Application of Remote Sensing imagery for investigation in the Haiphong estuarine and costal zone
Methodology and Data
In present day the Remote Sensing method with satellite and aerial imagery is widely used in Viet name and gradually comes in to a stable technology. In combination with fieldwork. Remote sensing method has got a lot of advantages to the traditional one it includes in this study:
- Oplieal and chemical processing of satellite
and aerial data: Black and white enlarging and printing false color
composition of satellite images (see photo slide)
- Rectification: The purpose of this step is to
correct distortions existing in the data as accurately as possible
bared on the control points selected on both topographic maps and
satellite images. The reelifier SEG 5 rectified the images.
- Visual and stereoscopic identify and locate
the position of estuarine and coastal features.
- Ground truth: to check the result and correct map.
The data set as base materials analyzed in this study was collected from the following Landsat. Spot imagery. Aerial polo graphs, top maps:
- Landsat image scenes of 29.Dec. 1975 May 1984
and 7 Jan 1986 Spot image scene of 21 May 1988.
- Arial photographs during January 1976 and
December 1986 at sealer of 1:250000 and 1:20000 these aerial photos
were supplementary only used for the must changeable region, such as
pinch vu and Cat hai. Because map was established at scale of
1:100000.
- Water level and tidal data of the study area
collected by Department for hydremetgrology.
- Topographic maps at nine of 1:00000 and 1:50000 Ground survey data.
Some characteristics of the study area influencing on the HAI PHONG estuarine and coastal features
- Hydrology: The HAI PHONG coastal area has a
dense brook river system with height sediment content, especially
branches of the Red-Thai Binh river system. Also six rivers fall
within study area supplying with water for agricultural irrigation on
the year round.
They are Chanh. Bach Dang. Cam. Lach Tray. Van Uc and Thai Binh. These rivers have been running through the region of the Red-Thai Binh river system delta with soft alluvial soil bed. Bearring a great content of sediment to accrete their estuaries into large tidal flais.
The concavity areas located between 2 tidal flats have a negative relief. They formed weak place. On this distributions of breakers. Swells…. Are concentrated for scashore erosion (Dinh vu. Tien lang).
- Wave: The Hai pong coastal zone has been
under influence of alternating monsoons.
The North - East monsoon and the south - East one with an average speed of 6 - 8 m / sec. Especially typhoons gale storms often occur in July, August. September. October with high speed. It is the wind. That creates waves and provides them the same direction with most part of energy to hit seashore, causing erosion. The stronger storm is. The heavier wave. It causes .
However the pressure of
wave depends on the angle between its direction and shoreline. It
reaches the greatest value while this angle is a right one. that
happens from May to October when the South - East monsoon occurs and
creates coastal erosion. But under influence of the North - East
monsoon (from November to April), the wave direction is cutting the
shorline an acute angle. That is why the wave acts on the shoreline a
weak dynamic not create or coastal erosion. Tide exists one times per day with average tidal range of 3.7m.
