Center for Embedded Network Sensing

Increasing demands on water supplies, non-point source pollution, and water quality-based ecological concerns all point to the need for observing stream flow perturbations and pollutant discharges at higher resolution than was practical in the past. This work presents the results from a test of a rapidly deployable river observational approach consisting of four components: (1) existing geospatial data and federal, state, and private river gauging infrastructure for identifying key river reaches and critical sampling times, (2) human- actuated sensor deployments for broad spatial characterization of the targeted river reach, (3) stationary sensors embedded in the river and its sediments for longer term spatiotemporal observations within the targeted reach, and (4) the robotic Networked Infomechanical System (NIMS RD) for high resolution scanning of spatiotemporal hydraulic and chemical properties at specific points along the reach. The approach is demonstrated for a test bed deployment at the confluence of the Merced and San Joaquin Rivers in Central California. After identifying a suitable reach for the test deployment, a network of on-line gauging stations, accessed through the California Data Exchange Center (CDEC), is used to coordinate the timing of the subsequent three deployment aspects based on flow and river stage forecasts. Kayak-mounted sonar and water quality sensors are used to rapidly survey the test zone bathymetry and basic water quality parameters (temperature, salinity). Results from the rapid survey are then used to guide locations of the sediment- anchored sensor arrays (javelins) which include temperature, water pressure (depth) and water quality sensors distributed vertically at screened intervals. The NIMS RD is comprised of two supporting towers and a suspension cable delivering power and Internet connectivity for controlling and actuating the tram-like NIMS unit. The NIMS unit is capable of raising and lowering a payload of sensors, allowing a preprogrammed or data-actuated adaptive scan to be completed across a stream channel. In this work, NIMS RD is deployed to provide high resolution synoptic sampling of velocity, electrical conductivity (EC), nitrate, ammonium, pH, and temperature distributions across the San Joaquin River channel in the confluence zone. Results from the different aspects of the test deployment are presented and discussed in the context of potential science and engineering applications of this multiscale networked sensing strategy.