Urbanization and Urban Flood Risk Assessment in the Kathmandu Valley, Nepal

Keywords: Urban, Urbanization, Urban Flood, Flood Hazard, GIS, AHP, Weightage
Session Type: Virtual Paper Abstract
Day: Monday
Session Start / End Time: 2/28/2022 03:40 PM (Eastern Time (US & Canada)) - 2/28/2022 05:00 PM (Eastern Time (US & Canada))
Room: Virtual 18

Abstract

The increasing complexity of urban growth management has become one of the most important challenges in developing countries like Nepal. This study was conducted in the Kathmandu Valley (KV), surrounding the capital city of Nepal. An important urban concentration in Nepal, the valley possesses almost all facilities such as high quality education, health services, industries, and employment opportunities. The objective of this study was to detect significant changes in the built-up area of the KV over five-year intervals between 1990-2020. The different periods considered are 1990–1995, 1995–2000, 2000–2005, 2005–2010, 2010–2015 and 2015–2020. Urban expansion in the valley were calculated by 1) estimating land-use/land-cover change by unsupervised classification, and 2) calculation of Index-based Built-up Index. The expansion of built-up areas from the year 1990 to 2020 was significant both in terms of magnitude and direction. The built-up area was 10.40 km2 in 1990 and had expanded to 241.47 km2 by 2020 which was much significant. Some of the notable impacts of urbanization are on urban hydrology. Hence, the second objective was to identify urban flood risk zones due to haphazard urban sprawl. Analytical Hierarchy Process (AHP) was integrated with Geographic Information System (GIS) to identify the flood risk areas. Distance to River and Land Use are majorly responsible for flood at Kathmandu Valley, while soil type was the least responsible. Flood risk assessment shows that almost 100% of core city areas are at a very high to high risk of flood, and fringe areas are in medium to low risk zones.