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You are here : eLibrary : IAHR World Congress Proceedings : 35th IAHR Congress - Chengdu (2013) : THEME 6 - MARITIME HYDRAULICS AND COASTAL ENGINEERING : Analysis on Residual Currents at the Modaomen Estuary and Nearby Coastal Area
Analysis on Residual Currents at the Modaomen Estuary and Nearby Coastal Area
Author : Zhang Zhiwei, Deng Jiaquan and Wu Menwu
Modaomen estuary is dominated by fluvial action. The effect of runoff is strong and tide is relatively weak. Residual current is that reset of aperiodic currents while ocean currents excluding periodic tidal flow. It predicts the direction of sediment transport and diffusion of contaminants. Study on the residual current is important significance of scour and silting evolution and environmental protection of estuary. Residual currents usually form nonlinear flows while affected by wind field, sanity and temperature of the sea flow. In this paper, according to the Modaomen estuary synchronous tidal hydrology observation data on dry season in 2011 and 2012, flood season on 2012. According to the synchronous tidal hydrology observation data, divided the Modaomen estuary into three parts. Include area of estuary in water channel, transition area of between water channel and open sea and area of open sea. Stratified analysis this three parts of water area of residual currents on large, median and low tidal period, obtain stratified Eulerian residual currents by tidal cycle velocity vector averaging method. There are the following conclusions through analysis: Firstly, in the flood season, the area of Modaomen water channel is affected by strong runoff. The residual current maximum velocity appears at the surface and spring tide is relatively uniform. In dry season, runoff is weakened and tidal enhancement, the salinity of the surface layer and bottom layer difference increase result in underlying salt wedge. Secondly, the transition area of between water channel and open sea, residual currents maximum velocity appear at the 0.2H layer. Residual currents direction is mainly southeast, near shore waters of vertical mixing effect are strong and the velocity gradient is relatively uniform. In dry season, because of runoff weaken, Modaomen estuary east and west deep grooves at the bottom have a salt wedge back and generate an opposite direction current to coastal current currents. Impact of coastal currents, flows direction is mainly in southwest and west. Finally, residual currents are affected by wave, tide, runoff, wind, density flow and other factors on the area of open sea. Current of vertical mixing degree is high and the velocity difference is bigger, currents direction is in a messy and has no obvious rule. In dry season, impact of coastal current and northeast monsoon, the surface residual currents velocity of outer sea are larger and increase from east to west. Current deflect from the south by southwest to west.
File Size : 675,042 bytes
File Type : Adobe Acrobat Document
Chapter : IAHR World Congress Proceedings
Category : 35th IAHR Congress - Chengdu (2013)
Article : THEME 6 - MARITIME HYDRAULICS AND COASTAL ENGINEERING
Date Published : 18/07/2016
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