DROUGHTS IN THE MURRAY DARLING BASIN SINCE EUROPEAN SETTLEMENT

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1 DROUGHTS IN THE MURRAY DARLING BASIN SINCE EUROPEAN SETTLEMENT 1865 cartoon depicting Goyder in search of rainfall (SA Museum) Griffith Centre for Coastal Management Research Report No 100 July 2009 PREPARED FOR MURRAY DARLING BASIN AUTHORITY BY: P. HELMAN

2 Published by the Murray-Darling Basin Authority Postal Address: GPO Box 1801, Canberra ACT 2601 Telephone: (02) international Facsimile: (02) international info@mdba.gov.au Internet: All material and work produced for the Murray-Darling Basin Authority constitutes Commonwealth copyright. MDBA reserves the right to set out the terms and conditions for the use of such material. With the exception of the Commonwealth Coat of Arms, photographs, the Murray-Darling Basin Authority logo or other logos and emblems, any material protected by a trade mark, any content provided by third parties, and where otherwise noted, all material presented in this publication is provided under a Creative Commons Attribution 3.0 Australia licence. Commonwealth of Australia (Murray-Darling Basin Authority) The Murray-Darling Basin Authority s preference is that you attribute this publication (and any Murray-Darling Basin Authority material sourced from it) using the following wording within your work: Title: Droughts in the Murray Darling Basin since European settlement Source: Licensed from the Murray-Darling Basin Authority under a Creative Commons Attribution 3.0 Australia Licence The Murray-Darling Basin Authority does not necessarily endorse the content of this publication. As far as practicable, material for which the copyright is owned by a third party will be clearly labelled. The Murray-Darling Basin Authority has made all reasonable efforts to ensure that this material has been reproduced in this publication with the full consent of the copyright owners. Inquiries regarding the licence and any use of this publication are welcome by contacting the Murray-Darling Basin Authority. Disclaimer The views, opinions and conclusions expressed by the authors in this publication are not necessarily those of the Murray-Darling Basin Authority or the Commonwealth. To the extent permitted by law, the Murray- Darling Basin Authority and the Commonwealth excludes all liability to any person for any consequences, including but not limited to all losses, damages, costs, expenses and any other compensation, arising directly or indirectly from using this report (in part or in whole) and any information or material contained within it. Accessibility Australian Government Departments and Agencies are required by the Disability Discrimination Act 1992 (Cth) to ensure that information and services can be accessed by people with disabilities. If you encounter accessibility difficulties or the information you require is in a format that you cannot access, please contact us.

3 GRIFFITH CENTRE FOR COASTAL MANAGEMENT Griffith University Gold Coast Parklands Drive SOUTHPORT QLD 4215 PMB 50 Gold Coast Mail Centre 9726 Telephone (07) Facsimile (07) GRIFFITH CENTRE FOR COASTAL MANAGEMENT RESEARCH REPORT SERIES DOCUMENT CONTROL SHEET Document: Griffith Centre for Coastal Management Research Report No DRAFT Project: Droughts in the MDB since European Settlement Title: Droughts in the Murray Darling Basin since European Settlement Project Leader: Dr Peter Helman Author(s): Peter Helman Sponsoring Organisation: Murray Darling Basin Authority Contact:: Gemma Ansell Synopsis: Prolonged period of recurring drought challenges the security of water supply for broad acre and irrigated agriculture as well as land and river management. The issue raised is what if the drought period had continued for another decade? This paper combines observations and historic records to describe drought periods in the MDB extending back to the late 1700 s. Keywords: Drought, Murray Darling Basin, Historical Events. REVISION/CHECKING HISTORY REVISION REPORT NUMBER DATE CHECKED BY ISSUED BY 0 July 2009 R. Tomlinson P. Helman 1 DISTRIBUTION DESTINATION GCCM File GCCM Library MDB Authority REVISION i

4 TABLE OF CONTENTS 1 INTRODUCTION LEARNING FROM HISTORY SUSTAINABLE MANAGEMENT AND DROUGHT Drought Sustainability Drought and the Murray Darling Basin Past Records MDB Droughts DESCRIPTIONS OF DROUGHTS IN MDB SINCE THE LATE 1700S DARLING RIVER FLOWS CLIMATE PHASES AND MDB DROUGHTS Climate variability and Pacific Ocean oscillation ENSO/SOI RELATIONSHIP OF IPO TO ENSO Extended drought periods Dynamic conceptual model of IPO (PDO) climate phase INDIAN OCEAN OSCILLATION (IOD) SOUTHERN OCEAN EXCEPTIONS AND ANOMALIES FUTURE DROUGHTS Past climate Future Climate CONCLUSIONS REFERENCES APPENDIX Flow in the Darling River from 1788 to ii

5 TABLE OF FIGURES Figure 1: 1865 cartoon depicting Goyder in search of rainfall (SA Museum)... 2 Figure 2: Murray Darling Basin showing (A) Goyder s Line defined in 1865 as the limit of reliable rainfall in South Australia, (B) south eastern edge of arid zone extends into western side of MDB, (C) northern edge of winter dominated rainfall, (D) western edge of summer dominated rainfall Figure 3: Floods in the Darling River 1788 to Dashed floods inferred from coastal weather, Small bar - minor floods and freshes. Long bar - major floods Vertical lines - Positive and negative IPO phases Figure 4: Inverse IPO from 1890 to 2004 (plotted - solid pink positive phase, light blue negative phase) Figure 5: (a) Top panel. Positive and negative IPO phases. Phases to 1886 from IPO model Hadley Centre (2004), from 1886 to 1856 after Helman (2007), from 1856 to 1788 after Verdon and Franks (2006) (b) Bottom panel - Droughts in the Murray Darling Basin from 1788 to 2009 as described in Table Figure 7: Influence of positive and negative phases of IOD on rainfall over Australia, Ummenhoffer and others TABLES Table 1 Drought periods in the MDB... 6 iii

6 Droughts in the Murray Darling Basin since European Settlement 1 1 INTRODUCTION Since the late 1970 s the Murray Darling Basin, along with most of eastern Australia, has experienced recurring droughts. This prolonged period of recurring drought challenges the security of water supply for broad acre and irrigated agriculture as well as land and river management. The issue raised is what if the drought period had continued for another decade? This paper combines observations and historic records to describe drought periods in the MDB extending back to the late 1700 s. The pattern of droughts will be related to stream flow (Darling River at Bourke) from the early 1800 s recoded by the NSW Astronomer H C Russell (1886) and river boat records. The drought periods and stream flow will be related to interannual and multi decadal climatic phases. Some key features of the drought history are: A few years after European settlement in Australia, severe drought gripped the new settlement. Little rain was recorded from June 1790 to mid 1791 and creeks around Port Jackson ceased to flow until Governor Phillip wrote: I do not think it probable that so dry a season often occurs (Sherratt 2005) With some intervening wet years, periods of severe drought continued until In December 1828 Charles Sturt explored west to the Darling River near Bourke where no rain had fallen for two years and the river was a chain of saline pools. Prolonged drought had lowered the river so that salt springs ran from the banks into the pools (Favenc 1888). At the end of the century, Australia was again gripped by the severe Federation Drought ( ) and over the last three decades, we have again seen a long period of recurring droughts. Since Federation, (1901) and the establishment of the Bureau of Meteorology in 1907 when instrumental climate observations commenced, drought periods have been well documented. This study provides an analysis of droughts during the first century of European settlement using explorers accounts, property records and river flows to compile a drought history from the late 1700 s to present. The highly variable character of Australian climate is beginning to be unravelled. Understanding the range of climate variability and how it could alter with changing climate is essential for sustainable management. The late Professor Peter Cullen proposed a principle of sustainable NRM that landscapes should be managed for what they are, not for what we would like them to be. The history of Goyder s Line shows that, long wet and dry phases, lasting several decades, need to be considered in sustainable management of landscapes.

7 Droughts in the Murray Darling Basin since European Settlement 2 2 LEARNING FROM HISTORY Ignoring history leads to analysis of short term records which do not include long term (multi decadal) oscillations. Making projections from short term data without considering long term variability may be invalid. Uncertain science is not a satisfactory basis for sustainable natural resource decision making. McKeon and others (2000) suggest that history does not lend to teaching unless we can understand how the process of climate, ecology, management and policy interact. The problem is that climate and ecology operate over different time scales from management and political decisions. For example, multi decadal climate phases are difficult for decision makers to comprehend, effectively consider and respond to. This is illustrated in the history of Goyder s Line. In 1864 severe drought conditions in South Australia lead to landholders exerting political pressure for reduced lease fees. In 1865, the Surveyor General, Charles Goyder was instructed to determine: 'the line of demarcation between the portion of the country where the rainfall has extended and that where the drought prevails. Figure 1: 1865 cartoon depicting Goyder in search of rainfall (SA Museum) Goyder s Line is based on his assessment of natural vegetation communities that reflected the long term reliable rainfall. The line defined by Goyder broadly follows the 250mm [10 ] isohyet and crosses into the lower Murray Darling Basin near Blanchtown, SA.

8 Droughts in the Murray Darling Basin since European Settlement 3 In the late 1860 s during the wet climatic phase, good seasons followed the drought and settlers exerted political pressure to farm the never ending green fields extending north of Goyder s Line. Politicians relented and by 1880 agriculture, towns and railways extended well beyond Goyder s Line. In the short drought of the 1880 s and the extended Federation Drought from the mid 1890 s, farms and towns that had been established during the wet decades, were abandoned. Crumbling stone ruins and the plans of streets surveyed for towns remain today (Meinig 1962). Unfortunately, the two centuries of European management of Australian landscapes is littered with failures to grasp the reality that sustainable management needs to consider a critical climatic feature extended drought periods with severe droughts recurring over decades. 3 SUSTAINABLE MANAGEMENT AND DROUGHT 3.1 Drought In general terms, drought is a prolonged absence or marked deficiency of precipitation, resulting in water shortage for many uses or a period of abnormally dry weather sufficiently prolonged for the lack of precipitation to cause a serious hydrological imbalance. Drought has been defined in a number of ways. Agricultural drought relates to moisture deficits in the topmost one metre or so of soil (the root zone) that impacts crops, Meteorological drought is mainly a prolonged deficit of precipitation, and hydrologic drought is related to low streamflow, lake and groundwater levels (IPCC 2007). Drought and its severity can be numerically defined using indices that integrate temperature, precipitation and other variables that affect evapo-transpiration and soil moisture. Several indices in different countries assess precipitation deficits in various ways. The most commonly used index is the PDSI (IPCC 2007) that uses precipitation, temperature and local available water content data to assess soil moisture. These data are readily available for most parts of the world; the PDSI provides a measure of drought for comparison across many regions (IPCC 2007). The PDSI is not an optimal index, as it does not include variables such as wind speed, solar radiation, cloudiness and water vapour. It is widely used and can be calculated across many climates as it requires only precipitation and temperature data for the calculation of potential evapo-transpiration. 3.2 Sustainability The national strategy for ecologically sustainable development in 1992 states an aim to facilitate the ecologically sustainable development of agricultural industries so they contribute to long- term productivity and to Australia s economic well-being; protect the biological and physical resource base on which agricultural industries depend; and improve human health and safety. Past agricultural practices have contributed to land degradation, especially during drought periods. McKeon and others (2000) have described degradation episodes of dust storms, soil erosion and reduced infiltration capacity in dry periods. They also noted that some degradation occurred in wetter periods when over-stocking and woody-weed

9 Droughts in the Murray Darling Basin since European Settlement 4 infestation increased. Historical evidence suggests that where conservative stocking policies or rapid reduction in response to drought onset, degradation was minimal. Ecosystems of the basin are adapted to recurring droughts and very variable streamflow, from major floods to no flow. This presents considerable natural resource management challenges for both terrestrial and river ecosystems. 3.3 Drought and the Murray Darling Basin Review of drought in the Murray Darling Basin is set within the context of the wider Australian climate and oscillations of the surrounding oceans. D C B A Figure 2: Murray Darling Basin showing (A) Goyder s Line defined in 1865 as the limit of reliable rainfall in South Australia, (B) south eastern edge of arid zone extends into western side of MDB, (C) northern edge of winter dominated rainfall, (D) western edge of summer dominated rainfall.

10 Droughts in the Murray Darling Basin since European Settlement 5 While the western portion of the basin is the arid zone and recurring dry conditions could be expected, the demarcation of seasonal winter and summer rainfall patterns are based on average seasons. Yet annual to decadal analysis shows significant annual variation, and marked multi decadal phases. The extreme variation of Australian climate, reflected in river hydrographs, which over long time periods show distinct wet and dry periods. Erskine and Warner (1988) recognized alternating drought and flood dominated periods for coastal rivers and this characteristic is more marked for inland rivers. Drought and flood periods are now considered to represent positive and negative phases of Inter-decadal Pacific Oscillation (IPO) (McKeon and others 2000, Verdon and Franks 2006, Verdon 2007, Helman 2007 and McGowan and others 2009). Climate is rarely average which is a mean of distinct wet and dry phases, during which the extreme floods and droughts tend to occur. What is the extent of these extremes and have we experienced these during the last two centuries? 4 PAST RECORDS The records of early European explorers illustrate the striking differences in the landscape during wet and dry periods. In 1829 in western NSW Charles Sturt found no aboriginal people and concluded: this seemed a desert they never entered that not even a bird inhabited so long had the drought continued that the vegetation kingdom was almost annihilated and minor vegetation had disappeared Just four years later Mitchell in 1833 described the Darling River landscape as an: abundance of pasture, indeed such excellent grass as we had not seen in the whole journey covered the fine forest ground on the bank of the river. After several years of rain and extensive floods that had covered the floodplains to produce the excellent grass along the river. Sturt experienced western NSW in the late 1820 s, at the end of several decades of recurring droughts, during the early 1830 s there was rain and floods before drought conditions returned in the late 1830 s. To describe wet and dry periods in the MDB two approaches are used:. Description of the drought periods in the MDB from past records. Before the mid 1830 s records are scarce and drought conditions in the MDB are assumed. from surrounding areas Darling River flows at Bourke, assessed from a range of sources are inferred to Later flows are described from anecdotal records by Russell (1886) and river boat histories to the early 1900 s (Appendix 1).

11 Droughts in the Murray Darling Basin since European Settlement 6 A wide range of records were examined to provide indicators of wet and dry periods. These included explorer s journals, accounts of explorations, regional and station histories. These records have been integrated with Bureau of Meteorology, Queensland Centre for Climate Change Excellence (Long Paddock), drought descriptions and Parliamentary Inquires. 4.1 MDB Droughts Little is known about the extent of the drought in the basin that gripped the early European settlement. After the Blue Mountains road was constructed in 1815 explorers entered the basin and records become more comprehensive in terms of observations and geographical extent. Droughts in the MDB have been collated from numerous records and are listed in Table 1. Table 1 Drought periods in the MDB Drought Popular name Extent of drought Years Settlement Drought Probably SE Australia Probably whole basin Great Drought Probably whole basin Sturt s Drought Most severe in northern basin SE Australia Black Thursday Drought SE Australia Goyder s Line Drought Australia wide,1864 to1866 severe in western basin and South Australia Mostly inland, wet on coast Federation Drought Eastern Australia, devastating stock losses First War Drought Mainly eastern Australia, severe stock losses Mostly inland spreading to southern Australia Second War Drought Especially severe in SE, devastating stock losses 1952 Northern Australia to northern MDB MDB to Central Australia, devastating crop and stock losses Dust Cloud Drought Eastern Australia, with extensive loss of agriculture production Eastern and northern Australia Big Dry Eastern Australia contracting to SE, dams low, water allocation restrictions Of the 221 years since European settlement in 1788 it is considered that part or all the basin has been in drought conditions for 88 years. This reality of basin climate means that drought conditions need to considered in all water, river and natural resource management. 5 DESCRIPTIONS OF DROUGHTS IN MDB SINCE THE LATE 1700S The drought periods for the MDB are described below with the most attention to the early events. Due to the lack of records drought conditions are inferred from records on the east coast. Detailed paleo studies of wet and dry periods over the last few centuries

12 Droughts in the Murray Darling Basin since European Settlement 7 could be used to establish relative severity, as past records used changing assessment criteria. Settlement Drought Periods The first dry period at Port Jackson occurred between 1790 and Based on links between later east coast and inland droughts, dry conditions are likely to have been experienced inland. Wet years on the coast occurred between 1794 and 1796, 1805 and 1808, with a fresh in the Hunter River in The later part of this wet period may have been influenced by a major eruption in New Britain, PNG. Dry weather continued in the Port Jackson settlement with 1813 described as the great drought (Favenc 1888:55) and encouraged new attempts to cross the Blue Mountains. After the mountains had been crossed Surveyor General Oxley described the dry country found at the foot of the western slopes as desert unfitted ever to sustain settlement and considered that the great plain was an unprofitable waste (Favenc 1888:56) In 1815, the massive eruption of Tambora, Java was an event that influenced climate globally. On the east coast of Australia, 1816 and 1817 were wet stormy years. During 1817, Oxley made the first exploration of the eastern section of the MDB and found the Lachlan Marshes to be flooded from the recent rain but away from the rivers found little water. Oxley doubted that: these desolate plains be ever again visited by civilized man. In mid 1818 Oxley experienced wet weather travelling down the Macquarie River to the flooded Marshes and was forced to cross back to the coast at Port Macquarie. While 1822 was stormy earlier in the year, this did not appear to extend the northern basin as by September 1824 salt water was found further up the Brisbane River than the previous visit (1823) and the side creeks had dried up. Both 1825 and 1826 were wet in SE Qld with a major Brisbane River flood. It was probably wet in the upper basin catchments but may have been dry further inland. In October, 1824 Hume and Hovell found the Murrumbidgee River (near Yass) flooded [from seasonal snow melt]. Snow pack in 1824 was heavy as in October the snow level was described as one quarter of the height of the mountains. By 1826, severe drought had returned to both Port Jackson and Moreton Bay, although it was probably drier earlier in the northern MDB, during the early 1820 s. In August 1828 Cunningham explored from New England to the Darling Downs and described that the country was gripped by a sad drought [and that] the entire country through which we had passed had long been subjected to. When in December 1828 Sturt set out for western NSW no rain had fallen for two years. The Castlereagh River was dry: large saplings growing in the river beds, the large forest trees [on the banks] were drooping and many dead. The emus with outstretched necks, grasping for breath, searched the channels of the rivers for water, in vain Large saplings growing in the dry river bed indicates several years of no flow.

13 Droughts in the Murray Darling Basin since European Settlement 8 Later Sturt found Oxley s 1818 camp site, which had been on the edge of the marsh, he notes that he could not discern the waters of the channel, so much had the water fallen below the ordinary level. In January 1829 Sturt reached the Bogan River east of Bourke, which was not flowing but a reach was: an unbroken sheet of water broad evidently very deep literally covered with pelicans and other wild fowl, our surprise and delight may better be imagined than described.the men descended eagerly to quench their thirst that a powerful sun had contributed to increase, nor shall I ever forget the cry of amazement that followed their doing so or the looks of terror and disappointment with which they called out to me that the water was so salt as to be unfit to drink apparently a mixture of sea and freshwater. The long drought had lowered the rivers so that the brine springs in the banks predominated over the freshwater springs, which Favenc (1888) considered a common characteristic of inland water courses. Sturt later discovered both saline and fresh water springs in the river bank proving the saltiness was local and not from an inland sea. In late 1829 Sturt travelled by boat down the Murrumbidgee to the Murray River. Flow was low; grass covered the banks of the Darling River indicating no recent floods. It was not until April 1830 that a fresh come down the river. Of his experiences Sturt commented that during his expedition he had seen rivers cease to flow before me and sheets of water disappear the ground bare and permanent vegetation suffering moisture stress. Late 1830 s and early 1840 s droughts Two sequential droughts occurred between 1836 and 1839, although 1841 was a wet year with floods, drought conditions had returned by 1842 continuing to Mitchell found dry conditions in the Lachlan River valley in March 1836, but the cattle remained in good conditions due to previous good rains but further west Mitchell was forced to turn back from lack of water. McKernan (2005) reports cattle rushing at settlers to eat their cabbage tree hats. Heavy rain commenced in June 1839 and resulted in a major Brisbane River flood in 1841 and a flood in the Yarra River in December Dry conditions returned in 1842 and very severe drought set in until late West of the MDB at Strzelecki Ck in July 1845 Sturt experienced a hot wind that forced them to camp the whole day. sought shelter behind a large gum tree but the blasts of heat were so terrific, that I wondered that the very grass did not take fire the horses stood with their backs to the wind, and their noses to the ground, without the muscular strength to raise their heads, birds were mute and the leaves to the tree under which were sitting, fell like a snow shower around us. at noon I took a thermometer the mercury was up to 125 [degrees F] I put it in the fork of a tree sheltered alike from the wind and the sun I went to examine it about an hour afterwards, when I found that the mercury had risen to

14 Droughts in the Murray Darling Basin since European Settlement 9 the top of the instrument and that it s further expansion had burst the bulb, a circumstance that I believe, that no traveler has had to recount before (Favenc 1888). Black Thursday drought 1849 to 1853 The summer of was the driest for thirty years [since the 1820 s], Lake George was dry, and in south western NSW there was severe drought conditions, with major stock loss and no flow in the Darling River at Bourke. Heavy rain fell in central NSW during On 24 May 1852 the Great Flood on the Murrumbidgee River at Gundagai occurred. Yet it remained dry in Victoria leading to the Black Thursday Fires on 6 February Goyder s Line Drought, early to mid 1860 s Queensland was gripped by severe drought in While Burke and Willis commenced their attempt to cross the continent in good conditions as they travelled to the Gulf, on the return they suffered from the influence of the severe drought in Queensland. Good rain in July 1862 and heavy floods in January 1863 broke the drought in Queensland. Despite the Great Flood in the Darling River in January 1863, the river fell quickly as drought became severe in southern Australia during 1864 and continued until It was during this drought in South Australia that Goyder s Line was defined s drought The widespread severe drought that commenced late in 1880, after many years of good rains, caused considerable pastoral losses. Extremely dry and hot seasons across SA, NW Vic and SW NSW resulted in yield reduction and no harvests in marginal lands. This single bad season ended marginal cropping in northern South Australia. The poor yield for altered the minds of the most enthusiastic advocates who thought that agricultural settlement will pay in the remote districts of the North (Meinig 1962). At Haddon Rig (western NSW) in 1882 it was dry with no rain and plagues of locusts. There were short floods in the Darling River, (1882 and 1883) from monsoon rain in Queensland. During 1883 and 1884 drought spread north to SE Queensland with bushfires and the driest conditions since the 1860 s drought. Federation drought Severe drought occurred in eastern Australia from 1896 to One reason why this drought was so devastating is that, apart from the early 1880 s drought, good seasons had been experienced for three decades. At Narrandera after decades of 500mm annual rainfall the rain stopped. After decades when the grass had been as high as a sheep s back the country turned to bare ground. Sheep numbers were halved and cattle reduced over one third, in 1902 there was almost total loss of the wheat crop. At Haddon Rig an artestian bore was sunk and paddocks flood irrigated. The drought broke in southern Victoria during December 1902, then in NSW and Queensland during However, water was still being carted in the Mallee during Below average rainfall continued until 1920, including the First World War Drought. First War Drought This severe drought occurred in dry decades of the early 1900 s throughout southern and eastern Australia between 1911 and Wimmera farms were as dry as in the 1880 s, and the Murray River at Swan Hill was a series of stagnant pools. There were severe dust storms and extensive stock losses.

15 Droughts in the Murray Darling Basin since European Settlement 10 With the exception of a few good seasons ( and ) drought continued in parts of the basin until In 1925 a Royal Commission was held in Victoria into unviable soldier settlement was very dry in the western and southern basin: Haddon Rig (western NSW) was spending 4000 pounds a month hand feeding. Second War Drought Dry conditions in in SE Australia provided the conditions for the disastrous Black Friday fires in Victoria with 30 million sheep lost between 1939 and 45, severe dust storms and in western NSW wheat silos did not open for the season. By 1945 Hume Weir was dry and Burrinjuck Dam was low. Rain fell in Victoria in August s Drought There was an extremely dry year in northern Australia with the failure of the wet season (1951-2): drought extended south to the northern basin s Drought Drought occurred across SE Australia from 1962 to This drought varied in extent and severity over different years. Some places were as dry as the Federation Drought. Both Hume Weir and Burrinjuck Dam were dry in 1965, and there was widespread soil erosion and stock losses. Dust cloud drought From April 1982 and into 1983 there was widespread short and intense drought across eastern half of Australia with very severe dust storms, including the dust cloud that enveloped Melbourne on 8 February The Ash Wednesday fires occurred across SE Australia soon after on 16 February s Drought From 1990 to 1995 there was severe and widespread drought. It was not as severe in southern areas until During this drought there was a serious decline in rural production and extensive drought relief assistance. The Big Dry From 2000 rainfall declined and by 2003 severe drought had spread across the whole basin. The disastrous Canberra fires occurred on 16 February. There was rain in Victoria and along the east coast during early 2005 but drought conditions continued inland. In 2009, despite the heaviest wet season in northern Australia for 30 years, southern Australia remained dry. Most of the southern basin was in severe drought with low flow in the lower Murray River. Record heat wave conditions across SE Australia were followed by extreme fire conditions resulted in the disastrous Black Saturday fires (7 February 2009) in Victoria. 6 DARLING RIVER FLOWS The first exploration to the river was in 1829 with earlier flows inferred from the records of early settlement climate (Callaghan and Helman 2008) and the first explorers to travel into the MDB catchments. From the early 1800 s to 1886 Russell (1886) estimated flows in the Darling River using first hand accounts from settlers. Gauging commenced at Burke in 1871.

16 Droughts in the Murray Darling Basin since European Settlement 11 Flows in the Darling River from 1788 to early 1900 s are shown in Figure 3 and details are described in Appendix 1. _ + _ + _ + _ + _ Figure 3: Floods in the Darling River 1788 to Dashed floods inferred from coastal weather, Small bar - minor floods and freshes. Long bar - major floods. Vertical lines - Positive and negative IPO phases. 7 CLIMATE PHASES AND MDB DROUGHTS Distinct decadal wet and dry phases are related to the multi decadal positive and negative phases of the IPO. While shorter droughts are often related to negative SOI in the eastern basin and IOD in the southern basin, there are many exceptions. Russell (1886:156) postulated a 19 year cycle for Darling River floods and dry periods. As an astronomer he was seeking relationships between climate cycles and definable observable events. Such regular events do influence climate but interacting oscillations of a complex climate systems, operating in different time scales, means that Australian climate is highly variable in all time scales. Russell s speculation of mutli decadal phases is valid but the length of such phases is highly variable. 7.1 Climate variability and Pacific Ocean oscillation During the 1990 s a multi decadal oscillation of the Pacific Ocean was described as PDO for the north Pacific and IPO for the whole ocean. Increasingly, this oscillation has been related to significant climate phases. Research over recent years suggests that this oscillation modifies ENSO and possibly other shorter term oscillations (Verdon 2007). The positive and negative phases of PDO/IPO have been linked to climatic, geomorphic and ecological processes over multi decadal time scales. In Australia IPO/PDO phases have been related to: rangeland droughts and degradation (McKeon and others 2000, McKeon and others 2004); central and southern MDB rainfall and streamflow (Franks and Verdon 2006, Verdon 2007, McGowan and other 2009) and coastal storms and droughts (Helman 2007). While it is not understood what drives these multi decadal phases the links to climate phases is now well established. Considering that the Pacific Ocean covers one quarter

17 Droughts in the Murray Darling Basin since European Settlement 12 of the earth s surface it is considered that Pacific Ocean multi decadal climate oscillation has a pervasive influence. Figure 4: Inverse IPO from 1890 to 2004 (plotted - solid pink positive phase, light blue negative phase). SOI positive - dark blue, negative red. From McKeon and others (2004:28). 8 ENSO/SOI Nicholls (2005:19) describes the recognition by Henry Blanford that the severe drought in India was associated with abnormally high atmospheric pressure. Charles Todd in South Australia noting that dry conditions prevailed during this period, led to the conclusion: There can be little doubt that severe droughts occur as a rule simultaneously over the two countries (Todd 1888 in Nicholls 2005:19). This link was also proposed by Russell in NSW in 1886 (Grove 2005) and several decades later in 1929, Quayle demonstrated that atmospheric pressure at Darwin could be used for seasonal climate prediction in south east Australia (Nicholls 2005). The El Niño Southern Oscillation (ENSO) is now understood as a dominant short term climatic pattern indicated by temperature differences between the warm western and cool eastern Pacific Ocean over two to seven year periods (Allan and others 1991). The Southern Oscillation Index (SOI) measures difference in atmospheric pressure between Tahiti and Darwin. Positive SOI corresponds to cooler eastern Pacific Ocean temperatures resulting in higher rainfall over eastern Australia (La Nina years) and negative SOI (El Niño years) reflect warmer eastern Pacific Ocean conditions with low rainfall and drought in Australia (Nicholls 2005). When the central eastern Pacific SST is warm and IPO is positive, eastern Australia tends to be warm and dry (Power and others 1999). The most severe droughts occur when SOI is negative and IPO is positive (McKeon and others 2000).

18 Droughts in the Murray Darling Basin since European Settlement 13 9 RELATIONSHIP OF IPO TO ENSO The modification of ENSO by IPO has been described by Verdon and Franks (2006) and Verdon (2007) who demonstrated, from paleo records, that this relationship existed for the last four centuries. During positive IPO negative SOI is more frequent, and during negative IPO positive SOI is more frequent. On the coast Helman (2007) found marked wet and dry periods related to the inter action of these oscillations. 9.1 Extended drought periods During a positive IPO phase, as experienced over the last three decades, recurring years of negative SOI are often represented by years of severe drought, for example in the early 1980 s, mid 1990 s and from While some wet years occur (late 1980 s and 2001) rainfall is generally low and there is a cumulative impact on the water cycle; streamflow, dam storages, wetlands and water tables as seen over the last three decades. This period is similar to the extended drought period, from 1790 to 1830, which stressed early settlement. a + _ + _ + _ + _ + _ Figure 5: (a) Top panel. Positive and negative IPO phases. Phases to 1886 from IPO model Hadley Centre (2004), from 1886 to 1856 after Helman (2007), from 1856 to 1788 after Verdon and Franks (2006). (b) Bottom panel - Droughts in the Murray Darling Basin from 1788 to 2009 as described in Table Dynamic conceptual model of IPO (PDO) climate phase Three distinct periods of Australian climate periods are generally related to IPO phase: Negative IPO phase, when SOI positive wet period, storms and recurring floods. Monsoonal trough tends over inland areas. For example, late 1860 s to 1880 s and early 1950 s to mid 1970 s.

19 Droughts in the Murray Darling Basin since European Settlement 14 Positive IPO phase, when SOI negative dry conditions, periods of low streamflow and recurring droughts. For example, in the early 1900 s, mid 1940 s and over the last few decades from the 1980 s. Periods of transition between these phases for example, between 1946 and 1952 IPO was changing from positive to negative, with increasing rainfall and flooding. 10 INDIAN OCEAN OSCILLATION (IOD) Research on the Indian Ocean has identified many oscillations, the most important for Australia being the Indian Ocean Dipole (IOD) - a short term oscillation over years and possibly partially related to ENSO (Verdon 2007). Ummenhofer and others (2009) suggest that positive IOD phase is associated with drought conditions in southern Australia. Figure 6: Top graph shows phases of Indian Ocean Dipole back to Normal rain declines in positive phase. Grey bars indicate drought. Bottom graph shows rainfall anomalies (mm) Ummenhoper and others (2009). Positive IOD leads to below average rainfall across southern Australia with above average rainfall during negative IOD (Figure 7).

20 Droughts in the Murray Darling Basin since European Settlement 15 Figure 7: Influence of positive and negative phases of IOD on rainfall over Australia, Ummenhoffer and others SOUTHERN OCEAN Studies of oscillations in the southern Tasman Sea and the Southern Ocean suggest links to southern Australian rainfall are likely but are not examined in this paper. 12 EXCEPTIONS AND ANOMALIES No single climatic index fully explains the variation of Australian climate. The climate of eastern Australia generally responds to the oscillations of the Pacific Ocean, where dry and wet periods are generally associated with IPO and ENSO. The period has been recognised (Nicholls 2005, Helman 2007) as anomalous to the relationship. It is also possible that both the index may be changing over time, or that the relationships between climate indexes may also be changing. The magnitude and oscillation of multi decadal phases and the occurrence of anomalous periods suggest records are too short to make definite predictions of future behaviour. Useful deductions can be made from past records about climatic variability before observed records commenced, and present the possibility of long term understanding of the range of climate variability. 13 FUTURE DROUGHTS 13.1 Past climate Studies of past climate through paleo records or modeling suggest greater climatic variability than experienced over the last two centuries. Lough (2007) studied coral cores to reconstruct streamflow of north Queensland rivers. Long-term tropical rainfall and river flow variability has significant, though weak relationships to ENSO and PDO. When compared to instrumental records of interannual and decadal rainfall, past river flow variability has similar features during past centuries. Although there appears to be no

21 Droughts in the Murray Darling Basin since European Settlement 16 overall trend toward wetter or drier conditions, the results suggest that the variability of rainfall and river flow has increased during the twentieth century, with more very wet and very dry extremes than in earlier centuries, as projected as a consequence of global warming Future Climate What impact will climate change have on the recorded extreme climate variability in the MDB? CSIRO (2008) consider that over the next 20 years a decline in median water availability by 11%, and that in dry years up to 50% less in the southern basin. Evapotranspiration, will increase with rising temperature this will influence the speed of drought onset and severity. However the extreme range from years of no rain and low stream flow over decades due to IPO positive phases, and modification of shorter term oscillations have created periods of extended drought. What impact climate change will have on the extreme variability of wet and dry periods is uncertain. 14 CONCLUSIONS Examining the history of drought periods in the basin provides information on the characteristics of droughts during the last two hundreds years of climate history. Multi decadal wet and dry phases have been recognised for Australian climate and are reflected in rainfall and streamflow. The dry phases are linked to recurring severe drought years. During decades of positive IPO an extended drought period occurs over many decades, with recurring severe droughts and generally low rainfall, streamflow and lowered water tables. These climatic phases, with recurring droughts, lasting decades are the reality for the MDB and records show that this pattern has been experienced since European settlement. The drought history of the basin shows for over a third of the 221 years since European settlement part or all the basin has been in drought. Two long extended drought periods from 1795 to 1830, extending over 35 years, and 1980 to 2009, extending over 29 years show that over these periods there is a complete alteration to the water cycle. The Federation Drought lasted a decade, associated with positive IPO and negative SOI. If this drought had lasted for two or more decades there would have been very serious management problems. In general MDB droughts occur during positive IPO phases, with severe drought years linked to negative SOI or IOD. These climatic indices while providing indicative correlations do not correlate with all events. Grove (2005) considers this is due to the complexity of climatic system, the time for oscillations to pass through the global climate and interactions with the oceans. This may be further complicated by changing characteristics and relationships due to climate change.

22 Droughts in the Murray Darling Basin since European Settlement 17 Sustainable NRM of the MDB demands more consideration of both the droughts that have occurred during the last 200 years and indicated in paleo climatic records. It may be possible that the worst case of climate variability has not been experienced and future drought may be even longer and more severe. Prof Henry Nix s view on climate variability is that there will always be a higher flood and a longer drought. With this possibility in mind, the late Prof Peter Cullen considered: You can t drought-proof Australia We need to learn to live with the landscape, not try to fight against it all the time. This statement applies to both agricultural production and natural resource management as increasing efforts to drought proof will turn rivers into channels or drains without the natural variability needed by river ecosystems. With increasing temperatures and evaporation in the future, and possibly changing rain patterns drought planning rather than drought proofing needs to be considered. While areas are still in drought the current (2009) wet season in northern Australia, the most rain for three decades, combined with a cold winter, and rain in southern Australia is consistent with a change to negative IPO phase. Even if wetter conditions are experienced over the next decades, history shows there will be future droughts and planning for these should always be a consideration in future sustainable resource management decisions. What will be the interaction between a changing climate and extreme climate variability over the MDB?

23 Droughts in the Murray Darling Basin since European Settlement 18 REFERENCES Callaghan, J and Helman, P., 2008, Severe storms on the east coast of Australia Griffith Centre for Coastal Management, Griffith University, Gold Coast, Qld Colls, K. and Whitaker, R., 2001, The Australian weather book. New Holland Publishers (Australia) Pty Ltd CSIRO 2008, Water Availability in the Murray Darling Basin Davidson, B. R., 1969, Australia wet or dry? The physical and Economic limits to the expansion of irrigation. Melbourne University Press Favenc, E., 1888, The History of Australian Exploration: from 1788 to Turner and Henderson. Grove, R., 2005, Revolutionary weather: the climate and economic crisis of and the discovery of El Nino, in Sherratt, Tim, Griffiths, Tom and Robin, Libby (eds) A change in the weather: Climate and Culture in Australia National Museum of Australia Press, Canberra: IPCC 2007, Climate change 2007: The Physical Science Basis University Press, Cambridge, UK Jessop, J., 1981, Flora of Central Australia. The Australian Systematic Botany Society. Lough J.M, 2007, Tropical river flow and rainfall reconstructions from coral luminescence: Great Barrier Reef, Australia. Paleoceanography, Vol. 22, PA2218, doi: /2006pa Lunney, D. 1994, Royal Commission of 1901 on the western lands of New South Wales an ecologist s summary. in Future of the fauna of western New South Wales, eds D.Lunney, S. Hand, P. Reed and D. Butcher. Published by Royal Zoological Society of NSW: McGowan, H., Marx, S. K., Denholm, J., Soderholm, J. and Kamber, B. S., 2009, Reconstructing annual inflows to the headwater catchments of the Murray River, Australia, using the Pacific Decadal Oscillation Geophysical Research Letters Vol 36 Lo6707, doi /2008gl McKernan, M., Drought. The red marauder Allan and Unwin Sydney Meinig, D. W., 1962, On The Margins of the Good Earth: The South Australian Wheat Frontier, Reprinted Rigby 1972 Moorhead, A., 1963, Cooper s Creek. Hamish Hamilton Ltd. Mudie, I., 1961, Riverboats. Sun Books. Melbourne.

24 Droughts in the Murray Darling Basin since European Settlement 19 Nichols, N.,. 2005, Climatic outlooks from revolutionary science to orthodoxy. In A change in the weather: climate and culture in Australia. Sherratt, Tim, Griffiths, Tom and Robin, Libby National Museum of Australia Press. Russell, H. C.,1886, Notes upon the History of Floods in the River Darling. Transactions and Proceedings of the Royal Society of New South Wales: Sheldrick, J., 2005, Goyder s Line: the unreliable history of the line of reliable rainfall. in A change in the weather: climate and culture in Australia (eds) Tim Sherratt, Tom Griffiths and Libby Robin.. National Museum of Australia Press: Sherratt, T., 2005, Human elements. in A change in the weather: climate and culture in Australia, eds Tim Sherratt, Tom Griffiths and Libby Robin.. National Museum of Australia Press; 1 17 Sherratt, T., Griffiths, T. and Robin, L., (eds). 2005, A change in the weather: climate and culture in Australia. National Museum of Australia Press. Ummenhofer, C., England, M., McIntosh, P., Meyers, G., Pook, M., Risbey, J., Gupta, A., Taschetto, A., 2009, What causes Australia s worst droughts? Geophysical Research Letters Vol 36 L04706, doi /2008gl Whitaker, R., , Australia s natural disasters. New Holland Publishers (Australia) Pty Ltd.

25 Droughts in the Murray Darling Basin since European Settlement 20 APPENDIX 1 Flow in the Darling River from 1788 to Inferred flow (?) from Callaghan and Helman (2008) [C & H 2008] to 1829 and later flow from Russell (1886). A gauge was established in Bourke in 1871, with zero set 4ft above the river bar, the depth that paddle steamers needed to travel upstream. DATE FLOW DESCRIPTION NOTES REFERENCE 1788 Flood? Wet period Port Jackson C & H Low flow? Drought on coast C & H Low flow? Drought on coast C & H Low flow? Drought on coast C & H Low flow? Drought on coast C & H Low/no Drought on coast C & H 2008 flow? 1794 Flood? Wet on coast C & H Flow? Wet on coast C & H Flow? Wet on coast C & H Low flow Severe drought on coast C & H Low flow? C & H No flow? C & H No flow? C & H Flood? Wet on coast C & H Low flow? C & H Low flow? C & H Low/no C & H 2008 flow? 1805 Flood? C & H Flood? C & H Flood? C & H Flood? C & H Flow? C & H Flow? C & H Low flow? C & H Low flow? C & H No flow? Great drought coast and inland C & H No flow? C & H No flow? C & H Flood? C & H Flood? C & H Flood Oxley Macquarie and Castlereagh R flooded. Russell considered Darling Flooded 1819 Flood? C & H 2008