Australia: The Land Where Time Began

A biography of the Australian continent 

Drought, Groundwater Storage and Declining Stream Flow in Southwestern Australia

(1) In this study the authors1 examine the hydrological processes that are the basis for non-stationarity in hydrological predictions. Analysis of linkages between rainfall, groundwater storage, and runoff in Southwestern Western Australia (SWWA), a region in which stream flow has been declining since the mid-1970s. A close connection was found between rainfall and catchment groundwater storage with increases of storage in years when annual rainfall is above a threshold, 1050-1400 mm, declining when there are years of low rainfall. Runoff as a proportion of rainfall is highly correlated with groundwater storage where groundwater is in contact with the stream bed. The groundwater storage and runoff ratio have been reduced in recent years of drought. If there are no wetter years to replenish the groundwater, lower runoff ratios are subsequently maintained. The study found that at the present the runoff resulting from a given annual depth of rainfall is much lower than was produced by the same amount of runoff 15 years ago. The groundwater storage thus acts as the catchment's "memory". The authors1 suggest their study highlights the importance of catchment groundwater storage that may be used in the improvement of runoff prediction at a time when the climate is drying.


Sources & Further reading

  1. Hughes, J. D., K. C. Petrone, and R. P. Silberstein. "Drought, Groundwater Storage and Stream Flow Decline in Southwestern Australia." Geophysical Research Letters 39, no. 3 (2012): L03408.
Author: M. H. Monroe
Last updated 05/05/2013
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