Understanding hydroclimate processes in the Murray-Darling Basin for natural resources management

D. J. Karoly,D. C. Verdon-Kidd,A. J. E. Gallant,A. S. Kiem,R. C. Stone

doi:10.5194/hess-16-2049-2012

Abstract

Abstract. Isolating the causes of extreme variations or changes in the hydroclimate is difficult due to the complexities of the driving mechanisms, but it is crucial for effective natural resource management. In Australia's Murray-Darling Basin (MDB), ocean-atmosphere processes causing hydroclimatic variations occur on time scales from days to centuries, all are important, and none are likely to act in isolation. Instead, interactions between all hydroclimatic drivers, on multiple time scales, are likely to have caused the variations observed in MDB instrumental records. A simplified framework is presented to assist natural resource managers in identifying the potential causes of hydroclimatic anomalies. The framework condenses an event into its fundamental elements, including its spatial and temporal signal and small-scale evolution. The climatic processes that are potentially responsible are then examined to determine possible causes. The framework was applied to a period of prolonged and severe dry conditions occurring in the southern MDB from 1997–2010, providing insights into possible causal mechanisms that are consistent with recent studies. The framework also assists in identifying uncertainties and gaps in our understanding that need to be addressed.

Highlights

Periods of prolonged, severe drought and moisture surplus are challenging for natural resources management/managers (NRM)
There was a lack of high one-day rainfall totals4 (Murphy and Timbal, 2008; Verdon-Kidd and Kiem, 2009b), which is consistent with a reduction in the amount of rainfall associated with cut-off low pressure systems over this period5 (Pook et al, 2006; McIntosh et al, 2007) and an absence of persistent pre-frontal troughs that aid the penetration of rain producing cold fronts into the southern MDB6 (VerdonKidd and Kiem, 2009a; Alexander et al, 2010)
Given the lack of understanding about the physics behind both anthropogenic and natural processes, we suggest that if a framework similar to that presented here is utilised by NRM, that a weighting should be applied to each process that is inversely proportional to the uncertainty

Summary

Introduction

Severe drought and moisture surplus are challenging for natural resources management/managers (NRM). The second objective is to identify a broad framework that allows NRM to scrutinise existing climate knowledge in order to better isolate the potential cause/causes of extreme climatic periods. This might make information relating to hydroclimatic processes more useful in risk management applications. The framework highlights areas where the knowledge base is lacking (i.e., areas with large uncertainty or actual knowledge gaps), identifying areas of future research that, if undertaken, will prove useful for NRM To fulfil these objectives, the paper is presented as follows: first, a hydroclimatology of the MDB provides context. The framework for highlighting the potential cause/causes of specific climatic anomalies for NRM is presented and applied to the case of the prolonged drought that affected the southern MDB for over 13 yr from the mid 1990s

Hydroclimatology of the Murray-Darling Basin

Hydroclimate processes of the Murray-Darling Basin

Daily to intra-annual processes

Inter-annual processes: an update

Inter-decadal processes

Interactions between climate processes

A framework for focussing climate information for natural resource management

Spatial signatures

Temporal signatures

Small-scale evolution

Concluding remarks

Expanding data records – instrumental and palaeoclimate-proxies