Runoff-induced vertical thermal dynamics in a canyon-shaped reservoir during the summer monsoon
Do-Seong Byun A D , Yang-Ki Cho A , In-Ae Huh B and Deirdre E. Hart CA Department of Oceanography/Institute of Marine Science, Chonnam National University, Gwangju 500-757, Republic of Korea.
B Water Chemistry Division, National Institute of Environmental Research, 2-109, Incheon 404-170, Republic of Korea.
C Department of Geography, University of Canterbury, Private Bag 4800, Christchurch, New Zealand.
D Corresponding author. Email: dsbyun@hanmail.net
Marine and Freshwater Research 56(7) 959-968 https://doi.org/10.1071/MF04285
Submitted: 22 November 2004 Accepted: 31 March 2005 Published: 14 October 2005
Abstract
During the summer rainy season, double thermoclines were observed in a small canyon-shaped reservoir. The physical processes leading to thermocline evolution are examined from the vertical temperature profile observed along the reservoir before and after rain. Observations show that their evolution is related to the inflow of runoff, which is colder than the reservoir surface water and post-rain fair-weather conditions. Tongue-like distributions of turbidity, conductivity and nutrient concentrations downstream from the headwater clearly reveal the presence of runoff-induced intermediate inflows. In addition to supplying nutrients, the inflow provides the oxygen-deficient intermediate layer with a rich supply of dissolved oxygen. Concurrently, in the upper part of the reservoir runoff-induced inflows may drive the oxygen-deficient bottom water to shift downstream along the layer beneath the runoff-induced inflow. The water mass between the two thermoclines may operate as a source of nutrients for algal development in early autumn when the upper thermocline is destroyed by the convective overturn owing to the surface cooling.
Extra keywords: double thermocline, rainy season, runoff-induced inflow, thermal layer.
Acknowledgments
We would like to thank Mr. Youn-Jong Sun for data pre-processing support. The authors wish to thank three anonymous reviewers for their helpful comments on the manuscript. This work was supported by grant no. RO1-2004-000-10771-0 from the Basic Research Program of the Korea Science & Engineering Foundation.
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