(Erosion and Sediment Transport Measurement in Rivers: Technological and Methodological Advances (Proceedings of the Oslo Workshop, June 2002), IAHS Publication 283, 2003, pp. 21–27).
High-resolution monitoring of sand mass balance in the Colorado River below Glen Canyon Dam, Arizona, USA, is needed for environmental management. In the Grand Canyon, frequent collection of suspended-sedi-ment samples from cableways is logistically complicated, costly and provides limited spatial and temporal resolution.In situ laser sensors were tested in the Colorado River as an alternative method for monitoring the river's suspended transport. LISST data were collected at a fixed-depth, near-shore site while isokinetic measurements were simultaneously made from a nearby cableway. Diurnal variations in LISST grain size and concentration data compared well with depth-inte-grated, cross-section data. The LISST was also successfully used to electronically trigger an ISCO 6712 pump sampler to provide continuous monitoring during periods when suspended concentrations exceeded the LISST's measurement range. Initial results indicate that the LISST can provide useful high-resolution sus-pended-sediment data within the Colorado River, when optics are maintained on a weekly basis.
Colorado River, Environmental monitoring, LISST, Suspended-sediment transport
