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ADCP Measurements of Gravity Currents in the Chicago River, Illinois |
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| Authors: | Carlos M. García Kevin Oberg Marcelo H. García |
| Affiliation: | 1Professor, Instituto Superior de Recursos Hídricos, Universidad Nacional de Córdoba, Av. Filloy s/n, Ciudad Universitaria, Córdoba, Argentina (corresponding author). E-mail: cgarcia2mjc@gmail.com 2Hydrologist, U.S. Geological Survey, Office of Surface Water, 1201 W. University Ave., Urbana, IL 61801. E-mail: kaoberg@usgs.gov 3Chester and Helen Siess Professor, and Director, Ven Te Chow Hydrosystems Laboratory, Dept. of Civil and Environmental Engineering, Univ. of Illinois at Urbana-Champaign, 205 North Mathews Ave., Urbana, IL 61801. E-mail: mhgarcia@uiuc.edu |
| Abstract: | A unique set of observations of stratified flow phenomena in the Chicago River was made using an upward-looking acoustic Doppler current profiler (ADCP) during the period November 20, 2003 to February 1, 2004. Water density differences between the Chicago River and its North Branch (NB) seem to be responsible for the development of gravity currents. With the objective of characterizing the occurrence, frequency, and evolution of such currents, the ADCP was configured to continuously collect high-resolution water velocity and echo intensity profiles in the Chicago River at Columbus Drive. During the observation period, 28 gravity current events were identified, lasting a total of 77% of the time. Sixteen of these events were generated by underflows from the NB and 12 of these events were generated by overflows from the NB. On average, the duration of the underflow and overflow events was 52.3 and 42.1?h, respectively. A detailed analysis of one underflow event, which started on January 7, 2004, and lasted about 65?h, was performed. This is the first time that ADCP technology has been used to continuously monitor gravity currents in a river. |
| Keywords: | Field tests Acoustic techniques Rivers Density currents |