Groundwater dependent ecosystems of the Barossa Prescribed Water Resources Area (Stage 1)
Final Report
November 2011
Groundwater dependent ecosystems of the Barossa Prescribed Water Resources Area (Stage 1)
Barossa GDE Assessment (Stage 1) FINAL
November 2011
Sinclair Knight Merz ABN 37 001 024 095 Level 5, 33 King William Street Adelaide SA 5000 Australia PO Box 8291 Station Arcade SA 5000 Australia Tel: +61 8 8424 3800 Fax: +61 8 8424 3810 Web: www.skmconsulting.com
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Executive Summary
This study has undertaken a broad regional assessment of potential GDEs in the Barossa PWRA. A desktop analysis of geomorphology, groundwater and ecology was used to define several GDE types, which may be considered to have common biophysical settings based on their particular combination of attributes.
This method allowed for potential GDEs to be identified and an output of this process was the development of an inventory of potential GDEs for the study area (Table 7‐2).
The potential GDEs identified were assigned an overall priority rating based on a combination of their ecological value, groundwater dependence and the threat posed by groundwater extraction. The process enabled potential GDEs to be prioritised as low, moderate or of high significance.
For the Barossa PWRA, the following potential GDEs were identified as being high priority:
The headwaters of the North Para River in Flaxman Valley
The Barossa Valley Floor
For the ongoing management and assessment activities of GDEs in relation to the water allocation process, the following activities are recommended:
An ecological site assessment of potential GDEs to review the GDE typology and prioritisation described in this report, and to inform the derivation of EWRs.
A catchment‐wide assessment of surface water – groundwater interactions to more accurately determine the location, nature and magnitude of groundwater discharge to streamflow. The current mapping products and assessments do not accurately characterise these interactions.
Scoping the potential to develop a groundwater model for use in scenario testing.
Expansion of monitoring network near high priority GDEs to monitor the groundwater regime, the surface water regime and the ecological condition.
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Contents
1. Introduction 2 1.1. Background 2 1.2. Scope 2
2. Overview of GDEs 5
3. Methodology 7 3.1. Overview 7 3.2. Characterisation and identification of GDEs 8 3.3. GDE Prioritisation 9
4. Study Area 10 4.1. Location 10 4.2. Rainfall and surface drainage 10 4.3. Landscape and soils 11 4.4. Ecological Assets 11 4.5. Hydrogeology 19 4.6. Groundwater use 21
5. Existing information on GDEs 25
6. Existing Information on Surface Water Dependent Ecosystems 27 6.1. Identified surface water dependent ecosystems 27 6.2. Primary Research 27 6.2.1. Environmental Water Requirements 27 6.2.2. Surface Water Budget and Farm Dams 31 6.2.3. Watercourse Priority Setting Project 31 6.2.4. Current Research 34 6.3. Information Gaps 34
7. Characterisation and identification of GDEs 35 7.1. Methodology 35 7.2. Classification of GDEs 38 7.3. Ecosystems dependent on the surface expression of groundwater (Type 2) 40 7.3.1. Fractured rock discharge and baseflow (FRD) 40 7.3.2. Groundwater discharge in valleys (GDV) 41 7.4. Ecosystems dependent on subsurface presence of groundwater (Type 3) 41
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7.4.1. Break of slope GDEs (BoS) 41 7.4.2. Terrestrial vegetation on plains (TVP) 42
8. Prioritisation of GDEs 44 8.1. Introduction 44 8.2. Ecological value 44 8.3. Groundwater dependency 45 8.3.1. Ecological components indicative of wet environments 45 8.3.2. Significance of groundwater as a water input 47 8.4. Threats 49 8.5. Other threats relating to potential GDEs 53 8.6. Prioritisation 53
9. Groundwater dependency of downstream hydraulically-connected areas 55 9.1. Introduction 55 9.2. Previous Research 55 9.3. Hydrogeology 55 9.4. Ecology 56 9.5. Groundwater Extraction 56 9.6. Information Gaps & Recommendations 57
10. Recommendations to set EWRs and EWPs 58
11. Conclusions and recommendations 63
12. References 64
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Document history and status
Revision Date issued Reviewed by Approved by Date approved Revision type Draftv4 9/9/2011 S Richardson D Currie 9/9/2011 Draft for client Review D. Currie Final v5 24/11/2011 AMLR NRMB D. Currie 24/11/2011 Final for client issue WAPAC
Distribution of copies Revision Copy no Quantity Issued to V4 electronic Grant Lomman, Adelaide and Mount Lofty Ranges NRM Board V5 electronic Grant Lomman, Adelaide and Mount Lofty Ranges NRM Board
Printed: 25 November 2011 Last saved: 24 November 2011 07:23 PM I:\VESA\Projects\VE23576\Deliverables\Reports\Barossa GDE Assessment Stage 1 File name: FINAL v5.docx Author: Helen Braithwaite, Marion Santich Project manager: Dougal Currie Name of organisation: Adelaide and Mount Lofty Ranges NRM Board
Name of project: Groundwater dependent ecosystems of the Barossa PWRA (Stage 1)
Name of document: Groundwater dependent ecosystems of the Barossa PWRA (Stage 1) Document version: Final Project number: VE23576
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1. Introduction
1.1. Background
The Barossa Prescribed Water Resources Area (PWRA) is centred approximately 60 km northeast of Adelaide and includes the prescription of wells, watercourses and surface water within the PWRA (Figure 1.1). The groundwater resources (extraction from wells) of the Barossa Valley floor were first prescribed in July 1989, followed by the watercourses of the North Para River and its tributaries in May 1992. The prescription of surface water within these catchments occurred in December 1998 and the PWRA boundary was extended to include the Greenock catchment area in May 2005.
The current Barossa Prescribed Water Resources Area Water Allocation Plan was adopted by the Minister for Environment on 18 June 2009 and replaces the Barossa Water Allocation Plan dated December 2000. Water allocation planning is required under current legislation to take into account the water requirements of the environment and to make environmental water provisions for dependent ecosystems. The WAP acknowledges that there are significant knowledge gaps regarding groundwater dependent ecosystems (GDEs) in the PWRA by comparison to surface water dependent ecosystems. There is uncertainty surrounding the identification, the level and nature of their dependency to groundwater, their ecological value and the threat posed by groundwater extraction. This information is required to support the future determination of environmental water requirements and provisions to be implemented in the next WAP.
Given the current knowledge gaps, SKM was engaged by the Adelaide and Mount Lofty Ranges Natural Resources Management Board (the Board) to provide an initial regional assessment of GDEs across the Barossa PWRA. This assessment will underpin the future determination of environmental water requirements (EWRs) for GDEs.
1.2. Scope
The primary purpose of the Stage 1 assessment is to develop a knowledge base of potential GDEs in the Barossa PWRA and outline any further works necessary to adequately account for water needs of GDEs within the WAP framework. The study represents a first step in the water allocation process: characterising GDEs and determining their whereabouts. More targeted studies can follow that evaluate the water requirements of these systems. The scope of work includes: Collate previous information to summarise where GDEs have been identified and what is known about their current water requirements; Undertake desktop analysis to identify and describe all potential GDEs; SINCLAIR KNIGHT MERZ
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Conduct a risk‐based prioritisation of GDEs based on their ecological values, level of groundwater dependency and level of threat from groundwater extraction; Review the level of existing information and scope further works for downstream GDEs in areas hydraulically connected to the Barossa PWRA; Develop a management response framework for the WAP that is commensurate with the level of risk to GDEs; and In addition to the assessment of GDEs, the study will review the knowledge base for surface water dependent ecosystems to identify knowledge gaps and outline suggested further works related to their water requirements. Given the hydraulic connection between groundwater and many of the surface water dependent ecosystems, this review will be conducted prior to the GDE assessment.
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TANUNDA !
GAWLER !
ADELAIDE !
HAHNDORF !
MCLAREN VALE !
VICTOR HARBOR !
! Localities McLaren Vale PWA Western Mount Lofty PWRA Major Highways Central Adelaide Plains PWA Barossa PWRA Adelaide & Mount Lofty NRM Region Northern Adelaide Plains PWA
0 9 18 A4 : 1:793,561 Kilometers ± Figure 1.1 - Location map GDA 1994 MDA Z54
August, 2011 Groundwater-dependent ecosystems of the Barossa PWRA - Stage 1 I:\VESA\Projects\VE23576\Technical\GIS\
2. Overview of GDEs
GDEs are ecosystems that rely on groundwater for all or part of their water requirements. They differ in the nature and degree to which they are reliant on groundwater and both of these aspects are important factors in their identification and conceptualisation, especially in light of changing hydrogeological and climatic conditions. The nature and degree of groundwater dependency is likely to govern the susceptibility of GDEs to changes in hydrogeological conditions over time.
There are a number of ways in which GDEs can be classified, and the approach taken for the Adelaide Plains and McLaren Vale GDE Stage 1 study (SKM 2010) viewed GDEs simply as an ecosystem expression (e.g. wetlands, baseflow or terrestrial vegetation).
Since this study, the GDE Toolbox (in prep. SKM 2011) has been revised and a new typology of GDEs has been developed based on scientific literature. Eamus et al (2009) classified different types of GDE on a functional basis and provides a more holistic view of the ecohydrological system and the ability to conceptualise the role of groundwater in maintaining biodiversity and ecological condition. On the basis of the typology developed by Eamus et al (2009), the GDE Toolbox recommends that the following three classes of GDEs be adopted:
Aquifer and cave ecosystems (Type 1) where groundwater‐inhabiting ecosystems (e.g. stygofauna) reside. These ecosystems typically include karst aquifer systems, fractured rock and sedimentary environments. Ecosystems dependent on the surface expression of groundwater (Type 2) include wetlands, lakes, seeps, springs, and river baseflow. In these cases, the groundwater extends above the earth surface, as a visible expression. In these situations groundwater provides water to support aquatic biodiversity by providing access to habitat (especially when surface run‐off is low) and regulation of water chemistry and temperature. Ecosystems dependent on subsurface presence of groundwater (Type 3) (via the capillary fringe) include terrestrial vegetation which depends on groundwater on a seasonal, episodic or permanent basis in order to prevent water stress and generally avoid adverse impacts to their condition. In these cases and unlike the situation with Type 2 systems, groundwater is not visible from the earth surface. These types of ecosystems can exist wherever the watertable is within the root zone of the plants, either permanently or episodically.
Of the three GDE types, there is little available information regarding aquifer and cave ecosystems hosting stygofauna in the sedimentary and fractured rock aquifers of the study area. Apart from
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some broad surveys, knowledge regarding styofauna in South Australia is limited. Leijs and Mitchell (2009) report stygofauna being found in unconfined alluvial aquifers along the Bremer and Marne Rivers and in a fractured rock aquifer at the Saunders Gorge Sanctuary in the Mount Lofty Ranges. These findings suggest stygofauna would also be present in the Barossa PWRA. There is evidence from other studies in Australia (e.g. Hancock and Boulton, 2008) that non‐saline groundwater environments (EC < 1,500 µS/cm), with shallow water tables that are supplied with organic carbon (e.g. from tree roots) are the more favourable habitats for stygofauna.
The paucity of information regarding stygofauna in the study area does not allow for a detailed evaluation of their likely whereabouts and composition as part of this desktop assessment, other than to suggest that the alluvial aquifers near permanent streams will be the most likely habitat for stygofaunal occurrence. Further information on Type 1 GDEs can be found in Tomlinson and Boulton (2008). The study will focus on Type 2 and Type 3 GDEs.
GDEs can be dependent on several attributes of groundwater including: level or depth, flux or flow, quality, pressure and temperature. For ecosystems that are dependent on both surface water (flows or occasional inundation) and groundwater, such as baseflow dependent ecosystems and some riparian vegetation, the flux or flow (i.e. the temporal aspect) is typically the most important attribute. That is, they are reliant on groundwater and surface water inputs/inundation at certain times. For many plants and aquatic animals these periods are often associated with certain reproductive processes or phases, e.g. germination in plants or germination of tadpoles in amphibians. However, the majority of ecosystems that are dependent on groundwater alone (e.g. terrestrial vegetation) are primarily more likely to rely on depth to groundwater (exceptions include stygofaunal communities which live within groundwater itself). For marine and estuarine GDEs, it is likely that salinity, temperature and nutrients are the most important attributes of groundwater dependency. However, there are no marine or estuarine GDEs in the Barossa PWRA.
In addition to groundwater, GDEs will often rely on other water resources (surface water and/or soil moisture) to support their ecological functioning. It is important to recognise these connections in characterising the nature of GDEs. Groundwater and surface water are often managed as separate water resources; however it important to recognise their hydraulic connection in relation to GDEs.
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3. Methodology
3.1. Overview
Figure 3.1 presents an overview of the methodology applied in this project to conduct a regional assessment of GDEs. Three broad classes of GDEs were identified at the outset of the study, the two considered for the Barossa PWRA are:
Ecosystems dependent on the surface expression of groundwater (Type 2) Ecosystems dependent on subsurface presence of groundwater (Type 3) Surface water dependent ecosystems and the groundwater dependency of downstream hydraulically connected areas were also reviewed and existing information was collated to develop a comprehensive overview of these environmental assets. Identification of gaps in the knowledge base for these areas allowed for the recommendation of further works.
Collate existing information
Surface water Collate existing dependent ecosystems information
Groundwater dependent ecosystems Collate existing information
Groundwater dependency of downstream Characterisation & hydraulically identification connected areas
Ecosystems dependent on surface expression (Type 2) and subsurface presence (Type 3) of groundwater
Geomorphology, Ecology, Groundwater
Risk assessment Threats x values x dependency
Prioritisation
Management response Stage 2 framework for WAP. Determination of EWR and Commensurate with level provisions to inform WAP of risk. development
Figure 3.1 - Project methodology
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For ecosystems dependent on the surface expression of groundwater (Type 2) and ecosystems dependent on subsurface presence of groundwater (Type 3), a review of previous information preceded a desktop analysis of biophysical factors (geomorphology, ecology and groundwater) that was used to characterise potential GDE types and identify their occurrence across the landscape. A risk assessment was applied to the potential GDEs identified, which was used to develop a priority ranking and formulate a management response framework.
3.2. Characterisation and identification of GDEs
Potential GDEs can be characterised and identified by an analysis of biophysical factors that control their nature and dependencies. These interrelated factors are broadly grouped as geomorphology, groundwater and ecology.
Geomorphology describes landforms and soils. Landforms control surface drainage and are linked to recharge and discharge processes for groundwater. Soil properties such as water holding capacity, permeability and texture are important in defining the potential rooting depth of plants and the extent to which plants might be reliant on groundwater as opposed to soil water. Relevant factors related to groundwater include the depth of the water table, recharge and discharge processes, flow rates and water quality. Ecological information can also be used to infer the likelihood of groundwater dependence. For instance, the presence of certain vegetation assemblages with higher water requirements than surrounding vegetation may indicate access to a groundwater source.
To characterise and identify potential GDEs across the study area these three factors were examined in relation to the region’s ecological assets. Soil and landscape mapping products from DWLBC were used to describe geomorphic features on a broad, sub‐regional scale. The hydrogeology of the region was split into four main zones based on the assumption that the watertable occurred with the outcropping geological unit. The ecology of the region was mapped by targeting ecosystems that can be groundwater dependent (wetlands, permanent river reaches or those mapped as gaining, and Terrestrial vegetation assemblages that were previously identified as being potentially groundwater dependent – e.g. E. camaldulensis).
The spatial analysis of geomorphology, groundwater and ecology was used to define several GDE types, which may be considered to have common biophysical settings based on their particular combination of attributes. This method allowed for potential GDEs to be identified in addition to those that are already listed. An output of this process was the development of a GDE inventory for the study area.
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3.3. GDE Prioritisation
In the context of developing a WAP for groundwater extraction, the significance of a potential GDE asset (or prioritisation for management) can be defined as a combination of its ecological value, the nature and level of its groundwater dependence, and the threat imposed by groundwater extraction. The approach is essentially a risk assessment and is summarised by the following relationship:
GDE priority = value x dependence x threat
To undertake a preliminary assessment for the Barossa PWRA, all potential GDEs identified had scores of ‘high’, ‘moderate’ or ‘low’ assigned to each of these parameters. The ecological value score was assigned based on the condition of the asset, the biodiversity supported (species diversity and abundance), its conservation status and the presence of threatened species. A score for groundwater dependence was assigned based on the likely reliance of the asset on groundwater as opposed to other water sources (surface water or soil water). A score for threat was assigned based on the possibility of extraction pressures due to pumping from the watertable aquifer. Threats associated with pumping from deeper, confined aquifers (e.g. the Tertiary aquifers across the Barossa PWRA) were assumed to have minimal impact on the watertable and were not included in the analysis.
These ratings were combined in a subjective manner rather than quantitatively using the relationship stated above and the GDE priority was assessed as follows:
Potential GDEs that attain moderate to high scores for all classes have a high risk level and may be regarded as priority sites for further investigation. Potential GDEs that attain a low score in one category are classed as moderate risk. Potential GDEs that attain a low score in more than one category are classed as low risk. Uncertainty is built into the risk assessment. Potential GDEs lacking in data to support the allocation of a score for a particular category are assumed to rate as at least moderate in that category when the scores are combined to establish the overall risk.
This approach is described in more detail in Section 8 and Table 8‐2 provides a summary of the scores assigned to each of the potential GDE’s identified in the study and the overall significance or priority value.
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4. Study Area
4.1. Location
The Study Area is located approximately 60 km northeast of Adelaide and encompasses both the highland areas of the Barossa Ranges (part of the northern Mount Lofty Ranges) and the Barossa Valley and downstream hydraulically connected areas (Figure 4.1). The PWRA comprises approximately 529 km2 and contains the North Para River and its tributaries and for the purposes of this project, the study area also includes the North Para River between the confluence with the Lyndoch Creek and the town of Gawler, which is directly downstream of the Barossa PWRA and is the only section of the Gawler River watercourse that is not currently prescribed.
The Mount Lofty Ranges forms the eastern boundary of the study area, which extends to just beyond the township of Moculta. The catchment divide between the Tanunda and Jacobs Creek catchments and the South Para River catchment forms the southern boundary with Williamstown located in the southwestern corner of the Barossa PWRA. The northern extent of the Greenock Creek and North Para catchments forms the northern boundary of the study area and the catchment divide is located approximately 5 km north of the Greenock township. Gawler is located at the most easterly extent of the study area.
4.2. Rainfall and surface drainage
Average annual rainfall decreases steadily from south to north across the study area, with rainfall varying from approximately 700 mm/yr in the south near Williamstown to just below 500 mm/yr in the north at Greenock. These statistics are based on rainfall data from the period 1961‐1990 and this data has been used to produce the isohyets in Figure 4.2. However, more recent average localised rainfall of 750 mm has been recorded in the Flaxman Valley.
Topographically, elevations range from 650 m AHD in the Barossa Ranges to approximately 50 m AHD near Gawler. In the Barossa PWRA, topography is dominated by the steep ridgeline than runs from Lyndoch to Angaston, separating the flat valley floor from the Barossa Ranges and the Flaxman Valley. The Barossa Ranges are the ‘source’ of the water resources in terms of rainfall, streamflow and groundwater recharge. The main watercourse in the study area is the North Para River, which rises from the Barossa Ranges near Eden Valley and flows southwest through the Barossa Valley, passing through the towns of Nuriootpa, Tanunda, before merging with the South Para River in Gawler forming the Gawler River.
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The Greenock Creek also flows in a south‐westerly direction and joins the North Para River from the north at Rosedale. Other significant tributaries flowing into the North Para River from the south include Jacobs Creek and Tanunda Creek, which originate in the Barossa Ranges to the west of the study area. There are no major surface water storages in the PWRA but there has been extensive dam development for crop irrigation over the years.
4.3. Landscape and soils
The landscape and soils of the study area are shown in Figure 4.3.
The Barossa and Greenock Creek valleys comprise plains, flats and gentle slopes with alluvial soils, as well as soils formed on outwash sediments from the fractured rocks in the Barossa Ranges. There is little topographic relief in the valleys and soils are deeper than on the higher land, having formed on unconsolidated sediments. This is the result of wash‐off from the higher ground and deposition of sediment from fluvial processes.
The Barossa Ranges are part of the Mount Lofty Ranges and primarily run along the eastern side of the Barossa Valley. The highest point of the range is Mount Kaiserstuhl at 600 mAHD which can be found in the Kaiserstuhl Conservation Park. The soils in the Barossa Ranges overlie the fractured rock and are shallow in nature when compared to the valley floors. There is also an area of higher ground between the Barossa Valley and the Greenock Creek valleys running from a north east to south westerly direction to the north of Nuriootpa and Tanunda.
4.4. Ecological Assets
Despite intensive development of irrigated areas for the production of vine and fruit crops, there are areas of the Barossa PWRA that retain considerable ecological value and support a diverse assemblage of flora and fauna. A number of these flora and fauna species are listed as threatened at a national level (Environment Protection and Biodiversity Conservation Act 1999) (e.g. 7 flora, 1 mammal, 1 bird) or at a State Level (National Parks and Wildlife Act 1972) (e.g. 104 flora, 1 mammal, 10 birds, 1 reptile).
The primary ecological assets of the study area are shown in Figure 4.4. Approximately 50% of the threatened flora and fauna that occur in the area occur in Conservation Parks (including Kaiserstuhl and Sandy Creek Conservation Parks), Native Forest Reserves or Heritage Areas (e.g. Altona). Important habitats and ecosystems within and outside these areas include areas of remnant vegetation, wetlands, permanently flowing streams and dry season pools. Some of these assets may potentially depend on groundwater.
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Permanent pool or dry season pool data has been collected by the former DWLBC (now DFW) and the data is shown in Figure 4.4. A watercourse classification has also been undertaken by Earth Tech (Earth Tech 2003) and this identified areas of baseflow input termed the ‘Chain of Ponds’ formation. There is a deficiency of data and the permanent pool and stream classification coverages available from DFW are in conflict and hence permanent pools and gaining reaches cannot be identified with confidence.
It was felt that the permanent pool coverage did not correspond with areas of baseflow input identified. However, areas with the ‘Chain of Ponds’ formation (Earth Tech 2003) were used to identify areas of baseflow input, particularly in the headwaters of many of the watercourses in the study area. The ‘Chain of Ponds’ data coverage is shown in Figure 7.2. The limitations of these datasets are discussed further in Section 5 and Section 7.
Sandy Creek Conservation Park comprises 104 hectares and contains over 180 plant species. Dominant species include Silver Banksia (Banksia marginata), Native Pine (Callitris preissii) and Pink Gum (Eucalyptus fasciculosa) which are present in low woodlands to open forests with variable understorey. Other canopy species include South Australian Blue Gum (E. leucoxylon) and Peppermint Box (E. odorata). Nationally threatened flora species that occur in this CP include the Pale Leek‐orchid (Prasophyllum pallidum) and the Finniss Helmet‐orchid ((Corybas spp. finniss (R.Bates 28794) previously Toothy Helmet Orchid, Corybas dentatus)).
Kaiserstuhl Conservation Park comprises 329 hectares and vegetation association of primarily open forest Brown Stringybark (E. baxteri) with an understorey dominated by grass trees (Xanthorrhoea semiplana) and occasional Casuarina stricta, Acacia spp., Astroloma conostephioides. Nationally threatened flora species that occur in this CP include the Pale Leek‐ orchid and the White Beauty Spider‐orchid (Caladenia argocalla).
North Para River and Valley traverses through the centre of the study area. The North Para River has a continuous overstorey of River Red Gum (E. camaldulensis) on the river banks and floodplain. Aquatic plants occur in the river and in adjacent billabongs. Flood tolerant shrubs, including tea‐tree (Melaleuca spp. and Leptospermum spp.) and wattle (Acacia spp.) occur in the understorey. The Valley area vegetation comprises an open woodland (E. camaldulensis and E. leucoxylon) with native grass understorey.
As mentioned, over 100 threatened flora species have been recorded in the study area, primarily in conservation parks where ecological surveys have been undertaken as well as Heritage Areas, Forestry Reserves and some private properties. The distributions of threatened flora, including
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those with EPBC listings are shown on Figure 4.4. Flora species with an EPBC listing that have been recorded in the study area include: White Beauty Spider‐orchid, Osborn's Eyebright (Euphrasia collina ssp. osbornii), Finniss Helmet‐orchid, Pale Leek‐orchid, Large‐fruit Groundsel (Senecio macrocarpus), Silver Daisy‐bush (Olearia pannosa ssp. pannosa), Spidery Wattle (Acacia araneosa).
Ecological values which are anticipated to have a groundwater dependent component generally include the following broad community types:
Riparian fringes of streams (e.g. along the North Para River and Greenock Creek);
Woodlands, particularly within Conservation Parks (CP), Native Forest Reserves (NFR) and Heritage Areas (e.g. Altona CSR Landcare Reserve), generally restricted to Kaiserstuhl (CP and NFR) and Sandy Creek CP and their adjacent areas;
Scrublands, generally restricted to the Kaiserstuhl and Sandy Creek CPs and their adjacent areas and Heritage Areas (e.g. Redeemer Lutheran School Scrub); and
Wetlands; Poorly represented wetland associations include Silky tea‐tree (Leptospermum lanigerum) heath. Another poorly preserved wetland that occurs in the area is Prickly tea‐tree (L. continentale) closed heath over Water Fern (Blechnum minus). One known remnant of this association occurs on Forestry SA land, on the boundary of Kaiserstuhl Conservation Park and the Black Swamp at Mount Crawford.
These types of habitats support high levels of biodiversity, and have the potential to include species of conservation value as listed under State or Commonwealth legislation. This includes the following fauna groups:
Aquatic Reptiles (turtles) and species associated with wet environments, including lizards and snakes (e.g. Red‐bellied Black Snake, Pseudechis porphyriacus, Brown Snake, Pseudonaja textilis). Cunningham’s skink (Egernia cunninghamii), rated as ‘Endangered’ (NPWSA 1972), has been recorded within the study area, this species generally occurs in rocky outcrops.
Mammals, including bats, which may utilise wetland environments for feeding, together with woodlands supporting mature trees for refuge, foraging and roost opportunities. The southern brown bandicoot, Isodon obesulus, rated as ‘Endangered’ (EPBC Act 1999; NPWSA 1972) is also known to occur in this area. This species often refuges and forages in vegetation that is within or immediately adjacent to the riparian zone, in particular clumps of blackberry and native shrubs and dense ground covers.
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Birds (including water dependent and migratory species). Many Adelaide Hills and Plains birds utilize habitats in the Barossa area when migrating through the area. For example over 130 species are known to utilise Sandy Creek Conservation Park. Birds that are threatened (NPWSA 1972) in the region include: Common Sandpiper (Actis hypoleucos), Yellow‐tailed Black‐cockatoo (Calyptoryhynchus funerus), White‐winged chough (Corcorax melanorhamphos), Square‐tailed kite (Lophoictinia isura), Hooded robin (Melanodryas cucullata), Restless Flycatcher (Myiagra inquieta), Scarlet Robin (Petroica boodang), Diamond Firetail (Stagonopleura guttata), Australian Bustard (Ardeotis australis) and the Spotted Quail‐thrush (Cinclosoma punctatum) (this species also has an EPBC Rating).
Fish, a variety of native and exotic fish occur in‐stream environments (e.g. North Para River, various creeks), however data for density and distribution is limited. Native fish species may include Mountain Galaxias, Climbing Galaxias, Southern Pygmy Perch and a variety of others (NABCWMB undated). A survey of Greenock Creek found limited aquatic biodiversity suggesting there was poor structural integrity of pool habitats and inability for fish to migrate during high flows due to in‐stream dams (Social and Ecological Assessment 2002).
Macro‐invertebrate data is limited for the study area, however over 230 different types were identified in a survey last decade (Hicks and Sheldon 1999). The Jacobs Creek Rejuvenation Project reports mayflies and dragonflies have increased in the area as the riparian habitat has been restored.
Amphibians are likely to occur in riparian and in‐stream habitats. The Eastern Banjo Frog has been recorded in Sandy Creek Conservation Park and various riparian habitats (e.g. North Para River, Jacobs Creek (Rejuvenation Project).
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GREENOCK ! MOCULTA NURIOOTPA ! ! PENRICE ! k ee r a C r ck a ANGASTON no P ! e th re r G o N TANUNDA ! N o
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r KINGSFORD a a ! Major Highways r a ROWLAND FLAT P ! Watercourses th r o N Barossa PWRA
LYNDOCH GAWLER ! ! Date Source: Watercourses - DFW Roads - DTEI ±
0 5 10 Kilometers
Figure 4.1 - Study Area GDA 1994 MDA Z54
August, 2011 Groundwater-dependent ecosystems of the Barossa PWRA - Stage 1 I:\VESA\Projects\VE23576\Technical\GIS\ ! Localities Rainfall Isohyets (mm/yr) Watercourses Barossa WAP Elevation (mAHD) High : 622
GREENOCK ! Low : 48 MOCULTA NURIOOTPA ! !
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7
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0 ±
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Figure 4.2 - Rainfall and Drainage GDA 1994 MDA Z54
August, 2011 Groundwater-dependent ecosystems of the Barossa PWRA - Stage 1 I:\VESA\Projects\VE23576\Technical\GIS\ Legend ! Localities Watercourses Barossa WAP Flats, terraces and watercourses with modern alluvial soil Plains and gentle slopes with soils formed on outwash sediments GREENOCK derived from basement rock highs ! MOCULTA Plains and rises with mainly shallow NURIOOTPA ! ! non-calcareous soil on calcrete PENRICE ! Rises and plains with soils formed k ee on unconsolidated sediments r a C r ck a ANGASTON Rises, plains and low hills with no P ! e th re r soils formed on volcanic ash G o N Soils formed on basement rock TANUNDA ! N o Urban r
t BETHANY h ! P
a
r KINGSFORD a a ! r a ROWLAND FLAT P ! th r o N
Date Source: LYNDOCH Land Type - DWLBC GAWLER ! ! Watercourses - DFW ±
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Figure 4.3 - Geomorphology GDA 1994 MDA Z54
August, 2011 Groundwater-dependent ecosystems of the Barossa PWRA - Stage 1 I:\VESA\Projects\VE23576\Technical\GIS\ ! Localities ! Threatened Flora ! Threatened Fauna Stream classification ! Dry season baseflow
! No baseflow ( ! ! ! (! ! (!! ! Not observable ! ! !! Unsurveyed ! ! ! ! ! !!! ( ! GREENOCK ! !!! ! ! ! !! ! ! ! ! ! ! ! Dry season pool < 15m !! ! ! ! !! MOCULTA ! NURI!OOTPA ! ! !! !! ! !! Barossa WAP ! ! ! !! !! ! ! ! ! ! PEN!R!!ICE Subcatchments ! ! ! ! !! !! k ! ! ! !! ! ee ! r a!! ! ! C r ! NPWS SA Reserves ! ck a ! o ! P ! ! ANGASTON! n ! !! !! (! ! ! Remnant Vegetation ! ee ! th ! r ! r ! ! ! G ! ! o ! ( ! ! N Grassland ! ! ! ! ! TANUNDA ! ! ! ! N Grassland with Emergents ! o ! ! ! ! ! ! ! ! ! r t !! ! ! h !! BETHANY ! Grassy Woodland ! ! !!! !!!! !! ! ! ! ! P ! ! !!!!! ! ! a ! r ! Heathy Forest KINGSFORD !! ! ! a a ! ! ! ! !! r ! ! ! ! a ! !!! !! ! RO!WLAND FLAT ! ! ! ! !!! ! Heathy Woodland ! ! !!!!! ! ! !! !!!! P !!! !( ! !!!!! ! h !! !! ! ! ! t ! !! ! !! ! ! !!!! ! ! Riparian r ! ! ! ! o ! !!!! ! ! ! ! ! ! !! !! ! ! ! N !! ! ! !!!! ( ! ! ! !! ! ! !!! ! ! !! ! !(! ! ! !! ! ! ! ! ! ! (! ! !! !!!!!!!!!!! ! ! ! !!! ! ! !! !!( ! !!!!! !!!! ! !! ! ! ! ! ! ! ! ! !! ! ! (! ! !! ! ! ! LYNDO! CH !! ! ! ! ! ! ! ! GAWLER ! ! ! ! ! ! ! ! ! ! ! ! !! ! !(!! ! Date Source: ! !!!! !! !!!!! ! Flora & Fauna - Biological Database of SA !!!!!! ! ! ! !!!!!!!!!! !! !(!(! Dry Season Pools, Stream Classification - DWLBC !(!! ! ! !! ! Remnant Vegetation - AMLR NRMB ! !! !
! ! ! ! !! ± ! !!!!!
0 5 10 Kilometers
Figure 4.4 - Ecological Assets GDA 1994 MDA Z54
August, 2011 Groundwater-dependent ecosystems of the Barossa PWRA - Stage 1 I:\VESA\Projects\VE23576\Technical\GIS\
4.5. Hydrogeology
The groundwater resources of the Barossa PWRA occur within three major aquifers: the Upper and Lower sedimentary aquifers underlying the valley floor and the Fractured Rock Aquifer (FRA) which outcrops in the ranges to the east and west and also extends beneath the sedimentary aquifers (Figure 4.5). These aquifers are hydraulically connected and any one can be a source or recharge or a point of discharge to one or both of the other aquifers depending on the location within the valley. The hydrogeology is summarised in Table 4‐1.
Table 4-1 - Hydrogeology of the Barossa PWRA AGE STRATIGRAPHY HYDROGEOLOGY
Unit Lithology Unit Description Sands, gravels and silts Undifferentiated of modern drainage
Holocene Quaternary channels Upper Unconfined Pooraka Red‐brown sandy clays, Aquifer / confined aquifer Pleistocene Formation gravels, sands and silts Quaternary Miocence Rowland Flat (early‐late) Sand
Carbonaceous clays, Aquitard Confining layer
Miocence (early) Rowland Flat brown Sand Lower Cabonaceous clays, Confined aquifer Oligocene (early) gravel, sands and silts Aquifer Tertiary Kanmantoo Metamorphosed /Normanville greywacke, schist Fractured Cambrian Groups and marble Unconfined Rock Pre‐Cambrian / confined aquifer Aquifer (Proterozoic) Siltstones, shales, sandst Adelaide System quartzites (Source: REM 2006)
The FRA outcropping in the Barossa Ranges along the eastern boundary of the PWRA comprises Pre‐Cambrian and Palaeozoic sandstones and silts where groundwater is stored and flows through fractures and fissures. The FRA is recharged by rainfall and water generally flows in a westerly direction following topographical contours, towards the deeper sedimentary aquifers on the valley floor. The WAP (AMLRNRMB 2009) reports that it has been estimated that this lateral flow
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may be up to 1,680 ML/year. Beneath the valley sediments, the upper part of the FRA is generally a highly weathered clayey layer which acts as a confining layer between the FRA and the overlying sedimentary aquifers. The amount of water available for extractions in the FRA is very low, which has the potential therefore to result in significant changes in water level.
The Upper Aquifer predominantly exists in the main Barossa Valley, as well as in a broad valley to the south of Lyndoch. The aquifer consists of sediments overlying the carboniferous clay confining layer and includes Tertiary non‐carboniferous sands, lenticular sands and gravels within Quaternary clays and also Holocene sands and gravels associated with the drainage channels. On the eastern side of the valley, clay covers most of the aquifer, making it confined. The groundwater flow is generally in a westerly direction from the Barossa Ranges, rotating to a more south‐westerly direction beneath the Barossa Valley floor.
The Lower Aquifer is confined and consists of Tertiary carbonaceous clays, gravels, sands and silts that were deposited in the deepest part of the basin and form a complex system of interconnected sub‐aquifers. As described above, the Upper and Lower Aquifers are separated by a clay confining layer. Water levels in the Lower Aquifer are subject to large seasonal fluctuations in response to extraction for irrigation. Groundwater flow is generally in the same direction as the Upper Aquifer and it is likely that there is hydraulic connection between the FRA and the Lower Aquifer with recharge to occurring via lateral flow to the Lower Aquifer.
This study is focused on GDEs for which the water table aquifer is the most important source of water and this can occur where each of the major hydrogeological units outcrops (listed below).
For the purposes of this study, the hydrogeology of the region can be split into three main zones (based on the surface geology) as shown in Figure 4.5.
Fractured Rock aquifers associated with the Hills Face Zone i.e. Mount Lofty Ranges (Barossa Ranges);
Outcropping Tertiary aquifers in the upper Greenock Creek, Tanunda Creek catchments and in the broader Barossa Valley; and
Thick Quaternary sediments associated with plains in the Barossa and Greenock valleys.
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4.6. Groundwater use
Groundwater is extracted from the Tertiary sediments (Upper and Lower aquifers) within the Barossa PWRA, as well as from the Fractured Rock aquifer that underlies and surrounds the Barossa Valley. According to DFW (2010), metered extractions totalled 2,103 ML for 2009‐10, well below the current allocation of 7,400 ML. Water is also imported from the River Murray via the Barossa Infrastructure Limited (BIL) scheme, which provides an alternative source to the groundwater.
Locations of groundwater extraction from the Fractured Rock and the Upper and Lower aquifers are shown in Figure 4.6.
Approximately 270 ML/year was licensed for extraction from the Upper Aquifer in the 2009‐10 irrigation season. Extraction from this aquifer is located in the Barossa Valley close to the North Para River and is predominantly located between Nuriootpa and Penrice.
Licensed extractions from the Lower Aquifer dominate in the Barossa Valley and were approximately 720 ML/year in the 2009‐10 irrigation extraction. Extraction was largely from the Rowland Flats Sands geological layer.
Fractured Rock licensed extraction in the Barossa PWRA was 1100 ML/year in the 2009‐ 10 irrigation season. The majority of the extraction is located to the east and south of the Barossa Valley.
Extractions from the Fractured Rock Aquifer represent 54% of total groundwater use, followed by the Lower Aquifer (33%), with minor extractions from the Upper Aquifer (13%) which contains poorer quality groundwater.
The majority of the domestic groundwater extraction is located in the Flaxman Valley (upper North Para River) but there are also a small number of wells in the Barossa Valley
Accurately quantifying the historical water use in the Barossa is difficult because not all the water resource extractions have been metered. In addition to this, prior to the adoption of the current WAP some allocations were still area based (not volumetric) making it difficult to get an accurate record of water extraction from these licences. The conversion of area based licences to
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volumetric allocation implemented in the current WAP has enabled more accurate recording of water extraction and use in the PWRA.
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(! r KINGSFORD a a ! r a ROWLAND FLAT P ! th r o N (! Date Source: (! Monitoring Wells - Obswell LYNDOCH Watercourses - DFW GAWLER ! Geology - DWLBC ! (! Fault Lines - DWLBC (! (! (!(! (! (! (! ±
0 5 10 Kilometers
Figure 4.5 - Geology GDA 1994 MDA Z54
August, 2011 Groundwater-dependent ecosystems of the Barossa PWRA - Stage 1 I:\VESA\Projects\VE23576\Technical\GIS\ ! Localities Watercourses Barossa WAP (! (! domestic extraction Licensed GW Extraction (2009/10) Upper Aquifer (Ml/year) 0 - 10 10 - 25 25 - 50 GREENOCK ! MOCULTA 50 - 100 NURIOOTPA (! ! ! (! (! (! PENRICE (! (! Lower Aquifer (Ml/year) (! ! ek (! e ! (! 0 - 10 r a ( C r ! ck a (! ( 10 - 25 o P ANG(!ASTON n ! (! e th re r G o 25 - 50 (! N (! (!(!(! (! (! TANUNDA (! (! ! (! (!(! N (! o 50 - 100 (! r (! ! t BETHANY ( (!h ! P ! Fractured Rock (Ml/year) a ( (! (! (! r KINGSFORD a 0 - 10 a ! r a ROWLAND FLAT 10 - 25 P ! (! (! (! (!(!(!(! th ! ! r ( ( 25 - 50 o (! (! N (! 50 - 100 (! LYNDOCH GAWLER ! (! ! (!(! (! (! (! (! (! (! (! Date Source: ! ( Licensed GW Extraction - DFW (Irrigation Season 2009/10) (! Watercourses - DFW
(! (! ±
0 5 10 Kilometers
Figure 4.6 - Groundwater Extraction GDA 1994 MDA Z54
August, 2011 Groundwater-dependent ecosystems of the Barossa PWRA - Stage 1 I:\VESA\Projects\VE23576\Technical\GIS\
5. Existing information on GDEs
There is limited data regarding GDEs across the Barossa PWRA and very few studies have been undertaken regarding their identification and nature of their dependency to groundwater and their ecological value.
The Barossa WAP provides a summary of two important studies that have provided an understanding of the needs of water‐dependent ecosystems in the Barossa PWRA. These two reports provide an assessment of baseflow‐dominated systems in the PWRA and the importance of these ecologically, but focus predominantly on surface water systems. They are discussed in more detail in Section 6.
The former Department for Water, Land and Biodiversity Conservation (DWLBC), now the Department for Water (DFW) undertook an extensive aerial videographic survey of the streams of the Mount Lofty Ranges, Adelaide Plains and the Barossa over April and May 2003. Digital video imagery of streams was captured using a helicopter‐mounted gyrostabilised digital videa camera. The imagery was used to identify dry season or permanent pools. The imagery was captured in autumn which would normally be after a typically dry summer period where there is minimal runoff‐induced streamflow, and the presence of water can be used to infer locations of groundwater discharge to streams. The survey however, followed a wetter period than usual so caution should be taken when interpreting the data. The results may also be influenced by any dam releases and the presence of regulating structures (e.g. weirs) in streams.
The videographic survey highlighted that permanent pools exist throughout the Barossa PWRA, most of which are considered to be maintained through groundwater baseflow contributions from either the FRA in the hills area, or the shallow unconfined Quaternary aquifer on the valley floor. These permanent aquatic habitats are important refugia for aquatic biota and are known to support populations of aquatic plants, aquatic macroinvertebrates and fish. Of particular note is the ‘chain of ponds’ formation in the Flaxman Valley.
According to the Barossa WAP (AMLNRMB 2009), the section of the North Para River between Light Pass and Nuriootpa has been identified as a ‘losing stream’ where water from the watercourse recharges the Upper Aquifer. Current estimates suggest that approximately 1,200 ML/year of water recharges to the Upper Aquifer of the valley floor from creeks and streams. A
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‘gaining stream’ has also been identified between Nuriootpa and Tanunda on the North Para River, where groundwater discharges naturally to the watercourse and contributes to stream baseflow. It has been estimated that approximately 2,000 ML/year is discharged annually as a result of this interaction.
Much of the Gawler River, downstream of the PWRA is a losing system where surface water discharges into the groundwater system. Riparian vegetation along the Gawler River depends on the maintenance of natural discharge regime whereby 5,000 ML of surface water is lost to the Quaternary aquifer across the plains (AMLR NRMB, 2007).
The Board’s State of the Region Report (AMLRNRMB 2008) specifies the location of known wetland and baseflow GDEs in the Barossa PWRA (Table 5‐1):
Table 5-1 - Location of known GDEs
Type Location Description Type 2 GDEs: Kaiserstuhl Conservation Supports riparian vegetation communities Wetlands Park
Type 2 GDEs: North Para River passing Maintains riparian vegetation such as Eucalyptus Groundwater‐ through the Flaxman camaldulensis woodlands, Callistemon seiberi, sedges dependent Valley and reeds streams Northern end of the Water flowing through the coarse sediments and gravel Barossa Valley beds of the North Para River form the hyporheic zone which supports a suite of invertebrate species in the interstitial spaces between the sediments. Southern end of the As above Barossa Valley The riparian habitats listed in Table 5‐1 support plants that are likely to access water within the shallow unconfined Quaternary aquifer, such as River Redgum (Eucalyptus camaldulensis).
The Kaiserstuhl Conservation Park was dedicated in 1978 to protect one of the last remnants of native vegetation in the region. It also protects important seasonal creek and wetland habitats, and whilst no wetlands were identified within this study, this could be due to extended dry periods prior to more recent higher rainfall. The Sandy Creek Conservation Park also exists in the Barossa PWRA and is one of the few remaining tracts of undisturbed and undeveloped native bushland in the Barossa Valley. The Sandy Creek itself flows just to the south of the park boundary.
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6. Existing Information on Surface Water Dependent Ecosystems
6.1. Identified surface water dependent ecosystems
There have been various studies on surface water resources across the Barossa PWRA and this research has highlighted the key surface water dependent ecosystems across the area. These include the instream ecology and associated habitats and the riparian habitats along the watercourses. A summary list of reports from these studies (sourced from the Board) is provided in Table 6‐1. Key studies and primary research related to surface water ecosystems is discussed below.
6.2. Primary Research
The Barossa WAP provides a summary of two important studies that have provided an understanding of the needs of water‐dependent ecosystems in the Barossa PWRA:
Determination of Environmental Water Requirements for the Gawler System (EPA 1999);
The Barossa Prescribed Water Resources Area Surface Budget (DWLBC 2002);
Watercourse rehabilitation priority setting process’ project (Earth Tech 2003). These reports focus on surface water systems predominantly and in particular, the EPA (1999) study also quantified environmental water requirements for the Gawler River and listed the ecological assets across the catchment and estimated the hypothetical flow rates required to sustain them.
6.2.1. Environmental Water Requirements
As part of the ‘Determination of Environmental Water Requirements’ study, the Gawler River was divided into geomorphological zones on the basis of gradient, stream power, valley dimensions, boundary material, and sediment transport regimes. Each zone represents a unique assemblage of river morphologies or physical habitats, and therefore hydrological regime. Ecological information (macroinvertebrate, fish and vegetation) was gathered for each zone to assess the biological diversity and condition of the river system.
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The seven zones identified are as follows:
Zone 1 – Meandering Zone – between the town of Gawler and the coast.
Zone 2 – Constrained Zone – South Para River between the town of Gawler and the South Para River Reservoir.
Zone 3 – Pool Zone – South Para River above the Warren Reservoir.
Zone 4 – Mobile Zone – North Para between the town of Gawler and the junction of Lyndoch Creek.
Zone 5 – Incised Zone – North Para River between the junction of Lyndoch Creek and the town of Nuriootpa.
Zone 6 – Transition Zone – North Para River between the town of Nuriootpa and the Light Pass area near the junction with Duck Ponds Creek.
Zone 7 – Pool Zone – North Para River through the Flaxman Valley.
Only Zones 4 to 7 are located in the study area for this project and a summary of each of the zones in relation to geomorphology, ecology, key environmental assets and EWRs is provided in Table 6‐2.
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Table 6-1 – Summary of previous studies and reports for the Barossa PWRA Year, Author, Study Context Catchment Hydrology Geomorph/ Instream Invertebrates Fish Vegetation Fauna condition Ecology (undated) NABCWMB; Native Management, list of NAB Fish of the Northern Adelaide native and exotic fish, list 3 3 and Barossa Catchment of freshwater ecosystems 1996; Christie, Pastok & Clarke; Survey, species present North Para Condition of the North Para, and condition 3 3 3 South Para and Gawler River Systems. 1999; Hicks& Sheldon; Biotic Detailed Survey of Jacobs Survey of the Gawler River for surface water habitats Creek, the Mid North Riverine North Para 3 3 3 Management Planning Project River, Tanunda 1999; EPA; Determination of Collation of baseline North Para; Environmental Water information, id of riparian South Para 3 3 3 3 3 3 Requirements for the Gawler and in‐stream habitats River System. and EWRs 2001; NABCWMB; State of the General summary of NAB Catchment NAB Catchment condition & management 3 3 3 3 3 3 3 Area 2002; DWLBC; The Barossa Effects of farm dams on Barossa 3 Valley Surface Water Budget surface water resources. 2003; Earth Tech; Watercourse Condition and priority NAB (North Rehabilitation Priority Setting setting. and South Process. Para), Pat, 3 3 3 3 Onk, Torrens 2006, PB, State of the General summary of NAB 3 3 3 3 3 3 3 Catchment for Northern Group condition & management
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Table 6-2 – Geomorphic Zones and their Environmental Water Requirements Zone Geomorphology Ecology Key Environmental Assets Environmental Water Requirements Major Habitats Issues Key Flow Bands 4 Mobile bed sediment Condition of riparian zone varies Functional Unit – distinct Protect groundwater fed Baseflow (Mobile) Large sediment storage areas through this zone. Continuous high and low flow channels. hyporheic habitat Pool connection within the channel cover of river Red Gums. Mesohabitats –substrate Maintain pool‐riffle Mid‐flow Active channel. Understorey vegetation being composition such as gravels sequences Bank‐full modified to a range of mixed and organic matter. Maintain the riparian pasture grasses. Macrophytes condition through riparian common in the stream channel flows 5 Highly degraded channel with Intact canopy of river Red Gums Functional Unit – riffle‐ Maintaining a variety of flow Pool connection (Incised) gullies and very little in‐channel but a highly modified understorey. chute areas and large pool levels to satisfy a number of Mid‐flow structure and steep banks. Small Reduced flows and increased areas. ecosystem processes. Bank‐full floodplain nutrients led to introduced plants Mesohabitats – substrate Channel substrate – fine silt clays within the river channel and composition with areas of overlying bedrock‐cobble base in riparian zone. Riparian vegetation cobble‐gravels and sand. pools. is badly degraded and needs rehabilitation. 6 High‐energy zone with bed Highly modified vegetation. Functional Unit – low flow Maintain or restore vertical Freshets (Transition) sediments. Zone characterised by Construction of levees has altered channel (pools and riffles) linkages between the channel Bank‐full a series of small floodplains. original stream bank. Some river and high flow channel (flat and the hyporheic zone and Over‐bank Sediment source zone evidenced Red Gums. Original understorey is surfaces with incised restore the lateral linkages by terrace formations. In channel virtually non‐existent. Ecological channels) between the channel and the substrate dominated by cobble processes disrupted due to highly Mesohabitats – substrate floodplain. and gravel sized sediments. altered nature of this zone. composition with areas of Levee banks to protect vineyards cobble‐gravels. from flooding. 7 Series of pool‐riffle habitats and Riparian vegetation varies through Functional Unit – Ponds or Dams and storages reduce Baseflow (Pool) some degraded habitat (due to this zone. Continuous cover of river waterhole sections. flow within the channel, and Pool connection stock access and in‐stream dams) Red Gum with some elements of Mesohabitats – substrate if on‐stream, provides a Bank‐full understorey vegetation. composition with areas of significant barrier to fish Over‐bank silts and clays. movement and fragments channel habitats.
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6.2.2. Surface Water Budget and Farm Dams
Water‐diverting infrastructure, such as farm dams has affected the quantity and pattern of flows across the study area. According to AMLRNRMB (2008), modelling has indicated that dam development has reduced stream flow by approximately 20% in the North Para River catchment.
A catchment water balance model was developed in 2002 (DWLBC 2002) to help understand the hydrological cycle in the Barossa Valley and runoff was estimated on a sub‐catchment basis. The model was constructed to simulate the effects on flow as a result of the dam development on the North Para River, the primary surface water resource of the Barossa Valley, and the level of impact this has had on environmental water requirements. The impacts on ecologically important flow events appears from the modelling outputs of the study to be primarily on the lower flows (referred to as ‘baseflow’ and ‘pool connection’ flows in the environmental water requirements study). The level of impact is not, however, equal across the catchment. The study highlighted that the placement of dams across the landscape is as important as the size and water demands of the dams themselves.
6.2.3. Watercourse Priority Setting Project
A further watercourse classification (geomorphic style classification) has also been developed by Earth Tech (2003) as part of the ‘Watercourse rehabilitation priority setting process’ project. The project was undertaken to help the Board identify priority reaches for watercourse restoration. Priorities were determined based on geomorphic reach type, vegetation condition and hydrological information.
The following geomorphic styles were used to classify the streams (Table 6.2):
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Table 6.2 - Geomorphic Style Classification Geomorphic Description Zones Intact valley fill Valley setting can be confined or broad floodplain. No channel, generally featureless valley floor, comprised mud/sand, generally swampy, may contain freshwater meadows. Cut and fill Valley setting can be confined or alluvial. Featureless swampy valley floor/floodplain (as per intact valley fill). Channel incision (gully erosion) has created some degree of spatial or temporal continuity of channel. Incised channel is laterally inactive and low sinuosity, may have or be developing benches. A low flow inset channel may be developing features such as pools (chain of ponds). Macrophytes may completely cover the bed. Chain of ponds Valley setting can be confined or alluvial. Ponds separated by valley fill that may contain a swampy depression or freshwater meadow, generally featureless floodplain. Valley floor comprised of mud/sand. Ponds take a meandering path. Floodout Valley setting alluvial. Upstream channel disperses onto floodplain, possibly through an alluvial fan deposit. Valley floor comprised of mud/sand, often swampy as per valley fill. Floodout generally occurs at decrease in gradient and/or where stream debouches from a much more confined valley. Anabranching The valley is relatively broad and low gradient. There are multiple flow paths that swamp belt generally don’t have continuous well‐defined channels. The flow paths are similar to that of chain of ponds, open water ponds being separated by poorly defined flow paths. Sediments are fine grained, input and transport rates are low. Steep headwater Generally a 1st or 2nd order stream that is steep and has very little accumulated sediment in the valley floor. Typically a ‘V’ notch bedrock valley floor. Gorge Bedrock valley without floodplain units in the valley floor. Geomorphic units in the channel may include cascades, rapids, pools, boulder bars, islands and occasional waterfalls. The bed material texture is bedrock, boulders and gravels. Confined Confined valley setting with occasional, small, narrow, discontinuous floodplain pockets. Stream may be steep or moderate gradient. Geomorphic units in the channel may include steep bedrock steps, cascades, plunge pools, pools, riffles, glides/runs, bank attached and mid‐channel bars. The bed material is likely to be bedrock, cobbles or gravels. Banks are likely to have sediment ranging from coarse to fine. Partly confined 1 The valley is relatively straight or irregular. The channel meanders within the valley floor, largely independent of valley alignment, exhibiting moderate sinuosity and abutting the valley margin for 10‐50% of its length. The floodplain is dis/semi‐
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continuous. Geomorphic units in the channel include pools, riffles, benches, point bars, rarely lateral or longitudinal bars. The bed material can be gravel or fine grained, banks can be fine or coarse sediment depending on valley setting. Partly confined 2 As per ‘Partly Confined 1’ but the floodplain is discontinuous and may be terraced. Partly confined 3 As per ‘Partly Confined 1’ but has 50‐90% of the channel abutting the valley margin and the bed material is dominated by bedrock, gravels and coarser sediment. Alluvial The valley is broad relative to the stream, valley margin impingements by the Continuous 1 channel are rare. The floodplain is likely to be flat and contain few geomorphic units such as terraces and flood channels. The channel is laterally stable being comprised of mixed clay, silt and sand. Geomorphic units include benches, pools and runs. Alluvial As per ‘Alluvial Continuous 1’ but exhibits some lateral activity and the bed often Continuous 2 has gravels and occasional bedrock impingements. Reach may have involved from ‘Cut and Fill’ Alluvial As per ‘Alluvial Continuous 1’ but the channel exhibits low rates of lateral activity. Continuous 4 Alluvial As per ‘Alluvial Continuous 1’ but the channel exhibits moderate rates of lateral Continuous 5 activity due to sinuous planform. The bed and banks are comprised of sand and are likely to be stable if vegetated. Quarry Modified watercourse Tidal Tidal Large farm dam Modified watercourse Urban Modified watercourse Reservoir Modified watercourse Farm dam Modified watercourse
The study showed that the North Para had a large proportion of streams that were naturally swampy valley fills with discontinuous/absent channels but many of these streams have become continuously channelized (some by direct excavation, others through incision) in historical times. Half of the stream network length was 1st order streams, the majority of which were of the ‘Cut and Fill’ geomorphic classification. The results also show that a portion of the low order stream network is likely to have controls that inhibit channel incision i.e. farm dams and weirs. There is also a significant amount of channel length that has been classified as ‘Chain of Ponds’ (Earth Tech 2003).
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6.2.4. Current Research
The WAPs have specific requirements for monitoring, which are the responsibility of the Natural Resource Management Boards. This monitoring determines the success or otherwise of each WAP, facilitates policy development and informs ongoing assessment of the region’s water resources. This issue is being targeted by the Department for Water (DFW) and the Adelaide and Mount Lofty Natural Resource Management Board (the Board) to value add WDE baseline data and analysis to inform WAP development, using their current initiative entitled Verification of Water Allocation Science Program (V‐WASP).
The V‐WASP is a program which aims to provide a basis for the validation of ecological, hydrological and hydrogeological hypotheses and assumptions, used to develop recommendations for environmentally sustainable diversion limits and Environmental Water Requirements (EWR) for the three WAP areas in the Board’s Region: the Barossa, the Western Mount Lofty Ranges (incorporating McLaren Vale) and the Adelaide Plains (Central and Northern Adelaide Plains).
The V‐WASP objective is to improve future iterations of WAPs across the Region, through testing the achievement of predicted environmental, hydrological and hydrogeological outcomes resulting from the implementation of WAP policies. The findings will be able to directly inform and improve future water allocation plans in other regions with similar environments or component biota.
Part of this project is to identify reach types and functional groups from a number of information sources including Watercourse Priority Setting project (Earth Tech 2003).
6.3. Information Gaps
Both the water balance study and EWR study were undertaken some time ago and require revision. It is understood that the dam coverage for the Barossa PWRA needs to be field‐verified and the surface modelling then revisited and updated. The definition of reach types and functional groups will also assist in refining the surface water model for the Barossa PWRA. There would be benefit in extending the reach types and functional groups to cover the unprescribed stretch of the North Para upstream of Gawler. This would provide continuity in the classification.
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7. Characterisation and identification of GDEs
7.1. Methodology
The following steps were taken to identify potential GDE locations in the Barossa PWRA:
Conceptualisation A conceptual model (Figure 7.1) was developed to identify the nature of potential GDE and describe the settings where they might occur. The conceptualisation was supported by incorporating an understanding of the geomorphology, hydrogeology and ecology of the study area, as follows:
Geomorphology – landscape conditions, such as geology and soils are important when considering the potential locations for GDEs in a particular area. Upper catchments tend to be steeper and hillier in nature, and shallower soils often form on the outcropping geology. More sedimentary conditions occur in lowland areas with deeper, fluvial soils. The geomorphology can influence groundwater flow and consequently the surface expression of groundwater or subsurface presence of groundwater. This can then indicate where potential GDEs may occur.
Hydrogeology – GDEs tend to occur where groundwater levels are shallow (typically within 5m of the ground surface) and/or where groundwater discharges from the surface. Diffuse and point source discharge occurs more commonly in drainage lines and local topographic depressions.
Ecology – Ecological information can be used to infer the likelihood of groundwater dependence. For instance, the presence of certain vegetation may indicate access to a groundwater source, such as terrestrial vegetation in depressions and drainage lines or in‐stream ecological habitats resulting from the presence of permanent pools.
Classification of GDE types and functional groups In parallel with the development of a conceptual model, GDEs were categorised into GDE types and functional groups1 that describe their biophysical setting, with groupings based on a particular combination of attributes (Table 7‐1). A description of the classification is provided in Sections 7.2 and 7.3.
Identification of potential GDE locations
1 The term ‘functional group’ can have several meanings in ecology but it is used here as a collective term to group GDEs that have similar biophysical settings. SINCLAIR KNIGHT MERZ
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In order to map potential GDEs, spatial layers were used to identify where the various attributes common to a GDE functional group were present. Potential GDE locations in the Barossa PWRA using this classification are presented in Table 7‐2 and Figure 7.2. The watercourse classification undertaken by Earth Tech (Earth Tech 2003) has identified areas that have a ‘Chain of Ponds’ formation. This classification has been used to identify areas of baseflow input and has been utilised in the assessment of the significance of potential GDEs in the Barossa PWRA. The aerial videographic survey undertaken by the former DWLBC (now DFW) is shown in Figure 4.4 and was found to identify numerous areas where permanent pools were identified which did not correspond with the presence of groundwater baseflow, particularly in the Barossa valley floor. The permanent pools data was therefore found to ‘over‐represent’ areas of baseflow presence.
While the Earth Tech survey (2003) provides an interim classification of baseflow features, it is not based on a direct evaluation of groundwater discharge to streams. A more detailed analysis of surface water – groundwater interactions is warranted to more accurately determine the location of baseflow features.
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Figure 7.1 Conceptualisation of Barossa GDEs
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7.2. Classification of GDEs
There are three main categories used to describe GDEs, which have been based on the GDE Toolbox (in prep. SKM 2011):
Aquifer and cave ecosystems (Type 1) Ecosystems dependent on the surface expression of groundwater (Type 2) Ecosystems dependent on subsurface presence of groundwater (Type 3)
It is very difficult to identify where Type 1 GDEs would be occurring due to the very sparse information available on aquifer and cave ecosystems and the occurrence of groundwater‐ inhabiting organisms. As a result of this, only Type 2 and Type 3 will be considered in detail for the Barossa PWRA. Type 1 will not be discussed any further. Potential GDEs in the Barossa PWRA have been split into the following functional groups based on these GDE Types identified from the GDE Toolbox (in prep. SKM 2011) and these are shown in Table 7‐1:
Table 7-1 - GDE Type and Functional Groups GDE Type Functional Group Ecosystems dependent on the surface Fractured rock discharge (FRD) expression of groundwater (Type 2) Groundwater discharge in valley floors (GDV)
Ecosystems dependent on subsurface Break of slope GDEs (BoS) presence of groundwater (Type 3) Terrestrial vegetation on plains (TVP)
Table 7‐2 presents a summary of the potential GDE locations based on previous information regarding GDEs in the study area and an analysis of geomorphology, hydrogeology and ecology.
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Table 7-2 – Summary of Potential GDE Locations in the Barossa PWRA
GDE Type Functional Group Geomorphology Groundwater Ecology Potential GDE Locations Surface expression Fractured rock Regionally: steeper undulating Diffuse and point source discharge of Terrestrial vegetation. e.g. Kaiserstuhl Conservation Park and adjacent of groundwater discharge and hills with shallow stony soils local flow systems in fractured rock Heathy woodland (Eucalyptus areas (Type 2) baseflow (FRD) formed on outcropping fractured settings to streams. Discharge occurs obliqua) in localised depressions rock. more commonly in drainage lines and and drainage lines in headwater Areas of Eucalyptus obliqua (heathy local topographic depressions areas woodland) located in headwaters of the contributing to permanent pools in Lyndoch Creek, Tanunda Creek, Jacobs the upper catchment areas. Creek and the Flaxman Valley (North Para River). Regionally watertable is greater than 10m deep, but will be shallow (<5m) Groundwater discharge in the headwaters in the immediate vicinity of these of Greenock Creek catchment. GDEs. Chain of ponds (headwaters) and Headwaters – Lyndoch Creek, Tanunda permanent pools (valleys) to Creek, Jacobs Creek and the North Para provide habitat for aquatic fauna River (Flaxman Valley), Gomersol Creek and associated riparian vegetation communities Groundwater Sedimentary valleys with deeper, Groundwater discharge from Permanent pools (valleys) to Barossa and Greenock Creek valley floors discharge in valleys fluvial soils Quaternary aquifer on plain. provide habitat for aquatic fauna (GDV) Regionally DTW > 10m and riparian vegetation communities Subsurface Break of slope GDEs Soils formed on outwash Groundwater discharge at Terrestrial vegetation Areas of Eucalyptus fasciculosa (heathy presence of (BoS) sediments derived from topographic break of slope woodland) at Altona CSR Landcare Reserve groundwater basement rock highs. Generally between Rowland Flat and Lyndoch. (Type 3) deeper, fluvial soils, in contrast to shallow soils associated with Sandy Creek Conservation Park and fractured rock discharge. adjacent areas
Cockatoo Valley Barossa and Greenock Creek valley floors
Terrestrial Sedimentary plains Shallow watertables within Terrestrial vegetation (Eucalyptus North Para River just upstream of Gawler vegetation on plains Quaternary sediments camaldulensis) township (outside of Barossa PWRA) (TVP) Gawler River ‐ downstream of Gawler township on the Adelaide Plains.
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7.3. Ecosystems dependent on the surface expression of groundwater (Type 2)
This GDE type occurs where groundwater extends above the ground as a visible expression; and includes wetlands, lakes, seeps, springs and river baseflow. The key functional groups which occur within this type are:
Fractured rock discharge and baseflow
Groundwater discharge in valleys
A conceptual model for these functional groups is presented in Figure 7.1 and the location of potential GDEs is shown in Figure 7.2.
7.3.1. Fractured rock discharge and baseflow (FRD)
The ‘Fractured rock discharge and baseflow’ functional group tends to be located in the Barossa Ranges in the headwaters of a number of creeks. The Barossa Ranges are a series of undulating hills that form part of the Mount Lofty Ranges. This higher ground forms the ‘source’ of water in relation to rainfall, streamflow and groundwater recharge and the dominant outcropping geology in the upper catchment is the Cambrian and Precambrian Basement that hosts Fractured Rock aquifers. The soils in the Barossa Ranges that overlie the Fractured Rock and are shallow in nature and discharge occurs downslope where impermeable layers are encountered or where fractures outcrop.
Fractured rock discharge can occur on hillsides but more commonly occurs in local topographic depressions or drainage lines. The GDEs of this functional group are terrestrial vegetation communities that access groundwater seepage and associated shallow water tables. These may be dominated by River Red Gum or Blue Gum woodlands and aquatic and riparian vegetation along watercourses. Examples include the headwaters of the Lyndoch Creek, Jacobs Creek, Tanunda Creek, Greenock Creek and the upper North Para River in the Flaxman Valley.
In much of the upper catchment reaches, fractured rock aquifers discharge to watercourses and provide baseflow for streams. This is particularly evident in the Flaxman Valley. GDEs arising from fractured rock baseflow are permanent river reaches or pools, and the fringing riparian vegetation. These environments typically contain excellent examples of remnant terrestrial, semi aquatic and aquatic vegetation.
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Shallow watertables associated with fractured rock discharge may also support areas of terrestrial vegetation and native woodland species such as River Red Gum, Blue Gum and Stringy Bark, and their associated understorey communities. These communities can be found at the Kaiserstuhl Conservation Park and the adjacent forest and heritage agreement areas. The Conservation Park site was dedicated to protect one of the last remnants of native vegetation in the region and according to the literature, also protects important seasonal creek habitats.
7.3.2. Groundwater discharge in valleys (GDV)
The dominant groundwater flow path in the Barossa PWRA is from the Fractured Rock of the Barossa Ranges in the east to the sedimentary aquifers further west in the valley floor (typically Quaternary and Tertiary). Streams in the valleys may receive groundwater discharge via this flow mechanism which supports permanent or seasonal river reaches. Permanent pools can also be maintained through groundwater baseflow contributions from the watertable, unconfined aquifer on the valley floor.
The North Para floodplain and the Greenock Creek valley provide examples of this GDE type including the instream habitats and their associated riparian areas. The riparian habitats support plants that are likely to access water within the watertable unconfined Quaternary aquifer, such as River Redgums (Eucalyptus camaldulensis) sedges and reeds. These permanent aquatic habitats are important refugia for aquatic biota and are known to support populations of aquatic plants, aquatic macroinvertebrates and fish. Of particular note are the ‘chain of ponds’ reaches in the valley floor.
7.4. Ecosystems dependent on subsurface presence of groundwater (Type 3)
This GDE type occurs where ecosystems are dependent on the subsurface presence of groundwater and includes terrestrial vegetation.
The key functional groups which occur within this type are:
Break of slope Terrestrial vegetation on plains A conceptual model for these functional groups is portrayed in Figure 7.1 and the location of potential GDEs is shown in Figure 7.2.
7.4.1. Break of slope GDEs (BoS)
The ‘Break of slope’ functional group tends to occur at the base of hill slopes, particularly where higher relief fractured rock basement grades to sedimentary foothills and the valley floor. The
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change in topography can lead to shallower watertables and groundwater discharge sites. In comparison to GDEs that occur in fractured rock settings, Break of Slope GDEs occur in deeper sedimentary soils as opposed to more shallow, skeletal soils and the watertable lies within sedimentary aquifers (Tertiary or Quaternary sediments) as opposed to fractured rock.
GDEs of this functional group have been observed on the western side of the Barossa Valley where the area of higher ground that dissects the Greenock Creek from the Barossa Valley meets the valley floor. The break of slope is shallower on this side of the valley and the Upper or Tertiary aquifer outcrops in this area. There is evidence of a distinct break of slope in the Fractured Rock aquifer beneath the tertiary outcrop. In comparison, the fractured rock beneath the Barossa Ranges on the eastern boundary of the Barossa Valley is much steeper and the Quaternary aquifer completely overlies the Tertiary sediments.
Within the Barossa PWRA, GDEs of this functional group tend to be areas of terrestrial vegetation whereas in other areas such as the Hills Face Zone of the Adelaide Plains examples of wetlands and baseflow dependent ecosystems exist. Break of slope GDEs in the Barossa PWRA include the Sandy Creek Conservation Park and the Altona CSR Landcare Reserve near Lyndoch. Cockatoo Valley on the boundary of the Barossa PWRA also exhibits similar characteristics.
7.4.2. Terrestrial vegetation on plains (TVP)
Terrestrial vegetation on plains tends to be found on the lower reaches of the North Para just upstream Gawler. This section of the watercourse is located outside the Barossa PWRA. Examples of this functional group are also located on the Gawler River downstream of Gawler, as it flows across the Adelaide Plains.
Much of the North Para River (and Gawler River), downstream of the PWRA is a losing system where surface water discharges into the groundwater system. Riparian vegetation along the watercourse depends on the maintenance of a natural discharge regime of surface water from the Quaternary aquifer. In these areas, plant roots may be able to access shallow watertables to sustain their water needs.
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I:\VESA\Projects\VE23576\Deliverables\Reports\Barossa GDE Assessment Stage 1 FINAL v5.docx PAGE 42 *# (FRD) Potential GDE Locations Headwaters Chain of ponds (EarthTech 2003) (GDV) Greenock Creek Barossa Heritage Agreements Valley floor NPWS SA Reserves Barossa WAP *# Watercourse
(FRD) Remnant Vegetation Communities Headwaters Potential groundwater dependent vegetation Gomersal Creek Eucalyptus fasciculosa Eucalpytus camaldulensis k ee r a Eucalyptus obliqua C r ck a *# no P (GDV) e th re r Greenock G o N GDE Type Creek valley floor N Ecosystems dependent on surface expression of GW *# o (FRD) (Type 2) r
t h Headwaters Fractured Rock Discharge (FRD) P Examples:Kaiserstuhl Conservation Park, a Tanunda r Headwaters - Lyndoch Creek, Tanunda Creek a Creek a Jacobs Creek, Greenock Creek, Gomersal Creek r a and North Para. P *# th (FRD) Groundwater discharge in valleys (GDV) r (TVP) o Headwaters Examples: Barossa and Greenock Creek N *# North Para *# *# North Para valley floors *# Ecosystems dependent on subsurface presence of GW *# (Type 3) Break of Slope (BoS) Examples:Altona Reserve, Cockatoo Valley *# Sandy Creek Conservation Park (TVP) *# Terrestrial vegetation on plains (TVP) Gawler River (BoS) Example: North Para River, Gawler River Sandy Creek *# (FRD) Conservation *# Kaiserstuhl Park Conservation Park (FRD) (BoS) (FRD) Headwaters Cockatoo Headwaters Jacobs Creek Date Source: Valley Lyndoch Stream Classification - DWLBC (BoS) Creek Remnant Vegetation - AMLR NRMB Altona Chain of ponds - AMLR NRMB NPWS SA Reserves - NPWS ± Reserve Heritage Ageements - DEH 0 5 10 Kilometers
Figure 7.2 - Potential GDEs in the Barossa PWRA GDA 1994 MDA Z54
Groundwater-dependent ecosystems of the Barossa PWRA - Stage 1 August, 2011 I:\VESA\Projects\VE23576\Technical\GIS\
8. Prioritisation of GDEs
8.1. Introduction
The significance of a potential GDE asset can be defined as a combination of its ecological value, the nature and level of its groundwater dependence, and the threat imposed by groundwater extraction. Each of these factors has been assessed in turn in the following sections and a summary of the results can be found in Table 8‐2. The assessment is undertaken to prioritise potential GDEs so that management and assessment efforts can be appropriately focused.
8.2. Ecological value
Table 8‐2 provides a preliminary ranking of the relative ecological values of GDE sites identified within the study area. These have been broadly ranked as High, Moderate and Low. These preliminary scores are based upon information available within the desktop study and local knowledge, using the following rationale.
Areas designated as High value include:
Sites listed as a conservation area, such as Conservation Parks (e.g. Kaiserstuhl).
Sites which support a large number of flora or fauna species of conservation significance listed under the State (National Parks and Wildlife Act) legislation or species are listed under Commonwealth (EPBC Act) legislation.
Sites which support high biodiversity values, including extended chain of ponds such as those identified in the headwaters of the North Para River.
Areas designated as Moderate value include:
Sites which support a lower number of flora or fauna species of conservation significance listed under the State (National Parks and Wildlife Act) legislation.
Stream headwaters and chain of ponds, which generally support higher biodiversity than lower reaches.
Areas with a well defined riparian corridor, such as the headwaters and upper reaches of Tanunda Creek.
Areas designated as Low value include:
All remaining sites not classified as moderate or high value (assumed to have a lower ecological value).
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The Barossa region is a highly developed agricultural area and there tends to be only isolated or fragmented areas of ecological importance amongst these managed areas. These areas include patches of woodland, scrubland, conservation parks and discontinuous sections of riparian fringes along watercourses amongst the agricultural zones and managed areas. Their fragmented nature highlights the significance of protecting these remaining assets and as a result, the GDEs that have been identified have been classified as high or moderate ecological value.
There is a deficiency of data and the permanent pool and stream classification coverages available from DFW are in conflict and hence permanent pools and gaining reaches cannot be identified with confidence. Areas that have chain of ponds identified in the Watercourse Rehabilitation Priority Setting Project (Earth Tech, 2003) have been used to identify areas of baseflow input, particularly in the headwaters of many of the watercourses in the study area.
8.3. Groundwater dependency
Understanding the level and nature of groundwater dependency is critical to determining the appropriate management response for GDEs. A framework has been devised to assess the groundwater dependency of the potential GDEs identified. There are two aspects to this framework: 1) understanding the ecosystems ecological components; and 2) understanding the importance of groundwater to an ecosystem relative to other water inputs (surface water and soil water).
8.3.1. Ecological components indicative of wet environments
An indication of groundwater dependence can first be examined from an ecological perspective. For a regional assessment, the purpose is to identify ecosystems which contain species or habitats indicative of a wet environment; and/or contain species that are commonly associated with groundwater use2.
Scores were assigned to the potential GDEs identified using the following rationale:
High: contains habitats and species associated with wetter environments or includes species commonly associated with groundwater use
Moderate: contains habitats and species associated with wetter environments, but does not contain species commonly associated with groundwater use
2 Species commonly associated with groundwater use refers primarily to phreatophytic vegetation, such as River Red Gum (Eucalyptus camaldulensis), that in other parts of Australia have been found to use
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Low: does not contain species associated with wetter requirements. Species indicative of wet environments require permanent water or sustained wet conditions throughout the year. This also includes the presence of ephemeral pools where specialised aquatic flora may potentially occur. Habitats with high water requirements in the region include permanent pools and permanent watercourses including associated riparian zones. Sites where permanent or extended baseflows occur would be significantly impacted by declines in water availability. Aquatic flora which rely upon permanent or extended periods of inundation include a range of potential aquatic and emergent species, such as rushes and sedges (e.g. Carex spp, Cyperus spp, Juncus spp, Gahnia spp), reeds (Bullrush, Typha domingensis or Common Reed, Phragmites australis), and free floating (e.g. Potamogeton) or submerged (e.g. Water Ribbons, Triglochin) species.
Terrestrial flora species associated with riparian zones include River Red Gum (Eucalyptus camaldulensis) and Pink Gum (E. Fasciculosa) woodlands, as occurs in Sandy Creek Conservation Park which generally rely upon extended periods of inundation or provision of baseflows. These communities would in turn provide habitat for faunal groups, which may include species of conservation value, such as the Southern Brown Bandicoot. Associated understorey vegetation also reliant upon damp or ephemeral conditions include a number of shrubs, such as Silky Tea Tree (Leptospermum lanigerum), Blackwood Wattle (Acacia melanoxylon), Swamp Wattle (A. retinodes), Kangaroo thorn (Acacia paradoxa), Hop Goodenia (Goodenia ovata) and Groundsel species (Senecio spp.) All of these species and habitats may support both threatened flora (e.g. Orchids) and threatened or protected fauna (e.g. Bandicoot, a range of amphibians, and water dependent birds).
In addition, watercourse and wetland environments would provide habitat for a range of faunal groups such as: Fish; Macro‐invertebrates; Amphibians; Aquatic Reptiles (turtles) and species associated with wet environments, including lizards and snakes; Mammals, including bats, which may utilise wetland environments for feeding, together with woodlands for refuge, foraging and roost opportunities; and Birds (including water dependent and migratory species).
Fauna values associated with these habitats would also be sensitive to changes in water availability. This includes fish and macro‐invertebrates species, together with water dependent birds. Fish species clearly represent a fauna group highly susceptible to changes in water availability, particularly within isolated wetland sites and baseflow‐dependent river reaches.
groundwater to supplement their water supplies. The term is not meant imply these species solely use groundwater to the exclusion of other water sources.
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Areas where limited surface water resources occur have also been scored high. Examples include headwaters and hill faces, where groundwater may allow permanent pools or baseflows to occur during summer months. These sites may support high flora and fauna diversity and likely include threatened species.
8.3.2. Significance of groundwater as a water input
The significance of groundwater as a water input to an ecosystem is based on an understanding of groundwater, surface water and soil water dynamics. A framework has been developed to score potential GDEs (Table 8‐1). The framework examines the three broad GDE sub types of baseflow, seeps and shallow water tables and terrestrial vegetation independently.
Table 8-1 Framework to assign scores according to the significance of groundwater as a water input
Type 2 Type 2 and 3 Type 3 Level of groundwater inputs Seeps and shallow water tables relative to other FRD* and GVD* TVP* sources associated with FRD* and BoS*
High Identified baseflow with DTW# < 2m with gaining hydraulic DTW# < 5m with low soil extended chain of ponds gradients, and permanent water‐holding capacity soils waterlogging or no other (e.g. coarse textured soils) identifiable water inputs
Moderate Seasonal pools /reaches, DTW# < 2m with gaining hydraulic DTW# 5‐20m with high water‐ extensive riparian area gradients (at times), but only holding capacity soils (e.g. seasonal waterlogging or other loams), water inputs identified (e.g. in‐ stream wetland)
Low Ephemeral streams DTW# > 2m DTW# > 20m
*FRD = Fractured Rock Discharge, GVD = Groundwater Discharge in Valleys, BoS = Break of Slope, TVP = Terrestrial Vegetation on Plains #DTW = Depth to Watertable
For baseflow‐dependent ecosystems it is necessary to examine the importance of groundwater as an input to stream flow relative to surface water inputs from surface runoff / drainage or upstream flows that may be regulated. In the absence of a detailed numerical understanding of groundwater‐surface water connectivity, a simplified scoring scheme was developed. Potential GDEs were scored based on the presence of identified baseflow (i.e. chain of ponds classification) and the permanence of flow.
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Riparian vegetation and terrestrial vegetation associated with drainage lines and low lying areas (including wetlands) can receive water from many sources depending on their setting. The depth of the water table is an indicator of the relative importance of groundwater. The permanence of waterlogging may also be used as an indicator of groundwater inputs. For instance, if certain areas maintain a waterlogged condition during extended dry spells this may indicate groundwater discharge. GDEs that occur in areas with shallow water tables that may be permanently waterlogged or receive water from no other source are scored as high. Areas with shallow water tables that may be only seasonally waterlogged or receive significant water inputs from other water sources (e.g. some in‐stream wetlands) are scored as moderate. GDEs located in riparian areas where the water table is deeper than 2m are scored as low. Groundwater level data collated from the Obswell system was used to undertake this analysis.
Terrestrial vegetation GDEs may access water from groundwater or from soil water storage. The depth of the watertable and the plant‐available water holding capacity of soil were considered to be the two main factors that define the relative importance of groundwater. A shallow watertable (<5m) combined with limited soil water storage (e.g. shallow or coarse textured soils) suggests a high likelihood for groundwater to be the dominant water source. A moderately shallow water table (5‐10m) and a high water‐holding capacity soil (e.g. deep loams) suggest a moderate importance of groundwater. A water table deeper than 10m (nominally assumed to be the maximum rooting depth) suggests a low importance of groundwater3.
The scoring framework (Table 8‐1) was applied to potential GDEs identified in the region (Table 8‐2). For potential baseflow‐dependent ecosystems, the chain of ponds classification and reaches of the upper catchment streams were mostly scored as high. Lower catchment reaches were scored as moderate due to the lack of extensive riparian areas. A low score was assigned to the lower reaches of the Para River due to a high degree of stream regulation in the tributaries.
For terrestrial vegetation, break of slope and fractured rock discharge areas in the upper catchment assets were regarded as having a moderate degree of groundwater inputs due to water tables greater than 5 m depth. The relative importance of groundwater for terrestrial vegetation along the valley floors was considered to be moderate due to presence of high water‐ holding capacity soils and extended riparian corridors.
3 Note: a different scale of water table depth is applied to Terrestrial Vegetation GDEs compared to the fractured rock discharge and break of slope functional groups. Fractured rock discharge and break of slope GDEs are environments where groundwater discharge can occur, so the level of groundwater input is defined by a shallower range of water table levels. For Terrestrial Vegetation GDEs the significance of groundwater as a water source is defined over a greater range of water table depths.
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8.4. Threats
The level of threat assigned to GDEs throughout the study area has been classified as High, Medium or Low based on indicative extraction pressures to the watertable. The water table occurs in the surface layers of the major hydrogeological units where they outcrop such as the Upper aquifer in the sedimentary deposits of the valley floor and the Fractured Rock aquifer through the rest of the region. The threat posed was examined in relation to extraction from the unconfined aquifers.
The rankings were based on the following rationale:
High: there is significant extraction apparent in the immediate vicinity (within 2.5 km) of the potential GDE, either large metered commercial extraction volumes or a high number of stock and domestic wells.
Moderate: smaller volumes of extraction apparent in the immediate vicinity of the GDE (e.g. stock and domestic use or minor commercial metered extraction volumes)
Low: no extraction apparent within 2.5 km of the potential GDE site.
The rankings are documented in Table 8‐1. The location of groundwater extraction pressures in relation to potential GDEs is shown in Figure 8.1.
Metered groundwater use (2009/10) is available for the Barossa PWRA and has been sourced from DFW and all licensed extraction wells are presented in Figure 8.1.
Metered groundwater extraction from the Upper aquifer (with individual extractions up to 50 ML/year) is concentrated on the northern section of the Barossa Valley floor where the Earth Tech (2003) survey identified a ‘chain of ponds’ classification on the main channel of the North Para River. The ‘Groundwater Discharge in Valleys’ (GDV) GDE highlighted in the Barossa Valley has been assigned as a ‘High’ level of threat due to the concentration of Upper aquifer extractions in particular, in close proximity to areas where potential GDE locations have been identified.
In the upper areas of the North Para Catchment groundwater water extraction from the Fractured Rock aquifer is much lower than on the valley floor with surface water being the predominant source of irrigation water, and as a result, the headwaters of the North Para (Fractured Rock Discharge GDE) has been assigned as a ‘Moderate’ level of threat from extraction. There are
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relatively low numbers of wells classified as being used for domestic purposes throughout the area. The main extraction from the Fractured Rock aquifer occurs in the lower Flaxman Valley.
All other potential GDE locations are located in areas where there is minimal extraction in close proximity to the sites, and have therefore been assigned as a ‘Low’ level of threat from extraction. Particular examples include the various ‘Fractured Rock Discharge’ GDEs (headwaters of the Tanunda, Jacobs, Lyndoch and Greenock Creeks), the ‘Groundwater Discharge in Valleys’ GDE identified in the Greenock Creek valley floor and the ‘Terrestrial Vegetation on Plains’ GDEs identified in the Gawler River and the lower reaches of the North Para.
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Table 8-2 Significance assessment of potential GDEs
Groundwater dependency Overall Relative Threat rating Significance Ecology importance of (based on /Priority (value x Conservation Value Overall water groundwater as a groundwater dependence x Location Status Rating Description for ecology value rating requirements water source Comment extraction) Comment threat) Baseflow and extensive Kaiserstuhl Conservation Park and riparian with water adjacent areas Yes High EPBC flora High High Low Minor extraction Moderate logging on low water
holding soils Headwaters of Greenock Creek No High EPBC flora and fauna Moderate Moderate Lack of data Low Minor extraction Moderate catchment. Locally threatened species in South Headwaters – Lyndoch Creek No Moderate Moderate Moderate Lack of data Low Minor extraction Moderate Australia. Extensive riparian with Headwaters of Tanunda Creek Locally threatened species in South No Moderate High Moderate water logging on low Low Minor extraction Moderate Australia. water holding soils Extensive chain of Headwaters of Jacobs Creek ponds and extensive No High EPBC flora, ‘chain of ponds’ classification High High Low Minor extraction Moderate riparian on low water holding soils Extensive chain of Headwaters of North Para River Medium extraction ponds and extensive (Flaxman Valley) No High Extensive ‘chain of ponds’ classification High High Moderate increasing High riparian on low water downstream holding soils High level of Extensive chain of Barossa Valley floors No Moderate Riparian, permanent pools High Moderate High extraction in northern High ponds area of valley floor Altona CSR Landcare Reserve Vegetation potentially between Rowland Flat and Lyndoch Yes High EPBC flora, Heritage Agreement Moderate Moderate accessing shallow water Low Minor extraction Moderate table on variable soils. Sandy Creek Conservation Park and Vegetation potentially Low level of adjacent areas Yes High EPBC flora, SA Reserve Moderate Moderate accessing shallow water Low Moderate extraction table on variable soils. Extensive chain of Greenock Creek valley floors No Moderate Riparian veg, ‘chain of ponds’ classification High High ponds and riparian Low Minor extraction Moderate vegetation Extensive chain of Headwaters of Gomersal Creek No High Extensive ‘chain of ponds’ classification High High ponds and riparian Low Minor extraction Moderate vegetation North Para River just upstream of Extensive chain of Gawler township (outside of Barossa Locally threatened species in South No Moderate Moderate High ponds and riparian Low Minor extraction Moderate PWRA) Australia, riparian vegetation vegetation
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I:\VESA\Projects\VE23576\Deliverables\Reports\Barossa GDE Assessment Stage 1 FINAL v5.docx PAGE 51 *# Potential GDE Locations GDE Type (FRD) Headwaters Licensed GW Extraction (2009/10) Ecosystems dependent on surface expression of GW (Type 2) (GDV) Greenock Creek Upper Aquifer (Ml/year) Barossa (! Fractured Rock Discharge (FRD) ± 0 - 10 Examples:Kaiserstuhl Conservation Park, Valley floor Headwaters - Lyndoch Creek, Tanunda Creek 10 - 25 Jacobs Creek, Greenock Creek, Gomersal Creek and North Para. (FRD) 25 - 50 Groundwater discharge in valleys (GDV) Headwaters *# Examples: Barossa and Greenock Creek Gomersal Creek valley floors 50 - 100
Ecosystems dependent on subsurface presence of GW (Type 3) Lower Aquifer (Ml/year)
Break of Slope (BoS) (! 0 - 10 Examples:Altona Reserve, Cockatoo Valley (! (! (! Sandy Creek Conservation Park (! (! 10 - 25 k (! ee (! Terrestrial vegetation on plains (TVP) r a (! (! C r 25 - 50 Example: North Para River, Gawler River k a (! (! c *# (! o P n ! e th ( re r G o 50 - 100 (! N (! (!(!(! ! ! ( (GDV) (! ( (! (! (!(! N Fractured Rock (Ml/year) Greenock *# (! o (FRD) ! (! r ( (! (! t Creek valley h Headwaters 0 - 10
floor (!P Tanunda (! (!a (! 10 - 25 r Creek a a r a 25 - 50 (! (! (! P *# (!(!(!(! th (! (! (FRD) (TVP) r (! (! o Headwaters 50 - 100 N (! *# North Para *# *# North Para (! *# (! domestic extraction *# (! (!(! (! Chain of ponds (EarthTech 2003) (! (! (! (! !( ( Heritage Agreements (! (TVP) *# (! NPWS SA Reserves Gawler River (BoS) *# (! Sandy Creek *# (FRD) Barossa WAP Conservation # Kaiserstuhl Park * Conservation Remnant Vegetation Communities (! Park (FRD) Potential groundwater dependent vegetation (BoS) (! (FRD) Headwaters Eucalyptus fasciculosa Cockatoo Headwaters Jacobs Creek Valley Lyndoch Date Source: Eucalpytus camaldulensis (BoS) Extraction data - DFW Creek Stream Classification - DWLBC Eucalyptus obliqua Altona Remnant Vegetation - AMLR NRMB Reserve Chain of ponds - AMLR NRMB NPWS SA Reserves - NPWS 0 5 10 Heritage Ageements - DEH Kilometers
Figure 8.1 - Barossa GDEs and extraction locations GDA 1994 MDA Z54
Groundwater-dependent ecosystems of the Barossa PWRA - Stage 1 August, 2011 I:\VESA\Projects\VE23576\Technical\GIS\
8.5. Other threats relating to potential GDEs
When examining the significance of GDEs and their susceptibility to groundwater extraction, it is important to recognise that a potential GDE may be subject to a wide range of other threats that may outweigh the potential threats associated with groundwater extraction. The condition of potential GDEs may be affected by poor land management practices, urbanisation and surface water extraction.
The use of surface water via dams is extensive throughout the upper parts of the Barossa PWRA and the impact on baseflow has been documented in the WAP as being very high throughout the Flaxman and Tanunda Creek catchments. The lack of mechanisms on dams to allow low flows to continue downstream poses a significant threat to GDEs in the Barossa PWRA, particularly as this region has the highest proportion of chain of ponds environments in the Mount Lofty Ranges (as identified in the Earth Tech 2003 classification process).
Isolation and fragmentation of wetlands occurs where an absence or reduction in large scale flood events occurs, which provide important pathways and dispersion of fauna and flora (Finlayson & Rea, 1999). This may be influenced by a reduction in groundwater baseflow, with resultant disruption to colonisation and re‐colonisation to flora and some fauna groups, particularly fish. Impacts of isolation and fragmentation of wetlands may also result where dams impede flows from groundwater discharge.
Poor land management practices, such as not fencing off streams and wetlands from stock or inappropriate fertiliser management can also be detrimental to the condition of potential GDEs.
While these factors could not be included in the current assessment, an appreciation of other threats in relation to groundwater extraction pressures should be included in Stage 2 of this program when more detailed analyses are conducted.
8.6. Prioritisation
To prioritise potential GDEs in the region, the scores assigned to ecological value, groundwater dependence (overall water requirements and the relative importance of groundwater), and the threat posed by groundwater extraction were combined to provide an overall assessment of the significance or prioritisation of the GDEs in the Barossa PWRA. The overall assessment was assigned as follows:
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Potential GDEs that attain moderate to high scores for all classes have a high risk level and may be regarded as priority sites for further investigation.
Potential GDEs that attain a low score in one category are classed as moderate risk.
Potential GDEs that attain a low score in more than one category are classed as low risk.
A summary of the results for each of the factors and the overall prioritisation score assigned can be found in Table 8‐2.
Uncertainty is built into the prioritisation assessment. Potential GDEs lacking in data to support the allocation of a score for a particular category are assumed to rate as at least moderate in that category when the scores are combined to establish the overall significance or prioritisation for management.
For the Barossa PWRA, the following potential GDEs were identified as being high priority:
The headwaters of the North Para River in Flaxman Valley; and
The Barossa Valley Floor
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9. Groundwater dependency of downstream hydraulically-connected areas
9.1. Introduction
The downstream hydraulically‐connected area refers to the stretch of the North Para River between the town of Gawler and the junction with the Lyndoch Creek and its tributary catchments (including the Greenock Creek and Gomersal Creeks). This reach is directly downstream of the Barossa PWRA and is currently the only section of the watercourse not prescribed.
9.2. Previous Research
There has been very little previous research undertaken on the section of the lowermost reach of the North Para River. The ‘Determination of Environmental Water Requirements’ study (EPA 1999) discussed in Section 5, identified the reach as ‘Zone 4 – Mobile Zone’ and the environmental water requirements are listed in Table 6‐2.
In summary, the Barossa WAP notes that the key issues for this zone are:
Protecting underground water‐fed hyporheic habitats (region beneath and alongside a stream bed, where there is mixing of the watertable aquifer and surface water);
Maintaining the pool‐riffle sequences; and
Maintaining the riparian condition through riparian flows.
9.3. Hydrogeology
The hydrogeology of the area comprises the same geological layering as that found in the Barossa PWRA. The dominant outcropping geology is the FRA with the Upper and Lower aquifers being more prevalent in the Greenock Creek and the Sandy Creek catchments.
These aquifers are hydraulically connected and any one can be a source of recharge or a point of discharge to one or both of the other aquifers depending on the location within the valley. Groundwater flow is predominantly from west to east from the Mount Lofty Ranges towards the Barossa (or North Para River) Valley. There is a ridge of higher ground between the Barossa and Greenock Creek valleys where the Fractured Rock aquifer outcrops, suggesting a groundwater flow divide occurs at this point, with little lateral groundwater flow between the two catchments.
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These regions will be comprised of localised flow systems in the Fractured Rock aquifer and also along the Greenock Creek valley.
Much of the North Para River (and Gawler River), downstream of the PWRA is a losing system where surface water discharges into the groundwater system. Riparian vegetation along the watercourse depends on the maintenance of natural discharge regime whereby 5000 ML of surface water is lost to the Quaternary aquifer (AMLR NRMB, 2007).
Permanent pools are a common feature throughout the North Para catchment and these can also be found downstream of the Barossa PWRA. These features tend to be maintained through groundwater baseflow contributions from the FRA or the watertable, unconfined Quaternary aquifer on the valley floor.
9.4. Ecology
The condition of the riparian zone on the Greenock Creek, Gomersal Creek and the North Para (between Gawler and the junction of the Lyndoch Creek) varies considerably. Many of the banks are grazed and stock impacts are evident. There is still a fairly continuous cover of River Red Gums and other Eucalyptus species throughout, with the understorey vegetation being modified to a range of mixed pasture grasses. Macropyhytes are common in the stream channel. Species include common reed (Pragmites australis), bulrush (Typha sp), sharp‐leaf club‐rush (Schoenoplectus pungens), and spiny flat‐sedge (Cyperus gymocaulos). This zone contains the snail, Thiara balonnensis, which was collected on the North Para at Willaston. This species has restricted distribution in South Australia and has never been consistently collected from any sites.
Sandy Creek Conservation Park is located on the edge of the Barossa PWRA in the headwaters of Sandy Creek, and contains a number of native flora and fauna species, some of which are Nationally‐threatened. These are discussed further in Section 4.4. There are no other designated conservation areas in the area downstream of the Barossa PWRA.
The ecology is likely to be susceptible from water resource impacts in the upstream Barossa PWRA as well as the catchments in the immediate vicinity of the North Para and its tributaries in this area. These impacts include surface and groundwater extraction, overgrazing of riparian areas and farm dam diversions.
9.5. Groundwater Extraction
There is very little information available on groundwater extraction in the area downstream of the Barossa PWRA. However, it is envisaged that there is very little high‐yielding groundwater
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extraction occurring due to the presence of the Fractured Rock aquifer outcropping in much of the area. There are likely to be some local impacts resulting from stock and domestic groundwater extraction, but these will potentially be masked by surface water management activities such as farm dam diversions.
Groundwater investigations in the Greenock Creek catchment indicate that there are no significant groundwater resources in the area and the Fractured Rock aquifers underlying the catchment do not have any high rainfall areas to supply them, unlike the Barossa Ranges. As such, there is no significant groundwater irrigation development (DWLBC 2002).
The change in geology between the Barossa and Greenock Creek valleys is likely to result in a discontinuous groundwater flow across the area, and groundwater will predominantly flow along the North Para (or Barossa) valley floor. Impacts are therefore likely to be confined to altered surface water flows in the North Para River. Any impacts which may occur from the groundwater extraction in the Barossa PWRA are unlikely to manifest themselves in the local groundwater systems.
9.6. Information Gaps & Recommendations
Studies have not been undertaken on the lower Greenock Creek and Gomersal Creek catchments, which feed into the North Para River. In addition to the impact of the prescribed area, it is important to understand the contributions that these sources have to maintaining the environment of the North Para River in the reach below their confluence. A broad survey of the level of dam development in this area would be valuable for the development of the surface water budget of the North Para River.
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10. Recommendations to set EWRs and EWPs
The Department for Water (DFW) guidelines on Environmental Water Requirements and Provisions (DFW, 2010) contains a step‐by‐step guide to allocating water for the environment as part of the five‐yearly WAP review cycle. The process can be used as a framework to guide the management of potential GDEs, and is used here to structure recommendations to the Board regarding GDEs in the Barossa PWRA. The recommendations made in this chapter also draw on recent GDE assessment activities in the Adelaide Plains.
The DFW guidelines list the following steps for the development of environmental water requirements and provisions:
Step 1) Identify water dependent environmental assets, functions and values
Step 2) Identify environmental objectives
Step 3) Identify environmental water requirements
Step 4) Identify environmental outcomes under a number of possible scenarios
Step 5) Determine agreed environmental outcomes and establish environmental water provisions
Step 6) Draft WAP
Step 7) Implement monitoring, evaluation and reporting frameworks and review of WAP
Step 1) Identify water dependent ecological assets, functions and values
Step 1 has largely been undertaken by the desktop scoping study undertaken by this project. However it is recommended that the outputs of this project – namely the location and functional grouping of GDEs – are reviewed as part of field assessments conducted to establish EWRs (Step 3). The identification of water dependent assets, functions and values would also be enhanced by an assessment of surface water – groundwater interactions that play a critical role in the high priority GDEs identified in the Barossa.
Step 2) Identify environmental objectives
The identification of environmental objectives is largely a policy decision designed to articulate the desired state of the GDEs identified. Rather than defining specific site‐based objectives, the approach taken in the Adelaide Plains and Western Mount Lofty Ranges has been to define a
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broad, regional objective such as: the water regime required to maintain self‐sustaining populations resilient to drought. The broad objective can be interpreted on a site basis according to context. For example if a native fish species is located at a site, the objective is to provide a water regime that can support the ongoing survival of that species.
Step 3) Identify environmental water requirements to meet the objectives
Environmental water requirements (EWRs) need to be defined to describe the water regime that is required to support GDEs. As GDEs are numerous, it is not pragmatic to define EWRs for each and every asset. The approach taken in the Adelaide Plains has been to define EWRs at a functional group level using selected sites to represent the broader functional groupings. Sites with the most intact ecologies were selected as this is where the links between the water regime and the ecology can be most clearly identified. In defining EWRs, it is important to assemble all available ecological and hydrogeological information, which is preferably informed by site visits.
The level of detail outlined by an EWR will depend on the available information, but as a minimum the EWR should be a qualitative statement (supported by a conceptual model) that links the ecology of the GDE to the measurable parameters of the groundwater regime (e.g. groundwater level, salinity, gradient). The statement should also specify the temporal and water quality aspects of the groundwater regime that are required to support the ecosystem. If there is sufficient data available then the EWR should include quantified descriptors such as a minimum flux or water level. Given the significant data gaps available, the definition of EWRs is well supported by input from an expert panel in a workshop setting. The GDE Toolbox (SKM, 2011 in prep) provides a range of suggestions for the development of EWRs.
Step 4) Identify environmental outcomes under a number of possible scenarios
Step 4 is a scenario testing process where the desired environmental outcomes and EWRs can be tested against a range of possible future scenarios (e.g. climate change, different levels of development, use of different management options, land use change). This process tests the limits and sensitivity of the water regime to inform the development of Environmental Water Provisions (EWPs, Step 5). Ideally Step 4 should include some numerical analysis from a groundwater model or from more rudimentary approaches such as water balances or analytical solutions. However, scenarios could also be tested on a qualitative level using conceptual models.
A groundwater model has not yet been developed in the Barossa PWRA but would serve a number of purposes. In addition to trialling the impact of different extraction limits, it could be used to model surface water‐groundwater interactions and for scenario testing. If the model is to
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be used to examine EWRs then it needs to be of compatible spatial and temporal scales to the GDEs it is representing. Groundwater modelling could be a valid approach on the valley floor but is not recommended for fractured rock discharge in the catchment headwaters, as this is notoriously difficult to simulate and the region is data‐poor. Scenario testing of GDEs in the Barossa should also assess surface water hydrology and the impact of farm dams.
It is important to describe the natural temporal variability that is associated with groundwater conditions so that stakeholders can appreciate the frequency with which EWRs for GDEs can be delivered.
Step 5) Determine agreed environmental outcomes and establish environmental water provisions
The development of EWPs involves a trade‐off between environmental and socio‐economic needs, and the level of risk accepted in the frequency with which EWRs are likely to be delivered. It is informed by the acceptability of the environmental and socio‐economic outcomes as assessed in Step 4.
Step 6) Draft WAP
Both EWRs and EWPs will need to be documented in the WAP such that total extraction/diversion limit and timing of available extractions is specified. Additional management options for GDEs may include buffers (or pumping set‐back distances), restrictions on the timing of pumping, limitations on the replacement of wells or the issuing of new licences, and defining resource condition limits and triggers that are linked to a management response framework.
It is recognised that the Barossa is a mature water resource area, and management options for GDEs may have to be implemented retrospectively. However, it is recommended that the management responses are implemented with respect to prioritisation of GDEs, with high priority GDEs requiring a more focused management option – such as the definition of resource condition limits and triggers. Buffers tend to only delay impacts as opposed to preventing them and may only be a suitable management response in certain fractured rock settings where single wells may induce a localised but substantial water level drawdown. Table 10‐1 provides examples of management responses that are structured according to priority.
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Table 10-1 Examples of management responses according to priority
Priority Level Approach Range of Management Responses
Low Set ecological objectives and describe Recognition of low risk GDE in the WAP broad landscape setting, ecological values and groundwater extraction Regional monitoring and evaluation. related threats. Set buffers to limit future short term impacts Validate through expert panel Set EWP in context of historic range in groundwater conditions Moderate Set ecological objectives and describe Recognition of low risk GDE in the WAP broad landscape setting, ecological values and groundwater extraction Regional monitoring and evaluation. related threats. Set buffers to limit future short term impacts Targeted investigations to verify risk Set EWP in context of historic range in groundwater Validate through expert panel conditions High Set ecological objectives and describe Description of high risk GDEs within the WAP Flaxman Valley broad landscape setting, ecological Barossa Valley Floor values and groundwater extraction Setup a process that uses EWRs as a trigger or related threats. ‘screen’ as part of an adaptive management approach. That is, if EWR appears to have been exceeded then Undertake targeted investigations at go to investigation of reasons and need for further selected sites to determine EWRs using control of extraction. a combination of flux, water level and water quality indicators. Management options include: Resource condition limits (thresholds) Quantify threats using groundwater flow Minimum groundwater levels / fluxes Maximum rates of groundwater level models or analytical solutions. decline Salinity thresholds and rates of decline Quantify EWR in terms timing, frequency, Develop trigger and response framework magnitude and location for non-compliance Restrictions for high impact zones/bores
Pumping set-back distances from GDEs Undertake ecological assessment to Managing new groundwater applications determine relationship between Conjunctive water use management ecological processes and groundwater Environmental watering (supplementation) Responses tailored to environmental impact conditions sensitivity of pumping wells
Detailed hydrological, hydrogeological and ecological monitoring and evaluation
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Step 7) Implement monitoring, evaluation and reporting frameworks and review of WAP
Additions to the existing monitoring and evaluation network should be informed by the location of GDEs, the definition of EWRs, and their prioritisation. The EWRs should specify certain parameters of the groundwater regime that are required to sustain the ecosystem (e.g. water levels, groundwater salinities, hydraulic gradients). Where possible, these parameters should be monitored to determine whether the EWPs are being met, and also to gather additional information to refine and quantify the EWRs for the next WAP revision. Ecological monitoring (species abundance, condition) should also form part of this framework.
This scoping study suggests immediate monitoring effort should be prioritised to the permanent pools within the Barossa valley floor and in the Flaxman Valley of the upper North Para catchment, where groundwater discharge to streams supports baseflow. The monitoring regime at these locations should be set up to: a) monitor compliance of the EWPs; and b) fill data gaps so that future iterations of EWRs and EWPs can be defined with more certainty.
The monitoring network should monitor the groundwater regime, the surface water regime and ecological indicators. Monitoring wells should be incorporated with the existing network. The new wells should be established to:
Monitor the aquifer that interacts with streams (the fractured rock aquifer in the headwaters and the watertable aquifer in the Valley Floor), particularly near permanent pools or permanently flowing
Monitor gradients of groundwater conditions (water levels/pressures and water quality) by establishing vertical and lateral transects of wells
Monitor water quality so that the chemical signatures of groundwater can be established for the purposes of using isotopic tracers to study surface water – groundwater interactions. The surface water monitoring network should consider the establishment of gauging stations where water levels and flows can be monitored. A series of gauges along a stream can help quantify fluxes between surface water and groundwater, as well as monitoring the compliance of the EWRs.
Regular ecological monitoring of ecosystem condition and functions would also be of considerable value.
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11. Conclusions and recommendations
This study (Stage 1) has undertaken a broad regional assessment of potential GDEs in the Barossa PWRA. A desktop analysis of geomorphology, groundwater and ecology was used to define several GDE types, which may be considered to have common biophysical settings based on their particular combination of attributes.
This method allowed for potential GDEs to be identified and an output of this process was the development of an inventory of potential GDEs for the study area (Table 7‐2).
The potential GDEs identified were assigned an overall priority rating based on a combination of their ecological value, groundwater dependence and the threat posed by groundwater extraction. The process enabled potential GDEs to be prioritised as low, moderate and high significance.
For the Barossa PWRA, the following potential GDEs were identified as being high priority:
The headwaters of the North Para River in Flaxman Valley
The Barossa Valley Floor
For the ongoing management and assessment activities of GDEs in relation to the water allocation process, the following activities are recommended:
An ecological site assessment of potential GDEs to review the GDE typology and prioritisation described in this report, and to inform the derivation of EWRs.
A catchment‐wide assessment of surface water – groundwater interactions to more accurately determine the location, nature and magnitude of groundwater discharge to streamflow. The current mapping products and assessments do not accurately characterise these interactions.
Scoping the potential to develop a groundwater model for use in scenario testing.
Expansion of monitoring network near high priority GDEs to monitor the groundwater regime, the surface water regime and the ecological condition.
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12. References
Adelaide and Mount Lofty Ranges NRM Board. (2006). State of the Catchment report for the Adelaide and Mount Lofty Ranges NRM Board – Northern Group. Prepared by Parsons Brinckerhoff.
Adelaide and Mount Lofty Ranges NRM Board. (2007). Water Allocation Plan for the Northern Adelaide Plans Prescribed Wells Area.
Adelaide and Mount Lofty Ranges NRM Board. (2008). Volume A – State of the Region Report.
Adelaide and Mount Lofty Ranges NRM Board. (2009). Water Allocation Plan for the Barossa Prescribed Wells Area.
Christie, G., Pastok, J. & Clarke, S. (1996). Condition of the North Para, South Para and Gawler River Systems.
Clifton, C, Cossens, B, McAuley, C, Evans, R, Cook, P, Howe, P & Boulton, A. (2007). A Framework for Assessing the Environmental Water Requirements of Groundwater Dependent Ecosystems.Report 1: Assessment Toolbox. Prepared for Land and Water Australia Land and Water Australia.
Department for Water. (2010). Barossa PWRA Groundwater Status Report 2009‐10.
Department for Water, Land and Biodiversity Conservation. (2002). The Barossa Valley Surface Water Budget. Prepared by Pikusa, E.
Eamus, D, Froend, R, Loomes, R, Hose, G and Murray, B. (2006). A functional methodology for determining the groundwater regime needed to maintain health of groundwater‐dependent vegetation. Australian Journal of Botany 54, 97‐114.
Earth Tech. (2003). Watercourse Rehabilitation Priority Setting Process. Report for Northern Adelaide and Barossa, Onkaparinga, Patawalonga and Torrens Catchment Water Management Boards.
Environment Protection Authority (1999). Determination of Environmental Water Requirements for the Gawler River System. In conjunction with National Heritage Trust, and NABCWMB (2001). State of the Catchment Report Northern Adelaide and Barossa Catchment Area. Volume 5.
Evans, R. (2002). Environmental water requirements of groundwater dependent ecosystems – the South Australian approach in the national context. Sinclair Knight Merz.
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Finlayson, C.M. & Rea, N. (1999). Reasons for the loss and degradation of Australian wetlands. Wetland Ecology and Management 7, 1‐11.
Hancock P.J., Boulton A.J. (2008) Stygofauna biodiversity and endemism in four alluvial aquifers in eastern Australia. Invertebrate Systematics 22, 117–126
Hicks, D. & Sheldon, F. (1999). Biotic Survey of the Gawler River, report to the South Australian Department for Heritage and Aboriginal Affairs.
Leijs, R & Mitchell, J. (2009) Stygofauna and Stygomicrobe Research. Newsletter No. 2, Jan 2009. Flinders University.
NABCWMB (undated). Native Fish of the Northern Adelaide and Barossa Catchment. Northern Adelaide and Barossa Catchment Water Management Board.
REM. (2006). Groundwater Investigations to Support Water Allocation Planning in the Barossa. Final Report prepared for North Adelaide and Barossa Catchment Water Management Board.
Seaman, R. (2002). Wetland Survey of the Mount Lofty Ranges. Department for Environment and Heritage South Australia, Kensington.
Sinclair Knight Merz. (2010). Groundwater‐dependent environmental assets of the Adelaide Plains and McLaren Vale (Stage 1).
Sinclair Knight Merz. (2011 in preparation), Australian GDE Toolbox. A project for the National Water Commission
Tomlinson and Boulton (2008) Subsurface Groundwater Dependent Ecosystems: a review of their biodiversity, ecological processes and ecosystem services. Waterlines Occasional Paper No 8, October 2008. National Water Commission.
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