Changes in hydrological processes, such as runoff and transport of sediment and nutrient loads brought about by warming air temperatures and variations in rainfall under climate change pose challenges to the integrated management of water resources at catchment scale. Extreme events are expected to compound these challenges. Most assessments have focused on effects of changes in climate and land use and landcover, but less on the dynamical responses of vegetation and soil to changing climate and the resulting effects on catchment hydrological processes under future conditions. The exploitation and utilization of freshwater resources by humans has changed the natural flow regimes in rivers, but little attention has been paid to the impact on the downstream freshwater aquatic ecosystems as well as saline intrusion within estuaries. Future population growth and sea level rise may exacerbate conflicts in water resource allocations among different users. This thesis assesses the impacts of future climate change, population growth and water resources management on the water resources and hydrodynamics of different systems within the Nerang River catchment of South-east Queensland (SEQ) in Australia. [...]