서해안 어항에서 저면전단응력이 고려된 경험적 방법에 의한 장기퇴적변화

Abstract

In this study, large scale sedimentation occurred due to the construction of detached breakwater in the fishing port of the West Coast, Korea. And the evaluation of the sedimentation characteristics was analyzed based on the monitoring data of long-term change of depth in sea area. The long-term sedimentation of the fishing port were analyzed by long-term monitoring of water depth changes, and long-term sedimentation by an empirical method considered bottom shear stress in the around sea area. In addition, Seawater flow simulations were carried out using the EFDC model, taking into account the tidal current and wave-induced current of the SWAN model. It was verified by using tide and tidal current observation data measured in the field. So, It was considered that there was no significant difference between the tidal current and the wave-induced current. Only tidal current was considered.

The main results are summarized as follows : 1) The distribution of bottom shear stress due to the change of velocity around the fishing port is greatly decreased with the change of topography condition due to the breakwater, wharf etc. This indicates that the sedimentation environment has changed.

2) The monitoring results of long-term changes in water depth for about 8 years that erosion and deposition are occurring in each area. This change in seabed topography can be attributed to the change in bottom shear stress due to flow. And as a result of long-term monitoring of critical bottom shear stress, the maximum shear stress was less than 2.0 N/㎡ and the mean shear stress was less than 0.5 N/㎡.

3) The proposed formula was derived from the monitoring of long-term by regression analysis of the bottom shear stress on the sedimentation in the development of fishing port on the West Coast. Using an empirical method, we can improve the reproducibility and predictability of sedimentation phenomena. And the relation between the maximum and mean bottom shear stresses in the study area was derived, The maximum bottom shear stress and the proposed formula are as follows. 1.0 year : 2.0 year : 3.0 year : 4.0 year : The mean bottom shear stress and the proposed formula are as follows. 1.0 year : 2.0 year : 3.0 year : 4.0 year : Where, is the long-term sedimentation, the bottom shear stress.

4) The numerical simulations of the long-term sedimentation environment were simulated using the proposed formula. The numerical simulated values ​​were well reproduced with the observed values ​​of water depth monitoring. As a result, simulation data of sedimentation data are reproduced and predicted similar to the monitoring data in the fishing port. In this study, the long-term sedimentation by an empirical method considered bottom shear stress is the result of improved reproducibility and accuracy in the fishing port of West Coast, Korea.