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Research projects currently being undertaken include:
NORTHERN AUSTRALIA IRRIGATION FUTURES: BUILDING A BASIS FOR DEVELOPING SUSTAINABLE IRRIGATION ACROSS TROPICAL AUSTRALIA Project
Website This project will deliver a framework for use by policy makers, regulators, managers, and investors to ensure irrigation is developed in a sustainable manner across northern Australia. Stage I of the project will involve development of the full project team, key client/stakeholder/collaborative network, and detailed work plan and budget. Stage II will involve carrying out the work plan agreed to in Stage I. The project will use past experience and new knowledge to build an understanding of key landscape attributes (including soil and water resources, climate, vegetation, rivers, near shore marine environments) relevant to sustainable irrigation in tropical systems. This knowledge will be used to deliver a framework based on sustainability indicators and management criteria at a range of scales (field, farm, district, scheme, and catchment) to support planning, development, implementation and management of new schemes, and if necessary, modification of existing schemes across northern Australia. Project objectives
CAN IRON IN THE AQUIFER REDUCE NITRATE? In some of the aquifers in the world, a negative correlation has been found between nitrate and iron indicating there may be denitrification occurring in aquifers. Reddish deposits around the pumps and clogging of pumps observed in certain areas of the Lower Burdekin are the evidences for the existence of iron. This project aims to investigate the potential of the Lower Burdekin aquifer for denitrification.
A FRAMEWORK TO HELP GUIDE SUGAR INDUSTRY RESPONSE TO EXTERNAL DEMANDS FOR WATER REFORM IN THE LOWER BURDEKIN (CSIRO, CRC SUGAR) The aim of the project entitled "A framework to help guide sugar industry response to external demands for water reform in the Lower Burdekin" is to provide a framework to assess whether the sugar industry in the Lower Burdekin can remain economically viable when required to meet COAG and environmental requirements. The objective of the project is to support the regional sugar industry and other stakeholders by investigating the potential impacts of water reform on profitability of farms and viability of the industry and regional community. A stakeholder workshop was conducted on 6th December 2002. It provided an opportunity to discuss in detail how potential water reform measures might influence cane growing and irrigation activities. The workshop outcomes, combined with past and ongoing research in the Lower Burdekin, provides the basis for a framework for understanding the financial, social and environmental consequences of water reform. The framework will prove valuable for the sugar industry and other stakeholders in future negotiations about water reform. A detailed account of the workshop and its outcomes are being written up in a workshop report, which will provide a basis for framework development and ongoing discussions with stakeholders in the Lower Burdekin, to be conducted during February 2003. The project report will be submitted to the CRC for Sustainable Sugar Production in March 2003. Workshop photo (41 kB) GROUNDWATER FLOW AND SEAWATER INTRUSION MODELLING IN THE LOWER BURDEKIN Water quality degradation due to seawater intrusion is a major issue for the Burdekin Delta aquifer. The areas under the most threat of seawater intrusion are those closest to the shoreline or adjacent to tidal estuaries. Current data suggests that the seawater interface extends for some kilometers inland, placing some inland bores under threat of seawater invasion. The regions that are most susceptible to seawater intrusion are the coastal areas of the North Burdekin. The South Burdekin region is less prone to seawater intrusion due to smaller exposure of coastline, shallower basement and, stronger hydraulic gradient. A reduction in water levels in the coastal areas results in a rising of the seawater interface. Modelling of seawater intrusion into coastal plain aquifers is a complex task. Due to density contrast between the seawater and groundwater, a density dependent flow and solute transport model must be used to simulate such complexities. This requires skills and expertise in the use of such models. The model must also account for dispersion (mixing zone) at the seawater-groundwater interface. Objectives The main objectives of this project are: To establish suitable methodologies for analysing the behavior of the salt-water wedge through application of the SUTRA model in the lower Burdekin , and To use groundwater models to investigate likely impacts of various alternative management options in the assessment of the impacts of;
The purpose of the groundwater model is to simulate the behaviour of the groundwater system underlying the Burdekin River Delta area. As the groundwater model develops it will be used to assist with development of water use efficiency measures and other management strategies to ensure that irrigation in the Burdekin delta is sustainable. To achieve this, activities such as operation and maintenance of artificial recharge works, provision of irrigation water to farms and the use of water on farms have to be carefully examined. The aim of the groundwater model is to assist in determining the real or potential long-term effects that changes in water management might have on the sustainability of the groundwater systems. Key objectives in developing the groundwater model are to assist with
Further details on Groundwater Modeling (PDF, 367 kB) SOIL MAPPING & CHARACTERISATION The lack of adequate soils information and soil maps has been identified by the local industry stakeholders as a very high priority in the recently released "Draft Community based Natural Resource Management Strategy for the Burdekin - Bowen Floodplain Sub-region". This project will provide a comprehensive database of the soils of the Burdekin Delta thus addressing the themes/strategies above as well as several of the key high priority issues identified in the strategy. The maps and databases produced during the project will ensure adequate information is available to make informed management decisions and strategic plans for appropriate land utilisation in the Burdekin Delta. The data collected will provide information essential to the sustainable management of the regions groundwater resources, the development of appropriate irrigation practices guidelines and will be complimented by the soil hydraulic characterisations carried out during the survey. It will also help with identification of potential Acid Sulfate Soils and good quality agricultural land. MEASUREMENT OF DEEP DRAINAGE RATES & QUALITY The overall aim of this project is to provide a basis for the development of sustainable management strategies for the Burdekin delta groundwater systems. This aim will be achieved by providing:
ANALYSIS AND IMPROVEMENT OF ON-FARM MANAGEMENT PRACTICES It is the aim of this project to improve the knowledge of the impacts of current and modified water management practices (including recycling and water spreading and on-farm irrigation practices) on long term sustainability of the Burdekin delta groundwater systems, through:
ECONOMICS OF A RANGE OF ALTERNATIVE IRRIGATION AND WATER MANAGEMENT SCENARIOS The long-term 'health' of the groundwater systems in the Burdekin delta is critical to the economic and environmental well being of the whole region. Application of economic analyses that allow the impacts of allocating scarce groundwater resources to be assessed, and which allow the environmental and social opportunity costs and benefits of various irrigation management options to be evaluated will help in future decision making. A multi-period mathematical programming model is therefore being developed to estimate the responsiveness of water demand to price changes and to alternative water management and irrigation practices. UNDERSTANDING CAUSAL FACTORS OF OXYGEN DEPLETION IN WATERWAYS OF CANE GROWING REGIONS This project is a new CRC Sugar funded activity to investigate dissolved oxygen in waterways of cane growing areas. The project was initiated after low dissolved oxygen levels were measured in streams where fish kills had occurred. The processes influencing dissolved oxygen levels in waterways are currently poorly understood. Water temperature, shading by weed mats, algal blooms, rotting organic matter and groundwater flow are all believed to play a part. Monitoring sites are in place at Payard’s Lagoon to measure dissolved oxygen, pH, salinity, temperature and stream flow. As dissolved oxygen levels fluctuate greatly through a day and a season, detecting changes in trends requires regular monitoring. For this reason, CRC Sugar and CSIRO Land & Water have invested in automated monitoring equipment that is set to obtain continuous measurements at short time intervals. The research at Payard’s Lagoon is being carried out jointly with the Australian Centre for Tropical Freshwater Research (ACTFR) and the Australian Institute for Marine Science (AIMS), who additionally collect detailed water quality data including total nutrient and phosphate and heavy metals. They are working on a project of the Burdekin Bowen Integrated Floodplain Management Advisory Committee (BBIFMAC), “Management of fish habitat values in the Burdekin delta distributary streams” which also includes regular fish sampling. A study of in-field processes affecting the oxygen demand of run-off water is also underway as a part of this research initiative. FISH HABITAT VALUES OF THE LOWER BURDEKIN DELTA DISTRIBUTORY STREAMS The fish habitat project is aimed at identifying the status quo of fish habitats within the delta. In conjunction an assessment of fish community structure and health is being done. Presently we have sampled 10 lagoons in Sheep station and Saltwater Ck./Munro's diversion. We have identified that weed infestation is the major driver in poor water quality. Due to the activities at Payard's lagoon last year we found that native fish communities respond quickly to mitigation works. However, most of our sites show a highly depressed fish diversity. Out of a possible 43 fish species in the Burdekin only 27 have been recorded. Now we are focusing on the habitat characteristics of the sites. This includes assessment of riparian condition, instream plant growth, weed infestation, water quality parameters, and lagoon morphology. We are expanding our sampling in the delta to find sites with fish species that are missing in the main study area. If we can locate sites with missing species we can collect detailed habitat data which will enable us to identify limiting factors in the distribution of those species within the delta. We are specifically looking for bony bream, banded grunter, long toms and fork tailed catfish. Historically these species commonly occurred in the floodplain. Presently however these species have not been recorded in the floodplain lagoons. We will be conducting some sampling in the river itself to see if that is the main refuge for these species. Other areas we will be looking at include the Barratus and Collinsons lagoon system. FINFISH AND NUTRIENT MANAGEMENT Canals bringing water to the cane lands often become choked with weeds. Mechanical harvesting of aquatic weeds is costly and may disturb the environment. The Burdekin delta lies adjacent to the Great Barrier Reef (GBR) and ideally water discharged from the delta should benefit the GBR. Can aquaculture assist with sugarcane agriculture sustainability issues? Many overseas countries employ multiple water usage technologies - eg aquatic plants are used to strip dissolved nutrients and to feed secondary crops. Our challenge in Queensland is to identify the local species (eg fish) and the systems which are most suitable for multiple water use. This pilot study, in conjunction with the South Burdekin Water Board, will assess the capacity of several native fish to consume aquatic plants of the Burdekin and, indirectly, sequester dissolved nutrients. This new knowledge will promote the wider application of multiple water use systems to help maintain good quality waterways. View Finfish Poster (PDF, 245 kB) FinFish Progress Report (Word file, 27 kB) NITROGEN BALANCE AND NITRATES IN GROUNDWATER Water containing high concentrations of nitrate is unfit for human consumption and, if discharging to freshwater or marine habitats, can contribute to algal blooms and eutrophication. Nitrate pollution of groundwaters in coastal northeastern Australia is of particular concern because of its proximity to environmentally sensitive areas (eg the Great Barrier Reef) and the large number of people (in cities and rural areas) who rely on groundwaters for drinking water. A study was conducted to determine the extent of nitrate contamination in groundwater in this region, and examined the likely source of the nitrate (from interpretation of natural abundance N isotope concentrations of groundwaters). In bores where nitrate concentrations were elevated, and therefore likely to be a result of human activities, concentrations were subsequently monitored to provide an assessment of temporal trends in nitrate concentrations. Overall, groundwaters were relatively free from excessive nitrate contamination, with nitrate concentrations in only 3 % of bores above the drinking water guideline. However, a further 11 % had elevated nitrate concentrations (> 20 mg/L) with the greatest occurrence (14-21 % of bores affected) of elevated nitrate concentrations being in the Burdekin, Mackay and Bundaberg areas. These percentages are similar to those found in many other intensive agricultural areas. Nitrate in approximately half of these bores was likely to have come from fertiliser. Nitrate in very few bores is likely to have come from organic sources, such as sewage, septic or feedlot overflows. Thus, improvement of nitrogen fertiliser management practices is a key activity in managing groundwater nitrate concentrations. In the Burdekin and Mackay areas, there was no general trend in groundwater nitrate concentrations over 2 years of monitoring of bores with initial nitrate concentrations > 20 mg/L. However, there was considerable variability within bores between sampling times and further monitoring is required to understand these dynamics and whether there are any long-term trends. In Bundaberg, nitrate concentrations in 40 % of bores significantly declined over 6 years (1993-1999) of regular monitoring. While results for the Bundaberg area suggest that nitrogen fertiliser inputs were not excessive relative to the local aquifer’s nitrogen balance during the monitoring process, there are still opportunities for further improvements in nitrogen fertiliser management in these areas. MAKING BEST USE OF LIMITED WATER SUPPLIES In this project we are finding out how various yield-determining processes (leaf area, stalk and leaf elongation, dry and sucrose matter accumulation) are affected during the onset of water stress in order to assess consequences to cane yield and CCS when irrigation is limiting. We are also using state of the art technology to determine water requirements for sugarcane in order to help growers better match water supply and demand and to see if there are opportunities for saving water and improving crop water use efficiency. Some interesting results have emerged thus far: In one experiment, the order in which growth processes were first affected by water stress was as follows: Leaf elongation was the first process to suffer from water stress, then stalk elongation, then total fresh biomass accumulation, then fresh and dry cane yield accumulation and finally sucrose accumulation. After the onset of stress, stalk elongation suffered more than leaf elongation due to lack of water. In another experiment, a long dry off period from April to October had surprisingly little effect on cane yield. Sucrose content was increased by 2 or more units over a period of about one month rather than gradually as was expected. The results indicated that irrigation may not be required in some soils in the Burdekin after a good wet season. Research on crop water use has confirmed FAO standards for determining crop water use from readily available climatic data and has led to a small adjustment in the APSIM-Sugarcane model which can now calculate crop water use quite accurately. The research has been corroborated by findings in similar research conducted in Swaziland. A reliable means of determining crop water use is important for management of deep drainage and runoff. Good crop water use estimates are necessary to benchmark and improve water use efficiency and profitability and this capability is now well advanced in this project. BURDEKIN RIPARIAN REHABILITATION PROJECT The Burdekin Riparian Rehabilitation Project (BRRP) commences with 16 trainees undertaking training and duties with the Burdekin Shire Council. In the next few weeks work will commence on the rehabilitation project along Sheep Station Creek. This project should lead to better water quality and reduced weed infestation of this waterway, and will include work with the aquatic weed harvester when it is finally purchased. Further information can be obtained by contacting Tony Chandler or Brian Smith at the Burdekin Shire Council 4783 9800. ADDRESSING WATERWAY HEALTH - WATERWATCH PROJECT Addressing Waterway Health is a water quality monitoring program to help communities test their local waterways, and to help tackle any problems that may be found. The Burdekin Waterwatch project has the support of local Landcare and Canegrower groups, with assistance from the Natural Heritage Trust. Training workshops are being held to assist people learn how to water quality test. Further information can be obtained by contacting the Waterwatch Co-ordinator, David Reid on (07) 4721 4077. Further Reading
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