A Study on Settling Properties of Cohesive Sediments in Shihwa Lake

J. Ocean Eng. Technol. 2005;19(4):42-48.

LEE YOUNG-JAE;LEE SANG-HWA;HWANG KYU-NAM;RYU HONG-RYUL;

Department of Civil Engineering, Dong-A University;Department of Civil Engineering, Dong-A University;Department of Civil Engineering, Chonbuk National University;Department of Civil Engineering, Chonbuk National University;

시화호 점착성 퇴적물의 침강 특성에 관한 연구

이영재;이상화;황규남;류홍렬;

동아대학교 토목공학과;동아대학교 토목공학과;전북대 학교 토목공학과;전북대 학교 토목공학과;

Keywords: Cohesive Sediments, Suspended Sediment Concentration, Sooting Velocity

핵심용어: 점착성 퇴적물, 부유사농도, 침강속도

Abstract

The sediment of Shihwa Lake contains an abundant quantity of cohesive sediments. The transport processes of the cohesive sediments are complex and difficult to predict, quantitatively. The cohesive sediments are the primary reason for the pollution of the environment and water quality in the coastal region. In this study, a column test has been performed. In order to quantify the settling velocities of sediment from Shihwa Lake, an experiment was conducted using a specially designed 1.8m tall settling column. A series of settling tests and physico-chemical property tests on Shihwa Lake cohesive sediments has been conducted to investigate the correlation between settling properties and their physico-chemical properties, which are represented as grain size distribution, mineralogical composition, and percentage oj organic contents. Experimental results of physico-chemical property tests show that Shihwa Lake sediments are relatively large in average grain $size(74mu m)$ contain very small organic $material(6%)$, and are dominantly composed of Quarts, which has relatively low cohesion. Thus, Shihwa Lake sediments might be specified as those whose settling properties are more influenced by gravity than cohesion. It is concluded that the magnitude of settling velocities of muddy sediments can be quite different, regionally, and it implies that field or laboratory experiments for settling velocity measurement should be preceded over the numerical modeling of muddy sediment transport, in order to obtain the reliable prediction results for a given specific site.