Flood risk modeling using HEC-RAS and geospatial techniques

Abstract. This article presents a method to incorporate and promote quantitative flood risk analysis to support local action planning against flooding. The proposed approach aims to provide a standardized framework for local flood risk analysis, combining hazard mapping with vulnerability data to quantify risk in terms of expected annual affected population, potential injuries, number of fatalities, and economic damages. Flood risk is estimated combining GIS data of loads, system response and consequences and using event tree modeling for risk calculation. The study area is the city of Oliva, located in the Eastern coast of Spain. Results from risk modeling have been used to inform local action planning and to assess the benefits of structural and non-structural risk reduction measures. Results show the potential impact on risk reduction of flood defences, and improved warning communication schemes through local action planning: societal flood risk (in terms of annual expected affected population) would be reduced up to 51 % by combining both structural and non-structural measures. In addition, the effect of seasonal population variability is analyzed (annual expected affected population ranges from 82 % to 107 %, compared with the current situation, depending on occupancy rates in hotels and campsites). Results highlight the need for standardized methods for urban flood risk analysis replicability at regional, national and pan-European scale.

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Glaciers and Glacial Lake Outburst Flood Risk Modeling For Flood Management

Wastewater Reuse and Watershed Management ◽

10.1201/9780429433986-15 ◽

2019 ◽

pp. 157-162

Author(s):

Nity Tirkey ◽

P. K. Parhi ◽

A. K. Lohani

Keyword(s):

Flood Risk ◽

Flood Management ◽

Glacial Lake ◽

Risk Modeling ◽

Outburst Flood ◽

Glacial Lake Outburst Flood

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A Geospatial Expose of Flood-Risk and Vulnerable Areas in Nigeria

International Journal of Applied Geospatial Research ◽

10.4018/ijagr.20200701.oa1 ◽

2020 ◽

Vol 11 (3) ◽

pp. 87-110

Author(s):

Chukwudi Gbadebo Njoku ◽

Joel Efiong ◽

Nse-Abasi Ndiyo Ayara

Keyword(s):

Flood Risk ◽

Niger Delta ◽

Policy Formulation ◽

Geospatial Techniques ◽

Cross River ◽

Mitigation And Adaptation ◽

Risk Zones ◽

Risk Vulnerability ◽

High Flood ◽

River Niger

Flooding is recurrent in Nigeria, occurring yearly at different scales. This geared the need for a study to reveal local government areas (LGAs) that are at risk and vulnerable to flooding. The multi-criteria approach was adopted, using geospatial techniques and data. Factors considered were elevation, slope, rainfall intensity, and distance to river. The factors were classified, reclassified, rated, and weighed in a systematic process. Nineteen states and 114 LGAs face high risks, especially communities in the Niger Delta, around the lagoons of Lagos, along River Niger, Benue, and the Cross-River. Also, 125 LGAs in 18 states face medium flood-risk vulnerability. Consideration the population density of communities, Lagos State is the most vulnerable because of LGAs with high population densities within high flood-risk zones. Other states with communities exposed to high flood-risk vulnerability include Rivers, Kogi, Cross River, Akwa Ibom, Anambra, and Delta. The study provides information key to proactive policy formulation, mitigation, and adaptation to flood risk in Nigeria.

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