Understanding groundwater processes by representing aquifer heterogeneity in the Maules Creek Catchment, Namoi Valley (New South Wales, Australia)

Giambastiani, B. M. S.; McCallum, A. M.; Andersen, M. S.; Kelly, B. F. J.; Acworth, R. I.

Understanding groundwater processes by representing aquifer heterogeneity in the Maules Creek Catchment, Namoi Valley (New South Wales, Australia) | Compréhension des processus d’écoulement souterrain par représentation de l’hétérogénéité de l’aquifère du captage Maules Creek, vallée Namoi (Nouvelle-Galles du Sud, Australie) Comprensión de los procesos de agua subterránea mediante la representación de la heterogeneidad del acuífero en la cuenca del arroyo Maules, Namoi Valley (Nueva Gales del Sur, Australia) 了解地下水的运动过程:以澳大利亚新南威尔士州Namoi山谷Maules Creek流域的代表性非均质含水层为例 Comprensione dei processi delle acque sotterranee attraverso la rappresentazione dell’eterogeneità del bacino idrografico di Maules Creek, Namoi Valley (New South Wales, Australia) Como compreender os processos que ocorrem na água subterrânea a partir da representação da heterogeneidade do aquífero da Bacia de Maules Creek, Vale de Namoi (Nova Gales do Sul, Austrália)

2012

Giambastiani, B. M. S. | McCallum, A. M. | Andersen, M. S. | Kelly, B. F. J. | Acworth, R. I.

A FEFLOW three-dimensional (3D) groundwater model is developed to enhance the understanding of groundwater processes in the complex alluvial stratigraphy of Maules Creek Catchment (New South Wales, Australia). The aquifer vertical heterogeneity is replicated by indexing 204 lithological logs into units of high or low hydraulic conductivity, and by developing a 3D geological conceptual model with a vertical resolution based on the average lithological unit thickness for the region. The model mesh is populated with the indexed geology using nearest neighbour gridding. The calibrated model is successful in simulating the observed flow dynamics and in quantifying the important water-budget components. This indicates that the lateral groundwater flow from the mountainous region is the main inflow component of the system. Under natural conditions, the Namoi River acts as a sink of water, but groundwater abstraction increasingly removes a large amount of water each year causing dewatering of the system. The pumping condition affects the river–aquifer interaction by reversing the flow, from gaining to losing river conditions during the simulation period. The procedure is relevant for the development of groundwater models of heterogeneous systems in order to improve the understanding of the interplay between aquifer architecture and groundwater processes.

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