately predicted the long‐term evapotranspiration ( E ) and runoff ( Q ) for the Murray‐Darling Basin (MDB) in southeast Australia. We extend the theory by developing a simple and novel analytical expression for the effects on E and Q of small perturbations in P , E o , and n . The theory predicts that a 10% change in P , with all else constant, would result in a 26% change in Q in the MDB. Future climate scenarios (2070–2099) derived using Intergovernmental Panel on Climate Change AR4 climate model output highlight the diversity of projections for P (±30%) with a correspondingly large range in projections for Q (±80%) in the MDB. We conclude with a qualitative description about the impact of changes in catchment properties on water availability and focus on the interaction between vegetation change, increasing atmospheric [CO 2 ], and fire frequency. We conclude that the modern version of the Budyko framework is a useful tool for making simple and transparent estimates of changes in water availability.