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USE OF THESES

This copy is supplied for purposes of private study and research only. Passages from the thesis may not be copied or closely paraphrased without the written consent of the author. The Hydrology, Geomorphology

and Quaternary Palaeochannels of the Lachlan Valley,

Justine Kemp

A thesis submitted for the degree of Doctor of Philosophy, The Australian National University, Canberra

January 2001

Except where otherwise acknowledged, this thesis is my own work.

Abstract

This thesis examines the present-day and Late Quaternary fluvial geomorphology and hydrology of the upper Lachlan Valley in central western New South Wales. The sediments and morphology of the channel and floodplain are described from its principal alluvial reaches: the confined, single­ channel reach from Cowra to Gooloogong, the unconfined, single-channel reach between Gooloogong and Cadow, and the anabranching reach on the Plain.

Present-day channel and floodplain morphology in single-channel reaches of the is dominated by the highly variable hydrologic regime, which is accentuated in confined reaches of the river, but is also influenced by inherited channel forms. In confined reaches, where the effective floodplain is

In less confined reaches, large flood features are more subdued and channel inheritance locally controls meander patterns and channel slope. Inherited influences increase downstream as confinement of flood flows is less, and channels may become entrenched within highly sinuous palaeomeanders, developing only a narrow floodplain. The effect of variable streamflow is still exhibited in chute channels, scour complexes and zones of stripped floodplain, although the channel itself is governed by bankfull flows. Lateral channel activity increases in the downstream direction, reflected in both the sinousity and width of the active floodplain. These channel and floodplain characteristics continue throughout the anabranching reach on the plains.

Hydraulic geometry relationships in both single and anabranching reaches were constructed from streamflow records and surveyed channel cross-sections, and include sediment parameters. The relationship between channel shape and silt-clay content on the Lachlan differs from that described elsewhere. The exponents found for depth and velocity as a function of discharge also exhibit notable departures from trends reported for rivers elsewhere in the world, as the standard relationships are based on rivers which increase in size downstream, while both slope and particle size decrease. The Lachlan presents a reverse situation, where discharge, slope and sediment size all decrease downstream, and illustrates the need to develop regional rather than global relationships to estimate bankfull discharges for ungauged channels with a given set of characteristics.

Palaeochannels were described for the Lachlan Valley downstream from Cowra, where they are associated with two major alluvial terraces, and on the Plains downstream from Forbes, where they intersect with each other and with the modern floodplain. Three discrete fluvial systems were defined. The Gulgo Fluvial System is characterised by relatively narrow and deep channels and has a stable, anabranching pattern. A single TL date from point bar sediments of this system suggests these channels were active by at least 57,000 yrs ago and were replaced by channels of the Ulgutherie Fluvial System, characterised by sinuous, regular and scrolled meanders with wide and shallow channels. OSL dates on channel sediments and an overlying source-bordering dune suggests Ulgutherie channel construction and aeolian deflation of fluvial sediments were underway by 34,000 yrs and the system may have declined soon afterwards. Discharge estimates based on several formulae, including relationships developed for the modern river, indicate bankfull discharges of the Ulgutherie system were at least 4 to 7 times those of the present-day river. Ulgutherie channels were replaced by channels of the Nanima Fluvial System, which had a similar morphology to the Ulgutherie channels, with scrolled, regularly sinuous meanders, but smaller channel capacities and width-depth ratios, and sediment characteristics more similar to the modern Lachlan. Radiocarbon dates indicate Nanima channels were active by 6,000 yrs, if not before, and were replaced by smaller, irregularly meandering channels of the present fluvial system soon after 3000 yrs ago. Discharge reconstructions of Nanima channels indicate they carried bankfull discharges 1.5 to 2 times that of the present river. The higher discharges associated with meandering palaeochannels in the Lachlan Valley around 34,000 yrs and from >6,000-3,000 yrs is in good agreement with lake-level and other environmental records within the catchment. Acknowleduements

A number of people are owed thanks for assistance, professional and otherwise, throughout the course of this work.

For streamflow and river records I am indebted to Rod Kerr, hydrologist at Forbes DLWC, who assisted with collecting streamflow records, and to Brian Greenwood, DLWC Parramatta, for digging out deeply buried channel cross­ sections from DLWC archives in and Parramatta. Keith Haddon, of the NSW Department of Conservation and Land Management, provided me with survey data. Laurie Sherwin of NSW Department of Mineral Resources kindly provided details of unpublished thermoluminescence dates from the Lachlan Valley. Unpublished data on river morphology and bankfull discharges was provided by Ian Rutherfurd from his sites on the Murray River.

Thanks go to Peter Fagan, Mr and Mrs Johnstone, Ian Armstrong, Bill and Chris Murphy, Bruce and Mrs Herbert, Tony and Peter Townsend, John and Don Tildsley, Jimmy Foley, Eric West, Ruth Souter, Noel Pengilly, Gwen and Alan Bush, Bill and Mrs Marsh, Dick Gavel, Mr Crouch, Mrs Wallis, Colleen and Glenn Moxey, John and Mrs Bruce, Mr Girot, Colin Davey, and Peter and Chris Delaney, for allowing access their land, and to Jeffrey and Brian Delaney, who also housed the drilling rig over a couple of weekends, and to Charles Ousby for also taking an interest in the work and for providing me with a detailed account of the history of the river at "Cumberoona". I am grateful to owners of the Cowra Holiday Park and particularly Rick of the Fat Lamb Hotel, Eugowra, for hospitality and minding the caravan for long periods, allowing me to come and go on fieldwork.

Prof. Cheng Shaoping kindly had TL analyses done on a couple of my sediment samples in Beijing. Keith Fitchett gave advice on sediments, mapping and a thousand tiny things. Kay Dancey and Nev Minch drafted some of the figures. Damian Kelleher expertly supervised three weeks of drilling, assisted by Carlo Martinello, Jim Neale and Dave Buckle, who made the work enjoyable away from home in difficult conditions.

Helen McGregor provided true friendship through my time at RSES. I am deeply indebted and grateful to Alan Pymont for ingeniously contriving the fieldwork caravan and for generously making it available over many months, for his unwavering encouragement, friendship and support throughout the course of my studies at ANU, and for first introducing me in 1987 to the landscapes and people of western New South Wales from Binalong on the 'Slopes' to the banks of the Darling River at Tilpa and Menindee. Finally, thanks and immense appreciation go to John Chappell for introducing me to the amazing Lachlan palaeochannels in the Condobolin Plain, for two awe-inspiring flights over the Lachlan Valley (some of it by accident), for allowing me to pursue an developing passion for geomorphology, and for supervising this thesis.

9

Table of Contents

CHAPTER ONE: Introduction: Some Questions concerning Late Quaternary Hydrology of Southeastern Australia

1.1 Introduction 19 1.2 The study reach 23 1.3 Methods 24 1.4 Measures 26 1.5 Thesis layout 26

CHAPTER 1WO: Background to the Study Area

2.1 Introduction 29 2.2 Geology 29 2.3 Topography and drainage 35 Basin topography 35 Floodplain and terraces above Cowra 36 Lachlan channels below Cowra 39 2.4 Palaeogeography 43 2.5 Climate and streamflow 45 Secular changes in precipitation 51 Streamflow and ENSO 56 2.6 Land use 60

CHAPTER THREE: The Hydrology and Floodplain Deposits of the Lachlan Valley from Cowra to Gooloogong

3.1 Introduction 63 3.2 Flood history 64 3.3 Flood frequency and duration 65 3.4 Pre- and post-regulation changes in streamflow 73 3.5 Lachlan floodplain and terraces near Cowra: overview 75 The Crowther Terrace 77 The Mulyan terrace 78 The Erambie terrace 78 3.6 The present floodplain and channel 81 The floodplain at River Park and Farleigh 83 The floodplain at Meg's Wood 90 In-channel benches 92 3. 7 Sediment characteristics 98 3.8 Facies models of meandering rivers 103 3. 9 Channel ages and rates of change 107 Summary 112 3.10 Flood competence and peak discharge estimates 112 3.11 Discussion 118 10

CHAPTER FOUR: Channel Morphology and Hydraulic Geometry of the Lachlan from Cowra to

4.1 Introduction 121 4.2 Hydrology 124 4.3 Trends 131 4.4 Flood range and variability 131 4.5 Changes through time 134 4.6 Bankfull flow: definitions, recurrence interval and the floodplain question 135 4. 7 Lachlan data 138 4.8 Downstream trends in channel morphology 140 4.9 Reach One: Wyangala to Payten's Bridge 140 4.10 Reach Two: Gooloogong to Cadow 145 i) Payten's Bridge floodplain 151 ii) Yammafloodplain 155 iii) Wandary floodplain 157 iv) New Parkfloodplain 160 4. 11 Reach Three: The Condobolin plain 160 i) 'The Island" floodplain 165 ii) Borambil floodplain 165 4.12 Hydraulic geometry relationships on the Lachlan River 168 4.13 Channel shape and sediment type 170 4.14 Lachlan data 172 Width 173 Depth 177 Velocity 177 Channel shape and sediments 179 4.15 Regional hydraulic geometry relationships 184 Width and depth 189 Channel shape and sediments 189 4.16 Channel geometry relationships 192 4.17 Summary 196

CHAPTER FIVE: Palaeochannel Systems of the Lachlan Valley

5.1 Palaeochannels of the Riverine Plain 199 5.2 Morphology and sediments of palaeochannel systems 200 5.3 Lachlan Valley palaeochannels 203 5.4 Mapping and terminology 204 5.5 Palaeochannel systems 204 i) Gulgo Fluvial System 206 Summary 212 ii) Ulgutherie Fluvial System 212 Stratigraphic sections 217 Downstream changes in morphology and sediments 223 iii) Nanima Fluvial System 225 11

5.6 Palaeochannels, palaeohydrology and chronology 231 Gulgo system 234 Ulgutherie system 234 Nanima system 239 The presentfluvial phase 240 Summary 242 5. 7 Palaeodischarge reconstruction 242 Ulgutherie system discharges 245 Nanima system discharges 246 5.8 Fluvial changes in the Lachlan Valley 247 5.9 Regional fluvial events 249

CHAPTER SIX: Conclusions

The modemjloodplain 255 Fluvial history 256

Bibliography 261 12

List of Fi~ures

Fig. 1.1 Map of the Murray-Darling basin, showing its location within Australia (inset), the principle rivers, and places mentioned in the text. 20 Fig. 2.1 The Lachlan River catchment and its position within the Murray-Darling basin (inset) showing ephemeral wetlands and area inundated by floods. 30 Fig. 2.2 Geology of the Lachlan Valley upstream of Jemalong Weir. 31 Fig. 2.3 Geomorphic map of the Lachlan Valley between Darby's Falls and Cowra. 37 Fig. 2.4 Schematic section of the terrace sequence above Cowra. 38 Fig. 2.5 Eroded section of Brown terrace 1km upstream from . 38 Fig. 2.6 Longitudinal profile of the Lachlan River above Booligal. 42 Fig. 2.7 Surveyed heights of terraces above Cowra. 44 Fig. 2.8 Climate of the Lachlan basin showing isoheyts and evaporation. 46 Fig. 2.9 (a) mean monthly precipitation and evaporation at Cowra and (b) monthly runoff coefficient. 48 Fig. 2.10 (a) mean monthly water yield at Cowra and precipitation in the upper Lachlan prior to river regulation, 1893-1934 and (b) following river regulation, 1935-1995. 50 Fig. 2.11 Hydrographs beginning 4 September, 1974 at major Lachlan gauging stations. 52 Fig 2.12 Comparison of various climate records in the upper Lachlan basin for 1886-1998. (A) cumulative deviation from the mean annual precipitation, (B) annual water yield of the Lachlan at Cowra, (C) water levels at Lake George. 54 Fig. 2.13 Peak discharge of annual floods at Cowra, 1893-1994 with major historical floods shown from 1840-1892. 59 Fig. 3.1 Photo of the Lachlan River in flood from Bellvue Hill Lookout, June 1952. 66 Fig. 3.2 Reconstructed hydrograph for the flood of 12-30 June, 1952, Lachlan River at Cowra. 67 Fig. 3.3 Log Pearson III (LPIII) plot of annual flood series for the Lachlan at Cowra, 1893-1994. 69 Fig. 3.4 LPIII plot of annual flood series for the Lachlan at Cowra, 1893-1934 and 1945-1995. 70 Fig. 3.5 Plot of the partial flood series for the Lachlan at Cowra, 1893-1994. 72 _ Fig. 3.6 Relationship between discharge ratio to Q2 33 and return period in years. 74 Fig. 3.7 Geomorphic map of the Lachlan Valley between Cowra and Meg's Wood showing bedrock, alluvial terraces and larger geomorphic features. 76 Fig. 3.8 Geomorphic map of the Lachlan River, floodplain and terraces at Cowra, showing rail and road bridges and the location of the streamflow gauge. 79 Fig. 3.9 Section 1 across alluvial terraces at River Park. 80 13

Fig. 3.10 Geomorphic map of the floodplain and terraces at Farleigh. 84 Fig. 3.11 Detailed geomorphic map of the floodplain at River Park showing active geomorphic features of the floodplain, channel and Erambie terrace. 86 Fig. 3.12 Area of stripped floodplain on upstream facing bank at "Anabranch", 30 km downstream from Cowra. 88 Fig. 3.13 One of several large elliptical scour scars on the floodplain _ at River Park mapped in Fig. 3.11. 88 Fig. 3.14 Smaller elliptical scour scar mapped on the floodplain at Farleigh. 89 Fig. 3.15 Geomorphic map of the floodplain and terraces at Meg's Wood. 91 Fig. 3.16 Parallel flood channels over 3 metres deep on the floodplain near Meg's Wood. 93 Fig. 3.17 Back channel adjacent bedrock ridge on the floodplain at Meg's Wood. 93 Fig. 3.18 Sedimentary sequences of in-channel benches on the Lachlan between Cowra and Gooloogong. 95 Fig. 3.19 Photograph of an eroded in-channel bench in Lachlan River, Meg's Wood, 10 kilometres downstream from Cowra. 96 Fig. 3.20 Point bench at Meg's Wood located downstream from flood channel exit. 96 Fig. 3.21 Cumulative particle size curves for samples from various physiographic units on the floodplain and Erambie terrace between Cowra and Gooloogong, namely chute bar (a), chute fill (b) and point bar (c) sediments. 101 Fig. 3.22 Cumulative particle size curves for samples from bank top and levee deposits (d), in-channel benches and low banks (e) and bed (f) sediments. 102 Fig. 3.23 Average cumulative particle size curves ofvarious physiographic units on the floodplain at Cowra. 104 Fig. 3.24 Plot showing the relationship between silt-clay percentage and sand with height above the river bed. 106 Fig. 3.25 Alluvial facies model for active floodplain reaches downstream from Cowra. 106 Fig. 3.26 Section exposed in bank near centre of Fig. 3.10 showing aggrading bench deposit against stripped bank opposite an active chute bar. 108 Fig. 3.27 Surveyed cross-section of the floodplain at Meg's Wood showing compound levee, in-channel benches, back channel and sediments in cutoff meander JM -1. 110 Fig. 3.28 Surveyed cross-section of Lachlan Valley near Cowra streamflow gauge, showing 1870 peak flood stage. 114 Fig. 4.1 Lachlan catchment above Kiacatoo with adjacent small closed basins containing Lake George and Bredalbane. 122 Fig. 4.2 LPIII plot of annual flood series for the Lachlan at Forbes Iron Bridge, 1894-1934 and Cotton's Weir, 1945-1995. 125 Fig. 4.3 LPIII plot of annual flood series for the Lachlan at Gooloogong, 1944-1957 and Nanami, 1958-1994. 125 14

Fig. 4.4 LPIII plot of annual flood series for the Lachlan at Jemalong Weir, 1944-1981. 126 Fig. 4.5 LPIII plot of annual flood series for the Lachlan at Condobolin Bridge, 1896-1934 and 1964-1996. 126 Fig. 4.6 LPIII plot of annual flood series for the Lachlan at Booberoi Weir, 1921-1985. 127 Fig. 4.7 LPIII plot of annual flood series for the Lachlan at , 1893-1934. 127 Fig. 4.8 LPIII plot of annual flood series for the Lachlan at Willandra Weir, 1944-1985. 128 Fig. 4.9 LPIII plot of annual flood series for the Lachlan at Hillston, 1924-1960. 128 Fig. 4.10 LPIII plot of annual flood series for the Lachlan at Booligal. 1909-1944 and 1945-1994. 129 Fig. 4.11 Change in peak flood discharges downstream (a) and mean flow (b) on major Lachlan gauging stations. 130 Fig. 4.12 Relationship between return period of large floods and _ peak discharge ratio to Q2 33 for major Lachlan gauging stations between Cowra and Hillston. 132 Fig.4.13 Major streams of the Murray-Darling basin and some reported return periods of bankfull flow based on the annual flood series. 137 Fig. 4.14 Bankfull frequency and discharge of Lachlan River gauging stations between Cowra and Booligal based on post-1945 streamflow records. 139 Fig. 4.15 Map of the alluvium of the upper Lachlan Valley from Wyangala to 5 km above Gooloogong showing location of surveyed cross-sections. 141 Fig. 4.16 Surveyed channel cross-sections in Reach 1 from Wyangala to Gooloogong, and their position on the longitudinal profile of the river. 142 Fig. 4.17 Downstream trends in morphology and sediments for cross-sections on the Lachlan between Wyangala and Condobolin, specifically sinuosity (a), channel capacity (b). bankfull width (c) and depth (d), width-depth ratio (e). graphic mean of bed sediment (f) and bank silt clay (g). 144 Fig. 4.18 Relationship between channel capacity for cross-sections in Reach 1 and floodplain confinement, represented by the width of the Erambie terrace. 145 Fig. 4.19 Map of alluvium of the Lachlan Valley from Gooloogong to Forbes between areas of bedrock, showing Lachlan River and active flood channels occupying palaeochannel depressions. 146 Fig. 4.20 Map of the Lachlan Valley from Forbes to Cadow., showing location of cross-sections in Reach 2 from 16-23. 147 Fig. 4.21 Surveyed channel cross-sections in Reach 2 from Forbes to Cadow and their position on the longitudinal profile of the river. 149 15

Fig. 4.22 Oblique aerial view looking north of a complex meander cutoff, now Bocobigle Creek, above the Lachlan River, 13 kilometres west of Forbes. 151 Fig. 4.23 Geomorphic map of the Lachlan River floodplain and terraces at Payten's Bridge. 152 Fig. 4.24 Aerial view of the Lachlan River and floodplain at Payten's Bridge. 154 Fig. 4.25 Geomorphic map of the Lachlan River at Yamma. 156 Fig. 4.26 Photo of hairpin bend on the Lachlan at Yamma. 156 Fig. 4.27 Geomorphic map of the floodplain and terraces at Wandcuy. 158 Fig. 4.28 Flooded bench on convex (outer) bank of the Lachlan at New Park, 10 kilometres downstream from Forbes. 159 Fig. 4.29 The Lachlan River at Bedgerebong. 161 Fig. 4.30 Map of the alluvium of the Lachlan Valley between Cadow and Kiacatoo between areas of bedrock, showing Lachlan River and anabranches. and the location of cross-sections in Reach 3. 162 Fig. 4.31 Surveyed channel cross-sections in Reach 3 from Cadow to Kiacatoo and their position on the long profile of the river. 163 Fig. 4.32 Anabranching reach of the Lachlan River at "The Island". 166 Fig. 4.33 View of one active channel of the anabranching Lachlan River at "The Island". 167 Fig. 4.34 Geomorphic map of the Lachlan River and minor anabranching channels at Borambil. 167 Fig. 4.35 View of benches forming on convex and concave banks of the Lachlan at Borambil Park, 10 kilometres west of Condobolin. 168 Fig. 4.36 Relationship between bankfull discharge and channel width (a) and depth (b) for gauging stations on the Lachlan River between Cowra and Booligal. 174 Fig. 4.37 Relationship between channel width and bankfull discharge on Lachlan gauging stations. 180 Fig. 4.38 Relationship between channel shape, given by width-depth ratio, and bank silt-clay percentage for Lachlan channels. 180 Fig. 4.39 Relationship between channel shape, given by width-depth ratio, and channel perimeter sediment for Lachlan channel sections. 181 Fig. 4.40 Relationship between channel shape, given by width-depth ratio, and channel silt-clay percentage for channels on the Murrumbidgee River and USA Great Plains (Schumm 1968) and the Lachlan River. 183 Fig. 4.41 Relationship between basin size and bankfull discharge for streams in the Murray-Darling basin. 188 Fig. 4.42 Relationship between bankfull discharge and channel width (a) and depth (b) for stations in the Murray-Darling basin. 190 Fig. 4.43 Relationship between width and bankfull depth for streams in the Murray-Darling basin. 191 16

Fig. 4.44 Regional relationship between channel shape and bank silt-clay percentage. 193 Fig. 4.45 Regional relationship between channel shape and silt-clay percentage using bankfull width and bedwidth. 194 Fig. 4.46 Regional relationship between bankfull discharge and channel capacity. 195 Fig. 5.1 Palaeochannels in the Lachlan Valley at Ulgutherie Creek. 207 Fig. 5.2 Type reach for Gulgo Fluvial System, at South Gulgo, west of Condobolin. 209 Fig. 5.3 Section through the Gulgo channel at the Type Reach, South Gulgo. 210 Fig. 5.4 Geomorphic map of Gulgo channels, 2-5 km north and south of the Lachlan upstream of Forbes. 211 Fig. 5.5 Ulgutherie Type Reach four kilometres south of Cadow. 213 Fig. 5.6 Downstream change in meander wavelength of the Ulgutherie palaeochannels compared to the modern Lachlan River. 215 Fig. 5.7 Stratigraphic section through Ulgutherie palaeochannel at Wongara. 216 Fig. 5.8 Geomorphic map of the Lachlan at "The Angle". 219 Fig. 5.9 Section through Ulgutherie palaeochannel at "The Angle". 220 Fig. 5.10 Section through Ulgutherie channel at Wandary. 222 Fig. 5.11 Section through Ulgutherie channel at Type Reach on Ulgutherie Creek. 224 Fig. 5.12 Type Reach of Nanima Fluvial System on the Lachlan River at Payten's Bridge. 226 Fig. 5.13 Section through infilled Nanima channel at The Angle. 228 Fig. 5.14 Drilled section through Nanima meander cutoff channel at Payten's Bridge. 230 Fig. 5.15 Geomorphic map of the Lachlan at Glen Avy showing gravel pit and location of the dated section. 235 Fig. 5.16 View north over sand quarry at Glen Avy, 10 km south of Eugowra. 236 Fig. 5.17 Oblique aerial view of the sand and gravel quarry and cut- off Ulgutherie meander at Glen Avy. 236 Fig. 5.18 Exposed section in sand quarry at Glen Avy. 238 Fig. 5.19 Location of a drilled site on a cutoff meander of the present fluvial regime at GM-1. 241 Fig. 5.20 Relationship between channel shape and channel silt clay percentage for channels on the Murrumbidgee River and the USA Great Plains, and the modern and palaeochannels of the Lachlan River. 246 17

List of Tables

Tab. 2.1 Coefficient of variability of annual daily flows before and following river regulation. 52 Tab. 3.1 Major floods in the Lachlan Valley at Cowra since settlement above 'critical height' of 12.2 metres. Average recurrence intervals (ARI) from the annual and partial flood series are also given. 66 Tab. 3.2 ~ Comparison of flood discharges on the Lachlan at Cowra from the annual and partial duration series, 1893-1994. 72 Tab. 3.3 Statistics for particle size analyses for representative samples from various physiographic units shown in Fig. 3.23. 104 Tab. 3.4 Radiocarbon dates on floodplain sediments in the Cowra region. 108 Tab. 3.5 Estimates of bed shear stress and stream power on Erambie terrace and floodplain at Cowra. 117 Tab. 4.1 Streamflow records, catchment area and number ofyears of complete record from major gauging stations on the Lachlan River and anabranches. 124 Tab. 4.2 Skew coefficients used in LPIII models for Lachlan gauging stations. 133 Tab. 4.3 Pre- and post-river regulation changes in magnitude and return period of bankfull flow, mean flow, mean annual . flood and the magnitude of the Q 158 and Q2 33 flows for major Lachlan gauging stations. 134 Tab. 4.4 Values of exponents and coefficients obtained from downstream hydraulic geometry relationships for the Lachlan River at natural bankfull discharge. 175 Tab. 4.5 Morphologic, hydrologic and sedimentologic characteristics of gauging stations on the Lachlan River between Cowra and Booligal. 176 Tab. 4.6 Bankfull discharge, velocity and channel roughness for gauged stations on the Lachlan River. 175 Tab. 4. 7 Hydraulic geometry relationships for the Lachlan River encorporating a sediment parameter. 182 Tab. 4.8 Regional data set of morphologic, sedimentary and hydrologic variables. 186 Tab. 4.9 Values of exponents and coefficients obtained from downstream hydraulic geometry relationships for rivers in the Murray-Darling basin. 191 Tab. 4.10 Hydraulic geometry relationships for the Murray-Darling basin which include a sediment parameter. 193 Tab. 4.11 Regional channel geometry relationships between morphologic variables and bankfull discharge. 195 Tab. 5.1 Gemorphic characteristics and ages of dated Quaternary palaeochannel systems of the Murray-Darling basin. 201 Tab. 5.2 Morphologic and sedimentologic parameters of meandering palaeochannels in.the Lachlan Valley. 218 18

Tab. 5.3 Radiocarbon and luminescence sample sites from palaeochannels in the Lachlan Valley. 232 Tab. 5.4 Details of the field site at Glen Avy, including field and laboratory dosimetry measurements. 237 Tab. 5.5 Bankfull discharge for Lachlan Valley palaeochannels. 244

List of Maps Map 1 Geomorphic map of the Lachlan Valley at Cowra, from Darby's Falls to Crowther Creek. Map2 Geomorphic map of the Lachlan Valley at Goologong, from Crowther Creek to Payten's Bridge. Map3 Geomorphic map of the Lachlan Valley from Payten's Bridge to Forbes. Map4 Geomorphic map of the Lachlan Valley at Jemalong, from Forbes to Cadow. Map5 Geomorphic map of the Lachlan River and near . Map6 Geomorphic map of the Lachlan River and anabranches on the Condobolin Plain, from Cadow to 5 kilometres upstream from Micabil Weir.