Forest Hydrology and Catchment Management: An Australian Perspective

445 Pages·2023·16.206 MB·English

by  Leon Bren

Leon Bren
Forest Hydrology
and Catchment
Management
An Australian Perspective
Second Edition
Forest Hydrology and Catchment Management
Leon Bren
Forest Hydrology
and Catchment Management
An Australian Perspective
Second Edition
Leon Bren
Hydrology and Catchment Management
Ballarat, VIC, Australia
ISBN 978-3-031-12839-4 ISBN 978-3-031-12840-0 (eBook)
https://doi.org/10.1007/978-3-031-12840-0
1st edition: © Springer Science+Business Media Dordrecht 2015
2nd edition: © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer
Nature Switzerland AG 2023
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Preface
This book provides a concise account of the discipline and findings of forest
hydrology in Australia, with some considerations of overseas work as well. The
book is complementary to textbooks on river hydrology—although the world of engi-
neering hydrologists and forest hydrologists do intersect, their problems are rarely
the same. The book is aimed at undergraduate students, practising land managers,
and interested citizens. It should be suitable for a first course in hydrology and is
based on the teaching experience in such courses at The University of Melbourne.
The subtitle of the book suggests that Australia is somehow “different”. At the
hydrologic process level, there appears little difference between Australia and other
countries. However Australian hydrology does seem to go from extremes more than
other countries—particularly droughts to floods. Chapter 9 which examines the role
of fire also highlights some distinctly Australian behaviour—recent work suggests it
has literally formed the continent! We also have the only known forest tree in which
water use is a clear function of age, so perhaps we are different.
The book attempts to give a “snapshot” of this discipline in Australia, with the
expectation that students will read other texts to obtain necessary detail. There is
a huge (and over-whelming) worldwide literature on forest hydrology, and I have
attempted to use only material relevant to Australia. The result has been a tendency
to generalise and reduce referencing to improve readability, for which I apologise in
advance.
The Second Edition remedies what I perceived (in hindsight) as omissions in
the First Edition. These include salinity, climate change, the relation between big
and small streams, and much more on some forest types. An underlying guilt at my
disregard of some “classic” areas of soil and groundwater physics is still evident,
even though the disregard is because they don’t work in forests.
v
vi Preface
Finally, I would like to thank my wife, Elizabeth, and family for their support in
production of this. Let me also thank my colleagues at The University of Melbourne
Department of Ecosystem and Forest Science at the Creswick (Victoria) campus for
their help.
Ballarat, Australia Leon Bren
Contents
1 The Basics of Catchment Hydrology ............................ 1
1.1 About the Hydrologic Cycle .............................. 1
1.1.1 The Hydrologic Cycle (and Forests) ............... 1
1.1.2 Critiquing the Hydrologic Cycle .................. 4
1.1.3 Ownership of the Hydrologic Cycle
and the World’s Water ........................... 5
1.2 About Water Catchments and Stream Networks .............. 5
1.3 Topographic Analysis and Catchment Boundaries ............ 6
1.3.1 Catchment Flow Vectors and Streamlines .......... 6
1.3.2 Defining Catchment Boundaries for a Specific
Stream Cross-Section ........................... 11
1.4 Stream Networks ........................................ 14
1.5 Hydrologic Units and Catchment Arithmetic ................ 18
1.6 Introduction to Hydrographs and Averaging of Units ......... 20
1.6.1 Runoff Expressed in Depth Units ................. 21
1.6.2 The Instantaneous Hydrograph ................... 22
1.7 How Does Forest Hydrology Differ from Hydrology? ........ 24
1.8 What is Different About Australian Forest Hydrology? ....... 25
References .................................................... 27
2 Hydrologic Measurements and the Water Balance ................ 29
2.1 Introduction ............................................ 29
2.2 Basics of Measurement on a Catchment .................... 30
2.2.1 Rainfall and Hyetograph Measurement ............ 30
2.2.2 Hydrograph Measurement ....................... 35
2.2.3 Measurements of Slope Water Storage ............. 38
2.2.4 Measurement of Plant Water Use ................. 39
2.3 Analysis of Streamflow Hydrographs ...................... 40
2.3.1 Flow Separation Analysis ........................ 42
2.4 Using Field Data to Form a Water Balance .................. 48
2.5 Using “Zhang Curves” to Estimate Water Balance ........... 50
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viii Contents
2.5.1 Percentage Runoff and Rainfall Elasticity
Using Zhang Curves ............................ 52
References .................................................... 54
3 The Fundamental Building Blocks—First-Order Catchments ..... 57
3.1 Introduction ............................................ 57
3.2 The Dominance of “Headwater Streams” ................... 58
3.3 The Prototypical First-Order Catchment, and Streams ........ 59
3.4 Groundwater Outflow Versus Downslope Soil Movement ..... 60
3.5 Colluvium and Bedrock Erosion ........................... 62
3.6 Moving Upstream—Can We Define Zero-Order Streams? ..... 65
3.6.1 Ephemerality of Low-Order Streams .............. 67
3.7 Beds and Streams ....................................... 68
3.8 Hydrologic Characteristics of Forested Catchment Soils ...... 68
3.9 Continuum Levels ....................................... 70
3.10 Characteristic Outflow Behaviour of Catchment Elements ..... 72
3.11 Similitude and Scaling of Catchment Processes .............. 74
References .................................................... 76
4 Dynamics of Catchment and Slope Processes ..................... 79
4.1 The Role of Science and Maths in Slope Dynamics .......... 79
4.2 Overview of Dynamics of Slope Processes .................. 81
4.3 The Stream Channel as a Connecting Link .................. 83
4.4 Overland Flow and Slope Infiltration ....................... 86
4.4.1 Measuring Infiltration ........................... 89
4.5 Saturated (Groundwater) and Unsaturated Flow .............. 91
4.5.1 Applications of Groundwater Theory to Model
Forest Slopes .................................. 93
4.5.2 “Perched” Groundwater and “Deep”
Groundwater ................................... 95
4.5.3 Does a “Wave” of Groundwater Recharge
Occur? ........................................ 95
4.6 Slope Evaporation ....................................... 96
4.7 Hewlett’s Variable Source Area Concept of Stream Runoff .... 98
4.8 Use of Hydrographs to Examine Dynamic Processes ......... 101
4.9 Exciting Future Directions for This Field ................... 101
References .................................................... 103
5 Field Measurement of Water Use of Forests ...................... 105
5.1 Why Study This? ........................................ 105
5.2 Paired Catchment Experiments ............................ 106
5.2.1 What is a Paired Catchment Project? .............. 106
5.2.2 An Example of a Paired Catchment Project:
Croppers Creek ................................ 109
5.2.3 Traditional Approach to Paired Catchment
Calibration and Analysis ......................... 112
Contents ix
5.2.4 A Modern Example of Paired Catchment
Statistical Treatment ............................ 116
5.2.5 What Time Units to Use? ........................ 120
5.2.6 How Long Does Calibration Need to Be? .......... 121
5.2.7 Where Do Paired Catchments Sit in the World
of Experiments? ................................ 124
5.2.8 Paired Catchment Projects in Australia ............ 124
5.3 Single Catchment Studies of Water Use .................... 126
5.4 Plot Measurements of Water Balance ....................... 127
5.4.1 Case Study: Rachel Nolan and Impact of Fires ...... 127
5.4.2 Advantages and Disadvantages of Plot
Hydrology Work ............................... 128
5.4.3 Where Do Plots Sit in the World of Experiments? ... 129
5.4.4 “Closing the Water Balance” on Plots .............. 129
5.5 The Scaling Issue ....................................... 130
5.5.1 Spreadsheet Approach of Weighted Assessment ..... 130
5.5.2 Modelling Approach to Scaling ................... 130
5.5.3 Hydrologic Modelling from First Principles
of Vegetation Growth ........................... 131
5.5.4 Scaling up Controversies ........................ 133
References .................................................... 134
6 Hydrology of Managed Eucalypt Forest ......................... 137
6.1 Introduction ............................................ 137
6.1.1 Sources of Information and the Role of Science ..... 137
6.2 Fog Drip and Interception by Native Eucalypt Forests ........ 139
6.2.1 Fog Drip ...................................... 139
6.2.2 Canopy Interception ............................ 140
6.3 Basic Runoff Curves for Native Eucalypt Forest ............. 142
6.4 Mountain Ash Water Use and Runoff Curves ................ 144
6.4.1 Quantifying the Yield Decline—“Kuczera
Curves” ....................................... 148
6.4.2 Response to Logging ............................ 151
6.4.3 Other Melbourne Water Paired Catchment
Logging Experiments ........................... 151
6.4.4 The “BISY” Model of Ash Water Yield (Age
and Rainfall) ................................... 154
6.4.5 Later Work on Mountain Ash Age–Yield
Relationships .................................. 154
6.5 Hydrology of Jarrah Forests .............................. 156
6.5.1 The Annual Flow Cycle ......................... 158
6.5.2 Evapotranspiration and Water Yield ............... 159
6.5.3 Water Yield Changes After Forest Treatment ....... 160
6.5.4 Mining and Jarrah Hydrology .................... 162
6.5.5 Effect of Jarrah Dieback on Water Yield ........... 163
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6.5.6 Obsolescence of the Jarrah Forests as Water
Supply Catchments ............................. 163
6.6 Is There an “Age-Yield” Response for Non-ash Eucalypts? .... 164
6.6.1 Yambulla Paired Catchment and Plot Studies ....... 166
6.6.2 Karuah Paired Catchment Project ................. 166
6.6.3 Tantawangalo Paired Catchment Project ........... 166
6.6.4 Political Aspects of Native Forest Water Use ....... 167
6.7 Thinning of Native Forests for Water Production ............. 167
6.7.1 Thinning of Mountain Ash Forests ................ 168
6.7.2 Thinning of Mountain Forest at Tantawangalo ...... 170
6.7.3 Thinning of Jarrah .............................. 171
References .................................................... 175
7 Non-eucalypt Forest Hydrology—Rainforests and Brigalow ....... 179
7.1 About Rainforests ....................................... 180
7.2 Wyvuri Paired-Catchment Experiment ..................... 181
7.2.1 The Experimental Catchments .................... 183
7.2.2 The Effects of Clearing on the North Creek
Hydrology ..................................... 187
7.2.3 Sub-Surface Hydrology Processes
in the Catchments .............................. 188
7.3 A Plot Approach to Water Balance of Rainforests ............ 190
7.4 Rainforests—The Darlings of the Urban Dwellers? ........... 191
7.5 Hydrochemistry of Rainforests ............................ 193
7.6 Brigalow and the Brigalow Catchment Study ................ 194
7.6.1 The Brigalow Catchment Study ................... 196
7.6.2 Gilgai ......................................... 197
References .................................................... 200
8 Hydrology of Man-Made Forests (Plantations) ................... 203
8.1 Introduction ............................................ 203
8.1.1 What is Different About Plantations? .............. 204
8.1.2 Are All Plantations the Same? .................... 204
8.1.3 Defining the “Water Use” of a Plantation ........... 205
8.2 Runoff Curve Approaches to Plantation Water Use ........... 205
8.2.1 “Zhang Curves” ................................ 205
8.2.2 “Holmes and Sinclair” Relationships .............. 206
8.2.3 Nänni Curves .................................. 207
8.3 Water Use of Radiata Pine on Well-Drained Sites ............ 208
8.3.1 Absolute Water Use ............................. 208
8.3.2 Relative Change in Water Use .................... 212
8.4 Water Use of Eucalyptus Plantations ....................... 213
8.5 Water Use When Plantations Can Tap Groundwater .......... 214
8.6 Paired-Catchment Work—Eucalypts Versus Pasture
in SW Victoria .......................................... 215
8.7 Other Australian Plantation Species ........................ 216