IAHR, founded in 1935, is a worldwide independent member-based organisation of engineers and water specialists working in fields related to the hydro-environmental sciences and their practical application. Activities range from river and maritime hydraulics to water resources development and eco-hydraulics, through to ice engineering, hydroinformatics, and hydraulic machinery.
Log On
About IAHRDirectoryCommitteesMy IAHRNews & JournalseLibraryeShopEventsJoin IAHRWorld CongressDonate
spacer.gif
spacer.gif eLibrary
spacer.gif eLibrary
You are here : eLibrary : IAHR Asia Pacific Division Proceedings : 19th IAHR APD Congress, Hanoi 2014 : Session 1: ENVIRONMENTAL HYDRAULICS : NUMERICAL APPROACH TO THE LONG-TERM VARIATION OF SALINITY CONDITION IN LAKE OGAWARA , JAPAN
NUMERICAL APPROACH TO THE LONG-TERM VARIATION OF SALINITY CONDITION IN LAKE OGAWARA , JAPAN
Author : M. YASUKOCHI(1), T. KINOSHITA(2) , R. AKOH(3), T. ISHIKAWA(4)
Lake Ogawara is a brackish water lake with a strong halocline has become eutrophicated very rapidly due to the contaminant upwelling from anaerobic hypolimnion. In this study, a numerical model of salinity circulation was constructed to explain the process of lake condition change. By referring the past field observations, three sub-processes were considered to compose the total model; (a) seawater inflow through the river under the effect of tide, (b) dilution of saltwater with lake freshwater in the process of gravity current on the lake bed slope, (c) vertical turbulent mixing and upward salinity transport in the lake. The processes-(a) and (b) were formulated being based on field observation data. The process-(c) was calculated by vertical 1-D k-¦Ĺ model taking into account the buoyancy effect caused by salinity and water temperature.ˇˇComputation for ten years when the lake condition got worse explained the long-term trend of salinity condition in the lake. Major points are as follows; the depth of halocline used to be almost constant around 20 meters before 2000, started to rise in 2002 and reached the depth of 14 meters in 2008. The area of halocline became three times larger, showing the increase of bottom water transport to the surface layer. As a result, surface salinity increased three times larger than the past stable condition. The simulation results also showed a good agreement with observations on seasonal changes of vertical profiles of salinity and water temperature.
File Size : 1,995,775 bytes
File Type : Microsoft Word Document
Chapter : IAHR Asia Pacific Division Proceedings
Category : 19th IAHR APD Congress, Hanoi 2014
Article : Session 1: ENVIRONMENTAL HYDRAULICS
Date Published : 10/03/2015
Download Now