An autonomous low-power instrument platform for monitoring water and solid discharges in mesoscale rivers

Abstract

Abstract. We present the development of the River Platform for Monitoring Erosion (RIPLE) designed for monitoring at high temporal frequency (∼10 min) of water discharge, solid fluxes (bedload and suspended load) and properties of fine particles (settling velocity) in mesoscale rivers, i.e. which drain mesoscale catchments (≈10–103 km2). This platform responds to a request to continuously measure these variables in rivers using a single, centralized device, and to do this in the most direct way possible. The platform integrates the following instruments: (i) for water discharge, water level radar, and surface velocity radar, digital cameras and an echo sounder; (ii) for fine sediment load, turbidimeters and automatic samplers including the SCAF (a sediment settling velocity characterization device); (iii) for bedload, a hydrophone; and (iv) for water quality, a conductivity probe and water sampling. As far as water discharge monitoring is concerned, priority has been given to non-intrusive instruments to improve the robustness of the system. All the instruments are driven by a data logger (Campbell® CR6), which locally stores the data and then uploads them to a remote server every hour during the day using a 3G modem. SMS (Short Message Service) alerts can be sent depending on scheduled conditions (e.g. low battery voltage, water level threshold, all samples of the automatic sampler collected). The platform has been designed to be as autonomous as possible: it is powered by a battery that is supplied by a solar panel. Limiting the power consumption of the platform was one of the main technical challenges because of the quantity of instruments integrated. A simple 100 W solar panel is sufficient to power the entire platform, even during winter or low insulation conditions. A user-friendly interface has been developed, enabling to visualize the data collected by the platform from an internet connection. It is also possible to remotely configure the platform within this interface, e.g. to modify water sampling thresholds or alert thresholds. Finally, the platform is relatively easy to move from one site to another, because its installation requires little civil engineering. To date, RIPLE has been tested on two rivers of the Alps in France: the Romanche river in Bourg d'Oisans from September 2016 to July 2018 and the Galabre river in La Robine sur Galabre since October 2018, demonstrating the proper functioning of the platform.

Estimation of fine sediment stocks in gravel bed rivers including the sand fraction

“…A second station (‘Riple station’ in Fig. 1) was installed in 2018, 2.5 km downstream of the Galabre station, to measure suspended sediment fluxes draining an area of 34 km 2 (Nord et al ., 2020). An acoustic discharge instrument was installed at the outlet of the Clarette sub‐catchment to measure the water discharge.…”

Streamflow monitoring at high temporal resolution based on non-contact instruments in a river prone to bathymetric shifts

“…A new station called RIPLE (River Platform for Monitoring Erosion) was installed in October 2018 on the Galabre river, 2.5 km downstream of La Robine sur Galabre. Nord et al (2020) presented the developpement of the RIPLE platform, an autonomous low-power instrument manuscript submitted to Water Resources Research platform for monitoring water and solid discharges in mesoscale rivers. The RIPLE station is equipped with a fixed surface velocity radar (so-called V radar), a water level radar (so-called H radar) and a video camera dedicated to Large Scale Particle Image Velocimetry (LSPIV) analysis as illustrated by the schematic diagram in Figure 1.…”