brick and building materials; ground subsidence caused by pumping up underground water; and changing mass balance in the watershed area (Haruyama 2000,
2002). Therefore, the sand supply has been decreasing since the construction of the
tidal irrigation system in the coastal zone. This decrease in the amount of sand in the
Red River consequently has resulted in the coastline’s receding (Vu and Nguyen
1992; Haruyama et al. 2002).
The banks have been constructed near the sea shore with a standard height of
4 m. These banks are not strong enough and are sometimes washed away by
typhoons. The budget for constructing banks is insufficient, so the village people
make the banks the primitive way, by heaping up soil. Some NGO plant mangroves
in the eroded area to protect the shoreline, but mangroves are easily washed away
when they are little.
10.3 Research Methods
10.3.1 Altitude Map
SRTM (Shuttle Rader Topography Mission) provides the altitude data for this
study. C-band and X-band SAR (Synthetic Aperture Radar) were mounted on the
Space Shuttle for 11 days in February 2000. SRTM covers 80 % of the continent
except for polar areas. There are two kinds of SRTM data: SRTM-3 has 3 s (about
90 m) meshes covering the whole world except for the polar areas, and SRTM-1 has
1 s (about 30 m) meshes in the U.S. SRTM-3 was used in this study, the altitude
rounded to the nearest whole meter. To illustrate the altitude map, the software of
Kashmir 3D Ver. 9 on a PC was used.
10.3.2 Climate Analysis
Climate analysis is an important tool for assessing the damage caused by coastal
erosion. In this study, wind data was available. In the Van Ly Observatory Station,
wind speeds and directions are recorded four times a day. In this study, the highest
wind speed and its direction from 1991 to 2000 were used. The average numbers of
days with strongest wind speed were calculated. The directions and the average
wind speeds were calculated respectively.
10 Mapping Coastal Erosion Risk in the Southern Red River Delta, Vietnam
203
2002). Therefore, the sand supply has been decreasing since the construction of the
tidal irrigation system in the coastal zone. This decrease in the amount of sand in the
Red River consequently has resulted in the coastline’s receding (Vu and Nguyen
1992; Haruyama et al. 2002).
The banks have been constructed near the sea shore with a standard height of
4 m. These banks are not strong enough and are sometimes washed away by
typhoons. The budget for constructing banks is insufficient, so the village people
make the banks the primitive way, by heaping up soil. Some NGO plant mangroves
in the eroded area to protect the shoreline, but mangroves are easily washed away
when they are little.
10.3 Research Methods
10.3.1 Altitude Map
SRTM (Shuttle Rader Topography Mission) provides the altitude data for this
study. C-band and X-band SAR (Synthetic Aperture Radar) were mounted on the
Space Shuttle for 11 days in February 2000. SRTM covers 80 % of the continent
except for polar areas. There are two kinds of SRTM data: SRTM-3 has 3 s (about
90 m) meshes covering the whole world except for the polar areas, and SRTM-1 has
1 s (about 30 m) meshes in the U.S. SRTM-3 was used in this study, the altitude
rounded to the nearest whole meter. To illustrate the altitude map, the software of
Kashmir 3D Ver. 9 on a PC was used.
10.3.2 Climate Analysis
Climate analysis is an important tool for assessing the damage caused by coastal
erosion. In this study, wind data was available. In the Van Ly Observatory Station,
wind speeds and directions are recorded four times a day. In this study, the highest
wind speed and its direction from 1991 to 2000 were used. The average numbers of
days with strongest wind speed were calculated. The directions and the average
wind speeds were calculated respectively.
10 Mapping Coastal Erosion Risk in the Southern Red River Delta, Vietnam
203