Integration and Optimisation of Salt Interception in the Sunraysia Region

Project: Integration and Optimisation of Salt Interception in the Sunraysia Region

Aim: Find the optimal approach to reducing salt accession to the River Murray in the Sunraysia Region.

Investigation Activities

Literature Review
Preliminary Hydrogeolocial Investigations
Concept Development
River Salinity Monitoring
Community Involvement
Identify implementation process

Project Overview

For the purpose of this study the "Sunraysia Region" stretches from Colignan to immediately upstream of lock 10 at Wentworth.

The River Murray in the "Sunraysia Region" benefits from a number of salt interception and drainage disposal schemes on both sides of the river in New South Wales and Victoria. Although these schemes are currently operated independently, it has been suggested there may be benefits from integrating their operation and infrastructure, such as a cross-river pipeline and shared evaporation basins. There may also be potential to enhance interception capabilities through augmentation of infrastructure and management options that reduce groundwater movement.

A regional "no borders" approach will be used to identify the most critical influences on salt movement and based on available technology, identify opportunities to redesign, augment or enhance the existing schemes to optimise salt interception in the region.

Build and non-build options are to be identified via a 'Greenfield' approach, ie initially ignoring the existing salt interception schemes. Once the 'Greenfield' options are established, they will be used to develop further options that may incorporate current schemes with new technology, opportunities for redesign, optimisation of operation and integration of resources.

Steps towards a Solution

Project Management
To oversee this investigation a project management committee was established in November 2000, comprising representatives from NSW, Vic and the Murray-Darling Basin Commission. The NSW Department of Land and Water Conservation was appointed as the Project management Authority.

In August 2001 Sinclair Knight Merz and Australian Water Environments were appointed as the consulting team to undertake this project.

Literature Review
Groundwater movement in the region is complicated by three overlying aquifers, distorted by faults and folds. Further complications occur from groundwater mounds forming under irrigation areas and spreading out around weir pools.

Over the decades many studies have been conducted to understand the groundwater movement. Over 100 reports were collated into two summaries - a summary of the hydrogeology and a summary of scheme infrastructure and performance.

These summaries now serve as the main technical references for this project. They have already saved technical specialists considerable research time and will prevent duplication of research efforts in the future.

Hydrogeological Investigations
Decades of monitoring the Buronga Salt Interception Scheme gave some puzzling results as the groundwater salinity failed to decrease as predicted. To solve the puzzle, bores were drilled into the aquifer and then tested for groundwater pressure, salinity with depth, pumpout rates, gamma readings and EM39 induction. Similar, tests were conducted on the opposite side of the river to assess the influence of pumping at Buronga.

The test results are now being used to create a three-dimensional computer model of this part of the region.

Concept Study
This study looks to determine the most optimum approach to reducing salt accessions to the River Murray. It takes a ' no borders' approach so that it is independent of State and local boundaries.

The first step brings together monitoring data to construct a regional water balance. The water balance will show the origin of water seeping into the ground and the path it takes to push saline water into the River Murray. Next, a range of possible options to protect the river will be examined by a diverse group of people including representations from technical experts and the local community.

A preferred solution will be selected which will then be used as a basis for more detailed investigation and development including the review and upgrading of monitoring systems and the development of an integrated regional groundwater model.

River Salinity Monitoring
Salinity monitoring in the River Murray has lead to the development of various salt management initiatives including salt interception works. This project is looking to fine-tune salinity monitoring so that the impact of groundwater pumping on salinities in the River can be more efficiently and effectively assessed. Conversely an improved monitoring network will also provide valuable data to assist in improving the effectiveness of interception works.

To provide a baseline profile of River salinities, the SA Department of Water Resources has recently completed a 'run-of-river' salinity survey.

Community Involvement
Discussions have been held with the Local Water Authorities, Catchment Management Authorities, and local councils in both NSW and Vic to firstly advise them of what the aim of this project is and secondly to determine the most appropriate avenue to involve the local community in understanding the project and having input to the preferred concept.

A workshop to examine a range of concepts to optimise and integrate salt interception in the region will be held in the region in March 2002. It is anticipated that the outcomes from this workshop will define the preferred option that will be presented for consideration to the Murray-Darling Basin Commission. This presentation will also include recommendations on the most appropriate means of implementation.

Any feedback or comments arising from this website article will be presented at the workshop.

If you would like more information on this project or have any suggestions that may assist in enhancing salt interception in the region, please contact:

phil.pfeiffer@rmw.mdbc.gov.au

Content correct as of :04/ 06/ 2004