Deducing the spatial variability of exchange within a longitudinal channel water balance
Version of Record online: 20 MAY 2013
Copyright © 2013 John Wiley & Sons, Ltd.
Volume 28, Issue 7, pages 3088–3103, 30 March 2014
How to Cite
Schmadel, N. M., Neilson, B. T. and Kasahara, T. (2014), Deducing the spatial variability of exchange within a longitudinal channel water balance. Hydrol. Process., 28: 3088–3103. doi: 10.1002/hyp.9854
- Issue online: 13 MAR 2014
- Version of Record online: 20 MAY 2013
- Accepted manuscript online: 15 APR 2013 05:16AM EST
- Manuscript Accepted: 8 APR 2013
- Manuscript Received: 20 AUG 2012
- channel water balance;
- subsurface exchange;
- spatial variability
Developing an appropriate data collection scheme to infer stream–subsurface interactions is not trivial due to the spatial and temporal variability of exchange flowpaths. Within the context of a case study, this paper presents the results from a number of common data collection techniques ranging from point to reach scales used in combination to better understand the spatial complexity of subsurface exchanges, infer the hydrologic conditions where individual influences of hyporheic and groundwater exchange components on stream water can be characterized, and determine where gaps in information arise. We start with a tracer-based, longitudinal channel water balance to quantify hydrologic gains and losses at a sub-reach scale nested within two consecutive reaches. Next, we look at groundwater and stream water surface levels, shallow streambed vertical head gradients, streambed and aquifer hydraulic conductivities, water chemistry, and vertical flux rates estimated from streambed temperatures to provide more spatially explicit information. As a result, a clearer spatial understanding of gains and losses was provided, but some limitations in interpreting results were identified even when combining information collected over various scales. Due to spatial variability of exchanges and areas of mixing, each technique frequently captured a combination of groundwater and hyporheic exchange components. Ultimately, this study provides information regarding technique selection, emphasizes that care must be taken when interpreting results, and identifies the need to apply or develop more advanced methods for understanding subsurface exchanges. Copyright © 2013 John Wiley & Sons, Ltd.