Hydrology & Surveying for Catchment Management

Project Overview

An emergency response hydrology project in South Darfur State supporting conflict-affected communities through infrastructure-based flood risk reduction. Combining Sentinel-1 SAR flood extent mapping with GPS-RTK topographic surveys of 6 major wadi catchments, the project developed HEC-HMS runoff models calibrated against ADCP discharge measurements. Intervention recommendations (check dams, drainage diversions) were evaluated through HEC-RAS inundation scenarios, identifying cost-effective measures that reduced estimated property and livelihood flood exposure by 40%.

Methodology

1. 01Sentinel-1 SAR dual-polarization (VH/VV) flood extent mapping during 2019 flood event
2. 02GPS-RTK topographic surveys of 6 wadi catchments (total ~1,200 km²)
3. 03HEC-HMS hydrological modelling with SCS curve number parameterization
4. 04HEC-RAS 2D unsteady flow inundation modelling for design floods (25-year, 50-year return)
5. 05ODK Collect mobile data collection for community vulnerability assessment (320 households)
6. 06Intervention scenario comparison: check dams, drainage diversion, settlement relocation

Key Outputs

• 40% reduction in estimated flood risk through recommended interventions
• Flood inundation maps for 25- and 50-year return periods across 6 catchments
• Community vulnerability database (320 households) linked to spatial flood zones
• Engineering design brief for 4 priority check dams submitted to ZOA engineers

40% flood risk reduction achieved through interventions