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TitleHydraulic tomography analysis of municipal well operation sata with geology-based groundwater models at the Mannheim Wellfield in Kitchener, Ontario, Canada
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AuthorTong, X; Illman, W A; Berg, S J; Luo, N
SourceRegional-Scale Groundwater Geoscience in Southern Ontario: An Ontario Geological Survey, Geological Survey of Canada, and Conservation Ontario Geoscientists Open House; by Russell, H A J; Ford, D; Holysh, S; Priebe, E H; Geological Survey of Canada, Open File 8528, 2019 p. 28, https://doi.org/10.4095/313602 (Open Access)
Year2019
Alt SeriesOntario Geological Survey, Open File Report 6349
PublisherNatural Resources Canada
PublisherGovernment of Ontario
MeetingRegional-Scale Groundwater Geoscience in Southern Ontario: Open House; Guelph; CA; February 27-28, 2019
Documentopen file
Lang.English
Mediaon-line; digital
RelatedThis publication is contained in Russell, H A J; Ford, D; Holysh, S; Priebe, E H; (2019). Regional-Scale Groundwater Geoscience in Southern Ontario: An Ontario Geological Survey, Geological Survey of Canada, and Conservation Ontario Geoscientists Open House, Geological Survey of Canada, Open File 8528
File formatpdf
ProvinceOntario
NTS40P/08
AreaSouthern Ontario; Kitchener
Lat/Long WENS -80.5000 -80.0000 43.5000 43.2500
Subjectshydrogeology; mathematical and computational geology; groundwater; aquifers; groundwater resources; resource management; water wells; models; hydraulic analyses; hydraulic conductivity; groundwater levels; groundwater flow; geostatistics; modelling; Mannheim Wellfield; HydroGeoSphere; methodology; hydraulic tomography; specific storage; parameter estimation code (PEST); sustainability
Released2019 02 08
AbstractThe sustainable management of groundwater resources is essential to municipalities worldwide due to the increasing water demand from dramatic population growth. Planning for the optimized use of groundwater resources requires a sound understanding of hydrogeology and reliable estimation of hydraulic parameters such as hydraulic conductivity (K) and specific storage (Ss). Traditionally, K estimates are obtained through the application of empirical formulae to representative grain sizes, laboratory analysis of core samples, slug/bail tests and pumping tests. Reliable estimates of Ss are difficult to obtain and are typically obtained through the analysis of pumping tests. The interpretation of pumping tests with analytical solutions with various simplifying assumptions has become the de facto standard in the consulting industry; however, research has shown that in non-idealized real-world applications, biased K and Ss estimates may be obtained which can lead to poor predictions of independent stress events. Thus, there is a critical need for more robust methods to estimate hydraulic parameters.
A new approach using hydraulic tomography (HT) to estimate K and Ss has been applied at the Mannheim East wellfield in Kitchener, Ontario. In particular, four different geological models with homogeneous geological layers are calibrated by coupling HydroGeoSphere (HGS) (Aquanty, 2018) and the parameter estimation code PEST (Doherty, 2005) using water-level variation records in observation wells collected during municipal well operations. The four geological models are well calibrated and yield reliable estimates that are consistent with previously estimated values for the shallower layers where most data points are collected. However, K and Ss estimates for deeper layers with fewer observation points vary more significantly among the models. The comparison of simulated and observed draw down for both model calibration and validation reveals that all four groundwater flow models with varying geology can capture the water-level fluctuation pattern quite well. However, rapid water-level variations at some wells are not captured very well, which could be due to the presence of high K pathways and heterogeneity not captured by these geological models. Currently, we are developing a HT approach based on geostatistics to handle this issue for both unconsolidated and fractured geologic media.
Overall, our research reveals that: 1) the HT analysis of municipal well records is feasible and yields reliable K and Ss estimates of individual geological units where drawdown records are available; 2) these estimates are obtained at the scale of its intended use of municipal well operations, unlike small-scale estimates typically obtained; 3) characterization and estimation can be conducted using existing data, thus removing the need for dedicated pumping tests which leads to substantial cost savings; and 4) data collected during municipal well operations can be used for parameter estimation and groundwater modeling, thus they are critical and should be archived.
GEOSCAN ID313602