Plantation forestry and water management guideline
June 2009
Plantation forestry and
water management
guideline
This guideline is part funded by the Australian
Government under Water for the Future’s- Water Smart
Australia program.
Department of Water
June 2009
Department of Water
168 St Georges Terrace
Perth Western Australia 6000
Telephone
+61 8 6364 7600
Facsimile
+61 8 6364 7601
www.water.wa.gov.au
© Government of Western Australia 2009
June 2009
This work is copyright. You may download, display, print and reproduce
this material in unaltered form only (retaining this notice) for your personal, non-commercial
use or use within your organisation. Apart from any use as permitted under the Copyright Act
1968, all other rights are reserved. Requests and inquiries concerning reproduction and
rights should be addressed to the Department of Water.
ISBN 978-1-921637-65-0 (print)
ISBN 978-1-921637-66-7 (online)
Acknowledgements
The Department of Water would like to thank the Forest Products Commission for providing
photos for the online version of this guideline.
For more information about this report, contact the Water Allocation Planning Branch.
Plantation forestry and water management guideline
Contents
1
Guideline purpose ................................................................................................................1
2
1.1 About this guideline ....................................................................................................1
1.2 What do local government and the plantation forestry industry want? .......................1
1.3 A water resource management issue .........................................................................1
Current management ...........................................................................................................2
3
2.1 Our current roles in managing plantation forestry.......................................................2
2.2 Providing advice to local government .........................................................................2
2.3 Allocating water for use ..............................................................................................3
Future management.............................................................................................................5
4
3.1 Licensing plantation water use ...................................................................................5
3.2 We are preparing new policy ......................................................................................5
WA Snapshot .......................................................................................................................6
5
4.1 Plantation forestry is concentrated in the south west corner ......................................6
4.2 Clearing of forests increased stream salinity in some areas ......................................8
4.3 Reforestation is improving water quality and reducing dryland salinity.......................8
Some basic science .............................................................................................................9
6
5.1 New plantation forests decrease available water .......................................................9
5.2 Measuring water use and impacts on available water ................................................9
5.3 Comparing forest and pasture water use....................................................................9
5.4 Effects on available water vary ...................................................................................9
Current research ................................................................................................................10
Glossary ......................................................................................................................................11
Appendices
Appendix 1. Plantation forestry in the Gnangara groundwater areas..........................................12
Appendix 2. Plantation forestry in the Gingin, Jurien and Arrowsmith groundwater areas .........15
Appendix 3. Plantation forestry in the Whicher surface water area.............................................17
Appendix 4. Plantation forestry in the South West groundwater areas .......................................20
Appendix 5. Plantation forestry in the Upper Collie catchment ...................................................22
Figures
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Decision process for plantation development applications ....................................3
Location of water management plan areas ............................................................4
Plantation forestry in the Perth region....................................................................6
Plantation forestry in the South west region...........................................................7
Plantation forestry in the South coast region .........................................................8
Table 1
Factors that determine how much plantation forestry reduces stream flow
and groundwater level............................................................................................9
Tables
Department of Water
iii
Plantation forestry and water management guideline
1
Guideline purpose
1.1
About this guideline
The purpose of this guideline is to clarify the Department of Water’s role in the management
of plantation forestry. Our target audience is local government and the plantation forestry
industry.
This guideline covers current and future management arrangements, a snap shot of
plantations and their effects on water resources in Western Australia, some basic science,
current research and some important definitions.
1.2
What do local government and the plantation forestry
industry want?
The Department of Water has identified plantation forestry as a major water resource
management issue through stakeholder engagement as part of the development of water
management plans across the South West of the state. Local governments suggested that
we should manage plantations through licensing and regulation. The plantation forestry
industry requested clarification of a number of definitions, expressed interest in how we
calculated plantation water use and identified the need for research into plantation water use.
The industry also indicated a willingness for ongoing communication and cooperation with
the Department of Water.
This guideline is a response to this stakeholder feedback.
1.3
A water resource management issue
The conversion of pasture to plantation forestry is a significant water resource management
issue for Western Australia. It can result in less groundwater and stream flow. This has a
negative impact by reducing the amount of groundwater and surface water available for other
water users and the environment. In some areas, plantations can trigger the release of
sulfuric acid and metals from soils into streams. In other areas, development of plantation
forestry can have a positive effect by reducing stream salinity and reducing the effects of soil
salinity on plant growth.
Department of Water
1
Plantation forestry and water management guideline
2
Current management
2.1
Our current roles in managing plantation forestry
The Department of Water cannot regulate plantation water use under current water resource
management legislation, the Rights in Water and Irrigation Act (1914). This means that while
we can grant a water access entitlement for the purposes of irrigated agriculture, we cannot
grant a similar water access entitlement for a plantation forest.
However, the Department of Water currently has two roles in the management of plantation
forestry and water resources:
1.
To provide advice to local government on potential water availability and water quality
impacts associated with plantation development applications.
2.
To consider current and projected plantation development in deciding how much water
is available in a particular surface or groundwater resource or area for all users. We
usually do this as part of preparing a water allocation plan.
2.2
Providing advice to local government
Proponents submit plantation development applications to local government. Local
government may require a plantation developer to undertake a water resource impact
investigation and provide a statement.
Local government may ask the Department of Water for advice on water resource
management issues related to proposed plantation developments. We may provide advice
on expected changes to water availability and water quality.
The Department of Environment and Conservation is the lead state government agency for
providing advice on acid sulfate soils and impacts on river and wetland ecology. Their
decisions are made under the Environmental Protection Act (1986).
Local governments make final decisions under the Planning and Development Act (2005) on
whether plantation developments can proceed and under what conditions. Local government
also manages other issues, such as aesthetic amenity, development of prime agricultural
soils and community demographics. This process is shown in Figure 1 below.
2
Department of Water
Plantation forestry and water management guideline
Figure 1
2.3
Decision process for plantation development applications
Allocating water for use
Water allocation planning involves deciding how much water is available for consumptive use
and how this water can be accessed. The department considers the effects of plantation
forestry on water resources in these decisions. A number of allocation plans have already
been developed, or are underway, for areas across the state with plantation forestry. These
include:
The Gnangara groundwater areas cover the northern half of the Perth metropolitan region.
Decreasing rainfall, over-allocation, and urban expansion are stressing groundwater
resources in this area. Clearing of pine plantations in the central and northern parts of the
Gnangara groundwater area will continue in accordance with the Wood Processing
(Wesbeam) Agreement Act 2002, which commits the State Government to provide wood to
the Laminated Veneer Lumber Plant from its plantations until 2029. The Forest Products
Commission will investigate the potential for modifying harvesting strategies to increase
water availability within the constraints of the Act. In 2005, the total area of plantation forestry
was about 24,000 hectares.
The Gingin, Jurien and Arrowsmith groundwater areas extend from about 50 kilometres
north of Perth to Geraldton. Plantation forestry is sparse, because low rainfall and sandy
soils limit tree growth and the types of trees that can grow. In 2005, plantation forestry
covered approximately 9,500 hectares.
The Whicher (surface water) area and South West groundwater areas are located about
250 kilometres south of Perth and cover most of the same area. Plantation forestry is
expanding, particularly in areas that were cleared and previously used for pasture. In 2005,
plantation forestry covered approximately 38,500 hectares of the area covered by these two
plans.
Department of Water
3
Plantation forestry and water management guideline
The Upper Collie catchment is located approximately 200 kilometres south of Perth.
Plantation forestry was established in the upper parts of the catchment to reduce the salinity
of water flowing into Wellington Reservoir. In 2005, the total area of plantation forestry was
about 19,000 hectares.
Figure 2
4
Location of water management plan areas
Department of Water
Plantation forestry and water management guideline
3
Future management
3.1
Licensing plantation water use
The Intergovernmental Agreement on a National Water Initiative recommends that plantation
water use is licensed under certain circumstances. The Western Australian government
signed the agreement in 2006.
The state government is preparing new legislation, called the Water Resource Management
Bill. The draft Bill proposes to allow the Department of Water to licence plantation water use
when a detrimental effect on other water users is expected.
We will generally licence plantation forestry where there is competition for water and where
available water will decrease as a result of plantation forestry. Competition for water is high
or increasing in the water planning areas identified in this guideline (see Current
Management). We will generally not licence new plantation forestry where stream and
dryland salinity can be significantly reduced (see WA Snapshot).
3.2
We are preparing new policy
The Department is currently developing policy to support the implementation of the Water
Resource Management Bill. This policy will define:
 What is a detrimental effect of plantation forestry on other water users.
 How water volumes for plantation forestry water access entitlements and licences are
calculated.
 How to determine whether a plantation forest is accessing groundwater, surface water
or both.
 Any special features of a plantation forestry water access entitlement or licence.
Department of Water
5
Plantation forestry and water management guideline
4
WA Snapshot
4.1
Plantation forestry is concentrated in the south west
corner
Click on the links below to see maps showing the distribution of plantation forestry across
different rainfall zones in Western Australia. These maps show that plantation forestry is
concentrated in the south west corner.
Figure 3
6
Plantation forestry in the Perth region
Department of Water
Plantation forestry and water management guideline
Figure 4
Plantation forestry in the South west region
Department of Water
7
Plantation forestry and water management guideline
Figure 5
4.2
Plantation forestry in the South coast region
Clearing of forests increased stream salinity in some
areas
Settlers cleared south west forest areas mostly between the 1940s and 1970s to develop
pasture for grazing and crops. This reduced the volume of water used by vegetation. In some
areas (particularly low rainfall areas), groundwater levels rose and increased volumes of
saline groundwater entered streams. Some fresh streams became saline.
4.3
Reforestation is improving water quality and reducing
dryland salinity
Some areas originally cleared for agriculture are being reforested with plantations. This is
lowering groundwater levels and decreasing the volume of saline groundwater entering
streams and reducing stream salinity.
Reforestation in upper catchment areas is reducing the volume of water recharging to deep
groundwater. The result is a decrease in waterlogging and the area of dryland salinity in
lower parts of valleys.
Plantation forestry has reduced stream and dryland salinity in areas that receive an average
annual rainfall of less than about 900 mm.
8
Department of Water
Plantation forestry and water management guideline
5
Some basic science
5.1
New plantation forests decrease available water
Afforestation is the conversion of bare or cultivated land into forest. Water taken up by roots
is transpired from leaf pores to the atmosphere. Water also evaporates to the atmosphere
from leaf litter and soil. Trees can also access water in the soil and shallow groundwater.
New plantation forestry reduces water available from streams and groundwater.
5.2
Measuring water use and impacts on available water
Evaporation and transpiration are together referred to as evapotranspiration.
Evapotranspiration measures of how much water is used by forests, but does not measure
overall effects on available water. Impacts on available water can be determined by
measuring or modelling change in stream flow and change in groundwater level.
5.3
Comparing forest and pasture water use
Forests use more water than pasture. The difference in water use by the two land uses is
larger in high rainfall areas. This difference is important in predicting and managing the
effects of land use change on available water.
5.4
Effects on available water vary
Each plantation forest is unique and effects on stream flow and groundwater levels vary.
Variation can result from the factors identified in Table 1.
Table 1
Factors that determine how much plantation forestry reduces stream flow and
groundwater level
A large reduction in stream flow or
groundwater level is related to:
A small reduction in stream flow or
groundwater level is related to:
Large area of plantation forestry
small area of plantation forestry
plantation forests in valleys and close to streams
plantation forests in upper areas of catchments
high tree density
low tree density
high leaf cover or density
low leaf cover or density
no thinning or harvesting of trees
thinning and harvesting of trees
mature trees with large canopies
immature trees with small canopies
light or medium textured soils
clay soils
fresh groundwater
saline groundwater
shallow groundwater
deep groundwater
Department of Water
9
Plantation forestry and water management guideline
6
Current research
There are a number of research projects being implemented across Australia to improve
information and modelling tools for estimating plantation water use. The National Water
Commission, CSIRO, CRC Forestry, the Department of Water, the Forest Products
Commission and industry are each supporting one or more of the following four projects.
Methods to accurately assess water allocation impacts of plantations aims to develop
nationally consistent methods to assess (1) risk of new plantations to water access
entitlements at the catchment scale, and (2) site scale impacts (e.g. soils, plantation thinning)
of plantations on stream flows.
South West sustainable yields aims to build and run a new surface water model using
existing data to model catchment yields under scenarios including current plantation
development as well as proposed plantation development.
Impacts of plantations on water security: Review and scientific assessment of
regional issues and research needs aims to develop regionally specific recommendations
regarding the information needs for the forest industry to engage with state government
agencies for the purpose of implementing the National Water Initiative.
Water use and water use efficiency of eucalyptus plantations: From stand to
catchment scale aims to (1) investigate the effect of plantation establishment and growth
cycles on surface water flows, (2) develop and implement a modelling approach that better
links stand and catchment estimates of water use, and (3) develop an approach for
describing the trade off between carbon capture, water use and other outcomes associated
with plantation production.
10
Department of Water
Plantation forestry and water management guideline
Glossary
Afforestation is the conversion of bare or cultivated land into forest.
Consumptive use is for private and public benefit purposes including irrigation, industry,
urban, livestock and domestic use.
Evapotranspiration is the combined processes of evaporation from the ground and
vegetation surfaces (i.e. after rainfall) and transpiration from vegetation.
Farm is a business enterprise engaged predominantly in agriculture other than plantation
forestry.
Farm forestry is part of a mix of activities on a farm, is not the main product of the farm in
terms of financial returns, and where the planted area of trees is a small proportion of the
total farm area.
Overland flow is the movement of water over land surface before passing to a waterway,
infiltrating soil, or evaporating.
Plantation area is the vegetated buffer area plus the planted area.
Plantation establishment is the period that includes site preparation, weed control, planting,
fertilising, infill planting and seedling protection for a period of approximately two years.
Plantation forest is a non-irrigated crop of trees grown or maintained so that the wood, bark,
leaves or essential oils can be harvested or used for commercial purposes, including through
the commercial exploitation of the carbon absorption capacity of the forest vegetation.
Rotation is the number of years between plantation planting and harvest.
Riparian zone is the area adjacent to, or surrounding a water body or waterway that is
influenced by the passage and storage of water.
Reforestation is the establishment of forests on land that is cleared, but was previously
forested.
Thinning is the removal of a portion of trees in a plantation. Thinning may be used to
procure a specific product, to increase the growth rate of retained trees, or increase available
water.
Values are what people view as important or of worth.
Water access entitlement is a perpetual or ongoing entitlement to exclusive access to
water.
Water interception is the use of water associated with land use activities including
plantation forestry, farm dams, bores, and storing of overland flows. Sections 55, 56 and 57
of the National Water Initiative imply that water interception is the capture or use of water not
included in water licensing or water entitlement systems.
Water management area is based on hydrological boundaries, is defined in a water
management plan, and is subject to a set of water management rules.
Department of Water
11
Plantation forestry and water management guideline
Appendix 1. Plantation forestry in the Gnangara
groundwater areas
12
Department of Water
Plantation forestry and water management guideline
Allocation limits, water availability and area of plantation forestry in Gnangara groundwater
sub-areas
Map
reference
Allocation
limit (ML/yr)1
Is water
available?2
Area of
plantation
forestry (ha)
Adams
1
1000
no
4
Ballajura
2
6000
no
0
Bandy Spring
3
350
no
14
Beechboro
4
1000
yes
0
Beermullah Plain South
5
3000
no
170
Carabooda
6
6400
no
4
Carramar
7
1700
yes
6
Central Swan
8
1000
no
0
Sub-area name
City of Bayswater
9
2300
yes
0
City of Fremantle North
10
700
yes
0
City of Nedlands
11
2300
no
0
City of Perth
12
1500
no
0
City of Stirling
13
11150
no
0
City of Subiaco
14
1000
yes
0
Cockman Bluff
15
1500
yes
157
Deepwater Lagoon South
16
3500
yes
0
East Swan
17
750
no
0
Eglinton
18
15450
yes
0
Guilderton South
19
11000
no
0
Gwelup
20
7950
no
0
Henley Brook
21
1600
no
0
Improvement Plan 8
22
5500
no
0
Jandabup
23
200
no
4
Joondalup
24
1500
yes
0
Lake Gnangara
25
7500
no
0
Lake Mungala
26
3400
no
0
Landsdale
27
1400
yes
0
Mariginiup
28
4000
no
0
Neaves
29
2000
no
0
Neerabup
30
2650
yes
387
North Swan
31
2000
no
94
Nowergup
32
2000
no
25
Pinjar
33
500
no
2
Plantation
34
600
yes
1
Quinns
35
24650
yes
1
Radar
36
2000
no
0
Reserve
37
9000
no
15673
Shire of Peppermint Grove
38
100
yes
0
Shire of Swan North
39
1000
yes
0
South Swan
40
4000
no
0
State Forest
41
1000
yes
297
Town of Bassendean
42
500
yes
0
Department of Water
13
Plantation forestry and water management guideline
Sub-area name
Map
reference
Allocation
1
limit (ML/yr)
Is water
available?2
Area of
plantation
forestry (ha)
43
3500
yes
0
Town of Cambridge
Town of Claremont
44
700
yes
0
Town of Cottesloe
45
300
yes
0
Town of Mosman Park
46
500
yes
0
Town of Vincent
47
1000
yes
0
Wanneroo Wellfield
48
12000
yes
7061
Whiteman Park
49
1000
no
0
Whitfords
50
22430
no
0
Yanchep
51
10870
yes
Total
0
208950
23900
1
Allocation limits for superficial aquifer
2
Contact a Swan-Avon regional office for the latest information on water availability
14
Department of Water
Plantation forestry and water management guideline
Appendix 2. Plantation forestry in the Gingin,
Jurien and Arrowsmith groundwater areas
Department of Water
15
Plantation forestry and water management guideline
Allocation limits, water availability and area of plantation forestry in the Gingin, Jurien, and
Arrowsmith groundwater sub-areas
Sub-area name
Map
reference
Allocation
limit (ML/yr)1
Is water
available?2
Area of
plantation
forestry (ha)
Arrowsmith
Allanooka
1
0
no
0
Darling
2
2500
yes
9
Dongara
3
8000
yes
0
Eneabba Plains
4
14600
yes
138
Mingenew
5
0
no
0
Morrison
6
0
no
0
Tathra
7
0
no
0
Twin Hills
8
0
no
276
Total
25100
423
Jurien
Badgingarra
9
0
no
60
Cervantes
10
30000
yes
0
Dinner Hill
11
3200
yes
1130
Nambung
12
4000
yes
255
Watheroo
13
900
yes
Total
132
38100
1577
Gingin
Beermullah Plain North
14
9600
yes
236
Bindoon
15
2400
yes
0
Deepwater Lagoon North
16
1900
no
0
Eclipse Hill
17
4400
yes
719
Gingin Townsite
18
5001
yes
253
Guilderton North
19
9900
no
0
Karakin Lakes
20
24000
yes
491
Lake Mungala
21
3400
no
0
Lancelin
22
27400
no
1592
Moora
23
800
yes
0
Namming Lake
24
13300
yes
281
North Moore River Park
25
12900
yes
0
Red Gully
26
6600
yes
1378
Seabird
27
22100
yes
183
South Moore River Park
28
7500
yes
4
Victoria Plains
29
4400
yes
2047
Wedge Island
30
81700
yes
494
Total
237301
7678
1
Combined allocation limits for superficial and surficial aquifers if both are present
2
Contact a Mid West Gascoyne regional office for the latest information on water availability
16
Department of Water
Plantation forestry and water management guideline
Appendix 3. Plantation forestry in the Whicher
surface water area
Department of Water
17
Plantation forestry and water management guideline
Allocation limits, water availability and area of plantation forestry in the Whicher surface water
sub-areas
Map
reference
Allocation
limit (ML/yr)
Is water
available?1
Area of
plantation
forestry (ha)
10 Mile Brook
1
1000
No
0
Adelaide
2
0
No
0
Ballan
3
0
No
15
Beenup
4
290
Yes
3
Biljedup
5
330
Yes
34
Boodijidup
6
3210
Yes
164
Bramley
7
1810
Yes
413
Buayanup
8
201
Yes
1376
Sub-area name
Calgardup
9
2530
Yes
172
Capel River Central
10
980
Yes
41
Capel River North Branch
11
4700
Yes
38
Capel River South Branch
12
2730
Yes
317
Capel River West
13
490
No
113
Carbunup
14
165
Yes
69
Carlotta
15
5850
Yes
1824
Chapman
16
2100
Yes
99
Cowaramup
17
450
Yes
0
Dunsborough Coast
18
3000
Yes
296
Ellen
19
1180
Yes
34
Ellis
20
130
Yes
530
Five Mile Brook
21
87
Yes
0
Glenarty
22
1110
Yes
203
Gunyulgup
23
1090
No
0
Gynudup Brook and Tren Creek
24
1380
Yes
747
Lower Margaret
25
1670
Yes
3
Lower Blackwood Estuarine Reach
26
2840
Yes
1202
Lower Blackwood Hardy Estuary
27
1200
Yes
183
Lower Blackwd Hut Reach
28
260
Yes
58
Lower Blackwood Nannup Reach
29
2600
Yes
2374
Margaret Town
30
910
Yes
114
McAtee
31
0
No
0
McLeod SW
32
4270
Yes
439
Middle Margaret
33
3200
Yes
298
Milyeannup
34
30
Yes
0
Naturalist
35
310
Yes
Poison
36
0
No
5
Quininup
37
550
No
0
Readia
38
0
No
0
Red Gully
39
80
Yes
58
Rosa
40
0
No
328
Rushy
41
1050
Yes
94
Scott
42
16010
Yes
6186
18
Department of Water
Plantation forestry and water management guideline
Sub-area name
St John
Map
reference
Allocation
limit (ML/yr)
Is water
1
available?
Area of
plantation
forestry (ha)
43
750
Yes
5331
Tanjannerup
44
140
No
199
Turner SW
45
2140
Yes
159
Turnwood
46
360
Yes
538
Upper Chapman
47
2800
Yes
123
Upper Margaret
48
170
No
3933
Vasse Diversion
49
3340
Yes
853
West Bay
50
940
Yes
301
Wilyabrup
51
2480
No
81
Wonnerup
52
4240
Yes
1949
Total
1
87153
31297
Contact a South West regional office for the latest information on water availability
Department of Water
19
Plantation forestry and water management guideline
Appendix 4. Plantation forestry in the South
West groundwater areas
20
Department of Water
Plantation forestry and water management guideline
Allocation limits, water availability and area of plantation forestry in the South West
groundwater sub-areas
Sub-area name
Australind
Allocation
limit (ML/yr)1
Map reference
Is water
available?2
Area of
plantation
forestry (ha)
3
690
yes
0
Beenup
12
2400
yes
1582
Blackwood Plateau North
15
300
yes
9111
Blackwood Plateau South
14
300
yes
170
Blackwood-Karri
24
no limit
yes
352
Bunbury East
20
2700
yes
0
Bunbury West
21
2000
yes
0
Bunbury-Karri
25
no limit
yes
125
Busselton-Capel
19
18500
yes
2228
Cape to Cape North
17
400
yes
722
Cape to Cape South
23
400
yes
2254
Coastal
1
4100
yes
0
Cowaramup
26
2400
yes
2053
Dardanup
22
290
yes
121
Donnybrook
18
500
no
81
Dunsborough-Vasse
16
9900
yes
620
Harvey
8
11500
yes
1307
Jasper
10
2000
yes
2080
Kemerton Industrial Park North
5
790
yes
343
Kemerton Industrial Park South
4
210
no
51
Lake Preston North
2
9300
yes
1416
Lake Preston South
9
10500
no
1777
Myalup
6
7350
yes
704
Rosa
13
1100
yes
269
Scott
11
2000
yes
5225
2150
yes
Wellesley
Total
7
91780
39
32630
1
Allocation limits for superficial aquifer (Green: Combined allocation limits for superficial and
Leederville aquifers)
2
Contact a South West regional office for the latest information on water availability
Department of Water
21
Plantation forestry and water management guideline
Appendix 5. Plantation forestry in the Upper
Collie catchment
22
Department of Water
Plantation forestry and water management guideline
Allocation limits, water availability and area of plantation forestry in the South West
groundwater sub-areas
Sub-area name
Collie River Central
Allocation
limit (ML/yr)
Map reference
Is water
available?1
Area of
plantation
forestry (ha)
1
86600
Harris River
2
15000
no
22
Lower Harris
3
1220
yes
13
Collie River East Branch
4
14000
no
8904
Collie River Lower East Branch
5
1000
yes
1023
Bingham River
6
0
no
1207
Collie River South Branch
7
5020
yes
5893
Total
1
yes
122840
2117
19179
Contact a South West regional office for the latest information on water availability
Department of Water
23