AN ASSESSMENT OF SECONDARY DRYLAND SALINITY IN …

AN ASSESSMENT OF SECONDARY DRYLAND SALINITY IN VICTORIA

February 1994

CENTRE FOR LAND PROTECTION RESEARCH

Technical Report No. 14

Land Protection Branch

(•) Department of Conservation


February 1994

CENTRE FOR LAND PROTECTION RESEARCH

Technical Report No. 14

Margaret Allan

ISBN No. 0 7306 4046 9

ISSN No. 1038-216X

Land Protection Branch

Department of Conservation & Natural Resources

Allan, M.J.

631.41 6

An assessment of secondary dry land salinity in Victoria

Bibliography. ISBN 0 7306 4046 9

1. Salinity - Victoria. I. Centre for Land Protection Research. II. Victoria. Dept. of Conservation and Natural Resources. III. Title. (Series: Technical Report (Centre for Land Protection Research (Vic.)); no. 14).

2 Department of Conservation & Natural Resources

CONTENTS

ABSTRACT ... .............. ........ ................ ............ ........... ...... .... ....... .. ...... ........................ .......... .... .... ... ........ .. .. ...... ... ..... 5

INTRODUCTION .............................................. ......... ... ....... ............ .... ... ..... ............ .... .. .... .. .. ... ... ... ..... .... ......... ..... .. .. 5

Statewide Estimates of Dry land Salinity ..................... .. .............. .. ....................... ............. ... ... ..... ... ....... .......... ..... 5

Early Regional Mapping ............................. ............. ...... .............. ....................... ... ... ... ... ....... ....... ... .......... ...... ... .. 6

The Statewide Dryland Salinity Assessment Project .......... .. ........ .. ................................ ............ .... .... .. .. .... ........ .. . 6

Primary Salinity ......................... .......... ... ......... ... ....................... .. ... ..... ..... ... .. ...... .. .... .... .. ... ........... .... .... ....... ...... .. 6

METHOD ... ....... .. .. .... ............... .... ........ .... ... .... ......... ........... ...... .......... ......... .. ................ ..... ........ ..... ......... .... .... .. ...... .. ?

Field Procedure ..... ............... ...... .. ....... ................... ..... ...... ........ ... ........... ........ .. ... .... ...... ..... .... .. .... .... .. ..... .... ..... .. .. 7

Recognizing and Assessing Salinity .... .... ... ......... ....... ...... ... .. ............................. .... ............... ......... .. ..... ... .... ...... ... 7

The Mapping Procedure ............................... ....... .... ....... ... ......... .......... ... .... ..... ........ ... ..... ... .. .......... ... .. ........... .... .. 8

Determining the Origin of Salinity ................ .. .. ..... ...... ....... ............ ........ .... ............ ........ .... ........................ .. .. ... ... 8

RESULTS ... .... ........ ...... ......... ... ............... ..... .... ........... ................ ... ..... .. ........ .. .. ....... .... ...... .. .. .... ...... ... .. .. ....... .. .. ...... .. 8

Dryland Salinity in Victoria ..... ...... .. ..... ... ... .... ... ...... ........... ..... ....... .. .. ..... .... ....... ........ ...... ......... ...... .. .. ... .. ...... ...... 8

The Victorian Dry land Salinity Database ....... : .... ......................... ...... ........... ..... ............. .. ... .. .. .. .......... .............. .. . 9

Rate of Spread of Dry land Salinity .......... .. ........ .. ....... .. ..... .............................. ... .. ......... ................. .. ..... .... .. ........ 13

Salinity Classes ..................................................... .......... ...... ... .... .. .. ..... ....... ................. ...... ...... .. ... ..... ..... ... .... .... 13

An Overview ofDryland Salinity Discharge by Salinity Region .......................... .............. .................. ........ .. .... 13

CONCLUSIONS ... ......... ... .... ........ .......... ... .... ......... ........... .. .... ............ ....... ............. ... ......... ... ... .... ...... ... .... .... ...... .... 15

RECOMMENDATIONS .......... .. ... ... .. ....... .... .... ............ ..... ..... ...... .... ....... ..... ............ ........ ... ... .. ... .. ...... .... ...... ... .... .... 15

ACKNOWLEDGEMENTS ........ ............. ...... ...... ..... ............ ........ ....... .......... ....... .... ........................ ........ .... ..... ... ..... 16

REFERENCES ....... .......... ........... .... ....... .. .... .. ....... ......... .. .... ...... ..... ......... ........... ..... ...... ... .. ............ ... ........ .. .... .... ... .. 16

APPENDICES

Appendix 1. Recognising and Confirming Salinity .............. .. .. ...... ....... .... ..... .... .................... .......... .... ............... .. ... 18

Appendix 2. Salt Tolerant Plants .............................. ........... ...... .. ........ ... ......... ..... ............... ........ .. ... .... ..... ... .. .. .. ..... . 21

Appendix 3. Some Known Salt Sensitive Plants ............................ .. ........ .... .... ...... ........ ...................... ........ .. .. .. .. .... .24

Department of Conservation & Natural Resources 3

List of Maps

Map 1. Dry land Salinity Planning Regions. .............. ..... ...................... ...... ...... .............. ............ ............ .... ...... ...... .. 11

Map 2. CNR Regional Boundaries. .......................................................................................................................... 12

Map 3. Distribution ofDryland Salinity in Victoria (inside back cover)

List of Tables

Table 1. Natural Salinity in Victoria .......................... ...... .... .... .. ... .......... .. .......... .. ................. ........ .. ............. .... .......... ?

Table 2. Secondary Dryland Salinity by Salinity Planning Region ....................... ................................ ..... ................ 9

Table 3. Secondary Dryland Salinity in Victoria by CNR Region .... .. ........................ .............. .. ............ .. .... ........... 10

Table 4. Size Analysis on Discharge Sites in the Victorian Dryland Salinity Database by Salinity Plan Region .... 10

Table 5. Size Distribution of Discharge Sites in the Database ............ .... ............ .......................... ........ ......... ........... 13



February 1994

M.J.ALLAN

Centre for Land Protection Research, Department of Conservation and Natural Resources, 22 Osborne Street, Bendigo, Victoria, 3550

ABSTRACT

The amount of land affected by secondary dry land salinity in Victoria has been calculated to total 120 000 hectares.

The majority of the discharge sites have been assessed, recorded onto 1:25 000 scale maps, and are contained on the

Victorian Dryland Salinity Database. ·

Dryland salinity occurs in most regions of the State, except the forested Eastern Highlands. The more intensely

affected areas include the Mallee, the Wimmera, the Hamilton area, central Victoria, Colac region, Phillip Island and

Lake Wellington hinterland. A portion of the affected areas were salty before European settlement, however a number

of these sites have expanded or increased in severity due to land-use change since settlement.

INTRODUCTION

t Pry land salinity is a term used to describe salt that has

J )milt up in soil and water syste~s as a consequence of

f~.~native v~getatio~ clearing and its replacement w~t~ Io~ . i'water-usmg agncultural systems. Secondary salm1ty IS

\

used specifically to describe dryland salinity that has

occurred since European settlement, and to distinguish it

from primary (natural) salinity which existed long before

settlement.

Irrigation salinity is not addressed in this report, as the

causes of and solutions to the problem vary to those of

dryland salinity.

The Statewide Dryland Salinity Assessment (SDSA)

Project commenced in 1989, with the aim of collating

existing data on secondary discharge1 sites, and to

coordinate the collection of further data by CNR

regional staff, in order to derive accurate figures on the

extent of the problem. Previously, there had been a

variety of methods used to assess and classify salinity

sites so that direct comparisons between regions were

not possible. Also, not all parts of the State had been

surveyed and consequently estimates of the total area

affected by salinity in Victoria varied widely (see

1 Discharge refers to the dissipation of groundwater which is the driving·force behind dryland salinity.

following).

Statewide Estimates of Dry land Salinity

In the 1950s, Cope (1958) conducted the first appraisal

of dryland salinity in the State and estimated there to be

over 5000 ha affected.

After a series of wet years in the early seventies led to a

rapid expansion in area of discharge, interest in the

phenomenon of dryland salinity increased and further

surveys were carried out. By 1978 a figure of 85 000 ha

was used by the Soil Conservation Authority (1978) for

total dryland salinity in the state. In 1983 it was

estimated that 90 000 ha of 'seeps' (dryland discharge

sites) and 60 000 ha of scalds (where erosion of topsoil

leaves salty subsoil exposed) existed when ACIL (1983)

completed a study on dryland salinity for the

Government of Victoria. However when the major

policy document "Salt Action:Joint Action"

(Government of Victoria 1988) was released, a

conservative estimate of 55 000 ha of dryland salinity

was employed, which represented only the area of

salinity which was confidently known to exist.


Early Regional Mapping

Prior to the establishment of th is project, a small number

of regions had been mapped for dryland salinity, and a

total of 18 000 ha were recorded.

A study of salinity in north-west Victoria (west of a line

from Swan Hill to Wycheproof) in the late-1960s

calculated that there were 5000 ha of salinity due to both

local and regional groundwater systems (Rowan 1971 ).

The amount of salinity was determined by Rowan to

The survey method of salt-affected land was based on

earlier work conducted under the federally funded

National Soil Conservation Program (NSCP) project

ISCON - the Inventory of Soil Conservation Needs

(Salinity Component). Extensive field work was

conducted under ISCON to develop a methodology for

recognising, assessing and recording dryland salinity

sites in Victoria (Matters 1987a; Matters 1987b ). The

basic tenet underlying the identification of discharge

sites was the use of plants as indicators of salinity.

have been underestimated as sites were mapped from Primary Salinity aerial photographs with limited ground-truthing.

It has been estimated that around 250 000 ha of natural

From 1976 to 1980 a fiel d survey of dryland salinity was (also known as primary) salting exists in Victoria (see

conducted in the Soil Conservation Authority region of Table 1). There are a number of types of natural salting

Otway (Duff 1983), and 7500 ha were identified. Three as described below.

categories of severity were used, however the categories

were not applicable across the state.

A comprehensive salinity survey was detailed in a report

prepared by the Ballarat Region (DCFL 2 1988). The

report incorporated previous fieldwork conducted over

sub-sections of the Region (Sturmfels 1982; Duff 1983;

Moore 1984) and in total 5500 ha of saline discharge

was recorded. A rating for severity of salinity was

allotted to some of the sites.

These surveys demonstrate the variation in approach to

salinity mapping which had been adopted, and

highlighted the need for a standardized methodology to

be used in all regions so that comparisons and priorities

for Statewide action could be made.

Salt marshes

This term is used to describe coastal plant communities

growing within the tidal influence of the sea (the source

of salts in these cases). A variety of native plants are

found in Victorian salt marshes (refer Bridgewater et al.

1981 ). An estimated 70 000 ha of salt marsh exists in

Victoria (Table 1), the main locations being Discovery

Bay (western Victoria), Westernport Bay, Andersons

Inlet, north of Wilsons Promontory, and along the

Gippsland Lakes.

The degree of influence. of the sea on the watertable

along the Victorian coast varies with geological

conditions. The coincidence of salt marsh and adjacent

dryland (groundwater driven) salting has been recorded

The Statewide Dryland Salinity Assessment in Yarram Region. A bore at one such site is artesian,

Project and the influence of seawater cannot be completely

discounted in this case.

A coordinated effort across the State was made to map

all known but previously unrecorded dryland salinity Salt pans

sites, and as far as possible, locate and record newly

emergent and previously unknown sites. In addition These are areas where the watertable is intermittently at

information was collated on expansion rates. the surface, and soil salinity levels are too high to allow

2 Department of Conservation, Forests and Lands (DCFL) is now called Department of Conservation and Natural Resources. DCFL Regions, of which Ballarat

was one, have been superseded by catchment based

management.


plant growth. Such sites have also been known as 'salt

lakes' . Salt pans are predominantly found in · north

western Victoria, though this category also includes the

Lake Corangamite lacustrine complex (Working Party

on Dryland Salting 1982), and lakes around Willaura in

western Victoria.

Salt flats A total of I 00 000 ha of salt pans and salt flats is

Land with watertable close to, but not at the surface, estimated to exist in Victoria (SCA I983).

supporting salt-tolerant plants. Distributed throughout

the Mallee and Wimmera.

Table 1: Natural Salinity In Victoria (areas in hectares)

0

*

+

Note:

Wetlands0

Semi-permanent saline (includes coastal and inland) 66 IOO

Permanent saline - Intertidal flats (exclusively coastal) 69 IOO

- Shallow (predominantly inland) 3I 300

- Deep (predominantly inland) 40 700

Subtract: Freshwater wetlands that have become saline * 4 900

Man-made saline wetlands (mainly evaporation basins) 1 500

Saline areas increased in size 60

Total natural saline wetlands in Victoria 199 740

Dry lands

Estimated natural saline drylands (salt flats) in Victoria+ 50 000

Total natural salinity in Victoria 249 740

Wetlands data from Andrew Corrick, Wetland Survey Group, Flora and Fauna Branch, CNR.

Conservative estimate of total amount salinized, as it is impossible to determine the original condition of all wetlands, and hard to quantify land-use effects since European settlement (Corrick pers. comm.) .

S.C.A. estimate (Speedie and Gibbons, 1984) oftotal natural inland dryland and wetland salinity is 100 000 hectares. No separate calculation was made for amount of salt flats in Victoria, so it was assumed to be half (50 000 ha). Salt pans are quantified in Corrick's survey as they are permanent, saline wetlands (shallow and deep); salt flats (where the watertable is below the surface) are not.

Definitions for both salt pans and salt flats vary slightly between the Wetland Survey Group where pans and flats are coastal or inland, and Dryland Salinity Research (see S.C.A. 1983) where the terms are used exclusively for inland natural discharge sites.

METHOD

Field Procedure

remaining sites were located by systematic surveys m

each of the study areas.

At each of the discharge sites an examination and record

Field work was conducted by assessors who were was made of evidence for dryland salinity . Once salinity

supervised by Salinity Officers, in each of the I5 was confirmed at each site, the assessor would examine

participating Regions (all except Orbost Region, which the wider region for associated discharge.

has negligible salinity). Co-ordination of data collection

was conducted by the author. Geological information Recognizing and Assessing Salinity and aerial photographs were utilized to conduct broad

reconnaissance of the regions to locate apparent

discharge sites. Local landholder responses were sought

on the location of discharge through mailouts, LandCare

There are five major indicators of salinity (see Appendix

I for details) :

groups, and articles in local newspapers. Known I . Vegetation

discharge sites provided training sites for assessors. The 2. Position in the landscape


3.

4 .

5.

Surface moisture

Bare soil

Salt stains.

Vegetation was also used to assess the level of salinity at

a site . The three classes of salinity (see below) are based

on known field tolerances of a range of plant species, a

method developed (Matters 1987a) for conditions within

V ictoria.

Soil salinity class

2

3

EC 1:5 (!lScm-1 )

300- 600

600-1 400

> 1400

So il testing was conducted where there was uncertainity

salinity, an effort was made to distinguish it from

primary sites in the field . Primary salinity however may

also have a secondary (induced) component due to land

use since European settlement that has caused an

increase in salinity severity at the site, an expansion of

the original site, or both. Where primary sites have been

reactivated, an estimate of the area of expansion was

made for the purposes of calculating total secondary .

salinity in the region, and in the state.

Undisturbed primary sites are characterised by the

presence of native salt-tolerant species which tend to be

mature, perennial, and halophytic, whereas sites of

induced salinity are colonized by volunteer species

which are usually annuals.

as to what class the site was in, or whether there was In the north-west of the state, the presence of clay

salinity at all. Soil test resu lts at the same site however lunettes--crescentic dunes on the eastern side of lakes or

can vary depending on when the samples are taken. This depressions-is also an indicator of natural salinity.

variation is attributable to leaching and concentration of

salts that occur on a seasonal basis, and between years, The grazing of some primary sites has lead to the

related to rainfall patterns. Plant indicators were found to introduction of volunteer salt-tolerant species and other

be more consistent than soil testing, as they give a weeds, making the distinction between primary and

picture of the range of salinity conditions experienced at secondary salinity difficult in these cases.

a site .

The Mapping Procedure

Because of the small size of most of the discharge sites

(50% are less than 2 ha), the standard scale adopted fo r

record ing data was 1 :25 000. For most areas of the state,

aerial photography and topographical bases are available

at this scale. Sites were drafted from the aerial photos

onto copies of the 1 :25 000 bases. Areas were measured

using digital planimeter, digitizer, or dot grid.

Sites have also been digitized onto the CNR GIS

(Geographic Information System) to enable the

discharge mapping to be overlaid with other data, and to

be displayed at a range of scales fo r specified areas. The

full Australian Map Grid Reference of six-digit Easting

and seven-digit N orthing was calculated for each site to

enable small-scale (less than 1:250 000) map work to

also be performed using GIS .

RESULTS

Dryland Salinity in Victoria

The total area of secondary dry land salinity in Victoria is

around 120 000 hectares. This figure consists of

85 000 ha that have been mapped, and an additional

35 000 ha known to occur but not yet documented. This

result is slightly above the estimated figure of

100 000 ha (using data collated from regional sources at

the beginning of the project) and compares to the

estimate for irrigation salinity of approximately 140 000

hectares (Government of Victoria 1988). The salinity

area is 1.0% of the total cleared or naturally treeless,

non-irrigation, non-urban land (also referred to as

dryland agricultural area) in the state. The results are

presented by salinity region or plan area in Table 2 (see

also Map 1 ). The data in Table 2 does not contain all the

salinity in the state as some parts of the state have not

been included in plans. The results in Table 3 give a

Determining the Origin of Salinity more accurate picture of statewide secondary salinity.

As the aim of the project was to document secondary The mapping project has confirmed or exceeded original


estimates within each of the former CNR Regions (refer both of which were recorded.

Table 3 and Map 2). In most cases the area was greater

than originally believed due to : The Victorian Dryland Salinity Database

I.

2.

3.

4.

inclusion of low level salt-affected land in this

mapping project, which is not as visually apparent

as the higher classes, and has tended to be

overlooked in previous surveys;

discovery of previously unknown discharge sites;

the process of committing the known sites to maps

revealed more salinity than previously had been

thought to exist.

lack of ability by some of the original assessors to

accurately estimate size. All areas in the Victorian

The database (Allan 1993) consists of every mapped

discharge site in the State. The record for each site

includes a unique number, an area in hectares, an Easting

and a Northing. Depending on the level of assessment,

there may also be a salinity class. Sites that were

assessed as being predominantly (>95%) or totally

natural, or due to irrigation or seepage from a water

supply channel, have been recorded, but are not included

on the database.

Dryland Salinity Database (Allan 1993) have been Five thousand discharge sites, encompassing a total area

measured from maps. of 85 000 ha, have been located. Three thousand of the

sites are recorded onto I :25 000 mapsheets, three

The most startling result was for Bendigo CNR Region hundred in number; the remainder are recorded only as

where a six-fold difference exists between the original point data.

estimate (5000 ha) and the actual result (30 000 ha).

The sites range in size from less than one hectare, up to

The apparent over-estimate in 1989 prior to the two thousand hectares. However, fifty percent of the

commencement of assessment, for Horsham and sites are less than two hectares in size, and only one-

Geelong Regions, is due in part to the differentiation quarter of the sites are greater than 25 hectares. See

between sites of primary and sites of secondary origin, Tables 4 and 5 for analyses of sites in the database.

Table 2: Secondary Dryland Salinity by Salinity Plan Region (areas in hectares)

Salinity Plan Region Secondary Salting Secondary Salting as

in Dryland Agricultural Percentage ofDryland

Areas Agricultural Area 1

Avoca 5 570 0.9

Avon-Richardson 10 500 3.6

Campaspe 3 200 0.9 Corangamite 10 900 0.7 Glenelg 20 ooo4 1.0

Goulbum 3 500 0.3 Lake Wellington 10 000 4.5

Loddon 7 400 1.0

Mallee 15 ooo4 0.6 North-East 250 <0.1 South-East2 10 000 0.6 Wimmera3 13 000 1.0

Dryland agricultural areas derived using CNR GIS data

2 Excluding Lake Wellington catchment

3 Excluding Avon-Richardson catchment

4 Not a final figure- accurate mapping is incomplete (Glenelg) or is out of date (Mallee)


Table 3: Secondary Dryland Salinity in Victoria by CNR Region (areas in hectares)

CNRRegion Area estimated at June I989 Area mapped at June I993 Estimated total Alexandra 900 900 1 800 Baimsdale 376 543 1 000 Ballarat 5 500 5 5I5 5 515 Benalla 2 600 2 600 5 200 Bendigo 5 500 30 oooi 30 000 Central Gippsland IO I20 I5 8602 20 000 Co lac 7 500 8 650 8 650 Dandenong I 000 2 000 2 000 Gee long 6 000 I 22I I 221 Horsham 20 000 9 000 9 000 Melbourne - I70 300 Mil dura I2 000 5 000 I5 000 North-East 90 200 250 Portland I3 000 0 I6 000 Yarram 600 700 2 000

1 This figure includes 3500 ha of salinity mapped on non-agricultural land, which is predominantly wetland around Lake Buloke.

2 This figure is derived from calculated areas for the Lake Wellington catchment (Lake Wellington SMP Technical Support Group 199I) as follows:

Dry land Wetland

Private land 12 000 3 980

• Public land

540 4 I45

Table 4. Size Analysis on Discharge Sites in the Victorian Dryland Salinity Database

Dryland Salinity Plan No. of Sites Average Size Minimum Size Maximum Size

Region (see Map 1) (ha) (ha) (ha)

Avoca 63 84.1 0.1 985.6

A von Richardson 57 I94.1 1.0 2000.0

Campaspe 143 14.9 0.6 108.1

Corangamite 847 13.3 0.1 935.4

Glenelg 436 8.3 0.1 I89.0

Goulburn 449 I O.I 0.1 I45.6

Lake Wellington 116 139.1 0.1 1552.4

Loddon II5 62.9 0.2 761.2

North-east 25 3.9 O.I 29.4

Phillip Island 28 44.9 2.7 428.8

South-east 1 I35 8.8 O.I I58.5

West ofWimmera 2 54 25.2 0.2 222.0

Wimmera catchment 546 I6.8 O.I 329.6

Excludes Lake Wellington and Phillip Island data. See separate listings.

2 The area west of Wimmera catchment is not incl uded in a plan.

Note: Detail mapping necessary for the above analysis was not available for sites in the Mallee. The data presented

here for Glenelg only includes sites that have been mapped, and these occur in the north-east corner of the Region.


Table 5: Size distribution of discharge sites in the quantified (and qualified) at regular intervals.

Database

Size

category (ha)

::;1

1 - 10

10- 100

> 100

Percentage of sites

(rounded to nearest 5%)

20

50

25

5

It is likely that rates will vary with geology, topography,

history of clearing, and land-use.

Salinity Classes

Salinity class has been recorded for 57% of mapped

sites. Comparisons based on class, between sites and

regions, can be conducted to a limited degree as many

At this stage 75% (by area) of total estimated dryland factors, including geology, land-use, climate and season,

salinity in the State has been mapped. Regions with a affect the level of salinity

large area to survey and a large estimate of salinity

(Mallee and Glenelg) are yet to complete discharge In the Corangamite Region mapping exercise, soil

assessment. salinity levels, sampled in summer, were higher than

expected for the indicator plants present, when compared

Even in those Regions where assessment has been to the three ISCON salinity classes and recorded

substantially completed, further sites may be located in tolerance levels of the plants. This phenomenom is due

the future . The database will need to be updated to the plants being able to tolerate the high salinity levels

regularly for this reason, and also because of the active recorded at the time of sampling for limited periods

nature of many discharge sites. only. The plants that establish and persist reflect the

general salinity levels experienced at a site; the soil

The map references of each site on the database, has

been combined with a broad analysis of salinity in

Glenelg Region, to produce Map 3 at a scale of

1:1,000,000 using GIS.

Rate of Spread of Dry land Salinity

To date scant data has been available on the annual

samples were giving only a snapshot of conditions

experienced throughout the year.

An Overview of Dry land Salinity Discharge by Salinity Region

Avon-Richardson

percentage increase in dryland salinity across the State. There has been 14 200 ha of discharge mapped, and this

An arbitrary figure of 2% has been used (Govt. Viet. occurs throughout the catchment, concentrated within

1988) as an average Statewide, though in estimates so and beside low-lying areas such as watercourses and

far obtained, the rate at individual sites varies from zero lakes. Three-quarters of the salt-affected land is

to around 15% (Dept. CFL, 1988). agricultural. The remaining quarter (3 500 ha) is around

wetlands.

Salinity area increase was calculated at a number of sites

across a geographical range in the Corangamite Salinity Campaspe

Region, and was found to range from 1.2% to 6.6%, and

gave an average of 2% (Corangamite Salinity Forum Major outbreaks of salinity are found along Mt Camel

1993). Range and at Knowsley (north and west of Heathcote

respectively), Elphinstone, west of Tooboorac, and the

In order to develop a range of reliable data from which sedimentary country south-east of Bendigo, including

salinity growth rates could be calculated, a series of Axe Creek catchment.

monitoring reference areas is being established across

the state. Representative discharge areas are pegged, and The area of salinity mapped totals 3200 ha, though an

soil and plant information recorded. This information additional 780 ha is estimated to be affected.

will be used as a baseline from which changes can be


Corangamite Due to the steep dissection of land in the Upper

Goulburn, discharge sites are relatively small, and the

Of the 16 200 ha of sal inity mapped, 11 000 is total area affected is limited, however the greater impact

considered to be secondary salinity. The secondary is of discharge directly into streams.

salinity is predominantly found in the Heytesbury

settlement, Upper Woady Yaloak, and the Bamgamie- Loddon-Avoca Meredith area, on the basalt plains, in the Upper

Maribyrnong catchment, at Moriac and Barwon Downs.

Detail on the mapping results is reported in Scott (1992)

and Muske ( 1992). Mapping has yet to be completed for

Discharge in these two catchments total 13 000 ha, and

this is concentrated in the southern, upland areas.

Localities with significant levels of salt-affected land are

the areas south of Ballarat, and the southern Burkes Flat, Natte Yallock, Lexton, Ravenswood,

Corangarnite. Nuggetty (near Maldon), Leichhardt, Woodstock,

Eddington, Dunluce, and north of Campbelltown. In the

The remaining 5000 ha is natural salinity and this is

distributed around Lake Corangamite (Beeac and Leslie

Manor locales), Lake Murdeduke, Bellarine Peninsula,

and the coast between Geelong and Point Cook.

Glenelg

Approximately 20 000 ha of salinity has been calculated

as occurring in Glenelg Region. This is based on

extrapolation from existing mapping.

Major outbreaks occur in the Dundas Tablelands, the

Willaura Plains and Victoria Valley.

Discharge occurs in almost every gully and creek line on

the Dundas Tablelands.

The alluvial and basalt areas of the Willaura Plains, to

the southeast of the Grampians, is an area in the region

where detailed mapping has been conducted, and 3600

ha of salinity recorded. Salinity presents a threat to many

wetlands on the basalt plains.

Goulbum-Broken

northern Loddon, major outbreaks occur at Kamarooka

and Bears Lagoon.

Mallee

A total of approximately 105 000 ha of discharge has

been calculated as occurring in the Mallee. This figure is

derived from salinity mapping for the area conducted in

the late 1960s (Rowan 1971 ). Of this total, roughly

90 000 ha is termed natural and was present at the time

of European settlement. Major discharge features

associated with natural salinity include Pink Lakes, Raak

Plains, Lake Tyrell, Noora Depression and Kowangee.

The estimated 15 000 ha of secondary (induced) salinity

has been brought about by low water-using agricultural

practices. Twelve thousand hectares of secondary

salinity is due to rises in the regional water-table, and the

remaining 3000 ha is discharging on dunes and near

water-supply channels from local groundwater systems.

There is a program currently in operation that replaces

the open, earthen water-supply channels with concrete

pipe, which will minimize discharge from this source.

Control of salinity from other sources is concentrating

Intensive mapping exercises have located 3500 ha of on improving water use over a large part of the Mallee

discharge in this region . Around Benalla, discharge is landscape through strategic tree planting, sowing lucerne

concentrated around the northern and western flanks of and other perennial pastures, and minimizing fallow.

the Strathbogie Uplands and the roll ing hills north of

Violet Town. Further south, discharge is concentrated in

the Majors, Gardiner, Whiteheads and Hughes Creek

catchments, and these have been assigned priority for

treatment in the Salinity Management Plan (Goulburn

Broken Salinity Pilot Program Advisory Council 1989).


North-east

Salinity has been found in the Springhurst and Byawatha

areas (north-east of Wangaratta), and at Middle Indigo

(east of Chiltern). Further investigation is to be

conducted in the King River Valley, where salinity is

thought to be a larger problem than currently recognised.

South-east

Twenty thousand hectares of dryland salinity have been

recorded in this region.

The worst affected areas are at Phillip Island, and the

hinterland of Lakes Wellington and Victoria (in the

western Gippsland Lakes).

Salinity on Phillip Island is widespread, with discharge

occurring in many of the drainage lines. There is a total

of 1200 hectares of salinity which represents 12% of the

island.

The hinterland of Lake Wellington carries significant

areas of wetland which has high conservation value,

particularly for waterbirds. However these wetlands are

threatened by increasing salinity levels (Nash 1991).

The causes of salinity in the hinterland are complex.

There would have been lake edge salinity before

European settlement (estimated at 5% of the current

area). After the permanent opening of Lakes Entrance,

levels in the lakes dropped, and salinity increased.

Salinity has also come about through tree-clearing and

grazing/cropping regimes in the upper catchment.

To the north-west of Lake Wellington are located the

Nambrok-Denison and Macalister Irrigation Districts,

and a proportion of the water applied on these areas

reaches the watertable and plays a role in dryland

salinity lower in the catchment, around the Lake.

Wimmera

Over 18 000 ha of dry land salinity have been recorded in

this region. Most of the class 3 (high-severe level)

salinity occurs along the Wimmera River south of Lake

Hindmarsh, and most of this is natural discharge from

the regional Parilla Sand aquifer. This system continues

along a string of lakes west of Mt Arapiles. Natural

salinity is estimated to total 7000 hectares.

Small amounts of salting occur m restricted irrigation

districts near Horsham. Channel seepage from the

Wimrnera-Mallee Stock and Domestic Water Supply

System occurs at various locations throughout the

Region.

Salinity Management Plans

The information reported in this section and Tables 2

and 3 has been obtained from regional staff, in particular

the assessors, in each of the relevant CNR offices (see

acknowledgement list) . Further information can be

obtained by consulting the salinity management plan for

any salinity region. The plans are available through

CNR.

CONCLUSIONS

The extent of dryland salinity is much larger than

previously recorded. The difference between the fmal

figure of 120 000 ha, and the previously published figure

of 55 000 ha (Government of Victoria 1988), does not

represent the magnitude of increase in salinity area over

that period, but illustrates the effort invested in recording

salinity.

There is no doubt that there are some discharge sites that

have been overlooked during the surveys, but this is

believed to be equivalent to a very small proportion of

the total area mapped statewide. Updating of the

database will be an ongoing task.

RECOMMENDATIONS

It is necessary to complete discharge mapping in

Glenelg, and update the Mallee, in order to complete

discharge mapping for the state, in line with aims and

targets of the Statewide Dryland Salinity Assessment

Project.

Reference areas, to monitor salinity, have been

established at a number of discharge sites in the Loddon,

Campaspe, Corangamite, and Wimmera Regions. The

sites have been selected on the basis of representing the

broad range of groundwater systems, rainfall, and land-


use. This project should continue to complete the

network within these Regions, and across the state. Cope, F. (1958) Catchment salting in Victoria. Soil

Reassessment of the salinity reference areas should be Conservation Authority, Victoria, Technical Series

conducted at 2-yearly intervals. 1.

ACKNOWLEDGEMENTS Corangamite Salinity Forum (1993) Restoring the

balance. A strategy for managing salinity m the

The salinity field mappers: Corangamite Salinity Region. CNR, Colac.

H . Anderson- mid Wimrnera, C. Barry-Bengworden, Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and

M. Blurnl-Dandenong CNR Region, P. Codd, J. Duff, Leigh, J.H. (1981) Plants of Western New South

J. Modra, E. Muske and K. White--Colac CNR Region, Wales. Soil Conservation Service ofNSW.

R. Durie--Bendigo CNR Region, M. McKenzie,

G. M oore & C. Sturmfels- Ararat district, Department of Conservation, Forests and Lands (1988)

J. M atters- Lake Wellington hinterland, Salinity control strategy. Ballarat Region ( unpubl.)

J. Rowan- Mallee, K. Scott--Geelong CNR Region,

G. Slater- N orth-east, J. Smith & B. Garrett-Benalla Duff, J. S. (1983) Soil salting in the Lake Corangamite

CNR Region, G. Stockfeld- northern outskirts of region of south-western Victoria. M.Ag.Sc. (thesis),

M elbourne, D . Strudwick & M. Wilson-Lower Uni. ofMelbourne.

Wimmera, G. Trease- Yarrarn CNR Region.

The following CNR staff for general assistance: P. Codd,

D . Herpich, L. Hodgson, A. Kennelly, T. Lewis, J.

M cRoberts, P . Ockenden, J. O'Neill, N. Penrose, B.

Radford, C. Sturmfels.

Colleagues at CLPR: C. Clifton, C. Day, S. Hill,

T. Kevin, S. Ryan & D. Strudwick, fo r advice

throughout project, and reviewing this report. P. Cook,

W. Harvey, R. Clark & L. Wieneke, for technical

assistance. J. Bowman and K. Ferrari for word

Goulburn-Broken Salinity Pilot Program Advisory

Council (1989) Goulburn dryland salinity

management plan.

Government of Victoria (1988) Salt Action:Joint Action,

Victoria's strategy for managing land and water

salinity.

Lake Wellington Salinity Management Plan Technical

Support Group (1991) The Lake Wellington

catchment salinity management plan, draft outline

processing assistance. report.

Special thank you to James Matters for training in the Matters, J.M. (1987a) Dryland salinity component

mapping method, and for imparting his extensive criteria and methodology of assessment. Land

knowledge on salt-indicator plants. Protection Division, Viet. (unpubl.)

REFERENCES Matters, J.M. (1987b) Metliod of assessment of dryland

ACIL (1 983) Causes, extent and effect of salinity m

Victoria ACIL Australia Pty. Ltd .

Allan, M.J. (1993 ) Victorian dryland salinity database.

CLPR, CNR, Bendigo.

Bridgewater, P.B., Rosser, C. and de Corona, A. (1981 )

The Saltmarsh Plants of Southern Australia.

Monash University, Melbourne.


salinity. Land Protection Division, Viet. (unpubl.)

Matters, J.M. and Boruvka, V. (1987) Field Guide to

Plants Associated with Saline Soils of Victoria. Dept.

Conservation Forests and Lands.

Matters, J.M. and Bozon, J. (1989)Spotting Soil Salting.

DC FL.

Moore, G. (1984) A survey of dryland salting in the

Willaura district. SCA, Victoria (unpubl.)

Muske, E. (1992) Saline discharge in the Corangamite

Salinity Region. Background report no. 2, Colac

Region, CNR.

Nash, N. (1991) Lake Wellington catchment wetlands

salinity study. Central Gippsland Region, Dept.

Conservation and Environment.

Ross, J.H. (1990) A census of the vascular plants of

Victoria (Third Edition). National Herbarium of

Victoria, Dept. of Conservation, Forests and Lands.

Rowan, J.N. (1971) Salting on dryland farms in north

western Victoria. Soil Conservation Authority.

Scott, K. (1992) Salinity discharge mapping for the

eastern section r of Corangamite Salinity Region.

Background report no. 1, Geelong Region, CNR.

Soil Conservation Authority (1978) Dryland salting in

Victoria, Australia.

Soil Conservation Authority (1983) Dryland salinity in

Victoria. Evidence for parliamentary enquiry.

Speedie, T. W. and Gibbons, F. R. (1984) Dryland

salinity in the Victorian Mallee. Soil Conservation

Authority.

Sturmfels, C. (1982) Survey of saltland in the Ararat

district, Victoria. Soil Conservation Authority,

Victoria (unpubl.)

White, K.G. (1981) Plants as indicators of dryland soil

salinity. Soil Conservation Authority ( unpubl. ).

Willis, J. H. (1970) A Handbook of Plants in Victoria:

Vol. I (Ferns, Conifers and Monocotyledons)

Melbourne University Press.

Willis, J.H. (1972, publ. 1973)A Handbook to Plants in

Victoria: Vol. II.

University Press.

(Dicotyledons). Melbourne

Willis, J.H. ( 1988) A Handbook to Plants in Victoria -

Supplement. Melbourne University Press.

Working Party on Dryland Salinity (1982) Salinity of

non-irrigated land in Australia. SCA, Victoria, for

the Standing Committee on Soil Conservation.


APPENDIX 1. RECOGNISING AND CONFIRMING SALINITY

1 Major Indicators

The following characteristics are major indicators of

salinity.

1.1 Vegetative indicators

1.1.1 Salt-tolerant species

The most common criterion for recognising salinity was

1.1.3 The plant community

With increasing salinity a previously non-saline

vegetation community will change in composition from

one containing salt-sensitive species to a community

containing an increasing number and variety of salt

tolerant species. . In pasture and natural vegetation

associations, a change would be evident over a number

of seasons, to a dominance by annuals (White 1981;

Matters 1987a). White (1981) also found in his study of

saline discharge sites in the Corangamite region of

Victoria, that the number of grasses and clovers

decreased with increasing salinity, while species in the

rush and sedge groups thrived. the presence of known salt-tolerant species (listed in

Appendix 2). The presence of two to three known salt

tolerant species with any of the physical indicators 1.2 (listed later) generally confirmed salinity without the

Groundwater

need to take soil samples. Free water or dampness at the ground surface

(particularly in summer) may be due to groundwater

In the absence of known salt-tolerant species it was discharge, though of course recent rain and waterlogging

necessary to examine the plants present for (see later section on waterlogging) are also possible

morphological evidence of salt-tolerance, such as causes. The free water was analysed for salt using a field

stunting, thickening of the cuticle, reduction of leaf electroconductivity (E.C.) meter.

hairiness, short internode length, semi-succulence in

leaves, and reddening of the plant.

1.1.2 Salt sensitive species

Salt-sensitive species (see Appendix 3), including some

crop and pasture plants, were used as indicators of

increasing salinity in the absence of salt-tolerant plants,

as the following changes are observed in populations of

salt-sensitive plants (Matters 1987a): much slower

growth rate, incomplete life cycle, diminished

abundance, depressed health (commonly apparent by

characteristic yellowing and stunting of crop or pasture

species), greater susceptibility to disease, decreased seed

viability, decreased germination rate.

The absence of salt-sensitive species, for example

subterranean clovers, otherwise present in the near

1.3 Bare soil

The soil may be bare due to death of the original salt

sensitive native vegetation, crop or pasture, or at the

other extreme, the soil salinity may be too high for any

plants to tolerate. Once bare, the soil is prone to erosion,

and salt accumulates at a faster rate, as higher

evaporation rates of groundwater occur than when the

soil is vegetated. A pattern of baring begins in low points

in the microtopography, these being marginally but

critically closer to the watertable. As part of the process

of degradation salt-tolerant species may then establish,

though this is dependent on a suitable seed source in the

region.

1.4 Salt

vicinity, is an indicator of salinity. This was an Salt was sometimes observable (more so on bare soil) as

important diagnostic tool, particularly where the only a white stain, or actual salt crystals (an encrustation).

salt-tolerant species present are also capable of growing This is one of the more definitive indications of salinity.

in non-saline environments.


1.5 Position in the landscape

Local groundwater aquifer systems have watertables

confusion was avoided to some extent by leaving

assessment to late spring, summer or early autumn, when

rainfall is generally lower.

which generally follow the surface topography. Regional

groundwater' aquifer systems have flat or gently sloping 3.2 Plants outside documented range

watertables and extend under a number of surface water

catchments. Discharge within both systems tends to

appear at topographically low sites on flats, drainage

lines, lake margins, depressions and stream banks where

the surface intersects the watertable. Local systems may

also discharge on hillsides from perched watertables

caused by an aquifer overlaying a confining (usually

clay) layer. Break-of-slope describes a change in surface

gradient correlated with an increase in clay thickness

causing groundwater to 'slow down' and consequently

discharge.

2 Secondary Indicators

In general, the distribution maps in the Spotting Soil

Salting booklet (Matters and Bozon 1989) and Willis

(1970 and 1972) can be used as an aid to plant

identification. However, by the very nature of induced

salinity, which is an unnatural environmental situation

that is worsening, a salt indicator plant (especially an

introduced species) may be found outside the previously

recorded range. In such cases a record, including a

pressed specimen, was made and the State Herbarium

and the SDSA Officer notified.

4 Physical Factors Affecting Assessment

Less common indicators of soil salinity include tree 4.1 health decline and soil blackening.

Masking

2.1 Tree health Cultivation, slashing or harvesting can conceal the

presence of salinity at a site.

Dieback or death may be due to salinity, though other In a suspected case of masking, a return visit was paid

factors can cause tree decline and this was a when the next crop or pasture had developed

consideration during field assessment. For this reason

tree decline is used only as a secondary indicator.

2.2 Soil blackening

Soils low in phosphorus and nitrogen, and saline affected

can sometimes be recognized by a blackening due to the

dispersion and dark coloration of the organic matter of

the soil (Matters 1987a). This phenomenon was not

encountered during this study.

3 Limitations of Plants as Indicators

3.1 Salt-sensitive plants in discharge sites

4.2 Waterlogging

It is necessary to distinguish waterlogged sites from

discharge of saline groundwater. Waterlogging is the

ponding of surface water due to slow or inadequate

drainage. Waterlogging is a serious problem in itself,

and may exacerbate salinity discharge. Plants adapted to

waterlogging include sedges and rushes.

Mild salinity was recorded in closed depressions in the

Wimmera Catchment well above the watertable, through

a process whereby salt in the surface water is

concentrated by high evaporation rates (D. Strudwick,

CLPR, CNR, pers. comm.). This was distinguishable

Confusion can arise when salt sensitive species such as from groundwater driven salinity only where the depth to

Subterranean Clover or Yorkshire Fog Grass occur in watertable was known.

what appears to be a discharge site. This may be due to

leaching of salt during periods of high rainfall, and is If surface water was present, a salinity test was

more likely to happen during winter when annual plants performed, and the usual criteria (see Major Indicators)

in particular can complete their life-cycle before salt applied, in order to determine if dryland salinity was

levels in the soil rise again as summer progresses. This occurring.


4.3 Incipient salting

Low levels of surface salinity can be due to a high

watertable which is close to, but not actually discharging

at, the soil surface, and which is within the reach of plant

roots (known as incipient salting and included in the

mapping) . Low incipient-type levels of salinity can also

result from leaching of salt down the soil profile after

rain; this process can also reduce the level of apparent

salinity at the soil surface to a lower class (e.g. from S3

to S2, or from S2 to S 1 ).


APPENDIX2. SALTTOLERANT PLANTS

Below is a list of plant species compiled during the

ISCON project and found in association with saline soils

in Victoria. The salinity classes of only · those plants

featured in the handbooks (Matters and Boruvka 1987;

Matters and Bozon 1989) are known.

Taxonomy has been updated using Willis (1970, 1973,

Herbs

(?) Angianthus preissianus

* (?) Aptenia cordifolia

* (?) Carpobrotus aequilaterus

* (A) Cotula bipinnata

(AlP) Cotula coronopifolia

(P) Disphyma crassifolium

ssp. clavellatum

(?) Dysphania glomulifera

(?) Einadia trigonos

(?) Lawrencia glomerata

* (A) Lotus subbiflorus

* (?) Medicago minima

(?) Mesembryanthemum crystal/inurn

(A) Myosurus minimus

(?) Osteocarpum salsuginosum

* (P) Plantago coronopus

(P) Samolus repens

(P) Sarcocornia quinquejlora

* (?) Sarcozona praecox

(?) Selliera radicans

(P) Spergularia marina

* (?) Spergularia media

*(A/B) Spergularia rubra

(P) Suaeda australis

* (?) Trifolium arvense

* (P) Trifolium fragiferum

* Trifolium campestre

Zygophyllum crenatum

(A) Zygophyllum iodocarpum

1988), Cunningham eta/ (1981), and Ross (1990).

Life Cycle:

*

A- Annual

B- Biennial

P - Perennial

? -not known

Exotic species

Salt Angianthus

Heart Leaf Iceplant

Angled Pigface

Ferny Cotula

Water Buttons

Rounded Noon-Flower

Red Crumbweed

Lax Goosefoot

Clustered Lawrencia

Hairy Bird's-foot Trefoil

Little Medic

Ice Plant

Mousetail

'Bonefruit

Buck's-Hom Plantain

Creeping Brookweed

Beaded Glasswort

Sarcozona

Selliera (Swamp Weed)

Salt Sand-spurrey

Coast Sand-spurrey

Red Sandspurrey

Austral Seablite

Hare's-foot Clover

Strawberry Clover

Hop Clover

Notched Twin-leaf

Violet Twin-leaf


Grasses

* (?) Aira caryophyllea Silvery Hair-grass

(A) Agrostis avenacea Blown Grass

(?) Bothriochloa decipiens Pitted Blue Grass

* (A) Briza maxima Large Quaking Grass

* (A) Briza minor Lesser Quaking Grass

* (A) Bromus rubens Red Brome

* (P) Chloris gayana Rhodes Grass

(AlP) Chloris truncata Windmill Grass

* (A) Critesion marinum Sea Barley Grass

(P) Cynodon dactylon Couch

(P) Danthonia eriantha Wallaby Grass

(B!P) Diplachne fusca Brown Beetle-grass

(P) Distich/is dischtophylla Australian Salt Grass

(P) Eragrostis australasia Cane Grass

(P) Eragrostis setifolia Bristly Love-grass

* (A) Hainardia cylindrica Common Barb-grass

* (A) Lolium rigidum Wimmera Rye-grass

* (P) Lophopyrum elongatum Tall Wheat Grass

* (A) Parapholis incurva Coast Barb-grass

* (A) Parapholis strigosa Slender Barb-grass

* (A) Poa annua Annual Meadow-grass

* (P) Poa bulbosa Bulbous Meadow-grass

* (A) Polypogon monspeliensis Annual Beard-grass

(A) Puccinellia stricta Australian Saltrnarsh-Grass

(P) Sporobolus actinocladus Katoora

(P) Sporobolus caroli Yakka Grass

(P) Sporobolus virginicus Salt Couch

(P) Stipa tuckeri Spear-grass

(P) Tripogon loliiformis Rye Beetle-grass

* (A) Vulpia bromoides Squirrel-tail Fescue

Shrubs

(P) Atriplex leptocarpa Slender-fruit Saltbush

(P) Atriplex nummularia Old-man Saltbush

(A) A triplex pseudocampanulata Saltbush

(P) Atriplex vesicaria Bladder Saltbush

(P) Enchylaena tomentosa Ruby Saltbush

(?) Halosarcia pergranulata Samphire

(?) Maireana aphylla Cotton Bush

(?) Maireana brevifolia Short-leaf Bluebush

(?) Maireana georgei Satiny Bluebush

(?) Maireana humillima Bluebush

(P) Melaleuca ericifolia Swamp Paper-bark

(P) Melaleuca halmaturorum Salt Paper-bark


(P) Nitraria billardieri Dillon Bush

(?) Osteocarpum acropterum Babbagia

(P) Sclerolaena brachyptera Short-winged Copperburr

(P) Sclerolaena diacantha Grey Copperburr

(P) Sclerolaena divaricata Pale Poverty-bush

(P) Sclerolaena eriacantha Silky Copperburr

(?) Sclerostegia tenuis Slender Glasswort

(?) Sclerostegia triandra Desert Glasswort

Rushes

(?) Jsolepis congrua Club-rush

(A) Isolepis hookeriana Club-rush

* (A) Jsolepis hystrix Awned Club-rush

(A) Isolepis victoriensis Club-rush

* (P) Juncus acutus Spiny Rush

(A) Juncus bufonius Toad Rush

(P) Triglochin striata Streaked Arrowgrass


APPENDIX 3. SOME KNOWN SALT SENSITIVE SPECIES

Grasses

* Anthoxanthum odoratum Sweet Vernal-grass

* Briza minor Shivery Grass

Danthonia carphoides Short Wallaby Grass

Deyeuxia sp. Creeping Bent Grass

* Holcus lanatus Yorkshire Fog Grass

Hordeum leporinum Barley Grass

* Latium perenne Perennial Rye Grass

* Romulea rosea Onion Grass

Themeda triandra Kangaroo Grass

Rushes

* Juncus articulatus Jointed Rush

Juncus planifolius Broad-Leaf Rush

Juncus subsecundus Finger Rush

Herbs

* Arctotheca calendula Capeweed

Erodium sp. Heron's-bill

* Leontodon taraxacoides Hairy Hawkbit

Spergularia diandra Small Sandspurrey

* Trifolium subterraneum Subterranean Clover

* Trifolium dubium Suckling Clover

* Trifolium tomentosum Woolly Clover


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