Page 48 - 2022 Abstract Book RUICHSS_2022_11_17 after conference

University of Ruhuna ISSN: 2706-0063
Matara, Sri Lanka

Geospatial Analysis of Flood Vulnerability Assessment and
Mapping in the Bulathsinhala DS Division

P.W.S. Fernando
Department of Geography, University of Ruhuna.
wasanasurandi@gmail.com

Floods are considered the most devastating hydro-meteorological disaster in the
world, which causes the destruction of human lives and properties. Human-induced
land use changes, climate change and morphological changes in rivers cause to
accelerate the severity and intensity of floods. The Bulathsinhala DS division is
highly vulnerable to flood hazards every year due to the overflowing of Kuda Ganga
from a tributary of Kalu Ganga. The main objective of this study is to demarcate
flood-prone areas using Geographical Information systems. Geospatial analyses are
an appropriate technique for making wise decisions to mitigate the adverse impact of
natural disasters. The secondary objective is to assess the vulnerable areas of the
Bulathsinhala DSD. Multi-Criteria Decision Analysis (MCDA) was adopted as a
methodological process. Rainfall, elevation, slope, Digital Elevation Model
(DEM)land use pattern, population density, drainage distance, distance of road
network, and building distribution have been selected to assign the weightage under
the weighted overlay method. In addition to previous flood records data have been
used as secondary data. Each of the flood indicators was reclassified as very high risk,
moderate risk, less risk and risk free. The flood risk map revealed that very high risk
area covered 24.7 (12.53%) square kilometres, moderate risk areas covered 106
(53.80%) sq km Low risk areas covered 63.4(32.18%) sq. km and areas free from risk
areas covered 2.8 (1.42%) sq km. In order to improve the effectiveness of the
emergency response support and aid to victims for greater preparedness potential, it
is projected that this susceptible flood map would be able to help responsible
government bodies.

Keywords: Assessment, Flood, Hazard, Multicriteria Decision Making, Vulnerability

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