Surface water numerical modelling for the Clarence-Moreton bioregion. Product 2.6.1 from the Clarence-Moreton Bioregional Assessment

No abstract available

Surface water numerical modelling for the Clarence-Moreton bioregion. Product 2.6.1 from the Clarence-Moreton Bioregional Assessment

No abstract available

Which crops should be included in a carbon accounting system for Australian agriculture?

Dryland agriculture is both a potential source and potential sink for CO2 and other greenhouse gases. Many carbon accounting systems apply simple emissions factors to production units to estimate greenhouse gas (GHG) fluxes. However, in Australia, substantial variation in climate, soils, and management across >20 Mha of field crop sowings and >30 Mha of sown pastures in the intensive land use zone, provides substantial challenges for a national carbon accounting system, and simple emission factors are unlikely to apply across the region. In Australia a model framework has been developed that requires estimates of crop dry matter production and harvested yield as the first step to obtain carbon (residue) inputs. We use Australian Bureau of Statistics data to identify which crops would need to be included in such a carbon accounting system. Wheat, barley, lupin, and canola accounted for >80% of field crop sowings in Australia in 2006, and a total of 22 crops account for >99% of the sowing area in all States. In some States, only four or six crops can account for 99% of the cropping area. We provide a ranking of these crops for Australia and for each Australian State as a focus for the establishment of a comprehensive carbon accounting framework. Horticultural crops, although diverse, are less important in terms of total area and thus C balances for generic viticulture, vegetables, and orchard fruit crops should suffice. The dataset of crop areas presented here is the most comprehensive account of crop sowings presented in the literature and provides a useful resource for those interested in Australian agriculture. The field crop rankings presented represent only the area of crop sowings and should not be taken as rankings of importance in terms of the magnitude of all GHG fluxes. This awaits a more detailed analysis of climate, soils, and management practices across each of the regions where the crops are grown and their relationships to CO2, nitrous oxide and methane fluxes. For pastures, there is a need for more detailed, up to date, spatially explicit information on the predominant sown pasture types across the Australian cropping belt before C balances for these can be more reliably modelled at the desired spatial scale. Murray Unkovich, Jeff Baldock and Steve Marvane

Mapping Economic Returns to Agriculture for Informing Environmental Policy in the Murray-Darling Basin, Australia

We integrate information from several disparate data sources including agricultural statistics and remote sensing to quantify and map the distribution and dynamics of agricultural returns to land and water resources from 1996/1997 to 2000/2001 in the Murray–Darling Basin (MDB), Australia. Total profit to agriculture was estimated at AUD3.86B in 1996/1997 and AUD3.73B in 2000/2001. The mapping reveals a high spatial concentration of economic returns to land and water resources from agriculture. Dryland agriculture covers over 82% of the study area. Irrigated agriculture covers 1.7% of the land area (2000/2001) but returns one third of the total profit to agriculture. We found that around 80% of the profit to agriculture comes from just over 5% of the land area. The results from this regional scale economic mapping can inform regulatory policy and public investments in natural resource management through targeting industries and regions that provide low marginal returns to the natural resource baseBrett A. Bryan, Stefan Hajkowicz, Steve Marvanek and Mike D. Youn

Atlas of Australian Acid Sulfate Soils: recent developments and future priorities

The Atlas of Australian Acid Sulfate Soils (AAASS) is a web-based hazard assessment tool with a nationally consistent legend, which provides information about the distribution and properties of acid sulfate soils (ASS) across Australia. This tool is available on ASRIS (Australian Soil Resource Information System: www.asris.gov.au) and every polygon or mapping unit is attributed with information pertaining to: (i) 4 classes of “probability of occurrence”, (ii) 4 levels of confidence relating to the quality of data source, and (iii) 10 additional descriptors such as desiccation cracks. In Australia, ASS occupy an estimated 215,000 km2 of which 58,000 km2 is coastal ASS and 157,000 km2 is inland ASS (Fitzpatrick et al. 2008a). In the coastal zone, 41,000 km2 are exposed at some point during the tidal cycle, with the remaining 17,000 km2 being permanently subaqueous. More than 126 km2 of coastal ASS with sulfuric material have been mapped, however this is a significant underestimate, which will be modified with future work. Being web-based the Atlas is a constantly evolving national map of available ASS information, which also includes priority case studies at a range of localities across Australia. With ongoing recent field investigations and acquisition of more detailed local spatial data sets, especially in the Lower Lakes region in South Australia, resolution and accuracy of the inland ASS component are being continually improved from its current, first cut “broad brush” depiction. Future priorities are to constantly integrate ASS data from any new regional ASS investigations to enhance, update and refine the AAASS and new case studies.Rob Fitzpatrick, Steve Marvanek, Bernie Powell and Gerard Grealishhttp://www.iuss.org/19th%20WCSS/WCSS_Main_Page.htm

Distribution and impacts of Tasmanian devil facial tumor disease

The Tasmanian devil, Sarcophilus harrisii, is the largest extant marsupial carnivore. In 1996, a debilitating facial tumor was reported. It is now clear that this is an invariably lethal infectious cancer. The disease has now spread across the majority of the range of the species and is likely to occur across the entire range within 5 to 10 years. The disease has lead to continuing declines of up to 90% and virtual disappearance of older age classes. Mark-recapture analysis and a preliminary epidemiological model developed for the population with the best longitudinal data both project local extinction in that area over a timeframe of 10 to 15 years from disease emergence. However, the prediction of extinction from the model is sensitive to the estimate of the latent period, which is poorly known. As transmission appears to occur by biting, much of which happens during sexual encounters, the dynamics of the disease may be typical of sexually transmitted diseases. This means that transmission is likely to be frequency-dependent with no threshold density for disease maintenance. Extinction over the entire current range of the devil is therefore a real possibility and an unacceptable risk

Surface water numerical modelling for the Clarence-Moreton bioregion. Product 2.6.1 from the Clarence-Moreton Bioregional Assessment

Coal and coal seam gas (CSG) development can potentially affect water-dependent assets (either negatively or positively) through direct impacts on surface water hydrology. This product presents the modelling of surface water hydrology within the Clarence-Moreton bioregion. First, the methods are summarised and existing models are reviewed, followed by details regarding the development of the model. The product concludes with predictions of the hydrological characteristics of the system that may change due to coal resource development (referred to as hydrological response variables) also taking into account uncertainty. Results are reported for two potential futures considered in the Clarence-Moreton Bioregional Assessment (BA): baseline coal resource development (baseline): a future that includes all coal mines and CSG fields that are commercially producing as of December 2012. coal resource development pathway (CRDP): a future that includes all coal mines and CSG fields that are in the baseline as well as those that are expected to begin commercial production after December 2012. The difference in results between CRDP and baseline is the change that is primarily reported in a BA. This change is due to the additional coal resource development – all coal mines and CSG fields, including expansions of baseline operations, that are expected to begin commercial production after December 2012. The Clarence-Moreton bioregion baseline includes one existing coal mine, the Jeebropilly Coal Mine in the Bremer river basin. An additional coal resource development is the Metgasco West Casino CSG project near Casino, NSW, in the Richmond river basin. As the baseline coal mine is far from the additional coal resource development, and there is no hydraulic connectivity between the Richmond and Bremer river basins, the conceptual hydrogeological model focuses on the geological, hydrogeological and hydrological characteristics of the Richmond river basin. A recent decision by Metgasco (16 December 2015) to sell back their petroleum exploration licences (PELs) to the NSW Government, as well as withdraw their petroleum production license application (PPLA), effectively means that future development of any CSG resources in the Clarence-Moreton bioregion is highly uncertain. However, as per companion submethodology M04 for developing a CRDP, once the CRDP is determined, it is not changed for BA purposes, even in cases such as this where Metgasco have discontinued their operations in the Clarence-Moreton bioregion. Surface water modelling in the Clarence-Moreton bioregion follows the approach outlined in companion submethodology M06 for surface water modelling. No river modelling has been carried out because the effects of regulation are small. There is an existing river system model of the Richmond River that uses Department of Primary Industries’ (DPI Water’s) Integrated Quantity and Quality Model (IQQM). Alternatively, the integrated modelling environment software known as Source IMS could be used to develop a Richmond River model. Neither IQQM nor Source IMS will be used in BAs. The Richmond river basin has low levels of stream regulation, so the routing parameters in IQQM are not needed for impact predictions. Instead, predicted streamflow is obtained by accumulating output from the Australian Water Resources Assessment landscape model (AWRA-L). AWRA-L has an accessible code, is relatively easy to set up and calibrate, and there is ready access to local expertise. AWRA-L performed well at estimating streamflow in the Richmond river basin and surrounding area. The conceptual model for the Clarence-Moreton bioregion in product 2.3 (Conceptual modelling for the Clarence-Moreton bioregion) indicates, based on current information, no new coal mines are expected in the foreseeable future and CSG development is restricted to the Richmond river basin of north-eastern NSW. The surface water modelling domain comprises parts of the Richmond river basin and includes 16 model nodes, which are located where daily streamflow predictions are reported as output. The model simulation period is from 2013 to 2102. Seasonal climate scaling factors are used that result in a reduction in mean annual precipitation of 1.8% per degree of global warming for the Clarence-Moreton bioregion. The AWRA-L model was regionally calibrated at nine unregulated streamflow gauging stations using two calibration schemes: one biased towards high streamflow and another towards low streamflow. Two parameter sets obtained from the two model calibrations were used as starting points to generate 10,000 parameter sets that can be used for the uncertainty analysis. It is noted that when the regional model is calibrated against observations from the nine streamflow gauging stations it does not generate a uniform model performance. While in general, model calibration results performed well across both the high- and low-streamflow calibrations, they both perform poorly in some areas. Quantitative and qualitative uncertainty analyses were undertaken for surface water modelling in the Clarence-Moreton bioregion to provide a systematic overview of the model assumptions, their justifications and the effect on predictions. In the uncertainty analysis the optimised parameters are used to inform the prior parameter distributions. The quantitative uncertainty analysis highlights the importance of constraining parameters with observations of the same type as the prediction, and it is clear that the hydrological response variables are sensitive to different parameters. For the high-flow metrics, the most important parameters are those controlling the quick-flow and interflow components of the hydrograph. The low-flow hydrological response variables are most responsive to the variable that controls the slow-flow component of the simulated hydrograph. The qualitative uncertainty analysis provides a summary of the major assumptions and model choices underpinning the Richmond river basin surface water model. The change in surface water hydrology predicted due to the additional coal resource development in absolute terms is predicted to have a median decrease of less than 0.01 GL/day, which corresponds to a change of about 0.01%. These changes are several orders of magnitude smaller than the observed mean streamflow. Their effect on mean and high-flow hydrological response variables will therefore be minimal. Even the effect on low-flow hydrological response variables will be very small, especially in the perennial streams. In addition to this, such low changes in flow are extremely hard to observe as the largest uncertainties in the rating curves used to transfer measured stage heights to flows are associated with low-flow measurements. The modelled impacts indicate that the number of zero-flow days (ZFD) across the region will not increase, with the exception of two nodes (CLM_007 and CLM_006). CLM_006 is at the downstream end of Shannon Brook where the median change in the number of ZFD is 3 days. The 95th percentile of change in zero-flow days is 120 days. As noted earlier, small changes in simulated flow can result in large changes in the number of zero-flow days, as zero-flow days are defined as days with streamflow less than 0.01 ML/day. The modelling of measurement of such low flows are problematic and uncertainty in these predicted impacts is high. Accurately measuring and simulating low-flow conditions is very challenging and requires further efforts. The surface water numerical modelling described in this product provides input into product 2.6.2 (groundwater numerical modelling) for the Clarence-Moreton bioregion. The impact and risk analysis (product 3-4) will not be conducted in the Clarence-Moreton bioregion due to very small hydrological changes predicted at or near the surface due to the additional coal resource development. Outcome synthesis (product 5) is the final technical product being developed for the Clarence-Moreton bioregion

An assessment of the historic Bradfield Scheme to divert water inland from north Queensland. A technical report to the National Water Grid Authority from the CSIRO Bradfield Scheme Assessment.

Eighty-three years after first being proposed, the Bradfield Scheme and its variants still arise as part of the national discourse on drought and water security. The term Bradfield has become almost synonymous with ideas for ‘solving drought’ by turning north Queensland rivers inland and/or moving water from northern Australia south. Interest in ‘Bradfield concepts’ rise especially in times of drought and are generally promoted as means to stimulate ‘nation building’ through creating significant and enduring regional economic development opportunities in water supply and irrigation. Recent interest in Bradfield Scheme concepts and variants have been further fuelled by projections of a drier future climate in south-eastern Australia, prolonged drought events such as the Millennium Drought (2001–2009) in southern and eastern Australia and the recent drought throughout northern and western Queensland (2014 to present). The Australian Government commissioned CSIRO, through the National Water Grid Authority, to undertake an independent, comprehensive desktop assessment of the technical and economic viability of the Bradfield Scheme and variants. These studies have taken a contemporary scientific approach to assess the technical feasibility and economic viability of the original 1938 scheme proposed by Dr John Bradfield, his 1942 variation and more recent proposals. At our disposal are tools that Dr Bradfield could only dream of. High-end computing to support complex modelling, remote sensing, and an ability to develop new engineering and modelling tools to solve and optimise the design, have allowed a level of objective assessment of the schemes, not previously feasible. The imagination and ingenuity of Dr Bradfield is admirable and this study considers his bold ideas on their merit. We know that the merits, or otherwise, of redirecting water in north Queensland rivers inland and south will continue to be debated and many people will have differing views. However, this study is presented to provide an objective scientific assessment to underpin those discussions

An assessment of contemporary variations of the Bradfield Scheme. A technical report to the National Water Grid Authority from the Bradfield Scheme Assessment

In 1938 Dr John Bradfield, an eminent engineer at the time, proposed an ambitious scheme to divert water via a series of dams and tunnels from the east-draining Tully, Herbert and Burdekin rivers on the north-east Queensland coast to the westerly draining semi-arid Flinders River and then to the arid internally draining Thomson River, which flows into Kati Thanda–Lake Eyre. Eighty-three years after first being proposed, the Bradfield Scheme and its variants still arise as part of the national discourse on drought and water security. Interest in ‘Bradfield concepts’ rise especially in times of drought and are generally promoted as means to stimulate ‘nation building’ through creating significant and enduring regional economic development opportunities in water supply and irrigation. Instead of diverting water to western Queensland, many contemporary variations of Bradfield’s scheme propose diverting water to the Murray–Darling Basin (MDB) where there is already an established irrigation industry and supporting infrastructure and demand for water. The Australian Government through the National Water Grid Authority commissioned CSIRO to undertake an assessment of contemporary variations to Bradfield’s scheme. This Assessment found that a partially solar photovoltaic (PV) powered pumped pipeline from the upper Tully catchment to the upper Herbert catchment and a ~62-m high dam and gravity diversion tunnel from the upper Herbert River to the upper Burdekin catchment, combined with runoff from the upper Burdekin catchment could generate a combined mean annual inflow of 2644 GL to a potential ~98-m high dam at Hell’s Gates on the upper Burdekin River, while ensuring sufficient water was released down the Tully, Herbert and Burdekin rivers to meet the needs of existing downstream entitlement holders. A 152-m (500 foot) dam, as proposed by Bradfield (1942) and some contemporary commentators, would never fill because the net evaporation from the reservoir surface would exceed the long-term inflows. After releasing water to meet the needs of downstream entitlement holders a potential ~98-m high Hell’s Gates dam could potentially release 2280 GL in 75% of years into a water supply channel with an offtake ~45 m above the base of the dam. This offtake height would enable a 1600-km gravity channel with a deep cutting or a slightly longer gravity channel with a 43-m re-lift station to convey water to St George on the Condamine-Balonne River in the northern MDB, the first major irrigation area along the potential channel alignment. Taking into consideration the 28% annual flow loss in the adopted channel configuration to St George, a pumped pipeline from the potential Hell’s Gates dam to St George had a levelised cost (i.e. the annualised cost divided by the mean annual diversion) greater than three times that of the channel configuration. There is little scope to enhance channel diversions between the potential Hell’s Gates dam and the northern MDB by capturing additional water en route. Major drainage lines that intersect the potential channel alignment have unfavourable topography for potential off-line channel storages, and resulting dams would be low yielding and costly. There is also limited potential to generate hydro-electric power along the backbone infrastructure water supply line. Opportunities to supply water to other industries along the water supply channel are also limited. The potential channel alignment traverses the most resource poor parts of Queensland, largely due to the extensive sedimentary cover. Furthermore, relative to agriculture, mining requires relatively little water and does not typically require high-quality water. Mining companies usually have sufficient resources to be self-sufficient in terms of their water requirements. No regional centres with water security issues are located near the potential channel alignment, and therefore the contemporary Bradfield Scheme offers little benefit for improving the water security of regional centres in Queensland. The optimal backbone infrastructure configuration (i.e. dams, pipes, tunnels and channels along the main water supply line) to St George is estimated to cost between $15 billion and$30 billion (assuming favourable geological conditions) with an annual cost of between $130 million and$255 million (including operation and maintenance, annual pumping costs and net revenue). After taking 7 to 10 years for approvals it is estimated that the backbone infrastructure would take a minimum of 12 years to construct. For a mix of ‘high’ priority (100% reliability) and ‘medium’ priority (75% annual time reliability) water, a mean of ~1270 GL of water could be diverted to St George after losses, which is equivalent to 25% of the average annual volume of water used for irrigation in the MDB between 2015 and 2019. It should be noted, however, in the Bradfield Scheme source catchments no releases were made to mitigate impacts to downstream water-dependent ecosystems or meet environmental flow objectives stipulated in the state government water plans. Releasing water for this purpose would reduce the volume of water that could be diverted. Adjacent and downstream of the existing Beardmore Dam (capacity 81.7 GL) near St George there is approximately 90,000 ha of land already developed for irrigated cotton and other broadacre crops and 600 ha of land already developed for irrigated horticulture. However, collectively, irrigators along the Condamine-Balonne River can only extract their full entitlement in about 40% of years, and this area of developed land is only fully irrigated in very wet years when ‘flood harvesting’ is possible. In drier years large extraction shortfalls occur because there are relatively few large dams and weirs to regulate the highly variable flows in the river, and the northern MDB more generally. Although high-value horticulture is approximately two to nine times more profitable per unit of irrigation applied than cotton, which is the most profitable broadacre/industrial crop, large-scale expansion of horticulture in the northern MDB is limited by the reliability of water supply, and as discussed later, ultimately, markets. South of St George along the Condamine-Balonne River and the nearby Moonie River there is more than 780,000 ha of soil potentially suitable for irrigated agriculture, of which about 150,000 ha are sandy and loamy soils potentially suited for horticultural crops. It was found that under the ‘optimal’ Bradfield Scheme backbone infrastructure configuration, which included a 43-m re-lift pump station and a large terminal storage, sufficient water could be delivered to increase the reliability of fully irrigating the existing 90,000 ha of cotton and broadacre cropping in 75% of years, as well as fully irrigating an additional 80,000 ha of new cotton in 75% of years and about 30,000 ha of new high-value horticulture in 100% of years. Thirty thousand hectares of citrus, the most profitable crop per megalitre of water consumed that could be grown in the St George region, was adopted for this analysis to represent an optimistic economic ceiling for horticultural production. Assuming the total cost of backbone and reticulation infrastructure to be $21 billion, under a set of extremely optimistic assumptions used to estimate an unattainable upper bound of financial performance, a discounted cash flow analysis over the lifetime of the scheme (100 years) showed water would have to be charged at$2310 for each megalitre supplied to cover the costs of the scheme. Net farm revenue was sufficient to afford no more than $580 per megalitre of water supplied, which would only cover about a quarter of the scheme’s costs. The cost of diversion infrastructure alone would add a premium of$1920 to the cost of each megalitre of water used to irrigate crops, making water cost about six times what it would without the diversion infrastructure. The inclusion of renewable energy and pumped pipelines made a very small change to the overall economics of the scheme, mainly because the cost of the water storage and particularly the main water supply channel from potential Hell’s Gates dam to the northern MDB dwarf all other costs. However, this analysis is highly optimistic. Infrastructure that involves substantial subsurface excavation, such as dams, tunnels and channels, have long construction periods and are particularly susceptible to large cost overruns. Australian and international studies of large-dam and mega-dam projects report a mean cost overrun of 120 and 100% respectively. Further, market projections estimate horticultural growth in the St George region would be unlikely to exceed 13,000 ha by 2050, even if unconstrained by the availability of water. Allowing for a modest combination of risks (including a 20% infrastructure cost overrun and slower more realistic expansion of horticulture) lowers the proportion of the revised scheme’s costs for which irrigators could pay to 8%. The Bradfield Scheme storage and diversion infrastructure offers minor financial benefit in mitigating flooding in the lower Tully, Herbert and Burdekin catchments relative to the overall capital and annual operation and maintenance costs of the backbone infrastructure. If implemented it was calculated that the Bradfield Scheme could result in an overall reduction in anthropogenic load of total suspended solids and particulate nitrogen delivered to the Great Barrier Reef of 10 and 8%, respectively. Although there may be some potential for possible ecological benefits in diverting water from north Queensland and strategically releasing it to try and achieve better environmental outcomes for the northern MDB, it would need to be considered against the range of possible ecological impacts both within the northern MDB and within the Bradfield Scheme source catchments. These impacts are likely to be large. The upper limit of the regional benefit from expanded farming would be less than $6.1 billion per year and create up to 11,000 jobs, but this would only occur if: • Horticulture in the vicinity of St George were to expand by an amount equivalent to 30% of the gross value of all fruit, vegetable and nuts currently produced in all of Australia (which could take more than 100 years if this were even possible) • Farmers did not have to pay for water. Most of the new jobs would be for seasonal fruit picking and packing work, which historically has largely been undertaken by foreign and domestic migratory workers from outside the region (so much of the benefit would accrue outside the northern MDB, and partially outside Australia). The fundamental weakness of Bradfield-style schemes are the high costs of diversion infrastructure (without an offsetting locational benefit) and large volumes of expensive water (in excess of what high-value industries could expand to consume and pay for in the medium term). While it may be difficult to find new water development options that are financially viable in their own right, it would at least be possible to find more efficient alternatives that avoid such needlessly high financial losses. Such alternatives could involve strategically planned regionally-distributed additional water storages that could be progressively staged to scale with the demand of high-value water users. This could be done in two ways, depending on whether the priority was to cost-effectively expand local bulk water supply volumes or increase regional water security (or some combination of the two). If the priority were on increasing water volumes to allow local high-value industries to expand, then augmenting regional water storage capacity to capture additional water supplies and meet local demands would likely achieve the highest benefit per million dollars of infrastructure spending. If the priority were on improving local water security and water supply reliability, then drought-related water shortfalls could be mitigated by gradually building additional water supply capacity and by linking relatively smaller pieces of new and existing infrastructure into a number of ‘interconnected regional grids’. However, this may come at the expense of inefficiencies from having infrastructure on standby in non-drought periods during which it would not be used to its full capacity. These alternative options for configuring water infrastructure would be able to meet the water supply and security objectives of Bradfield-style schemes with less risk, lower cost and better matching of water infrastructure development to where demands and opportunities (in terms of where natural resources and other existing infrastructure are located) are already greatest