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Reservoir storage for managing floods in urban areas: a case study of Dzorwulu basin in Accra
Author(s) -
Owusu P. A.,
Odai S. N.,
Annor F. O.,
Adjei K. A.
Publication year - 2012
Publication title -
hydrological processes
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.222
H-Index - 161
eISSN - 1099-1085
pISSN - 0885-6087
DOI - 10.1002/hyp.9286
Subject(s) - hydrograph , hydrology (agriculture) , flood myth , floodplain , routing (electronic design automation) , environmental science , runoff curve number , structural basin , 100 year flood , inflow , digital elevation model , drainage basin , geology , geography , remote sensing , geomorphology , cartography , meteorology , geotechnical engineering , computer science , computer network , archaeology
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 × 10 6 m 3 of flood water was generated during this 10‐h rainstorm, inundating a total area of 6.89 km 2 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.