Spatial appraisal of flood risk assessment and evaluation using integrated hydro-probabilistic approach in Panjkora River Basin, Pakistan

Globally, flood is one of the devastating hydrometeorological disasters, causing human losses and damages to properties and infrastructure. There is a need to determine and geo-visualize flood risk to assist decision-making process for flood risk reduction. The current study is a local level pioneering attempt regarding the spatial appraisal of flood risk assessment and evaluation in Panjkora River Basin, eastern Hindu Kush. An integrated hydro-probabilistic approach is implemented by clubbing the results of Hydrologic Engineering Centre's River Analysis System (HEC-RAS) and Hydrologic Engineering Centre's Geographic River Analysis System (HEC-Geo-RAS) in geographic information system (GIS) environment. An Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Global Digital Elevation Model (GDEM) is used as input data to delineate the target basin and generation of river geometry. Hydraulic and hydrological data were used to estimate and geo-visualize vertical profile and spatial extent of various floods in the active floodplain of Panjkora River. Gumbel's frequency distribution model is applied in analyzing daily peak discharge recorded during the past 32 years, and 200-year flood magnitude (1392m(3)/sec), probable inundation (45.5 km(2)), and vertical profile (19 m) are modeled. Analysis revealed that likelihood of such flood has increased the risk of potential damages to roads (46 km), retaining walls (49 km), bridges (16), and culverts (46). The analysis further revealed that built-up area (10.4 km(2)) and agricultural land (20.2 km(2)) will also come under flood with life loss. The resultant flood risk zones and spatial appraisal will definitely help in bringing down the probable flood damages. Similarly, current study has potential to assist disaster managers, hydraulic engineers, and policy makers to understand the flood risk and implement location-specific effective flood risk reduction strategies.