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ABSTRACT
Flood is one of the natural disasters in this country. However human
activities in river basin changes flood behaviour such as increase
in the flood magnitude which affects human life and properties.
Structural measures to mitigate flood such as river widening and
straightening, must be well understood since this kind of work may
transfer the flood problem from upstream to the downstream part of
the river system. Therefore an understanding of the flood behaviour
is an important step in reducing the damage cause by flood. River
hydrodynamic modeling using computer is able to carry out flood
simulation along a river which will produce flood level along the
river and floodplain.
Sg. Selangor basin was selected as the study area. This basin is
located besides Klang Valley which is highly developed. It is
expected that there is a potential development in the near future
within this basin. The main river of Sg. Selangor is about 106 km in
length with the catchment area of 1960 km2. The basin has been
identified having enough and suitable information to carry out the
intended research.
Among input required to make the present research successful is the
river cross section, floodplain information, activities in the
catchment, contour, soil types and landuse. Other information on
flood record such as flood level and discharge at hidrological
station within the floodplain is useful for the purpose of the
calibration process.
The approach use in this research is to develop a river hydrodynamic
model covering the main river and its flood plain. The river
tributaries are modelled as hydrologic input from the respective
subcatchments. Calibrations were carried out at several locations
along the river namely downstream, middle reach of the river and in
the floodplain. Flood behaviour from the model is compared with 1971
flood which is the largest flood that had occured in the basin.
The impact from land reclamation to the flood behaviour was further
analysed for and area of 400 hectares along Kg Asahan. The
simulation shows that water level increases from 38 mm to 128 mm at
surrounding areas. Analysis between cross-section km 53 to km 67
shows that the areas flooded are 736 hectares and 889 hectares for
50 and 100 year return period respectively. The development of the
flood risk map will assist the Lembaga Urus Air Selangor (LUAS),
river engineer and planner in carrying out effective measures for
planning and implementing of projects within Sg. Selangor river
basin.
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