Making an Informed Water Decision
Note Number: AG1391
Published: January 2010
Updated:
The past few years of low water allocations have meant that growers have not always received enough water when it was needed.
Information for Murray system for the 2009/2010 irrigation season
Allocations and critical watering times
Flowering and fruit set are the most critical times for adequate water to be available to ensure a good yield, see the table below. However as the fruit expands the volume of water needed increases rapidly with the most water being used in the warm spring and summer months. Demand for water then slows as the fruit ripens. The graph above plots the allocations for the last two seasons against typical water demands of three crop types, on a percentage basis. The table to the right shows that in dry seasons water allocations have not been adequate for crop demands, particularly early in the season.
For the last three seasons there has been no high security water allocations for the Murray until September, as can be seen in the table on the right. The current system for allocating irrigation water in Victoria is to start with a 0% allocation and increase the allocation as the season continues. This has meant most growers needed to buy carry over water to satisfy plant water needs and avoid water stress.
Table 1: Allocations percentages at critical times over the past four seasons
| Year | July | Sept | Dec | Feb | Final Total |
| 2006/2007 | 81% | 85% | 93% | 95% | 95% |
| 2007/2008 | 0% | 5% | 26% | 36% | 43% |
| 2008/2009 | 0% | 0% | 24% | 35% | 35% |
| 2009/2010 | 0% | 2% | 60% |
What can we learn from the past few seasons?
Each season is different and there are going to be many factors that impact on the price of water.
Graphs of allocations verses price and volume traded verse price can be found for all sections of the river on the watermove website.
Carry over water has become important to manage the critical watering periods of early season when allocations are low.
Water costs have been at their highest in early spring over the past few seasons. Long term planning would suggest that buying water over the course of a season will even out some of the price fluctuations.
Table 2: Critical Water Use Timing
| Crop | Critical time for water availability |
Most water used
|
| Citrus | Flowering to fruit set Usually from 1 st September |
October- Feb |
| Grapes | Flowering to berry set Usually from 1 st October |
November- Feb |
| Almonds | Bud swell to four weeks past end of flowering Usually from 15 th August |
October- Jan |
Further References
Acknowledgements
This information note was developed by Sally-Anne Henderson, Farm Services Victoria. January 2010.
ISSN 1329-8062
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