Technical Event: Drainage Course Declarations for Irrigation Sustainability and Regional Resilience in the Shepparton Irrigation Region

INTRODUCTION
Implementation of the Shepparton Irrigation Region (SIR) drainage strategy commenced in 1995 and originally envisaged a network of larger authority-owned drains connected to smaller community-owned drains.  However, since the late 1990s a reducing irrigation footprint, drier climate, irrigation supply system modernisation and better on-farm water use efficiency have collectively decreased irrigation tailwater runoff, channel outfalls and drainage discharge.  The reduction of both irrigation and rainfall induced runoff has changed the economic benefits of surface drainage, based on the assumptions of the original strategy.

These changes have driven the need to find more economic ways of removing excess rainfall runoff on irrigated land by enhancing natural drainage courses, rather than continuing to construct excavated earthen surface water drainage systems.  A 2015 review of the Goulburn Broken Catchment Management Authority’s (GB CMA) SIR drainage strategy identified a “…clear need to address the changed economics by developing a new type of lower cost surface drainage system; and that this could be developed using a “hybrid drain” comprising of Drainage Course Declarations (DCDs) and constructed drains…”.  

Importantly, by reinstating natural drainage courses, this approach also provides greater opportunities for improved environmental and cultural outcomes.

DRAINAGE COURSE DECLARATION CONCEPT
Implementation of a Drainage Course Declaration (DCD) aims to connect natural drainage courses within a catchment that have become fragmented or are obstructed by artificial barriers (e.g. banks and undersized culverts).  By restoring and preserving the natural flow characteristics of a drainage course, water is able to flow down a natural drainage line or depression as it would have under near natural conditions.  The DCD approach also provides environmental benefits by reinstating more natural flows to features such as wetlands. 

This new approach relies primarily on establishing DCDs under section 218 of Victoria’s Water Act 1989.  The process also provides the necessary legislative power to ensure the DCD remains free of obstructions in the future.  The establishment of a DCD is accompanied by an obstruction removal program, which may include the removal or lowering of artificial levee banks, the augmentation of existing drainage culverts under roads, lowering of farm tracks and other barriers that impede flow shown in Figure 1.

Figure 1. Drainage Course Declaration Concept

Drainage Course Declaration schemes based on reinstating natural drainage courses are helping to support irrigation sustainability and build regional resilience by delivering improved economic, social, cultural and environmental returns that are strongly supported and endorsed by actively engaged landowners, regional agencies, Traditional Owners and the wider community based on successful implementation since 2017. Come along to hear about the outcomes and benefits of the program presented by Carolyn Nigro of Goulburn-Murray Water.

VENUE: Upstairs at Bill & Beats, 106A McLennan St, Mooroopna VIC 3629 (map)

TIME & DATE: 12.00pm – 1.00pm, Thursday 12th December 2024

COST: $20 includes lunch. Please advise dietary requirements in the Checkout: Additional Information – Order Notes.

RSVP: No later than 5pm, Monday 9 December 2024

RSVP now

We look forward to seeing you there.

Regards

IN-GV Committee