AbstractsGeography &GIS

A paleoclimate-informed examination of flood and drought epochs in the Murray-Darling Basin

by Michelle Ho

Institution: University of Newcastle
Degree: PhD
Year: 2014
Keywords: climate; paleoclimate; Murray-Darling Basin; flood; drought
Record ID: 1057137
Full text PDF: http://hdl.handle.net/1959.13/1048522


Research Doctorate - Doctor of Philosophy (PhD) The Murray-Darling Basin (MDB) is Australia’s largest water catchment and the nation’s reputed ‘food bowl’. Climate, and consequently water availability, in the region is highly variable both temporally and spatially, as evident in the regular occurrence of floods and persistent droughts and the regionally distinctive impacts of such events. A key limitation to accurately quantifying flood and drought risks in the region is the relatively short instrumental records (approximately 100 years at best) of rainfall and stream flow. Furthermore, research over the past few decades has revealed that flood and drought risks across the MDB are modulated by a number of different large-scale climate drivers (e.g. El Niño/Southern Oscillation, Southern Annular Mode, Indian Ocean Dipole and Interdecadal Pacific Oscillation) on seasonal to multi-decadal timescales. These climate mechanisms influence the MDB hydroclimate both individually and in combination. Current assessments of flood and drought risk are based on relatively short instrumental records and are therefore inadequate for properly evaluating either multidecadal variability or the influence of numerous largescale climate drivers on MDB hydroclimatic variability. This thesis aims to improve understanding of long-term flood and drought risk in the MDB through the use of paleoclimate records of both large-scale ocean-atmospheric processes and continental Australian rainfall. The use of paleoclimate data will enable improved insight into pre-instrumental climate variability. The efficacy of using paleoclimate proxy records of large-scale climate drivers (e.g. the El Niño Southern Oscillation, the Indian Ocean Dipole, the Southern Annular Mode, the Interdecadal Pacific Oscillation and the Pacific Decadal Oscillation) to reconstruct MDB rainfall was examined. In order to reconstruct MDB rainfall using these relationships, both linear and non-linear relationships between MDB rainfall and different climate drivers and combinations of drivers were quantified. Importantly, it was found that the MDB rainfall response was markedly different when climate drivers were considered in combination compared to the response to a single climate driver. Currently, numerous multi-centennial paleoclimate records exist for the El Niño Southern Oscillation and the Pacific Decadal Oscillation. However, paleoclimate reconstructions of other climate drivers are less developed, limiting the feasibility of paleoclimate driver based reconstruction methods. Nevertheless, this work has highlighted significant potential for using paleoclimate proxy records of large-scale climate drivers to reconstruct MDB rainfall variability should multi-centennial records of Indian and Southern Ocean variability for key seasons, as well as the Pacific Ocean Basin-wide Interdecadal Pacific Oscillation, become available in the future. In addition to assessing the possibility of reconstructing MDB rainfall using paleoclimate proxy records of large-scale climate drivers,…