| Title | Hydrogeological tools for characterizing groundwater discharges to surface water: advantages, disadvantages, and the importance of proper timing |
| Download | Download (whole publication) |
| Author | Brewster, C, Jr |
| Source | Regional-scale groundwater geoscience in southern Ontario: an Ontario Geological Survey, Geological Survey of Canada, and Conservation Ontario open house; by Russell, H A J; Ford, D; Priebe, E H;
Geological Survey of Canada, Open File 8212, 2017 p. 8, https://doi.org/10.4095/299764 (Open Access) |
| Year | 2017 |
| Publisher | Natural Resources Canada |
| Meeting | Ontario Geological Survey and Geological Survey of Canada groundwater geoscience open house; Guelph; CA; March 1-2, 2017 |
| Document | open file |
| Lang. | English |
| Media | on-line; digital |
| Related | This publication is contained in Russell, H A J; Ford, D;
Priebe, E H; (2017). Regional-scale groundwater geoscience in southern Ontario: an Ontario Geological Survey, Geological Survey of Canada, and Conservation Ontario open house, Geological Survey of Canada, Open File 8212 |
| File format | pdf |
| Subjects | hydrogeology; environmental geology; groundwater; aquifers; groundwater resources; resource management; groundwater discharge; surface waters; groundwater regimes; groundwater flow; water quality;
ecosystems; wetlands; floods; hydrologic environment; hydrologic properties; modelling; groundwater temperatures; water levels; piezometric levels |
| Program | Aquifer Assessment & support to mapping, Groundwater Geoscience |
| Released | 2017 02 22 |
| Abstract | Many of the water management responsibilities of Conservation Authorities require an understanding of groundwater/surface-water (GW/SW) interactions. GW/SW interactions play a major role in the
physical, chemical, and biological integrity of surface water and groundwater systems and are relevant to: source water protection; protection of groundwater dependent ecosystems; protection of wetlands, management of fisheries; assessment of the
effects of land use changes on watersheds; and the prediction and management of floods. The type and amount of hydrological data needed to answer specific management questions will vary greatly. If financial or personnel resources are limited, it is
a challenge to collect data at a sufficient scale and frequency to ensure a full understanding of the system.
The complexity of GW/SW systems means it can be difficult to collect enough data to put it all into proper hydrological context and
develop reliable conceptual models of the GW/SW interactions. Therefore, there is a need for inexpensive and cost effective methods and tools to efficiently characterize groundwater discharges and GW/SW interactions on both large and small scales. To
address this problem, a multi-scale, multi-technique characterization approach is proposed, where large-scale large-area reconnaissance methods are used to quickly assess large areas and identify the largest groundwater discharges. This work is then
followed by progressively smaller-scale characterization techniques (with successively higher sensitivity) to make point measurements of groundwater discharge and GW/SW interactions and quantify fluxes.
The reconnaissance methods consist primarily
of temperature-as-a-tracer methods (i.e., aerial thermal infrared surveys, drag probe surveys, and streambed/lakebed temperature mapping) that are very useful and relatively inexpensive methods for delineating groundwater discharges. The
reconnaissance results are used to pick locations for more conventional and/or point measurement techniques (i.e., differential streamflow gauging, monitoring water levels, mini-piezometers, seepage meters, and lakebed/streambed temperature
monitoring and modeling) to characterize the groundwater flow directions (discharge versus recharge) and quantify fluxes.
An overview of the overall approach and a brief description of the advantages and disadvantages of each technique will be
provided. This approach can obtain good spatial characterization of GW/SW interactions; however, timing of the data collection is critical. All data collected should be put into the context of (and help define) how the hydrological system changes
over time, because groundwater discharge and GW/SW interactions are not constant over time. For temperature-as-a-tracer methods, timing of data collection is of paramount importance. Temperature based GW/SW interactions methods are deceptively simple
and can provide excellent information; however, collecting data when there is poor or no contrast between surface and groundwater temperatures should be avoided, because it can result in useless or misleading results. If properly applied, the
multi-scale, multi-method characterization approach can be a cost effective way of comprehensively characterizing groundwater discharges and GW/SW interactions and help improve decision making with respect to managing natural resources. |
| GEOSCAN ID | 299764 |
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