Simulation Of Flood Inundation Map Associated With Sediment Transport For Sungai Pahang
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Date
2018-07-01
Authors
Chang, Chun Kiat
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Flood disasters are a major cause of fatalities and economic losses. Several studies
indicate that global flood risk is currently increasing. Rapid urbanisation has
accelerated impact on the catchment hydrology and geomorphology. When landuse
and land cover change as a result of development or human activities, such as
logging which takes place in river catchment areas, a dramatic increase in the surface
runoff and higher sediment yield are expected. The present study can be divided into
four (4) main parts. The first part is to carry out trend analysis using Mann-Kendall
test for the annual rainfall time series data. The results demonstrate that increasing
trends were detected for eleven (11) rainfall stations while four (4) stations showing
decreasing trends in Sungai Pahang river basin. The second part attempts to give an
overview of the channel changes and sediment transport phenomena in Sungai
Pahang including bed material movement from the upstream of Sungai Pahang to the
river mouth at Pekan. River geometry survey associated with the spatial variation in
sediment transport has confirmed that changes in river bed profile occurred due to
erosion or deposition along Sungai Pahang. The sediment distribution size for Sungai
Pahang was found to be made up of very coarse sand and gravel after December
2014 flood. A rainfall-runoff model is developed and implemented for Sungai Pahang
river basin. Performance evaluation of the InfoWorks PDM model was moderately
successful in reproducing 2003 and 2012 to 2014 hydrographs covering both low and
high flow, which have been the emphasis of the third part of this research. The fourth
part is intended to deal with flood simulation using InfoWorks RS with the
consideration of sediment transport modeling. The flood inundated area has been
estimated based on the input design hydrograph of the 100-year annual recurrent
interval and storm duration of 8 days. Peak water surface and channel bed changes
for Sungai Pahang indicated that the maximum flood level with and without sediment
transport modeling has a difference of at least 0.30m. The flooded area was identified
to increase by 306.84kmĀ² (30.21%) from the simulations results without sediment
transport compared to flood simulations with sediment transport. As a result, the
current study shows that it is essential to take into account the sediment movement
along the river channel for the prediction of flood inundation areas in order to
produce digital flood maps.