Investigation of Basin Characteristics: Implications for Sub-basins Level Flood Peak and Vulnerability Assessment

Abstract

Flood vulnerability is a significant component in assessing the probable degree of damage to various exposures in hazard conditions. In this study, a semi-distributed event-based hydrological model and indicator-based method were applied to evaluate the sub-basin level flood vulnerability using the Geographical Information System (GIS). The flood peak discharge of each sub-basin corresponding to the 2014 extreme flood of the Jhelum river was related with different sub-basins characteristics (terrain, hydrological, land use and soil) using a theoretical framework under an indicator-based method. The calibrated (2014) and validated (1992, 1997) hydrological model showed Nash-Sutcliffe Efficiency (NSE) of 0.98 and (0.99, 0.99) at relatively upstream gauging station Sangam against optimized Curve Number (CN) scaling factor of 0.98. The Anantnag and Kulgam districts, exhibiting multiple sub-basins contributing to the Sangam gauging station, are falling into a highly vulnerable category located in the Jhelum basin's southern part, Greater Himalayan Range. It was also revealed that sub-basins at the upstream of the Jhelum basin are more vulnerable compared to downstream area, where sub-basin W810 (Greater Himalayan), Anantnag district draining at Sangam gauging site is found as most vulnerable among the all other sub-basins. However, hydrological characteristics control the most vulnerable sub-basin peak discharge rather than other characteristics such as terrain, soil, or Land Use. Outcomes of the study will be helpful in prioritizing the flood mitigation planning not only with respect to the hydrological boundary (sub-basin level) but also with administrative district boundaries. The proposed method is generic and can be applied to any flood-prone river basin.