Your search found 4 records
1 Wetzelhuetter, C. (Ed.) 2013. Groundwater in the coastal zones of Asia-Pacific. Dordrecht, Netherlands: Springer. 382p. (Coastal Research Library Volume 7)
Coastal area ; Hydrogeology ; Models ; Salt water intrusion ; Aquifers ; Sea level ; Groundwater development ; Groundwater management ; Ecosystems ; NMR spectroscopy ; Geochemistry ; Chemical control ; Water quality ; Case studies / Asia-Pacific / China / USA / Hawaii / India / Australia / Thailand / Malaysia / New Zealand / United Arab Emirates / Hainan / Andhra Pradesh / West Bengal / Oahu / Eyre Peninsula / Songkhla / Uley Basin / Willunga Basin / Manukan Island / Kapas Island / Godavari Delta / Carnarvon / Gascoyne River / Yanzhoy River / Sanjiang River / Yanfeng River / Xi River / Wadi Ham Aquifer / Cook Islands / Pukapuka Atoll
(Location: IWMI HQ Call no: 551.457 G570 WET Record No: H046324)
(0.31 MB)
2 Davis, A.; Munday, T.; Somaratne, N. 2013. Characterisation of a coastal aquifer system in the Eyre Peninsula, South Australia, using nuclear magnetic resonance methods. In Wetzelhuetter, C. (Ed.). Groundwater in the coastal zones of Asia-Pacific. Dordrecht, Netherlands: Springer. pp.89-120. (Coastal Research Library Volume 7)
Groundwater ; Aquifers ; Coastal area ; NMR spectroscopy ; Moisture content ; Case studies / Australia / Eyre Peninsula / Uley Basin
(Location: IWMI HQ Call no: 551.457 G570 WET Record No: H046330)
The coastal aquifers of the Uley Basin, which are the most important source of potable groundwater for the Eyre Peninsula, consist of unconfined Quaternary limestone overlying Tertiary clays and sandstones. Despite its importance, elements of the connectivity and total water resource basin remain relatively poorly understood. To address this, hydrogeophysical methods have been employed to better characterise the aquifer systems present. Interpretation of airborne electromagnetic data provided evidence for the delineation of the base of the Quaternary (limestone) aquifer and a basement low in the southwest corner of the South Uley Groundwater Lens, where there is a limited number of lithological bores or groundwater wells. The basement low, adjacent to the coast, suggests a preferential groundwater flow path and a possible connection between the Basin aquifers and the Southern Ocean. Geophysical methods are routinely employed for groundwater exploration, assessment, and aquifer characterisation, particularly where access to land is limited and where other investigation techniques such as drilling may be limited or prohibited. In areas of environmental significance, or where access is generally difficult, non-invasive hydrogeophysical methods offer an alternative to exploratory drilling, by targeting areas of interest and better defining groundwater and aquifer characteristics in advance. We discuss the application of the hydrogeophysical technique of surface nuclear magnetic resonance (sNMR) for groundwater assessment. Presently, sNMR is the only hydrogeophysical technique that allows for direct detection of groundwater in the subsurface. To better understand the possible inter-connectivity between the Uley Basin and the Southern Ocean; and as a precursor to considering whether new groundwater resources could be tapped, we investigate a series of (sNMR) soundings along a transect and also at locations where information about the aquifer is better known. We confirm the presence of a Quaternary limestone aquifer containing potable water, extending 1–2 km across the south western corner of the Uley South Basin. The aquifer is defined to be about 15–20 m in thickness and possesses an effective porosity of around 20 %; it overlies clay layers that separate the limestone from a brackish Tertiary sandstone aquifer beneath. In conjunction with conductivity-depth sections derived from AEM data, our sNMR results deliver completely new knowledge and extend the hydrogeological understanding of this corner of the Uley Basin at a relatively low cost and minimal environmental impact.
3 Werner, A. D.; Dang, L. D. 2013. Three-dimensional seawater intrusion modelling of Uley South Basin, South Australia. In Wetzelhuetter, C. (Ed.). Groundwater in the coastal zones of Asia-Pacific. Dordrecht, Netherlands: Springer. pp.177-203. (Coastal Research Library Volume 7)
Groundwater ; Salt water intrusion ; Models ; Calibration ; Aquifers ; Water supply ; Water levels ; Pumping ; Wells ; River basins ; Climate change / Australia / Uley Basin / Eyre Peninsula
(Location: IWMI HQ Call no: 551.457 G570 WET Record No: H046333)
Groundwater in the Uley South basin is a vital source of water supply in the Eyre Peninsula, providing approximately 70 % of the region’s reticulated water. The groundwater resources are at risk of seawater intrusion given that the aquifer is in direct contact with the sea, and that a general lowering of hydraulic heads has occurred over the past two decades. Seawater intrusion has not been investigated thoroughly in Uley South basin; a similar situation for many of Australia’s coastal aquifers. This study develops a three-dimensional seawater intrusion model of Uley South basin using the code MODHMS. The modelling simulates for the first time the current extent of seawater in the aquifer, the temporal salinity variability, and the susceptibility of the aquifer to seawater intrusion, and as such, the model is a significant step forward beyond previous modelling attempts, providing important insights into salinity distributions and salinity mobility. While it is limited by the available information at the time, comparisons with alternative attempts at salinity measurements (e.g. an AEM survey) show a relatively close match between simulated and observed salinities; an encouraging result given well-documented uncertainties in seawater intrusion modelling. Simulations explore the effects of alternative pumping regimes, reduced recharge, and seasonality and other temporal variability effects on seawater intrusion that cannot be assessed using other methods. The impacts of pumping and recharge changes under climate variability are distinguished; both forms of aquifer stress potentially impact on heads and salinities to somewhat similar extents. The ability of the system to recover from long-term pumping is also assessed. At the basin scale, historical changes in the position of the freshwater-seawater interface are mostly localised due to the shape of the aquifer near the coastline (i.e. basement sloping towards the sea). However, the model predicts that some near-coastal piezometers may show increasing salinity trends in the future if current pumping practices continue, and in particular if recharge diminishes under climate change. A comparison between highly dynamic and averaged-stress conditions demonstrates that seasonality is a minor controlling factor in seawater intrusion trends. Aquifer recovery times exceed the periods during which the pumping stresses that induce seawater intrusion are applied. This occurs because cycles of pumping and recovery widen the transition zone between freshwater and seawater, and a large mass of salt remains in the aquifer even after an extensive recovery period.
4 Knowling, M. J.; Werner, A. D. 2016. Estimability of recharge through groundwater model calibration: insights from a field-scale steady-state example. Journal of Hydrology, 540:973-987. [doi: https://doi.org/10.1016/j.jhydrol.2016.07.003]
Groundwater recharge ; Models ; Calibration ; Estimation ; Hydraulic conductivity ; Aquifers ; Pumping ; Coastal area ; Spatial distribution ; Discharges / South Australia / Uley Basin
(Location: IWMI HQ Call no: e-copy only Record No: H047639)
(2.66 MB)
The ability of groundwater models to inform recharge through calibration is hampered by the correlation between recharge and aquifer parameters such as hydraulic conductivity (K), and the insufficient information content of observation datasets. These factors collectively result in non-uniqueness of parameter estimates. Previous studies that jointly estimate spatially distributed recharge and hydraulic parameters are limited to synthetic test cases and/or do not evaluate the effect of non-uniqueness. The extent to which recharge can be informed by calibration is largely unknown for practical situations, in which complexities such as parameter heterogeneities are inherent. In this study, a systematic investigation of recharge, inferred through model calibration, is undertaken using a series of numerical experiments that include varying degrees of hydraulic parameter information. The analysis involves the use of a synthetic reality, based on a regional-scale, highly parameterised, steady-state groundwater model of Uley South Basin, South Australia. Parameter identifiability is assessed to evaluate the ability of parameters to be estimated uniquely. Results show that a reasonable inference of recharge (average recharge error 100 K values across the 129 km2 study area). The introduction of pumping data into the calibration reduces error in both the average recharge and its spatial variability, whereas submarine groundwater discharge (as a calibration target) reduces average recharge error only. Nonetheless, the estimation of steady-state recharge through inverse modelling may be impractical for real-world settings, limited by the need for unrealistic amounts of hydraulic parameter and groundwater level data. This study provides a useful benchmark for evaluating the extent to which field-scale groundwater models can be used to inform recharge subject to practical data-availability limitations.
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