Geomorphological framework and its implications on 2018 Kerala Flood (India) - a study on coastal regions of the Vembanad catchment area
Kommireddi Chinni V NAGA KUMAR, Centre for Water Resources Development and Management (CWRDM), India
Gopika RAJAN, Centre for Water Resources Development and Management (CWRDM), India
K NASIH, Centre for Water Resources Development and Management (CWRDM), India
The Kerala state (India) has witnessed a severe catastrophic flood event during August 2018, leading to 483 causalities and more than 1 million people being displaced, resulting from a cumulative rainfall of 771 mm (which is 140% more than the normal) received during August 1-20, 2018. In this background, the most severe flood-affected coastal region of the Vembanad Lake catchment area in Kerala state is taken up to demonstrate the role of different landforms present and their implication on the 2018 Kerala Flood using the advanced SAR Remote sensing technology and GIS applications. Vembanad Lake, the second-largest Ramsar wetland in India, accounts for a total catchment area of about 14,380 km2 with seven rivers namely Chalakudy, Periyar, Muvattupuzha, Meenachil, Manimala, Pamba, and Achenkoil joining the lake area, and about 15% of the total catchment area (2192.87 km2) is the coastal region which is densely populated with nearly 71,13,865 people (as per 2011 census), is studded with landforms like a flood plain, coastal plain, swale, marshy, coastal plain, islands, brackish water creeks, etc.
Sentinel-1 Synthetic Aperture Radar (SAR) GRD satellite imagery pertaining to pre-flood (January 21, 2018) and post-flood (August 21, 2018) were downloaded from the European Space Agency (ESA) Copernicus open access hub and were used to map the flood-affected regions of the coastal regions of Vembanad catchment area through digital image processing techniques, i.e., k-means clustering. The results of the analysis showed that nearly 13% (281 km2) of the total coastal region of the Vembanad catchment area got affected during the 2018 flood, of which, flood plain (58.89%) and mudflat area (30.45%) together constituting about 89%, and interestingly both are low-lying and flat in nature. The study thus emphasis on mapping of different landforms, especially along the coastal regions, and understanding the degree of resistance of each landform to hazards (floods) and their risks.
Mots clés : Landforms|Flood Mapping|Hazard and Risks|SAR Remote sensing|2018 Kerala Flood (India)
A105281KV