Michael Morris

Senior Research Scientist, Irrigation Hydrology, Department of Economic Development, Jobs Transport and Resources, Victoria

Michael Morris

Senior Research Scientist, Irrigation Hydrology, Department of Economic Development, Jobs Transport and Resources, Victoria

In the past 7 years Mike has undertaken research on border-check irrigation in northern Victoria, initially focussed on the role of irrigation inflow rate on irrigation performance and more recently on improving irrigation performance through modified border-check bay surface designs.  This work has involved adaptation of the open source ANUGA tsunami and riverine flood model for use a 2D surface irrigation model, the development of soil moisture sensor networks and the supervision of field experiments to test the performance of modified bay surfaces.

His presentation will discuss the rationale for the investigation of new bay designs, the results of field evaluations  of modified bay surfaces and farmer experiences using modified bay surfaces.

Where: International Convention Centre, Sydney – Room E5. 10

When: Day 2 – Thursday, 14 June 2018, 13.30 – 14.00

Abstract Outline: Modernised irrigation supply systems in the regulated irrigation areas of southern NSW and Victoria now facilitate precise scheduling  and more efficient irrigations by delivering more timely irrigations at higher, more consistent and known flow rates. However these improvements have exposed some limitations that are inherent in conventional border-check bay design.

Border-check irrigation remains the dominant irrigation method in the southern MDB, using the land surface and gravity to convey water from the farm supply channel to the plant.  Typical border irrigation bays are rectangular, smoothly landformed surfaces 40 to 80 m wide, 200 to 800 m long and with surface elevation gradients in the long axis of between 1 in 200 and 1 in 1000.

A conventionally landformed bay surface helps to uniformly spread water, but is not efficient with respect to surface drainage from the bay after the water supply is cut off. On sites with low permeability subsoils, the duration of inundation within a conventional bay can vary from 2 hours to 2 days, reducing irrigation precision, affecting plant growth, increasing water losses to deep drainage and limiting irrigation efficiency.

Our work has used a two dimensional surface water flow model to investigate border irrigation bay surface modifications that could improve the precision of surface irrigations by reducing both the overall duration of inundation and its variation within bays during irrigations.  The model has been used to evaluate a range of potential bay surface modifications, assessed over reasonable ranges of inflow rate, bay dimension, slope, soil profile infiltration rate and resistance to surface water flow.

This paper presents the results of these simulations and results from field assessments of two modified bay surfaces undertaken in the past two years on commercial dairy farms in the Goulburn Murray Irrigation District and Macalister Irrigation District of Victoria. The work has shown that substantial improvement in border-check irrigation performance is feasible with simple bay surface modifications.  The discussion includes estimated costs of installation and maintenance of modified surfaces, and the practical experiences of farmers using border-check irrigation bays with modified surfaces.

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