Department of Natural Resources, Mines and Energy

Australian growers plant crops using different skip row configurations to minimize production risk in water-limiting environments. Previous studies have focused on comparing the effect of row configuration on crop yield, and information on soil water is still lacking. The objective of this study was to compare the water use, soil water extraction, and yield of dryland cotton (Gossypium hirsutum L.) planted using solid and single-skip row configurations. An experiment comparing two row configuration treatments (solid and single-skip) was conducted in a cotton field with heavy-clay soil in the sub-tropical climatic environment of Queensland, Australia, during 2007-2008. Water content in the soil profile was measured about weekly using the neutron probe method. Measurements were taken from three positions from the crop row: within a row (P1), between two rows (P2), and skip or planted row (P3). The soil water measurements indicated that, in general, the solid treatment tended to extract more water from shallower depths earlier in the growing season. The single-skip treatment resulted in taller plants, which extracted more water from deeper in the soil profile later in the season. For the entire season, however, both treatments used around the same amount of soil water (128 mm), suggesting that both treatments were water-limited and used all the water available to the crop. The 128 mm added to the seasonal rainfall of 271 mm allowed us to estimate the seasonal crop water use at about 399 mm, which was around half of the seasonal grass-reference evapotranspiration (ETo = 804 mm) for the site. The lint yield was statistically the same for both treatments, although the taller plants from the single-skip treatment tended to have a greater yield per plant (but not significantly different). The estimated water use efficiency (WUE) for the solid and single-skip configuration were 3.5 and 3.3 kg lint/ha/mm water use, respectively.

Do commodity prices, real exchange rate and trade openness influence economic growth in South Africa? This question is fundamental to academic research since it forms the basis of macroeconomic policies. Therefore, the comprehension of such a relationship is vital which has ushered this study into investigating the effect of real exchange rate, commodity prices and trade openness on economic growth in South Africa from 1984-2019. The purpose of this study is to contribute to the diverse literature on macroeconomics and international trade in the continent and the rest of the world. To achieve this, the Johansen cointegration method and Vector Error Correction Model were employed. The Johansen cointegration method confirmed the existence of a long-run relationship among the variables. Commodity prices and trade openness positively influenced economic growth while real exchange rate inversely influenced economic growth. The Vector Error Correction Model also confirmed that the disequilibrium in the model can be corrected in 1 year 9 months. The study`s findings suggest a methodical monetary policy synthesis that controls both the commodity price stability and exchange rate that spurs economic growth.

Abstract. As host to several world-class sediment-hosted Pb–Zn deposits and unknown quantities of conventional and unconventional gas, the variably inverted 1730–1640 Ma Calvert and 1640–1575 Ma Isa superbasins of northern Australia have been the subject of numerous seismic reflection studies with a view to better understanding basin architecture and fluid migration pathways. These studies reveal a structural architecture common to inverted sedimentary basins the world over, including much younger examples known to be prospective for oil and gas in the North Sea and elsewhere, with which they might be usefully compared. Such comparisons lend themselves to suggestions that the mineral and petroleum systems in Paleo–Mesoproterozoic northern Australia may have spatially, if not temporally overlapped and shared a common tectonic driver, consistent with the observation that basinal sequences hosting Pb–Zn mineralization in northern Australia are bituminous or abnormally enriched in hydrocarbons. Sediment-hosted Pb–Zn mineralization coeval with basin inversion first occurred during the 1650–1640 Ma Riversleigh Tectonic Event towards the close of the Calvert Superbasin with further pulses taking place during and subsequent to the onset of the 1620–1580 Ma Isa Orogeny and final closure of the Isa Superbasin. Mineralization is typically hosted by the post-rift or syn-inversion fraction of basin fill, contrary to existing interpretations of Pb–Zn ore genesis where the ore-forming fluids are introduced during the rifting or syn-extensional phase of basin development. Mineralizing fluids were instead expelled upwards during times of crustal shortening into structural and/or chemical traps developing in the hangingwalls of inverted normal faults. Inverted normal faults predominantly strike NNW and ENE, giving rise to a complex architecture of compartmentalized sub-basins whose individual uplifted basement blocks and doubly plunging periclinal folds exerted a strong control not only on the distribution and preservation of potential trap rocks but the direction of fluid flow, culminating in the co-location and trapping of mineralizing and hydrocarbon fluids in the same carbonaceous rocks. An important case study is the 1575 Ma Century Pb–Zn deposit where the carbonaceous host rocks served as both a reductant and basin seal during the influx of more oxidized mineralizing fluids, forcing the latter to give up their Pb and Zn metal. A transpressive tectonic regime in which basin inversion and mineralization were paired to folding, uplift, and erosion during arc–continent or continent–continent collision, and accompanied by orogen-parallel extensional collapse and strike-slip faulting best accounts for the observed relationships.

Monitoring is critical for effective groundwater management, especially in systems with competing groundwater interests, such as the Great Artesian Basin’s (GAB) Surat Basin (~180,000 km2) in Queensland, Australia. Coal seam gas (CSG) activities in the region have led to public concerns about potential impacts on groundwater and to landholder complaints about impacts on boreholes. To deal with these issues, the Queensland Government established the Groundwater Net and Groundwater Online citizen-science monitoring programs, which started in 2013 and were fully operational by 2018. Groundwater Net is a community-based education and groundwater monitoring program in which over 500 landholders across 16 local groups have attended workshops and provided over 1,000 groundwater-level/pressure readings from their boreholes using the My Groundwater Monitoring website. Annual workshops provide a forum to share and discuss monitoring results and knowledge. Regularly updated status reports compare monitoring data from CSG companies and the government with landholder data. Groundwater Online is a complimentary program using continuous-monitoring loggers and telemetry on 46 private boreholes. Citizen science now provides 13% of GAB monitoring boreholes in the CSG area. By effectively engaging with borehole owners, and empowering them to monitor, many opportunities arise for better groundwater management. Consequently, the spatial reach of groundwater monitoring and its frequency have increased, landholders are educated about groundwater systems, and borehole owners generally feel more confident about monitoring conducted by CSG companies and government.

The near-shore ocean ecosystem is influenced by catchment runoff. The Great Barrier Reef has been experiencing significant water quality deterioration over the past 150 years, due in part to agricultural intensification and urban settlement in adjacent catchments (Thorburn et al., 2013). There is a need for us to understand the influences of catchment characteristics on stream water quality, with an aim to mitigate and manage the water quality issue in the terrestrial stream runoff derived from the adjacent Great Barrier Reef catchments. The event-based water quality monitoring data set from the Paddock to Reef Integrated Monitoring Program across six Natural Management Regions provides a potential opportunity to develop a data-driven understanding of catchment characteristics affecting water quality at the catchment scale. This requires a robust and reliable modelling tool to relate the monitoring data to anthropogenic and natural processes. In this study, monitoring data of Total Suspended Solids (TSS) and dissolved Oxidised Nitrogen (NOX) from 32 sites across the Great Barrier Reef catchments are selected as case study constituents due to the high risk they pose to reef health when exported from catchments to the receiving marine environment. Also, these two constituents have distinct biogeochemical processes in catchments. Specifically, TSS is typically conserved (although mobilized and deposited) while travelling through river systems; while NOX can be potentially processed and removed from the system altogether. A Bayesian hierarchical linear modelling framework is adopted, due to its ability to borrow strength among sites, allowing information to be transferred across space, and due to its ability to provide uncertainty of the predictions. The Bayesian hierarchical linear regression model in this study is developed to evaluate the significance of various catchment characteristics (e.g., land uses, catchment topography and geology) on spatial variation in water quality. The main findings of this study are listed as follows, • Sites located in the Burdekin and Fitzroy Natural Management Regions tend to have greater TSS concentrations, illustrated by the modelled site-specific spatial random effects (deviation from the overall average concentration). Additionally, grazing and dry land agriculture land uses are positively correlated with the spatial random effect on TSS. The complexity of interaction between different catchment characteristics (e.g., land use and topography) can potentially result in a negative spatial random effect on TSS, which is reduced in the relatively steeper Great Barrier Reef catchments with a denser stream network. • Sugar cane is one of the most significant NOX contributors according to the modelling results, likely partially due to the excessive application of fertilizers; however, conservation land use has limited effect on NOX removal, indicating denitrification process alone may not be sufficient to remove NOX. The modelling results demonstrate different land management strategies are required for the purpose of reducing different constituents. This work will provide scientific insights for water quality management at the catchment scale.

Water availability is a major concern for irrigated vegetable cropping in the Lockyer Valley area of Australia. Soil water balance and in particular deep drainage were modelled for a representative site of this area for a range of irrigation scenarios over 12 years of cropping sequence. A scenario that refilled the soil to the drained upper limit (DUL) resulted in 530 mm yr−1 of irrigation, 673 mm yr−1 of transpiration and 84 mm yr−1 of deep drainage, whereas maintaining the soil to DUL+25% and DUL+50%, with soil moisture between DUL and saturation (75 and 50% free water respectively), resulted in similar transpiration but with increased irrigation (up to 717 mm yr−1) and deep drainage (up to 262 mm yr−1). For a given amount of available water, irrigations at fixed intervals were found to be less efficient (reduced crop transpiration) than irrigation scheduled according to a soil water deficit. This highlights the importance of moisture monitoring to optimize irrigation use efficiency. The study suggests solutions to improve irrigation efficiency by minimizing deep drainage under cropping sequences. Copyright © 2013 John Wiley & Sons, Ltd. La disponibilité limitée en eau d'irrigation pose un problème pour les cultures maraichères de la Lockyer Valley (Australie). Différents régimes d'irrigation ont été simulés au cours de 12 années de séquence pour un site représentatif de cette région. Le régime maintenant le sol à la capacité au champ (DUL) a nécessité 530 mm d'irrigation par an en moyenne, et a permis aux cultures d'utiliser 673 mm/an (transpiration), avec un drainage de 84 mm/an. Avec une irrigation (‘DUL+25%’ et ‘ DUL+50%’) maintenant l'humidité du sol entre capacité au champ et saturation (respectivement 75 et 50% d'eau libre), la quantité d'eau utilisée a augmenté (irrigation de 717 mm/an en moyenne) ainsi que le drainage (262 mm/an), sans qu'aucun bénéfice notable pour les cultures n'ait été simulé en terme de quantité d'eau transpirée. D'autre part, des irrigations à pas de temps réguliers se sont avérées moins efficaces (transpiration réduite) qu'un régime opportuniste, avec des irrigations régulées en fonction de l'état hydrique du sol. Cette étude renforce ainsi l'importance de contrôler l'état hydrique du sol pour adapter le régime d'irrigation. Les résultats suggèrent également que l'efficacité de l'irrigation sous des séquence peut être améliorée en minimisant le drainage profond. Copyright © 2013 John Wiley & Sons, Ltd.

This chapter provides a description of environmental considerations in dryland cropping in Australia, the rationale for development of the systems, and challenges facing agronomists in dealing with maintaining economic and natural resource sustainability. In the cropping zone, total rainfall decreases with distance from coasts, indicating that on-shore winds are a major source of atmospheric moisture. Temperature distribution and frost incidence determine which crop species are best suited to an environment. With runoff inevitable in such an environment, conservation measures are crucial for controlling soil erosion, especially in the high runoff summer months. Improved understanding of soil and climate and the main drivers of productivity has led to farming systems that are much more climate responsive. The most pressing challenge in weed management is the issue of herbicide resistance. Australia has a viable manufacturing industry that provides a wide range of specialist machinery options suited to conservation tillage practice.

La crise energetique des dernieres annees nous a davantage sensibilises au fait que les ressources non-renouvelables sont limitees ; en consequence nous nous interessons beaucoup plus, a l'heure actuelle, aux ressources minerales autres que les combustibles. L'evaluat'ion d'une ressource specifique suppose de notre part deux operations bien distinctes et precises ; en premier lieu, il faut determiner a quel point nous sommes certains de la presence, dans la croute terrestre, d'une quantite donnee de cette ressource ; il faut, en second lieu, mesurer l'attrait economique que celle-ci represente. Bon nombre d'entre nous, y compris ceux qui etablissent les politiques de developpement, avons tendance a ignorer certains aspects de la disponibilite des ressources, notamment de celles qui existent en abondance, comme c'est le cas pour les sables bitumineux du Canada. La presence des ressources en quantites suffisantes ne devrait jamais etre prise en consideration sans par ailleurs tenir compte de leur disponibilite. Nous proposons ici une representation graphique d'un processus d'evaluation d'une ressource donnee, dans laquelle nous tenons compte de ces deux facteurs. Nous dressons la courbe de l'approvisionnement sur une periode donnee, en etablissant une distinction entre (a) les reserves actuellement connues dans les gisements, (b) les prolongements presumes de ces gisements, (c) les autres gisements connus, mais encore inexploites, et (d) les gisements encore inconnus. Une telle approche a le double avantage de presenter une vue realiste de la disponibilite d'une ressource et de prevenir les craintes injustifiees de penuries futures, comme cela se produit lorsque les projections ne tiennent compte que des reserves actuellement exploitees. Lorsque nous etudions la demande future, nous devons prendre autant de precautions que lorsque nous etablissons des projections sur la disponibilite des approvisionnements. Comme les progres technologiques entrainent une utilisation plus efficace des ressources, les previsions uniquement fondees sur nos techniques actuelles d'utilisation peuvent entrainer une surestimation de la demande. D'une facon generale, une croissance soutenue de la demande semble inevitable, du moins dans un avenir rapproche. La reaction de l'offre a la demande - toujours ralentie par les delais necessaires a la mise en ceuvre de nouveaux gisements - mettra cependant en branle des mecanismes de plus en plus complexes, et nous continuerons de connaitre des periodes de penurie et de surabondance en raison de notre incapacite a gerer l'imprevisible. Afin d'attenuer les effets de penuries futures, il faudra promouvoir les economies - c'est-a-dire tirer le profit maximum des matieres premieres - grâce a une recuperation plus efficace, au recyclage, a la substitution et a une meilleure conception dans la fabrication des produits manufactures. Les changements dans les techniques d'utilisation des ressources auront probablement la plus forte incidence sur les courbes montrant la relation entre la demande et l'offre en mineraux. Nous ne devrions donc pas nous laisser induire en erreur par des juxtapositions simplistes de ressources chiffrees et de previsions de la consommation. L'accession aux ressources et leur consommation sont toutes deux soumises a des processus dynamiques, il existe bien des facons d'augmenter nos ressources et de modifier radicalement nos habitudes de consommation. Il n'en tient qu'a nous d'etablir un lien entre nos ressources et leur consommation - lien qui n'est pas predetermine.

ABSTRACT This paper describes a solution to the diffusivity equation, assuming boundary conditions for a reservoir during steam injection. It should be considerable value for the evaluation of steam drive projects, particularly inview of the growing importance of thermal recovery processes in Canada, INTRODUCTION IN THE THEORETICAL TREATMENT of steam drive processes for the recovery ofheavy oils, one of the problems encountered is the determination of thetemperature distribution ahead of the expanding steam zone. A knowledge of the temperature distribution is of value in predicting the location and rate ofadvance of a steam zone when a temperature build-up is observed at a production or observation well, or to assess the temperature development ahead of a steamzone when its location and rate of advance are known. This paper attempts toassist the resolution of the above problem by extending the theoretical work by Lauwerier which describes the temperature distribution in a line drive model with hot water injection. In this case, the boundary conditions are altered torepresent the situation with steam injection. The Laplace transformation isused to obtain an analytical solution to the equations that ai-e developed. Representative isotherms calculated from this solution are presented ingraphical form. THEORY A plane condensation front is considered to be advancing through permeablestrata bounded by an impermeable cap rock and base rock. The idealized verticalcross section is shown on Figure 1. The problem is formulated as an idealized model by including the following assumptions:The reservoir is homogeneous, isotropic and of constant thickness.The condensation front remains vertical within the sand layer, and thehot condensate flows uniformly through the oil sand ahead of the condensation front.Thermal equilibrium between the fluid and the sand grains is instantaneous.The thermal conductivities of the cap rock, base rock and oil sand are equal.The heat capacities and thermal conductivities are independent of temperatures and pressure.The heat conduction in the horizontal direction is neglected. The above assumptions allow the problem to be formulated by considering only the positive quadrant of Figure 1. because there is symmetry about themid- point of the oil sand. The temperature distribution is therefore described by the set of partial differential equations shown below. (See full paperfor equations)