Abstract. The groundwater resource contained within the sandy aquifers of the Swan Coastal Plain, south west Western Australia, provides approximately 60% of the drinking water for the metropolitan population of Perth. Rainfall decline over the past three decades coupled with increasing water demand from a growing population has resulted in falling dam storage and groundwater levels. Projected future changes in climate across south-west Western Australia consistently show a decline in annual rainfall of between 5 and 15%. There is expected to be a continuing reduction of diffuse recharge across the Swan Coastal Plain. This study aims to quantify the change in groundwater recharge in response to a range of future climate and land cover patterns across south-west Western Australia. Modelling the impact on the groundwater resource of potential climate change was achieved with a dynamically linked unsaturated/saturated groundwater model. A Vertical Flux Manager was used in the unsaturated zone to estimate groundwater recharge using a variety of simple and complex models based on land cover type (e.g. native trees, plantation, cropping, urban, wetland), soil type, and taking into account the groundwater depth. These recharge estimates were accumulated on a daily basis for both observed and projected climate scenarios and used in a MODFLOW simulation with monthly stress periods. In the area centred on the city of Perth, Western Australia, the patterns of recharge change and groundwater level change are not consistent spatially, or consistently downward. In the Dandaragan Plateau to the north-east of Perth there has been groundwater level rise since the 1970s associated with land clearing, and with rainfall projected to reduce the least in this area the groundwater levels are estimated to continue to rise. Along the coastal zone north of Perth there is an interaction between projected rainfall decline and legislated removal to pine forests. This results in areas of increasing recharge and rising water levels into the future despite a drying climate signal. To the south of Perth city there are large areas where groundwater levels are close to the land surface and not expected to change more than 1m upward or downward over the next two decades; it is beyond the accuracy of the model to conclude any definite trend. In the south western part of the study area, the patterns of groundwater recharge are dictated primarily by soil, geology and land cover. In the sandy Swan (northern boundary) and Scott Coastal Plains (southern boundary) there is little response to future climates, because groundwater levels are shallow and much rainfall is rejected recharge. The profile dries out more in summer but this allows more rainfall to infiltrate in winter. Until winter recharge is insufficient to refill the aquifers these areas will not experience significant falls in groundwater levels. On the Blackwood Plateau however, the combination of native vegetation and clayey surface soils that restrict possible infiltration and recharge mean the area is very sensitive to climate change. With low capacity for recharge and low storage in the aquifers, small reductions in recharge can lead to large reductions in groundwater levels. In the northern part of the study area both climate and land cover strongly influence recharge rates. Recharge under native vegetation is minimal and is relatively higher where grazing and pasture systems have been introduced after clearing of native vegetation. In some areas the low recharge values can be reduced to almost zero, even under dryland agriculture, if the future climate becomes very dry. In the Albany Area the groundwater resource is already over allocated, and the combination of existing permanent native vegetation with decreasing annual rainfall indicate reduced recharge. The area requires a reduction in groundwater abstraction to maintain the sustainability of the existing resource.
Managing the interaction between carbon dioxide storage and other basin resources should focus on preventing potential conflicts and enhancing synergies.
Reliable estimates of the hydraulic properties, such as porosity and permeability, are essential for construction of robust dynamic reservoir models. A variable density, non‐isothermal, hydrodynamic model of the Gippsland Basin is being developed to simulate impacts of CO2 injection into the Latrobe Formation on the aquifer pressures and migration of the saline formation water. For this study relationships between porosity and permeability derived from conventional core analysis and mercury injection capillary pressure tests, and the shale volume derived from gamma logs have been used. Shale volume has also been derived from inversion of 3D seismic data using constrained sparse spike inversion to facilitate distribution of porosity and permeability in 3D space. Formation water density distribution has been estimated based on salinity interpreted from self potential logs to assist in model calibration.
Abstract. This study assesses climate change impacts on water balance components of the regional unconfined aquifer systems in south-western Australia, an area that has experienced a marked decline in rainfall since the mid 1970s and is expected to experience further decline due to global warming. Compared with the historical period of 1975 to 2007, reductions in the mean annual rainfall of between 15 and 18 percent are expected under a dry variant of the 2030 climate which will reduce recharge rates by between 33 and 49 percent relative to that under the historical period climate. Relative to the historical climate, reductions of up to 50 percent in groundwater discharge to the ocean and drainage systems are also expected. Sea-water intrusion is likely in the Peel-Harvey Area under the dry future climate and net leakage to confined systems is projected to decrease by up to 35 percent which will cause reduction in pressures in confined systems under current abstraction. The percentage of net annual recharge consumed by groundwater storage, and ocean and drainage discharges is expected to decrease and percentage of net annual recharge consumed by pumping and net leakage to confined systems to increase under median and dry future climates. Climate change is likely to significantly impact various water balance components of the regional unconfined aquifer systems of south-western Australia. We assess the quantitative climate change impact on the different components (the amounts) using the most widely used GCMs in combination with dynamically linked recharge and physically distributed groundwater models.
The South West CO2 Geosequestration Hub (the South West Hub) is located in South West Western Australia in proximity to industrialised regions around Kwinana, Kemerton, and coal mining and power production facilities around Collie. Recognition that there is a potentially suitable geosequestration site in the region near extensive emission sources led to the formation of the South West Hub and its submission as a potential Flagship under the Australian Federal Clean Energy Initiative (CEI). An area with geosequestration potential was identified based on data from years of active research in the region to investigate oil and gas potential, ground-water resources and more recently for geothermal energy potential and now carbon storage. Three interesting factors stand out regarding this site: (1) the storage site relies primarily on residual and dissolution trapping, (2) some of the CO2 will be sequestered by mineralisation during the amelioration of bauxite residue from some nearby alumina plants, and (3) the subsurface storage area can be tested at a relatively early stage by accessing significant pilot-scale quantities of high-purity CO2 from existing industry in the Kwinana area. CO2 is already being captured and vented at a site in Kwinana, and a proposed pipeline will transport the CO2 to the alumina plants with the remainder of the gas used for a pilot-scale test. The upfront capital costs are therefore reduced to the pipeline cost rather than for a full-scale capture-ready power plant. In preparation for an investment decision (to drill a new data well addressing the main criteria for characterising carbon storage potential of the proposed Lesueur site) a series of studies have increased the understanding of the geology of the area. Modelling studies suggest that up to 6.4 million tonnes per annum could be stored in the Triassic aged Lesueur Sandstone, with total capacity estimates of 200–260 million tonnes of CO2 over the lifetime of the project. This paper primarily discusses the evolution of the geological understanding of the Lesueur Sandstone and associated formations in and around the Harvey Ridge structure, which falls within the Lesueur study area, as well as how the Collie coal users and producers and other local industries and government have become engaged in the project. Recent activities in the project have included seismic data acquisition and the drilling, coring and logging of a data well that will allow significant reductions in geological uncertainties for the project.
Abstract. This study assessed climate change impacts on water balance components of the regional unconfined aquifer systems in South-Western Australia, an area that has experienced a marked decline in rainfall since the mid 1970s and is expected to experience further decline due to global warming. Compared with the historical period of 1975 to 2007, reductions in the mean annual rainfall of between 15 and 18% are expected under a dry variant of the 2030 climate which will reduce recharge rates by between 33 and 49% relative to that under the historical period climate. Relative to the historical climate, reductions of up to 50% in groundwater discharge to the ocean and drainage systems are also expected. Sea-water intrusion is likely in the Peel-Harvey area under the dry future climate and net leakage to confined systems is projected to decrease by up to 35% which will cause reduction in pressures in confined systems under current abstraction. The percentage of net annual recharge consumed by groundwater storage, and ocean and drainage discharges is expected to decrease and percentage of net annual recharge consumed by pumping and net leakage to confined systems to increase under median and dry future climates.
'/%3e%3c/defs%3e%3cpath fill='%23012169' d='M0 0h10080v5040H0z'/%3e%3cpath stroke='%23fff' stroke-width='.6' d='m0 0 6 3m0-3L0 3' clip-path='url(%23b)' transform='scale(840)'/%3e%3cpath stroke='%23e4002b' stroke-width='.4' d='m0 0 6 3m0-3L0 3' clip-path='url(%23c)' transform='scale(840)'/%3e%3cpath stroke='%23fff' stroke-width='840' d='M2520 0v2520M0 1260h5040'/%3e%3cpath stroke='%23e4002b' stroke-width='504' d='M2520 0v2520M0 1260h5040'/%3e%3cg fill='%23fff'%3e%3cuse xlink:href='%23d' x='2520' y='3780'/%3e%3cuse xlink:href='%23a' x='7560' y='4200'/%3e%3cuse xlink:href='%23a' x='6300' y='2205'/%3e%3cuse xlink:href='%23a' x='7560' y='840'/%3e%3cuse xlink:href='%23a' x='8680' y='1869'/%3e%3cuse xlink:href='%23e' x='8064' y='2730'/%3e%3c/g%3e%3c/svg%3e)
'%3e%3cpath fill='%23012169' d='M0 0v30h60V0z'/%3e%3cpath stroke='%23fff' stroke-width='6' d='m0 0 60 30m0-30L0 30'/%3e%3cpath stroke='%23C8102E' stroke-width='4' d='m0 0 60 30m0-30L0 30' clip-path='url(%23b)'/%3e%3cpath stroke='%23fff' stroke-width='10' d='M30 0v30M0 15h60'/%3e%3cpath stroke='%23C8102E' stroke-width='6' d='M30 0v30M0 15h60'/%3e%3c/g%3e%3c/svg%3e)
