Developing GPS river flow tracers (GRiFTers) to investigate large scale river flow phenomena

Stockdale, Richard-James

Abstract

Existing flow measurement methods in natural gravel rivers are largely based on a series of point measurements detached from the dynamic nature of river flow. Traditional measurement methods are limited in many environments and locations due to an inability to access directly the channel; this situation is further complicated at high discharges where entry into the channel becomes impossible. The inadequacy of currently utilised flow measurement methods is highlighted in the study of riffle-pool sequences where limited data has produced gaps in the understanding of these fundamentally important bedform structures. Within the study of riffle-pool sequences the most prominent debates concern the precise means of sequence development and maintenance, the existence / operation of the velocity reversal hypothesis and the spatial compositions and periodicity of these quasi-regular bedform features.

The expanding usage of remote sensor monitoring techniques, the incorporation of GPS receivers into drifters to provide improved positioning, and the adaptation of drifters for use in the surf zone and in estuaries and lakes have combined to highlight the potential of producing a GPS river flow tracer (GRiFTer). The development of a GRiFTer suitable for deployment in a natural gravel bed river system is described whilst the logistics of performing a field based GRiFTer investigation, data acquisition and analysis methods and the achievable accuracy of the approach are also considered.

The development of a GPS River Flow Tracer provides an innovative approach to the acquisition of surface velocity measurements through the development of a series of GRiFTer based analysis tools and techniques. The suite of tools developed to date includes; the ability to measure a single primary flowline through a reach, a means of independently measuring the effective width of channel flow, the identification of low velocity zones (and the direction of flow within these areas), three different methods for the measurement of surface flow velocity (primary flowline, cross-sectional averaged and reach scale) and a means of defining riffles and pools from the relationship between depth and surface flow velocities.

The study ultimately concludes with a conceptual model for the development and maintenance of riffle-pool sequences based on an adaptation of the flow convergence routing hypothesis.

Citation

Stockdale, R. (2009). Developing GPS river flow tracers (GRiFTers) to investigate large scale river flow phenomena. (Thesis). University of Hull. Retrieved from https://hull-repository.worktribe.com/output/4213020

• Thesis Type: Thesis
• Deposit Date: Sep 12, 2012
• Publicly Available Date: Feb 22, 2023
• Keywords: Geography
• Public URL: https://hull-repository.worktribe.com/output/4213020
• Additional Information: Department of Geography, The University of Hull
• Award Date: Sep 1, 2009