Flood Vulnerability Assessment Across Alaknanda River Basin using GIS-based Combined Analysis of Geomorphometric Approach and MCDM-AHP

• Published in: Journal of the Geological Society of India 2023-11, Vol.99 (11), p.1604-1615
• Main Authors: Rautela, Kuldeep Singh, Kumar, Dilip, Gandhi, B. G. Bandaru Goutham Raveej, Kumar, Ajay, Dubey, Amit Kumar
• Format: Article
• Language: English
• Subjects: Analysis; Analytic hierarchy process; Concentration time; Decision analysis; Decision making; Disasters; Drainage; Drainage basins; Drainage density; Earth and Environmental Science; Earth Sciences; Economic impact; Floods; Form factors; Geographical information systems; Geology; Geomorphology; Hierarchies; Hydrogeology; Multiple criterion; Natural disasters; Original Article; Outlets; Rainfall; Relocation; River banks; River basins; Riverbanks; Rivers; Surface runoff; Vulnerability
• ISSN: 0016-7622; 0974-6889
• DOI: 10.1007/s12594-023-2512-9

Floods are one of the most devastating natural disasters, causing land destruction, economic loss, and massive disruptions to humans. The present study was conducted in the Alaknanda river basin with medium to high drainage density and stream frequency. The flood vulnerable zones (FVZ) are identified using geomorphometric analysis, and flood vulnerability zones are identified through analytical hierarchy processes (AHPs). Three factors, such as linear, relief, and aerial, have been used in the geomorphometric analysis of the Alaknanda basin. The weights were assigned on a scale of 1 for flood-induced factors such as slope (0.386), rainfall (0.192), drainage density (0.129), LULC (0.096), geology (0.077), soil (0.064), and DEM (0.055) have been determined using 7×7 decision matrix of multi-criteria decision making- analytical hierarchy processes (MCDM-AHP) model accounting for their varying importance from high to low priorities. A consistency ratio (CR) of 0.083 (less than 0.1) signifies the acceptance of the weights derived in the case. The high shape index, form factor, and rotundity factor indicate the basin allows quick drainage of surface runoff with a lesser time of concentration; as a result, sharp peaks of the hydrograph will be obtained at the outlet of the basin. However, most of the basin area is under the moderate vulnerability category, while the entire river banks along the valley are the most vulnerable. Additionally, a small-scale sociological study indicates that for a population that resides close to highly susceptible locations, temporary relocation is the most common strategy.