Flood Hazard Mapping
and Vulnerability Analysis Along Seti
River in Pokhara Metropolitan City
Anup Shrestha, Saraswati Thapa, and Bhola Nath Sharma Ghimire
Abstract Flood is frequent during every monsoon in Nepal which poses threat to
life and property in lowland areas. Among 6000 rivers and rivulets, most are prone
to floods in Nepal. Seti River flows from Machhapuchhre Rural Municipality in
the north, along the center of Pokhara Metropolitan City, and toward Tanahu which
meets with Madi River there. Seti flood of 2012 was one of the devastating floods
which took the life of many people and destroyed infrastructures along its way.
So, Pokhara Metropolitan City lies at a high risk of flood impacts. Hydrodynamic
simulation using HEC-RAS and GIS is one of the important methods of estimating
the probable loss due to flood of various scenarios quantitatively. In this study, flood
hazard maps of Seti River across Pokhara Metropolitan City has been prepared for
different flood scenarios. The flood frequency analysis was performed using Gumbel,
Log-Pearson, Log Normal, and Fullers Method. The goodness of fit was performed
using chi square test, and results of Gumbel method was used as it was found more
appropriate than other methods for this basin. One-dimensional steady hydrodynamic
modeling was done to create water surface profile which was used to prepare hazard
maps and vulnerability maps for various return periods. The model was evaluated
using statistical parameters, coefficient of determination R
2 ), and Nash–Sutcliffe
efficiency (NSE) whose values were found to be 0.951 and 0.819, respectively. The
maps prepared can be used for planning the built-up areas along the river sides and
may help in decision making for flood mitigation measures.
Keywords Flood · Hazard · Seti River · Pokhara Metropolitan City · HECRAS ·
GIS
A. Shrestha (B) · S. Thapa · B. N. S. Ghimire
Department of Civil Engineering, Institute of Engineering, Pulchowk Campus, Lalitpur, Nepal
e-mail: anoopstha50@gmail.com
S. Thapa
e-mail: saraswati.thapa@pcampus.edu.np
B. N. S. Ghimire
e-mail: bholag@ioe.edu.np
© Springer Nature Singapore Pte Ltd. 2021
C. Bhuiyan et al. (eds.), Water Security and Sustainability,
Lecture Notes in Civil Engineering 115,
https://doi.org/10.1007/978-981-15-9805-0_15
183
and Vulnerability Analysis Along Seti
River in Pokhara Metropolitan City
Anup Shrestha, Saraswati Thapa, and Bhola Nath Sharma Ghimire
Abstract Flood is frequent during every monsoon in Nepal which poses threat to
life and property in lowland areas. Among 6000 rivers and rivulets, most are prone
to floods in Nepal. Seti River flows from Machhapuchhre Rural Municipality in
the north, along the center of Pokhara Metropolitan City, and toward Tanahu which
meets with Madi River there. Seti flood of 2012 was one of the devastating floods
which took the life of many people and destroyed infrastructures along its way.
So, Pokhara Metropolitan City lies at a high risk of flood impacts. Hydrodynamic
simulation using HEC-RAS and GIS is one of the important methods of estimating
the probable loss due to flood of various scenarios quantitatively. In this study, flood
hazard maps of Seti River across Pokhara Metropolitan City has been prepared for
different flood scenarios. The flood frequency analysis was performed using Gumbel,
Log-Pearson, Log Normal, and Fullers Method. The goodness of fit was performed
using chi square test, and results of Gumbel method was used as it was found more
appropriate than other methods for this basin. One-dimensional steady hydrodynamic
modeling was done to create water surface profile which was used to prepare hazard
maps and vulnerability maps for various return periods. The model was evaluated
using statistical parameters, coefficient of determination R
2 ), and Nash–Sutcliffe
efficiency (NSE) whose values were found to be 0.951 and 0.819, respectively. The
maps prepared can be used for planning the built-up areas along the river sides and
may help in decision making for flood mitigation measures.
Keywords Flood · Hazard · Seti River · Pokhara Metropolitan City · HECRAS ·
GIS
A. Shrestha (B) · S. Thapa · B. N. S. Ghimire
Department of Civil Engineering, Institute of Engineering, Pulchowk Campus, Lalitpur, Nepal
e-mail: anoopstha50@gmail.com
S. Thapa
e-mail: saraswati.thapa@pcampus.edu.np
B. N. S. Ghimire
e-mail: bholag@ioe.edu.np
© Springer Nature Singapore Pte Ltd. 2021
C. Bhuiyan et al. (eds.), Water Security and Sustainability,
Lecture Notes in Civil Engineering 115,
https://doi.org/10.1007/978-981-15-9805-0_15
183