Interaction between Fresh and Sea Water in Tidal Influenced Navigation Channel
Kim Nam-Hoon, Seoul National University, Civil and Environment Engineering, Seoul, Korea, Republic of (South) and Jin Hwan Hwang, Professor, Civil and Environmental Engineering, Seoul, Korea, Republic of (South)
Abstract:
Nam-Hoon, Kim
1, Jin-Hwan, Hwang
2, Hyeyun-Ku
31,2,3 Department of Civil and Environmental Engineering, Seoul National University, Republic of Korea; 1nhkim0426@snu.ac.kr; 2jinhwang@snu.ac.kr; 3hyeyun.ku@gmail.com;
We have conducted field observations after freshwater discharges of sea dike during ebb tide in Geum River Estuary, Korea to understand the interaction between fresh and sea water. To measure spatial variability of the stratified flow, an Acoustic Doppler Current Profiler (ADCP) and a portable free-fall tow-yo instrument, Yoing Ocean Data Acquisition Profiler (YODA profiler) which can continuously measures three-dimensional velocity profiles and vertical profiles of the fine-scale features, respectively, within water column were used in a vessel moving at a speed of 1-2 m/s. The flow observations show the strong stratification and dispersion occurred near field region because of the ebb tide advection (Fig. 1). As moving toward the far field region, the stratification and dispersion was getting thin and weak but still remaining. The presence of mixing process between fresh and sea water was represented by the gradient Richardson Number. The mixing occurred throughout the near field region and potentially mixed in the far field region. This study have been conducted to serve as a basic research of understanding the Region Of Freshwater Influence (ROFI) in the tidal influenced navigation channel. We are going to perform a few more observations in the future. Key words: Richardson number, stratification, mixing, ROFI, ADCP, CTD
Figure 1. High-resolution observation data of salinity (psu) from YODA Profiler
Acknowledgement: This research was supported by grants from the Korean Ministry of Oceans and Fisheries entitled as “Developing total management system for the Keum river estuary and coast” and “Integrated management of marine environment and ecosystems around Saemangeum”. We also thank to the administrative supports of Integrated Research Institute of Construction and Environmental Engineering at Seoul National University.
