Novel, ultralight platform for mapping water quality parameters in low-order streams

Authors: FELTON, RYAN - Southern Cross University; Dalzell, Brent; Baker, John; FLYNN, KADE - University Of Minnesota; Porter, Sarah

Submitted to: ACS Environmental Science & Technology Water
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/2/2023
Publication Date: 8/16/2023
Citation: Felton, R., Dalzell, B.J., Baker, J.M., Flynn, K., Porter, S.A. 2023. Novel, ultralight platform for mapping water quality parameters in low-order streams. ACS Environmental Science & Technology Water. 3(10):3189-3446. https://doi.org/10.1021/acsestwater.3c00280.
DOI: https://doi.org/10.1021/acsestwater.3c00280

Interpretive Summary: Studying water quality in small headwater ditches and stream networks can be difficult because narrow channels, low water levels, and obstructions can make these locations inaccessible by most boats. We developed a sampling platform that can be deployed from an ultralight inflatable raft (Packraft) that is well suited for sampling these challenging headwater systems. Our new Packraft based sampling system was able to measure the impacts of land use, subsurface tile drainage, lakes, and wetlands on water quality in small agricultural watersheds. This sampling platform will be useful to scientists studying water quality as well as conservationists who need information about what areas should receive priority for conservation efforts.

Technical Abstract: dvances in portability, robustness, and availability of environmental water sensors have resulted in development of new techniques for spatial sampling of aquatic environments from moving platforms including passive drifters, piloted or automated drones, and boats. These new platforms for environmental monitoring have generated opportunities for improved observation of spatial patterns that shed new insight into how nutrients and organic matter are exported from the landscape to streams as well as biogeochemical cycling that occurs within watershed channel networks. Despite the range of new sampling platforms available, there remains an unoccupied niche for a platform that is large enough to support a scientist and instrument payload while also being lightweight and small enough navigate small headwater streams and ditches. In this paper, we describe the development and testing of a sampling platform deployed from an ultralight inflatable raft (Packraft) intended for use in small headwater systems. In addition to environmental sensors and a GPS unit coupled to a data logger, we also included a device for automated collection of discrete water samples which can be used to validate sensor performance or other laboratory analyses of water parameters that cannot be measured in-situ. The Packraft platform was tested by tracking nitrate (NO3-) and dissolved reactive phosphorus (DRP) in watersheds dominated by agricultural land use in Minnesota, USA. Data collected from the Packraft was effective for capturing the effects of land use, subsurface tile drainage, and the presence of lakes and wetlands on overall NO3- concentration in the stream channel. Repeated sampling campaigns revealed different spatial patterns of NO3- and DRP that changed over time, helping to identify biogeochemical hot spots and hot moments in this agricultural watershed. The Packraft-based approach to water sampling made it possible to study portions of the headwater ditches and streams that were previously inaccessible. These spatially-resolved observations about the interactions between watershed network features and land management on overall water quality and nutrient export can provide new insights into the biogeochemistry of managed landscapes and may be helpful to guide more effective conservation approaches.