3. Tuyen Quang reservoir (since 2007): Main features: high water level: 123 m;
total storage: 2.3 billion m
3 ; flood regulation storage 1–1.5 billion m
3 , and
installed capacity: 234 MW.
4. Son La reservoir (since 2010): Main features: high water level: 217 m; total
storage: 9.26 billion m
3 ; flood regulation storage 5.5 billion m
3 , and installed
capacity 2,400 MW (Nguyen et al. 2007).
The policies and laws to prevent the floods are still in the development stage in
Vietnam. The lack of comprehensive institutional framework has caused losses and
failures in water resources management practices in Vietnam (Nguyen et al. 2007).
10.2.4 Coastal Erosion in the Southern Red River Delta
The coastal erosion in the southern Red River Delta was estimated at 30–50 m per
year in 1905–1960, 20–35 m per year in 1960–1973, and 10 m per year in 1973–
1992 (Imamura and Dang 1997). The mouth of the Red River expanded until the
middle of the twentieth century by embankment and reclamation projects. Vinh
et al. (1996) clarified the coastline development from 1905 to 1992 in Nam Ha
province. Deposition occurred near the mouths of the Red River, the Ninh Co, and
the Day River. This resulted in shoreline developments in these areas of 2.5–6.5 km
in the seaward direction over the 87 year period. However, in Hai Hau district the
development was just the opposite. Over the last 87 years a strip some 16 km long
and about 2.5 km wide was lost to the sea. This is a time averaged shoreline retreat
of about 29 m per year. Duc et al. (2012) mentioned that the erosion coasts are
distributed either between the river mouths (Hai Hau) or near them (Giao Long,
Giao Phong, and Nghia Phuc). Erosion in Hai Hau is accelerated by sea level rise
and upstream dams. Sea dike stability is seriously threatened by erosion-induced
lowering of beach profiles, sea level rise, typhoons, and storm surges.
In the last 30 years, farmers in the Nam Dinh and Thanh Hoa provinces relocated
to Dac Lac province because the paddy fields had been washed away by coastal
erosion (Haruyama 1995, 2002). Based on the tidal activity data collected from Hon
Dau Observation Station in North Vietnam, it was determined that coastal erosion is
also affected by the recent sea level rise in the Gulf of Tonkin (Haruyama 2002).
Foreign non-governmental organizations (NGOs) headed by Sweden have
started to repair the sea-walls since 1990. At the same time, foreign assistance
groups planted mangrove trees with the aim of stopping spatial enlargement of
coastal erosion (Haruyama 2004). Coastal erosion in the southern Red River Delta
is mainly due to several major human activities including: the construction of the
Hoa Binh Dam beginning in 1994 in the upper part of the Red River. It is now the
largest dam in South East Asia. This dam has trapped sediments, thereby resulting
in decreased sedimentation in the lower part of the river; the destruction of the
natural sea-wall system by cutting the mangrove forests to make aquaculture farms;
a decrease in the amount of river sand because of dredging from the river bed for
202
M. Murooka et al.
total storage: 2.3 billion m
3 ; flood regulation storage 1–1.5 billion m
3 , and
installed capacity: 234 MW.
4. Son La reservoir (since 2010): Main features: high water level: 217 m; total
storage: 9.26 billion m
3 ; flood regulation storage 5.5 billion m
3 , and installed
capacity 2,400 MW (Nguyen et al. 2007).
The policies and laws to prevent the floods are still in the development stage in
Vietnam. The lack of comprehensive institutional framework has caused losses and
failures in water resources management practices in Vietnam (Nguyen et al. 2007).
10.2.4 Coastal Erosion in the Southern Red River Delta
The coastal erosion in the southern Red River Delta was estimated at 30–50 m per
year in 1905–1960, 20–35 m per year in 1960–1973, and 10 m per year in 1973–
1992 (Imamura and Dang 1997). The mouth of the Red River expanded until the
middle of the twentieth century by embankment and reclamation projects. Vinh
et al. (1996) clarified the coastline development from 1905 to 1992 in Nam Ha
province. Deposition occurred near the mouths of the Red River, the Ninh Co, and
the Day River. This resulted in shoreline developments in these areas of 2.5–6.5 km
in the seaward direction over the 87 year period. However, in Hai Hau district the
development was just the opposite. Over the last 87 years a strip some 16 km long
and about 2.5 km wide was lost to the sea. This is a time averaged shoreline retreat
of about 29 m per year. Duc et al. (2012) mentioned that the erosion coasts are
distributed either between the river mouths (Hai Hau) or near them (Giao Long,
Giao Phong, and Nghia Phuc). Erosion in Hai Hau is accelerated by sea level rise
and upstream dams. Sea dike stability is seriously threatened by erosion-induced
lowering of beach profiles, sea level rise, typhoons, and storm surges.
In the last 30 years, farmers in the Nam Dinh and Thanh Hoa provinces relocated
to Dac Lac province because the paddy fields had been washed away by coastal
erosion (Haruyama 1995, 2002). Based on the tidal activity data collected from Hon
Dau Observation Station in North Vietnam, it was determined that coastal erosion is
also affected by the recent sea level rise in the Gulf of Tonkin (Haruyama 2002).
Foreign non-governmental organizations (NGOs) headed by Sweden have
started to repair the sea-walls since 1990. At the same time, foreign assistance
groups planted mangrove trees with the aim of stopping spatial enlargement of
coastal erosion (Haruyama 2004). Coastal erosion in the southern Red River Delta
is mainly due to several major human activities including: the construction of the
Hoa Binh Dam beginning in 1994 in the upper part of the Red River. It is now the
largest dam in South East Asia. This dam has trapped sediments, thereby resulting
in decreased sedimentation in the lower part of the river; the destruction of the
natural sea-wall system by cutting the mangrove forests to make aquaculture farms;
a decrease in the amount of river sand because of dredging from the river bed for
202
M. Murooka et al.