Climate Variability and Change—Hydrological Impacts (Proceedings of the Fifth FRIEND World Conference held at Havana, Cuba, No

Climate Variability and Change—Hydrological Impacts (Proceedings of the Fifth FRIEND World Conference held at Havana, Cuba, November 2006), IAHS Publ. 308, 2006, 256–262.

Precipitation elasticity of streamflow in catchments across the world

FRANCIS H. S. CHIEW^1,2, MURRAY C. PEEL², THOMAS A. McMAHON² & LIONEL W. SIRIWARDENA²

1 CSIRO Land and Water, GPO Box 1666, Canberra, ACT 2601, Australia

2 Department of Civil and Environmental Engineering, University of Melbourne, Victoria 3010, Australia

francis.chiew@csiro.au

Abstract Estimates of the sensitivity of streamflow to climate are required to make informed decisions for managing water resources and environmental systems to cope with hydroclimatic variability and climate change. The precipitation elasticity of streamflow (e_P), defined as the proportional change in mean annual streamflow divided by the proportional change in mean annual precipitation, is a measure of the sensitivity of streamflow to precipitation. This paper uses a nonparametric estimator to estimate e_P for over 500 catchments across the world. The nonparametric estimator calculates e_P directly from concurrent historical annual catchment precipitation and streamflow data, and is particularly useful for global studies such as this because it does not require the selection of a single hydrological model and calibration criteria that are appropriate for catchments across the world. The results indicate that changes in precipitation are amplified in streamflow. The e_P estimates generally range from 1.0 to 3.0, that is, a 1% change in mean annual precipitation results in a 1–3% change in mean annual streamflow. The higher e_P values (greater than 2.0) are observed in southeastern Australia and southern and western Africa, while lower e_P values (lower than 2.0) are observed in southwestern South America and at mid and high latitudes in the Northern Hemisphere. There is a relatively strong inverse relationship between e_P and runoff coefficient, with higher e_P values observed in catchments with lower runoff coefficients. The e_P value is also generally lower than 2.0 in catchments with high mean annual streamflow (greater than 500 mm) or mean annual precipitation (greater than 1500 mm), and in cold climates (mean annual temperature lower than 10°C).

Key words climate change; elasticity; global; hydroclimatic variability; precipitation; streamflow