Damage assessment and risk analysis of flood using geoinformatics: a case study of Nagaon district, Assam
Student name: Ms Vidya Satija
Guide: Mr Chander Kumar Singh
Year of completion: 2012
Host Organisation: RMS India Pvt. Ltd, Noida
Supervisor (Host Organisation): Ms Bina Shetty
Abstract: The Nagaon District of Assam situated on the Floodplains of River
Brahmaputra. The mighty River Brahmaputra flows across the State of Assam
for a stretch of 35 kilometres. The Brahmaputra valley had experienced major
floods in 1954, 1962, 1966, 1972, 1974, 1978, 1983, 1986, 1988, 1996, 2000 and
2004. 2004 Flood was the most devastating and worst in last decade experienced
by Assam. The present study is having two board components (i) Preliminary
Damage Assessment and (ii) Hazard Mapping and Risk Analysis (based on
population density).The area inundated by flood during the year 2004 derived
from pre-flood and post Flood imageries were used to perform Preliminary
Damage Assessment (PDA). Radarsat pre and post flood imageries were used to
quantify the total flood inundated area. On processing the data it was found that
out of 1193 total villages present in the district, 962 were inundated and the
population estimated to be affected was about 18, 08,624. As per the calculation
performed using the satellite data it was found that total of 2, 25,686 hectares of
cropped area was affected with flood. The second part of the present study
consist of Flood Hazard mapping of the Nagaon District using the multicriteria
decision techniques like Weighted Overlay, Principal Component Analysis (PCA)
and Analytical Hierarchical Process (AHP).Five thematic layers were generated
and used for mapping the Flood Hazard zones for the Nagaon District. Satellite
dataset of IRS LISS III and SRTM (90m) was used to generate classified land
cover map, geomorphologic map, classified elevation and slope map
respectively. The entire area of the district is been classified into very high, high,
moderate, low and very low hazard zones based on the output (Flood Hazard
Maps) generated by different technique. Comparative analysis was performed on
the Flood Hazard Maps obtained by the Weighted Overlay and Analytical
Hierarchical Process (AHP). The last step was the generation of the Risk Map at
village level for the district based on the population exposed. The entire Nagoan
District is been classified (up to village level) into five major risk zones- very
high, high, moderate, low and very low.
Key words: Preliminary damage assessment, Flood Hazard mapping, Weighted
Overlay, Analytical Hierarchical Process (AHP), Risk Assessment.
