Monitoring ephemeral headwater streams: a paired‐sensor approach

• Published in: Hydrological processes Vol. 30; no. 6; pp. 888 - 898
• Main Authors: Bhamjee, Rashaad, Lindsay, John B., Cockburn, Jaclyn
• Format: Journal Article
• Language: English
• Published: Chichester Wiley 15.03.2016; Blackwell Publishing Ltd; Wiley Subscription Services, Inc
• Subjects: Electronics; ephemeral streams; headwater; Headwaters; hydrological connectivity; Hydrology; instrumentation; Monitoring; Networks; sensor network; Sensors; Storms; Streams; Ontario
• ISSN: 0885-6087; 1099-1085
• DOI: 10.1002/hyp.10677

This paper introduces a paired‐sensor approach to monitoring ephemeral streamflow. Part of this approach includes the design of a new flow detection sensor. This flow detection sensor addresses the limitation of previous electronic resistance sensors that use water presence as a proxy for flow for assessing hydrological connectivity, by explicitly measuring flow presence. Using paired electronic resistance and flow detection sensors, this paper evaluates the performance of each sensor individually, and as a pair. Individually, the sensors were tested for the amount of noise they contain and the types of errors they were prone to committing. As a paired set, the sensors were analysed by the percent of time they were in valid states versus invalid states. Valid states included when water was present but flow was absent, when water and flow were both present and when water and flow were both absent during a storm. One invalid case existed, where the sensors recorded flow presence but not water presence. These valid and invalid cases were assessed using data collected from sensor networks established at two study sites in southern Ontario. This analysis was completed for the overall corroboration at each site, for each storm at each site and based on the relative position of the sensors in the channel at each site. The sensors were in valid states 83% and 94% of the time at each respective study site. Differences in local site conditions were found to affect the performance of the sensor network; however, no significant correlation was found between storm characteristics and sensor performance. Particularly, bed roughness was found to be a factor as it restricted the placement of the sensors. Despite this, the paired‐sensor network helps to increase the understanding of the flow dynamics within headwater streams by explicitly separating the two hydrological characteristics. A discussion of the challenges, limitations and opportunities of monitoring ephemeral flow is presented, and insights into how to address those limitations are provided. Copyright © 2015 John Wiley & Sons, Ltd.