Flood Risk Mapping in Pilot Areas of Ethiopia and Sudan
Client: Eastern Nile Technical Regional Office
Location: Ethiopia and Sudan
Period: 2008 – 2009
Project Summary
Flood Prone Area
The Eastern Nile Technical Regional Office needed a means to reduce human suffering caused by frequent flooding while preserving the environmental benefits of floods. The Flood Preparedness and Early Warning fast-track sub-project is among the seven projects identified within Integrated Development of the Eastern Nile program. One of the major activities of the Flood Preparedness and Early Warning sub-project is flood risk mapping in pilot areas of the Eastern Nile countries of Ethiopia and Sudan.
Project Details
The Flood Risk Mapping Project is a subset of the Flood Preparedness and Early Warning (FPEW) Project. The Riverside Technology, inc. (Riverside) Team developed a comprehensive approach to assess flood hazard, vulnerability, and risk in the flood-prone pilot study area. The approach follows an open, flexible, step-wise assessment based on the following concepts of, and relationships between, these three basic elements:
- Flood Hazard – a representation of areas subject to flooding, together with probability of occurrence
- Vulnerability – a measure of how easily damaged the elements in flood-prone areas are as a function of the magnitude or depth of flooding
- Flood Risk – the product of hazard and vulnerability
Two key elements of Riverside’s approach are the use of readily available open-source models and full employment and integration of local partners and experts, the latter aimed at extending existing expertise and capacity in the engineering community.
Riverside provided the following services in executing the work:
- GIS analysis for topographic data development, including directing field surveys, collecting available digital elevation models (DEM), and merging data sources to construct digital terrain models that incorporate components of multiple data sources
- Hydrologic modeling to determine the frequency associated with different magnitudes of flows
- GIS processing and risk mapping to convey in a spatial context the risk of damage in the floodplains
- GIS processing and risk mapping to convey in a spatial context the risk of damage in the floodplains
- Spatial analysis and remote sensing for risk assessment, integrating risks throughout the floodplain to determine average annual damage
Riverside also directed local partners who participated in data collection activities and assisted with the above elements of the project, and provided training for local partners, client staff, and local stakeholders.
Riverside used several existing and custom tools to perform geographic information systems (GIS), remote sensing, and hydrologic/hydraulic modeling including ArcGIS, ERDAS Imagine, HEC-RAS, HEC-GeoRAS, HEC-HMS, and HEC-GeoHMS. To automate much of the GIS processing Riverside used ArcGIS Model Builder and Python Geoprocessing. Complete documentation and training was delivered to the client.