Groundwater investigation study
Background
The Swan Catchment Council provided $300,000 to the Department of Water to trial real-time monitoring of private groundwater abstraction in the Carabooda area. The Department managed this project, which was developed with input and expertise from Schlumberger and the CSIRO.
The Gnangara Mound Metering Project has implemented a study to link directly into the WaterWise on the Farm project, which is run in partnership with the Department of Agriculture and Food.
Both of these projects formed part of the Water Efficiency Trial Project. In September 2006, the Schlumberger component ended. The data is currently being verified and will be released shortly.
For more information, please send your enquiries to ben.trezise@water.wa.gov.au or (08) 6364 7720.
Aims
The Water Efficiency Trial Project aims to gather data to:
- meet the requirements of the Environmental Protection Authority for more active management of groundwater use on Gnangara Mound
- validate the current approach of calculating the water entitlements of irrigators (which is based on crop factors for water licensing)
- obtain accurate data for calibrating the Department of Water’s groundwater computer model (PRAMS)
- ensure that the groundwater monitoring network will be effective in managing the Mound’s groundwater resources
- provide data that will assist the development of state-wide policies
- encourage the use of best practice management by private water users
- develop benchmarks for water use efficiency.
The intensive study site aims to gain:
- a detailed understanding of water level fluctuations as a result of private abstraction and
- scientific evidence of water returning and nutrient infiltration to aquifer systems.
Outputs
- enabling direct feedback to licensees on the effectiveness of water use efficiency (working in conjunction with the WaterWise on the Farm project that aims for a 20 per cent increase in efficiency)
- improved communication with Gnangara Mound water users on the importance of water resource management
- improving the knowledge and skills of the Department in making more informed water allocation management and planning decisions
- validating the accuracy of water licence allocations to licensees
- improved data, allowing a more rigorous assessment of water allocations
- validation or contradiction of the crop factors applied in the water allocation and licensing process
- re-calibration of the PRAMS model based on real data to improve the integrity and accuracy of the Department’s decision-making processes
- improved information on resource use and monitoring to resolve issues discussed in the Auditor General’s report (that was written in response to the audit conducted by the Irrigation Review Steering Group).
Review of Crop Application Rates - Baldivis and Carabooda
Preliminary analysis of metering results has indicated that a number of vegetable growers are experiencing challenges remaining within their annual licensed allocation.
It is the view of some local growers that they consider that the current crop figures are unrealistic even if they applied a strict watering regime and adopted best practice. Many vegetable growers have supply contracts with supermarket chains and are under pressure to supply large quantities of produce to an increasing Perth population.
In recent years there has also been more emphasis on buying local produce, consequently increasing this pressure. Therefore, many growers have increased their crop cycles, when in the past, they have rested the soil in between crops. An increased frequency of cropping cycles will result in increased water use.
Based on the results of the metering project and the expressed views of some local growers, the department is investigating the accuracy of the crop water use rates for vegetable growers.
The Department of Water has supplied and installed meters on a licensee's market garden in Baldivis and Carabooda. After accurate data is collected the review of these application rates can commence.
Carnarvon Meter Replacement Program
The department also managed the Carnarvon Meter Replacement Program (specifically Basin A of the Carnarvon Groundwater Area). There are 186 metered sites in this area, each were physically inspected in December 2006 to determine what modifications were necessary to fit a new water meter and determine costs associated for materials, labour and freight.
All of the 186 meters were found to be beyond their serviceability and accuracy parameters and are being replaced with new technology. The data logger will collect, store and transmit information and will also help to:
- provide monthly meter readings, which will support compliance and enforcement purposes
- undertake remote meter readings, reducing the need for entry by departmental staff onto properties.
The replacement program commenced in early March 2007 and was finalised in May 2007. One of our Project Officers is now assisting with the set up of a remote meter reading program.
Wireless remote meter reading
During the installation and meter reading process, the metering team is required to negotiate with licensees to resolve property access issues and bio-security concerns like traversing cropped areas to read meters. To reduce anxiety and potential liability, the team has been trialling a number of remote meter reading technologies. By utilising a purpose built handheld device and attaching a data logger to the meter, readings stored in the logger can be transmitted to the handheld device up to a distance of 700m. The trial has proved successful and now forms part of the department's meter reading program
The GSM telemetry trial
This trial was run on a trial project property in Baldivis. These reads were automatically logged and then sent via the GSM network to a web page where the data could be readily accessed by the department. The trial was successful but not practical at this time because the readings could not be converted into a format compatible to the department's corporate database systems, the equipment was not cost effective, the ongoing cost for data retrieval and access to these systems was prohibitive.
Dethridge wheel replacement at the Ord
The metering team has embarked on a "dethridge wheel" replacement trial in the Ord River. Dethridge wheels are predominately used on the Ord River to measure and monitor water use. Dethridge wheels are inaccurate, and will not meet the new Australian technical specification and have many inherent occupational health and safety (OH&S) issues. The metering team has entered into a partnership arrangement with the Ord Irrigation Cooperative to fund and trial two new open channel metering systems to replace existing dethridge wheels.
The proposal will identify costs associated with purchase, installation and freight of materials, robustness and important occupational, OH&S issues. The metering team is undertaking trial installations on three project properties, trialling different technologies to see which one is the most practical. The state is only required to install meters on a small number of these types of sites throughout Western Australia. The rest of these types of dethridge wheels will be replaced by licensees. After accurate information is gathered, the department will be able to determine which of the technologies will be more suitable in each of the circumstance and can thus be accurately costed.
Meter accuracy testing on Water Corporation's National Association of Testing Authorities (NATA) accredited rig
The objective of the accuracy testing was to identify whether the various types of meters used and typical pipework configurations impacted on the meter's accuracy and efficiency parameters introduced into infrastructure for different meter types, installations and meter sizes. This included assessing accuracies in a number of configurations that were not recommended by manufacturers.
To achieve accurate results, the department engaged Water Dynamics Quinti and Co. to assist the department by fabricating a series of different configurations of pipework including bends, straight lengths and flanges that has uniform table "d" connectivity. It was decided that each of the tests that were conducted would need to be manufactured in the following sized water meters:
This project was undertaken for the following reasons:
- tThe companies that manufacture water meters are located outside Australia and the department needed evidence of accuracy of instruments in Australia
- the metering project team wanted to confirm accuracy of meters used in the project and the typical method of installation
- provide information to the National Water Initiative (NWI) Metering Expert Group who is working towards the development and introduction of an Australian standard for "non urban meters". This provided evidence of accuracy to assist the metering expert group
- meters being installed, privately or otherwise will have to be patent approved. Testing the accuracy of meters is a way of ensuring the meters are recording accurately within the tolerances prescribed by the manufacturer such as; identifying various disturbance factors (e.g. check valves, flow switches etc.).
As a result of the testing, the metering team identified that one of the brands of meters did not meet the department's required accuracy standards and is now no longer utilised. All of the other meters utilised in the project obtained NATA accreditation, many of the installations passing the accuracy tests despite exceeding the manufacturer's minimum specification or operating conditions.
The development of the metering policy
The metering team helped write the policy Metering the taking of water. The final draft has been written and is waiting final approval. In implementing the State Water Plan and National Water Initiative, the Department of Water, the state's primary water resource management agency, will be developing a Metering Implementation Plan for metering water use throughout the state. Until the department is funded to implement that plan, the policy provides guidance on when the Department of Water will likely impose metering requirements on water licences.