The River Basin Management Society is holding its biannual conference in Hobart on the 12-15th August 2018. This is a great opportunity for researchers, policy makers, consultants and practitioners to get together and share their experiences and investigations in the management of stream ecosystems and their catchments.
This is an important conference that Water Technology is proud to support. Water Technology staff from across Australia will be presenting:
- Hope for the best, plan for the worst: Managing sediment input in the upper catchment whilst preparing for avulsion at the mouth – Dr Michael Cheetham
- Development of the stream rehabilitation guidelines for Queensland – Luke McPhail
- Groundwater the known unknown in floodplain management – Andrew Telfer
- Werribee River Ecohydraulics – Parvin Zavarei
- When Perception and Evidence Based Practice Collide – Floodplain and Waterway Management in the aftermath of the 2016 Floods at St Marys, Tasmania – Julian Skipworth
- From planting willows to pulling them out: The past, present and future of riparian management in Victoria – Jo Slijkerman
- Wodonga regional waterway action plan: a community led waterway action plan – Tom Atkin
Abstracts for the presentations are below.
Download the conference program here.
Hope for the best, plan for the worst: Managing sediment input in the upper catchment whilst preparing for avulsion at the mouth
Michael Cheetham and Julian Martin
The George River in north east Tasmania runs from west of Pyengana to St Helens, where it flows out onto a large delta within Georges Bay. Previous research shows the delta, on which the township of St Helens it built, is Holocene in age. The George River and the Golden Fleece Rivulet to the south have both contributed to delta progradation during the Holocene and the George River has occupied several courses on the delta over that time. Currently, the George River occupies a course at the northern boundary of the delta; however, increased sediment accumulation in this section of the channel is causing rapid infill and avulsion to a new course on the floodplain is becoming imminent.
Sitting in a granitic catchment the George River is naturally subject to high sediment loads. However, historic hydraulic mining and land clearing have increased sediment loads substantially. The George River consists of alternating floodplain and gorge sections. As such, eroded sediment is forced rapidly through gorge sections and stored temporarily in the valley expansions, either as splays on the floodplain or sand slugs in the channel. Increased bank erosion due to a lack of vegetation or willow outflanking is leading to a substantially increased rate of sediment moving to the mouth, instead of being stored in these sections. Combined with substantial willow infestations in the lower reaches the river mouth is soon set to fill completely.
Management options to reduce sediment load include weed management, riparian revegetation and stock exclusion. However, the channel is very close to the threshold required for avulsion and the scale of bank stabilisation and revegetation required is vast. Whereas, managing sediment in the upper catchment is strongly recommended, preparing for avulsion at the mouth is essential to ensure a stable new course for the George River.
Luke McPhail, Michael Cheetham, Andrew Markham (Hydrobiology), Julian Martin, Andrew Brooks (Griffith University), Geoff Vietz (Streamology) Ben Pearson (Hydrobiology), Jim Tait (econcern) and Tim Pietsch (Griffith University)
The Queensland Department of Natural Resources, Mines and Energy is undertaking the production of the streambank, in-channel (instream) and riparian rehabilitation guidelines for Queensland (the Guidelines). The Guidelines, to be delivered in mid-2018, will provide users with a framework to understand the latest best practice rehabilitation principles; to evaluate intervention or monitoring approaches; and guide users to the appropriate sources of information to assess rehabilitation options based on their location within Queensland. The principles of streambank, riparian and in-channel rehabilitation and restoration, including stream classification, restoration objectives, management techniques, best management practice and demonstrable outcomes, and operational case studies are the foundation of the Guidelines. Regionally appropriate rehabilitation approaches will be identified to inform improved management practices relevant to the local context.
An extensive engagement program with a broad stakeholder group is key to the ultimate successful adoption of the guidelines. More specifically, a detailed engagement program with Natural Resource Management organisations, River Improvement Trusts and local government across Queensland is integral to this project. Stakeholder collaboration and consultation is to be used to evaluate and incorporate the hands-on practical knowledge, proven techniques, local context and experience that natural resource managers across Queensland can provide.
Andrew Telfer, Alison Charles and Whendee Young (Department of Environment Water and Natural Resources (SA))
The Lower Murray Floodplain is generally a saline environment, both the groundwater and the unsaturated zone. While native vegetation species are highly salt-tolerant, it is essential that sufficient, appropriate salinity, soil moisture is available to sustain growth and life cycle processes. Low salinity groundwater lenses (LSLs) provide an important source of water and support the ecological function of floodplains in an otherwise dry and saline environment. We advocate that the role of groundwater in sustaining floodplain vegetation needs to be more routinely considered in floodplain management.
In recent years, the behaviour of LSLs has become increasingly important in the management of Salt Interception Schemes (SISs). It is important to understand the relationship between pumping volumes and lens development, as this will determine how quickly salt inflow returns to the River and influence floodplain vegetation condition. In addition, the SARFIIP program is developing floodplain infrastructure that will address the continuing decline in ecosystem health and deliver improved ecological outcomes for floodplains along the Lower River Murray. Active management of groundwater to enhance ecological condition and manage risks associated with surface water inundation is an integral part of the program design.
The close relationship between groundwater and vegetation condition needs to be understood to make best use of environmental water. There has been considerable investment in improving vegetation along the River Murray floodplain, and groundwater management may provide one of the most cost-effective interventions, especially where there is existing infrastructure. The learnings from the River Murray are likely to be applicable to other floodplains.
Agriculture is the dominant land use in the Werribee River catchment. Flow regime of the river has been dramatically altered to provide water for drinking and irrigation in this area, resulting in a significant depletion of flows in the lower reaches of the river in recent years. As a result of depleted flows and high levels of nutrients, this area is affected by large-scale accumulation of floating weeds and blue-green algal blooms.
Due to high nutrient levels, it is unrealistic to reduce weeds and algal blooms through water quality management. Therefore, the best approach is to prevent their build up by supplying a large enough flow. This study assessed the performance of a set of environmental flow releases as the mitigation measure for this ongoing issue.
A 3D hydrodynamic (HD) and advection-dispersion (AD) model of the lower Werribee river, was developed using MIKE by DHI 3D FM model. Hydraulic control points along the river were identified during a field survey. A series of ADCP velocity profiles were collected across the river by Water Technology during 2 environmental flow release events. Modelled velocities were successfully calibrated and verified against the velocity measurements. The AD model assessed the performance of the flow release for residence time improvement and the prevention of accumulation of blue-green algae blooms.
It was concluded that lower environmental flow releases in the range of 6 to 80 ML/d are not sufficient to achieve satisfactory flushing of the lower Werribee River. An environmental flow of 100-200 ML/d performed best to mitigate algal bloom accumulation.
When Perception and Evidence Based Practice Collide – Floodplain and Waterway Management in the aftermath of the 2016 Floods at St Marys, Tasmania
St Marys is a small town near the east coast of Tasmania which experienced three significant flood events in 2016. The largest event occurred in January 2016 and resulted in extensive damage including above floor flooding to numerous dwellings. The event has been estimated to be larger than a 0.5% AEP (1 in 200 year ARI) event and also resulted in significant changes to the waterway through the township.
The St Marys Flood Risk Management Study was commissioned six months ago by Break O’Day Council and has since been completed by Water Technology in partnership with Council, the community of St Marys and a number of other key stakeholders. The study commenced in late September 2017 against a backdrop of strong public perception around the cause of flooding at St Marys and how it should be managed. Through extensive consultation, engagement and education the community and study team have come to better understand why the town floods, and the sort of flood risk management options that could be implemented which won’t adversely impact the town’s greatest natural asset – the St Marys Rivulet.
The study has almost concluded and has been a great success with a number of actions identified to improve flood risk that have the strong support of the community. While improving waterway management was not an objective of the study the community has also come to better understand riverine processes in the rivulet and as a community have committed to working together to maintain and improve the ongoing health of the waterway.
From planting willows to pulling them out: The past, present and future of riparian management in Victoria
Peter Vollebergh (Department of Environment, Land, Water and Planning (VIC)), Jo Slijkerman
Riparian management in Victoria before the 1990s largely meant planting willows. Since then, particularly after the formation of catchment management authorities (CMAs) in 1997, the emphasis has been on using revegetation, weed management, fencing and off-stream stock watering to maintain or improve the condition of riparian areas. The program has resulted in several waterways being more than 80% fenced and protected.
Strong policy and funding have underpinned the Victorian Riparian Management Program. The Victorian Waterway Management Strategy (2013) and its predecessors provided policy and strategic direction for how riparian management was implemented – from the general framework such as how nine CMAs deliver the program by working with landholders in voluntary partnerships, to resolving operational issues and obstacles to the implementation of on-ground riparian work. Examples of the latter include the development of controlled grazing guidelines, information about fire on riparian land, and policy changes that make it easier for farmers who fence to get access to stock water. Improvements to the licensing of Victoria’s Crown water frontages have also been a key component of the program.
A dedicated plan – the Regional Riparian Action Plan – was released in 2015. It is a high priority for state government with over $40 million allocated to its implementation for five years. It outlines policies and actions for the future of riparian management in Victoria.
Although undertaken in Victoria, the lessons learnt from riparian management in the state are transferrable and far reaching, well-beyond jurisdictional boundaries.
Tom Atkin, Julian Martin, James Kaye
In 2000, the City of Wodonga and the North East CMA jointly developed the Wodonga Waterway Action Plan. The original plan is now out of date with many of its objectives met and new issues arising from a change in social, environmental and economic factors in recent years.
The Wodonga Urban Landcare Network (WULN) were tasked with the development of a new Wodonga Regional Water Action Plan with support of the City of Wodonga and North East CMA. The project area encompasses all the waterways across the City of Wodonga. Each of these waterways have a unique range of values including ecological values, passive recreation uses and aesthetic values and threats including urban encroachment, stock grazing, historic mining, channel instabilities and weed dominance.
The new Regional Waterway Action Plan aimed to develop sustainable restoration and management strategies for the waterways across the project region, accounting for the community and waterway values, aspirations and priorities as they relate to the waterways of Wodonga. Importantly, the implementation of the Regional Waterway Action Plan shall be managed by the Wodonga Urban Landcare Network who work with 14 different community groups, including regional Landcare groups, school groups, TAFE, Universities, Wodonga City Council, the North East CMA, individual landholders and other land managers.
This paper discusses the approach and key lessons learnt from the development of a community led strategic waterway action plan.