Reservoir storage for managing floods in urban areas: a case study of Dzorwulu basin in Accra
Article first published online: 11 MAY 2012
Copyright © 2012 John Wiley & Sons, Ltd.
Volume 27, Issue 11, pages 1615–1625, 30 May 2013
How to Cite
Owusu, P. A., Odai, S. N., Annor, F. O. and Adjei, K. A. (2013), Reservoir storage for managing floods in urban areas: a case study of Dzorwulu basin in Accra. Hydrol. Process., 27: 1615–1625. doi: 10.1002/hyp.9286
- Issue published online: 9 MAY 2013
- Article first published online: 11 MAY 2012
- Accepted manuscript online: 8 MAR 2012 04:18AM EST
- Manuscript Accepted: 17 FEB 2012
- Manuscript Received: 24 AUG 2011
- reservoir storage;
- flood management;
- urban area;
- SCS-CN rainfall runoff model;
The study simulated the effect of using reservoir storage for reducing flood peaks and volumes in urban areas with the Dzorwulu basin in Accra, Ghana as case study. A triangulated irregular network surface of the floodplain was created using ArcGIS from ESRI by integrating digital elevation model and the map of the study area. The weighted curve number for the basin was obtained from the land use and soil type shape files using ArcGIS. The Soil Conservation Service curve number unit hydrograph procedure was used to obtain an inflow hydrograph based on the highest rainfall recorded in recent history (3–4 June 1995) in the study area and then routed through an existing reservoir to assess the impact of the reservoir on potential flood peak attenuation. The results from the analysis indicate that a total of 13.09 × 106 m3 of flood water was generated during this 10-h rainstorm, inundating a total area of 6.89 km2 with a depth of 4.95 m at the deepest section of the basin stream. The routing results showed that the reservoir has capacity to store 34.52% of the flood hydrograph leading to 45% reduction in flood peak and subsequently 38.5% reduction in flood inundation depth downstream of the reservoir. From results of the study, the reservoir storage concept looks promising for urban flood management in Ghana, especially in communities that are over-urbanized downstream but have some space upstream for creating the storage. Copyright © 2012 John Wiley & Sons, Ltd.