Doppler technology applied to large-river studies--National Park Service--WASO-INFO




	by Brian L. Cluer
		Resource managers often need river channel and hydraulic data to describe existing resource conditions or to estimate impacts of a past or potential change in the river’s watershed. In small rivers, technicians obtain these data by wading and taking simple measurements of depth and velocity. This topographic and flow information is logistically difficult or impossible to obtain in rivers too deep to wade or during flood events. In the past, flow information from large rivers has been obtained by taking depth and velocity measurements from cables stretched across rivers. Not only are these techniques slow, resulting in very little information for the effort expended, they also limit the locations for data collection. In recent years, hydroacoustic equipment has been produced that fills these scientific data collection needs in large-river environments. Hydroacoustic echo sounding is commonly used to measure water depth, providing topographic data for river channel mapping. A sophisticated multibeam, hydroacoustic echo sounder is now available that can also measure the velocity of river flows. By sending and receiving acoustic energy from different heights within the water column, and then applying the Doppler shift theory, the acoustic Doppler current profiler (ADCP) determines the velocity and trajectory of particles suspended in the water column. Recent advances have made these new ADCP echo sounder units operable in large rivers where average flow depths exceed 5 feet. Attaching an ADCP to a maneuverable boat, the three-dimensional velocity field of a reach of river can be measured quickly and accurately. When the ADCP is integrated with a navigation/tracking device, such as a survey-grade global positioning system (GPS), spatially precise map data can be collected on the channel bottom topography, the water surface, the three-dimensional flow field, and the discharge of a river reach. In 1998, staff from the Water Resources Division used an ADCP, integrated with a GPS-GLONASS (combined U.S. and Russian satellite surveying system), mounted on a motorized raft to collect needed flow and topographic data on the Green River in Dinosaur and Canyonlands National Parks in Utah. The integrated system delivered spatial positions with 4-cm accuracy vertically, and 1–2 cm horizontally, correlated with detailed flow depth and velocity data. More than 15,000 data positions distributed over a 4-mile reach were measured in about 15 hours from a powerboat zigzagging back and forth across the river channel. Channel maps, water surface maps, and flow field (velocity) maps of two 4-mile reaches were constructed from the data obtained in June 1998. The river channel and hydraulic data collected using the ADCP and GPS-GLONASS are substantially more detailed and accurate than data obtained using conventional means, and take much less time to acquire.

Doppler technology allows resource managers to safely and accurately map flow velocity and depth of large rivers. In this map of the Green River at Dinosaur National Monument (Colorado and Utah), flow direction and velocity are indicated by black arrows—the longer the arrow, the faster the flow. Although hard to appreciate in this depiction, flow depth is indicated by a gradient scale of color from black (2 feet deep) to white (38 feet deep). Click on the map to view close-up. brian_cluer@nps.gov Hydrologist, Water Resources Division, Water Rights Branch, Fort Collins, Colorado INTERNATIONAL CONTINGENT AT FUNDAMENTALS TRAINING In January, 20 resource managers from the National Park Service attended the third Fundamentals for Natural Resource Management at the Albright Training Center at Grand Canyon National Park (Arizona). In addition to NPS staff, five park managers from South Africa participated in the course. Their perspectives on such issues as subsistence uses and managing parks on tribal lands added a valuable dimension to the training. The fundamentals course provides a sound introduction to natural resource management in the national park system with two primary emphases: an ecosystem approach to management and planning, and the implementation of a resource management program that includes natural, cultural, and social science considerations. Back to Chapter 6: New Horizons President mandates coral reef protection by James Tilmant Feral burro removal: New solutions to an old problem by Christopher J. Stubbs Natural resource information tools make their way to the web by Jen Coffey Congress places a positive imprint on park management by Mike Soukup Solicitor opinions advance park protection by Julia Brunner and Carol McCoy Research and collecting permit procedures revised by Robert Winfree Fee demonstration funds bolster natural resource protection by Abigail Miller Home

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Last Updated: 07/22/99
Direct comments on this website to jeff_selleck@nps.gov
This article is from Natural Resource Year in Review--1998, published by the National Park Service, U.S. Department of the Interior, in June 1999 (publication D-1346)