气候变化领域集成服务门户(CCPortal): Application of an improved global-scale groundwater model for water table estimation across New Zealand

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DOI	10.5194/hess-22-6449-2018
	Application of an improved global-scale groundwater model for water table estimation across New Zealand
	Westerhoff R.; White P.; Miguez-Macho G.
发表日期	2018
ISSN	1027-5606
起始页码	6449
结束页码	6472
卷号	22 期号:12
英文摘要	Many studies underline the importance of groundwater assessment at the larger, i.e. global, scale. The groundwater models used for these assessments are dedicated to the global scale and therefore not often applied for studies in smaller areas, e.g. catchments, because of their simplifying assumptions. In New Zealand, advanced numerical groundwater flow models have been applied in several catchments. However, that application is piecemeal: Only for a limited amount of aquifers and through a variety of groundwater model suites, formats, and developers. Additionally, there are large areas where groundwater models and data are sparse. Hence, an inter-catchment, inter-regional, or nationwide overview of important groundwater information, such as the water table, does not exist. The investment needed to adequately cover New Zealand with high-resolution groundwater models in a consistent approach would be significant and is therefore not considered possible at this stage. This study proposes a solution that obtains a nationwide overview of groundwater that bridges the gap between the (too-)expensive advanced local models and the (too-)simple global-scale models. We apply an existing, globalscale, groundwater flow model and improve it by feeding in national input data of New Zealand terrain, geology, and recharge, and by slight adjustment of model parametrisation and model testing. The resulting nationwide maps of hydraulic head and water table depths show that the model points out the main alluvial aquifers with fine spatial detail (200m grid resolution). The national input data and finer spatial detail result in better and more realistic variations of water table depth than the original, global-scale, model outputs. In two regional case studies in New Zealand, the hydraulic head shows excellent correlation with the available groundwater level data. Sensitivity and other analyses of our nationwide water tables show that the model is mostly driven by recharge, model resolution, and elevation (gravity), and impeded by the geology (permeability). The use of this first dedicated New Zealand-wide model can aid in provision of water table estimates in data-sparse regions. The national model can also be used to solve inconsistency of models in areas of trans-boundary aquifers, i.e. aquifers that cover more than one region in New Zealand. Comparison of the models, i.e. the national application (National Water Table model: NWT) with the global model (Equilibrium Water Table model: EWT), shows that most improvement is achieved by feeding in better and higher-resolution input data. The NWT model still has a bias towards shallow water tables (but less than the EWT model because of the finer model resolution), which could only be solved by feeding in a very high resolution terrain model that incorporates drainage features. Although this is a model shortcoming, it can also be viewed as a valuable indicator of the pre-human water table, i.e. before 90% of wetlands were drained for agriculture since European settlement in New Zealand. Calibration to ground-observed water level improves model results but can of course only work where there are such data available. Future research should therefore focus on both model improvements and more data-driven, improved estimation of hydraulic conductivity, recharge, and the digital elevation model. We further surmise that the findings of this study, i.e. successful application of a global-scale model at smaller scales, will lead to subsequent improvement of the global-scale model equations. © 2018 Author(s).
语种	英语
scopus关键词	Aquifers; Catchments; Feeding; Groundwater flow; Hydrogeology; Input output programs; Runoff; Water levels; Digital elevation model; Groundwater assessment; Groundwater Flow Model; Groundwater modeling; Groundwater models; Shallow water tables; Simplifying assumptions; Very high resolution; Groundwater resources; global perspective; groundwater flow; groundwater resource; hydraulic head; hydrological modeling; model test; numerical model; parameterization; permeability; recharge; spatial resolution; transboundary cooperation; water depth; water table; New Zealand
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/159825
作者单位	Westerhoff, R., GNS Science, Taupo, New Zealand, Deltares, Utrecht, Netherlands; White, P., GNS Science, Taupo, New Zealand; Miguez-Macho, G., University of Santiago de Compostela, Santiago de Compostela, Spain
推荐引用方式 GB/T 7714	Westerhoff R.,White P.,Miguez-Macho G.. Application of an improved global-scale groundwater model for water table estimation across New Zealand[J],2018,22(12).
APA	Westerhoff R.,White P.,&Miguez-Macho G..(2018).Application of an improved global-scale groundwater model for water table estimation across New Zealand.Hydrology and Earth System Sciences,22(12).
MLA	Westerhoff R.,et al."Application of an improved global-scale groundwater model for water table estimation across New Zealand".Hydrology and Earth System Sciences 22.12(2018).