气候变化领域集成服务门户(CCPortal): Groundwater mean residence times of a subtropical barrier sand island

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DOI	10.5194/hess-24-1293-2020
	Groundwater mean residence times of a subtropical barrier sand island
	Hofmann H.; Newborn D.; Cartwright I.; Cendón D.I.; Raiber M.
发表日期	2020
ISSN	1027-5606
起始页码	1293
结束页码	1318
卷号	24 期号:3
英文摘要	Fresh groundwater on barrier islands is affected by changing sea levels and precipitation variability due to climate change and is also vulnerable to anthropogenic processes, such as contamination and groundwater over-abstraction. Constraining groundwater mean residence times (MRTs) and flow paths is essential for understanding and managing these resources. This study uses tritium (3H) and carbon-14 (14C) to determine the MRTs of groundwater along a transect across subtropical North Stradbroke Island, south-east Queensland, Australia. Hydraulic properties, major ion geochemistry and stable isotopes are used to validate residence times and to identify the processes responsible for their variability. 3H activities range from less than 0.01 to 1 TU (tritium units), which are values lower than those of local average rainfall (1.6-2.0 TU). 14C concentrations range from 62.5 to 111pMC (percent modern carbon). Estimated MRTs determined using lumped parameter models and 3H activities range from 37 to more than 50 years. Recharge occurs over the entire island, and groundwater MRTs generally increase vertically and laterally towards the coastal discharge areas, although no systematic pattern is observed. MRTs estimated from 14C concentrations display similar spatial relationships but have a much greater range (from modern to approximately 5000 years). Water diversion and retention by lowerpermeability units in the unsaturated parts of the dune systems are the most likely course for relatively long MRTs to date. The results indicate that the internal structures within the dune systems increase MRTs in the groundwater system and potentially divert flow paths. The structures produce perched aquifer systems that are wide-spread and have a significant influence on regional recharge. The geochemical composition of groundwater remains relatively consistent throughout the island, with the only irregularities attributed to old groundwater stored within coastal peat. The outcomes of this study enhance the understanding of groundwater flow, recharge diversion and inhibition for large coastal sand masses in general, especially for older sand masses that have developed structures from pedogenesis and dune movement.With respect to south-east Queensland, it allows the existing regional groundwater flow model to be refined by incorporating independent MRTs to test models' validity. The location of this large fresh groundwater reservoir, in dry and populous south-east Queensland, means that its potential to be used as a water source is always high. Background information on aquifer distribution and groundwater MRTs is crucial to better validate impact assessment for water abstraction. © Author(s) 2020.
语种	英语
scopus关键词	Abstracting; Aquifers; Carbon; Climate change; Flood control; Groundwater flow; Groundwater geochemistry; Groundwater pollution; Precipitation (meteorology); Recharging (underground waters); Reservoirs (water); Residence time distribution; Sea level; Tritium; Tropics; Anthropogenic process; Background information; Geochemical composition; Lumped parameter models; Major ion geochemistries; Precipitation variability; Regional groundwater flow modeling; Spatial relationships; Groundwater resources; climate change; geochemistry; groundwater flow; groundwater resource; inhibition; pedogenesis; rainfall; recharge; residence time; sand; subtropical region; Australia; North Stradbroke Island; Queensland; Queensland
来源期刊	Hydrology and Earth System Sciences
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/159470
作者单位	Hofmann, H., School of Earth and Environmental Sciences, University of Queensland, St Lucia, QLD, Australia, Geotechnical Engineering Centre, School of Civil Engineering, University of Queensland, St Lucia, QLD, Australia; Newborn, D., School of Earth and Environmental Sciences, University of Queensland, St Lucia, QLD, Australia; Cartwright, I., School of Earth, Atmosphere and Environment, Monash University, Clayton, VIC, Australia; Cendón, D.I., Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, Australia; Raiber, M., Commonwealth Scientific and Industrial Research Organisation (CSIRO), Dutton Park, QLD, Australia
推荐引用方式 GB/T 7714	Hofmann H.,Newborn D.,Cartwright I.,et al. Groundwater mean residence times of a subtropical barrier sand island[J],2020,24(3).
APA	Hofmann H.,Newborn D.,Cartwright I.,Cendón D.I.,&Raiber M..(2020).Groundwater mean residence times of a subtropical barrier sand island.Hydrology and Earth System Sciences,24(3).
MLA	Hofmann H.,et al."Groundwater mean residence times of a subtropical barrier sand island".Hydrology and Earth System Sciences 24.3(2020).