DRAINAGE SYSTEM AND STORM WATER MANAGEMENT FOR NDOLA CENTRAL BUSINESS AREA, ZAMBIA

Abstract: Flooding of urban areas is a worldwide problem as cities grow and the amount of impermeable surfaces increase generating more surface runoff. In the Zambian city of Ndola, the capital of the Copperbelt Province, flooding occurs in some parts of the city especially on Dag Hammarskjöld Drive at the underbridge, which has been flooding every rainy season consecutively for 8 years now. The main objective of the study was to assess the effectiveness of the storm water drainage system and management for Ndola Central Business Area (CBA) and to determine the possible changes, to avoid or minimise yearly flooding of the underbridge area. Both hard and soft solutions approach were employed. The procedure comprised of field study, data collection, modelling and analysis. It was concluded that the major problem with the system are blockages resulting from garbage being thrown into the system as well as silt build-up that accumulates overtime. Additionally, changing the size of the draining water pipe (P27=600mm) from the underbridge area would improve the drainage systems’ rainfall events’ handling capacity to more than 10yrs return period without flooding. Sustainable Urban Drainage Systems (SUDS) should be incorporated into the system in order to reduce and delay the peak flow downstream and subsequently in conduit P36 which contributes towards flooding by causing back water effects. Further studies should be conducted to ascertain specific SUDS adapted for the region owing to climatology and industrial activities.