Flood Hazard Mapping of Rivers in Snow- and Glacier-Fed Basins of Different Hydrological Regimes Using a Hydrodynamic Model under RCP Scenarios

Huma Hayat,Muhammad Ashraf,Romana Khan,Adnan Ahmad Tahir,Sher Muhammad,Shiyin Liu,Muhammad Saifullah

doi:10.3390/w13202806

Abstract

The global warming trends have accelerated snow and glacier melt in mountainous river basins, which has increased the probability of glacial outburst flooding. Recurrent flood events are a challenge for the developing economy of Pakistan in terms of damage to infrastructure and loss of lives. Flood hazard maps can be used for future flood damage assessment, preparedness, and mitigation. The current study focused on the assessment and mapping of flood-prone areas in small settlements of the major snow- and glacier-fed river basins situated in Hindukush–Karakoram–Himalaya (HKH) under future climate scenarios. The Hydrologic Engineering Center-River Analysis System (HEC-RAS) model was used for flood simulation and mapping. The ALOS 12.5 m Digital Elevation Model (DEM) was used to extract river geometry, and the flows generated in these river basins using RCP scenarios were used as the inflow boundary condition. Severe flooding would inundate an area of ~66%, ~86%, ~37% (under mid-21st century), and an area of ~72%, ~93%, ~59% (under late 21st century RCP 8.5 scenario) in the Chitral, Hunza, and Astore river basins, respectively. There is an urgent need to develop a robust flood mitigation plan for the frequent floods occurring in northern Pakistan.

Highlights

Floods are a recurrent and frequent natural disaster in Pakistan [1,2,3,4]
The flow simulated under Representative Concentration Pathways (RCPs) scenarios from all three basins [28,29] was used as input in flow conditions of the Hydrologic Engineering Center-River Analysis System (HEC-RAS) model
Based on the results obtained, it was observed that an increase in river discharge under mid- and late-21st century RCPs would result from an increase in temperature and precipitation

Summary

Introduction

Floods are a recurrent and frequent natural disaster in Pakistan [1,2,3,4]. In Pakistan, over60% of the land area is vulnerable to floods, 40% to earthquakes, and 6% to cyclones [1].Indus, the longest river in Pakistan, originates from the Hindukush–Karakoram–Himalaya (HKH) region and, along with its tributaries Chenab, Ravi, Sutlej, and Jhelum, runs north to south through the country [5]. Floods are a recurrent and frequent natural disaster in Pakistan [1,2,3,4]. 60% of the land area is vulnerable to floods, 40% to earthquakes, and 6% to cyclones [1]. The longest river in Pakistan, originates from the Hindukush–Karakoram–Himalaya (HKH) region and, along with its tributaries Chenab, Ravi, Sutlej, and Jhelum, runs north to south through the country [5]. Due to snowmelt and heavy monsoon rainfalls, significant flows are generated during summer [6]. The rivers overflow and enter their floodplains. The flood peaks of the rivers usually do not overlap but when they do, massive flooding results

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