Impacts of climate and land-use changes on floods in an urban catchment in southeast Queensland, Australia

Abstract

Over the coming decades, the projected land-use change, when coupled with climate change, could potentially lead to an increased risk of flooding in urban catchments. This research aims to examine impacts of climate and land-use changes on floods in southeast Queensland, Australia. A rainfall-runoff routing model, RORB, was first calibrated and validated using observed flood hydrographs for an urbanised catchment, the Bulimba Creek catchment, for the period 1961-1990. The validated flood model was then used to generate flood hydrographs using projected rainfall based on a global climate model, GFDL, and a regional climate model, CCAM, for 2016-2045. Projected daily precipitations for the two contrasting periods were used to derive adjustment factors for a given frequency of occurrence. Two scenarios of land-use change were considered to evaluate the likely impact of land-use change. Results showed that future flood magnitudes are unlikely to increase for large flood events for the urban catchment. Further, land-use change would not significantly affect flood magnitudes for a given frequency of occurrence in the urbanised catchment.