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Sediment transport and coastal evolution at Thuan An Inlet, Vietnam

Eriksson, Eva-Lena LU and Hjertstrand Persson, Madeleine (2014) In TVVR04/5002 VVR820 20131
Division of Water Resources Engineering
Abstract
The Tam Giang-Cau Hai lagoon is located outside of Hue in central Vietnam. Southeast of Thuan An
inlet, one of the two inlets of the lagoon, a groin was constructed in 2008 as a measure to reduce the
sediment transport to prevent the inlet from closing. This groin has caused erosion of the eastern sand
spit of the inlet and accretion of sediment on the coastline south east of the groin. The objectives of
this study was to make a model of the sediment transport on the southeast side of the groin to be able
to analyse how different measures to reduce the erosion of the inlet would affect the sediment
transport past the groin.
The field measurements and parts of the data collection took place in Vietnam during nine weeks in
the... (More)
The Tam Giang-Cau Hai lagoon is located outside of Hue in central Vietnam. Southeast of Thuan An
inlet, one of the two inlets of the lagoon, a groin was constructed in 2008 as a measure to reduce the
sediment transport to prevent the inlet from closing. This groin has caused erosion of the eastern sand
spit of the inlet and accretion of sediment on the coastline south east of the groin. The objectives of
this study was to make a model of the sediment transport on the southeast side of the groin to be able
to analyse how different measures to reduce the erosion of the inlet would affect the sediment
transport past the groin.
The field measurements and parts of the data collection took place in Vietnam during nine weeks in
the beginning of 2013. The position of the coastline at Thuan An inlet was measured and the rest of
the data, such as e.g. wave data, bathymetry data, previously measured coastlines and sediment
transport was obtained from Institute of Mechanics in Hanoi. Other data used in this thesis was also
obtained from The University of Agriculture and Forestry in Hue and from The Oceanographic
Institute in Nha Trang. The study area has a tropical monsoon climate with two monsoon season per
year – the southeast monsoon and the northwest monsoon. The micro tidal climate in the area is fully
semi-diurnal and gives that the main sediment transport is wave induced.
The modelling software GENESIS was used to model the sediment transport past the groin. The
model was calibrated and validated using measured data and then the sediment transport on the
southeast side of the groin was modelled during the years 2013 to 2017. First, the case where no
measures were taken was modelled, to see what will happen if no changes of the groin were made.
After that, three different measures to decrease the accretion of sediment on the southeast side of the
groin (i.e. increase the sediment transport past the groin in order to reduce the erosion of the Thuan An
inlet) were modelled and analyzed. These three measures were making the groin shorter, increasing
the permeability of the groin and dredging sand from southeast side of the groin.
The result of the model and the different measures to reduce erosion were discussed. The conclusion
was that interventions to reduce the erosion are needed to protect the lagoon and the people living
around it and making their livelihood from it. Many people work with e.g. fishery, aquaculture and
agriculture and these occupations could be severely affected of the results of continuous erosion, such
as changed water environment in the lagoon and flooding. (Less)
Please use this url to cite or link to this publication:
author
Eriksson, Eva-Lena LU and Hjertstrand Persson, Madeleine
supervisor
organization
course
VVR820 20131
year
type
H2 - Master's Degree (Two Years)
subject
keywords
Thuan An, Hoa Duan, Tam Giang-Cau Hai lagoon system, lagoon, inlet, groin, longshore sediment transport, Thua Thien-Hue province, GENESIS, Huong River
publication/series
TVVR04/5002
report number
14/5002
ISSN
1101-9824
language
English
additional info
Examiner: Hans Hanson
id
4393060
date added to LUP
2014-04-14 21:11:13
date last changed
2019-03-29 14:20:04
@misc{4393060,
  abstract     = {{The Tam Giang-Cau Hai lagoon is located outside of Hue in central Vietnam. Southeast of Thuan An
inlet, one of the two inlets of the lagoon, a groin was constructed in 2008 as a measure to reduce the
sediment transport to prevent the inlet from closing. This groin has caused erosion of the eastern sand
spit of the inlet and accretion of sediment on the coastline south east of the groin. The objectives of
this study was to make a model of the sediment transport on the southeast side of the groin to be able
to analyse how different measures to reduce the erosion of the inlet would affect the sediment
transport past the groin.
The field measurements and parts of the data collection took place in Vietnam during nine weeks in
the beginning of 2013. The position of the coastline at Thuan An inlet was measured and the rest of
the data, such as e.g. wave data, bathymetry data, previously measured coastlines and sediment
transport was obtained from Institute of Mechanics in Hanoi. Other data used in this thesis was also
obtained from The University of Agriculture and Forestry in Hue and from The Oceanographic
Institute in Nha Trang. The study area has a tropical monsoon climate with two monsoon season per
year – the southeast monsoon and the northwest monsoon. The micro tidal climate in the area is fully
semi-diurnal and gives that the main sediment transport is wave induced.
The modelling software GENESIS was used to model the sediment transport past the groin. The
model was calibrated and validated using measured data and then the sediment transport on the
southeast side of the groin was modelled during the years 2013 to 2017. First, the case where no
measures were taken was modelled, to see what will happen if no changes of the groin were made.
After that, three different measures to decrease the accretion of sediment on the southeast side of the
groin (i.e. increase the sediment transport past the groin in order to reduce the erosion of the Thuan An
inlet) were modelled and analyzed. These three measures were making the groin shorter, increasing
the permeability of the groin and dredging sand from southeast side of the groin.
The result of the model and the different measures to reduce erosion were discussed. The conclusion
was that interventions to reduce the erosion are needed to protect the lagoon and the people living
around it and making their livelihood from it. Many people work with e.g. fishery, aquaculture and
agriculture and these occupations could be severely affected of the results of continuous erosion, such
as changed water environment in the lagoon and flooding.}},
  author       = {{Eriksson, Eva-Lena and Hjertstrand Persson, Madeleine}},
  issn         = {{1101-9824}},
  language     = {{eng}},
  note         = {{Student Paper}},
  series       = {{TVVR04/5002}},
  title        = {{Sediment transport and coastal evolution at Thuan An Inlet, Vietnam}},
  year         = {{2014}},
}