title: Effects of urbanization and climate change on catchment hydrology in South East Queensland (SEQ), Australia
Creators: name: Ramezani, Mohammad R
Publisher: name: Griffith University
Year: 2023
Subjects: subject: climate change
subject: urbanisation
subject: remote sensing
subject: catchment hydrology

description: Climate change and urbanization are known to be the main factors leading to significant changes in catchment conditions worldwide. Changes in climate characteristics such as intensity (e.g., rain amount on wet days) and frequency (e.g., number of extreme heat waves each year) would affect the hydrological cycles of the catchment by increasing floods and droughts. Urbanization – the conversion of permeable to impervious areas – would degrade the catchment hydrology through increased surface runoff and flood peaks and decreased baseflow. Climate change and urbanization have been extensively researched around the world for their effects on catchment hydrology. However, no consistent conclusion on the impacts of climate change and urbanization has been defined, particularly for sub-tropical and populated regions such as Southeast Queensland (SEQ), Australia. The majority of previous research has focused on assessing the changes in hydrological conditions of the catchment due to climate change or urbanization separately. In this PhD research, we postulate that evaluating the combined effects of urbanization and climate change can yield more reliable results, particularly in regions that are highly affected by both factors, such as SEQ. As such, the overall aim of this study was to analyse the individual and combined impacts of climate change and urbanization on catchment hydrology in SEQ. To achieve this aim, three main objectives were formulated for this PhD thesis. First, a reliable relationship between population density and imperviousness in urban areas in SEQ was established. The results from this objective helped us predict imperviousness using SEQ population projections. Second, the performance of two widely-used rainfall-runoff models was improved by incorporating spatiotemporal data for imperviousness. This outcome is particularly beneficial for newly-urbanized catchments with limited flow data. Third, scenarios integrating climate and urbanization changes were modelled to study runoff changes in future scenarios in six catchments in SEQ. This study applied a holistic framework including a) a local model to develop more reliable urbanization projections; b) a multi-climate model ensemble approach to develop climate projections with greater certainty; c) a sub-pixel classification approach to derive reliable spatiotemporal imperviousness data in a large urban/rural area (used for the three objectives discussed above); and d) two widely-used rainfall-runoff models modified to reliably simulate runoff in developed urban catchments. The proposed framework and outcomes from this research can be used by local/global water resource managers and policy makers to create more efficient water management plans in the future and develop more sustainable adaptation and mitigation strategies at the catchment scale specifically in urban areas.