Analysis on the change of landscape in an unregulated sand-bed river
Event Type: Seminar
Event Date: 30 November 2018 - 3:00pm
Venue: ASE 3D Viz Laboratory Room (N2-B1c-16c).
Speaker: Chanjoo Lee & Won Jae Kim
About the speaker:
Speaker 1: Chanjoo Lee:
Chanjoo Lee is a senior researcher at the Korea Institute of Civil Engineering and Building Technology, a public research institute in South Korea. He holds Master’s degree in hydraulic engineering and a PhD in Geography, both from Seoul National University. Chanjoo’s research interest broadly include fluvial geomorphology, environmental fluid mechanics and water resources managements of small-medium sized rivers. He has extensive experience in river flow structure and discharge measurements using acoustic Doppler current profiler. Chanjoo is currently in charge of management of gauge stations in most of the major rivers in South Korea.
Speaker 2: Won Jae Kim:
Won Jae Kim is a research fellow at the Korea Institute of Civil Engineering and Building Technology. He is also a professor at the School of KICT, at the University of Science and Technology in Korea. He completed his PhD in civil and water resources engineering at the Tokyo University in Japan. His research interest include urban sewer system hydrology and hydraulics, and waste managements. He is engaged in water quality monitoring for rivers and lakes in Korea. He is also interested in pollution control management and policy, based on watershed pollution total load.
About the event:
Chanjoo Lee: In this talk I will describe some environmental characteristics related to the landscape change during 1971 to 2016 in the Naeseong Stream, which is one of the representative unregulated sand-bed river in South Korea. In the last 45 years, landscape of the Naeseong Stream changed from a nearly unvegetated open channel with abundant bare bars to a densely vegetated stream where more than half of floodplain is now covered with vegetation along with the development of islands. Stage-discharge relationship was established and continuous daily discharge was estimated at the Wolpo gauging station which has a long-term water level record since 1969. Statistical analysis of vegetated area and hydrological variables, showed significant inverse relationship between the change of vegetated area and the amount of summer peak discharges.
Won Jae Kim: Reservoirs in Korea are experiencing deteriorating water quality due to rapid eutrophication and increased stagnant area. The problems are (1) eutrophication by inflow of many water pollutants, (2) the occurrence of algal blooms, (3) the increase of oxygen consumption in the bottom water and anaerobic condition, and (4) the elution of nutrients (P, N, etc.) from the sediments. More than 90% of reservoirs in Korea have water depths less than 5m. We developed a Water circulation system to improves water quality by inducing the descent of surface water (epilimnion) using wind and water current energy. It prevents water stratification and anaerobic condition of the bottom layer. The test-bed was operated for more than 6 months and it is observed that the level of DO is substantially improved, supersaturation is reduced and it prevented increase of pH.