Estimating Land Surface Diversions (LSD) / Floodplain Harvesting Projects

The Murray-Darling Basin Ministerial Council in 1995 agreed to a Cap on diversions. Diversions from the floodplains and overland flows (called Land Surface Diversions LSD) are included in the Cap.

A Status Report on Land Surface Diversions prepared by the Murray Darling Basin Commission (MDBC) in 2006 estimated that LSD, accounts for 20-30% of total diversions from the M-DB river valleys in the northern NSW and southern Queensland. Currently there is not any readily available method to measure or estimate LSD with any reasonable accuracy. Consequently LSD is not being monitored and thus implementation of the Cap remains incomplete. The MDBC in early 2007 established a two-stage (stage 1 - scoping and stage 2 -implementation) pilot project in northern NSW and southern Queensland M-DB valleys. The Stage 1 project completed in mid-2007 evaluated the options for estimating LSD; and recommended that “on-farm water balance” using on-ground monitoring is the most feasible option to estimate these diversions (see Stage 1 Report).

Following the completion of the Stage 1 project, the MDBC in late 2007 established two projects for the Stage 2 to develop a suitable method for estimating LSD through “on-farm water balance”.

• On-ground Monitoring project and 
• Remote-Sensing project.

The On-ground Monitoring project will measure, monitor and analyze water movements on six selected farms (three each in southern Queensland and northern New South Wales Murray Darling valleys) for three irrigation seasons. Using the on-farm water balance principles it will separate the used water into its various sources (irrigation, river harvesting and LSD).

The Remote Sensing project will use remote sensing (eg satellite imagery) and geographical information systems (GIS) techniques to develop farm water balance models and use the data collected and analyzed by the On-ground Monitoring project to validate those models.

These two alternative methods provide the opportunity to cross-verify results from each method and determine which method is preferable. These projects have started and are expected to be completed by March 2010. On the completion of these projects, the MDBC is confident to have a tool developed to estimate LSD with reasonable accuracy.

These projects are technical investigations and do not present a policy position.

For more information contact:

MDBC (Awadhesh Prasad: 02 6279 0144; Awadhesh.Prasad[at] mdbc.gov.au)

NSW (Paul Simpson:  02 9895 7480; Paul.Simpson@dnr.nsw.gov.au)