Abstract:
"Kalu ganga" (river) is one of the major rivers in Sri Lanka situated in
south-western part of the country. Kalu ganga basin area is a highly populated area
comprising urban centres and agricultural fields. River floods frequently occur in this
area resulting severe damage and destructions. Local planers, decision makers and
disaster relief organizations lacks accurate information on the spatial distribution of
flooding and the land-use types. Only minimal efforts and resources have been
allocated to deal with this problem. The objective of this research is to develop flood
hazard zone maps for the Kalu ganga basin area in a Geographic Information Systems
(GIS) environment. The applied methodology is comprised of 5 phases. They are
preparation phase, fieldwork and data acquisition phase, modelling and flood hazard
map generation phase, validation phase and reporting phase. According to the
generated flood hazard map, Kuruvita, Elapitiya and Rathnapura divisional
secretariats have the highest risk of flooding. Most divisional secretariats in the
western province exhibit low or moderate risks of flooding. According to the analysis
of flood hazard map with land-use classes, 2307hectares of residential areas and 5568
hectares of agricultural fields were found to be at high risk of flooding.
