Flood risk assessment using spatial decision support systems

Urbanizing drainage basins are complex, dynamic man-environment systems. All too frequently the carefully balanced rural coexistence with the river and its flood-plain, developed by trial and error over many years (often centuries), is severely disrupted by the geomorphic response to urban development both inside and outside a drainage basin. Flooding can become both more frequent and more severe in terms of depth and duration. The consequences can be costly with disrupted livelihoods, damage to property and essential services, and even loss of life. The integration of geographical information systems (GIS) and hydraulic simulation of flood events for different development scenarios is proving an effective tool in planning and operational management.