Developing a holistic risk management plan in mitigating flooding risks for buildings adjacent to the Swan River in Perth, Western Australia

AbstractClimate change as a major issue in the 21st century has seen the rise of the sea level and worse storm surges. This has impacted on the further distribution of salinity and flooding of low laying areas even in further inland areas. As the consequence, buildings in the proximity of riverbanks are left susceptible to potential damages and shortened life cycles. Thus, there is a real need to change the way buildings in these areas to be designed and how risk of damages can be mitigated and managed. The city of Perth in Western Australia, like many other cities around the world, is laying on the riverbank of a large river, the Swan River. As the population of Perth increases dramatically, it will become important to ensure sustainability of its buildings to support the ever growing populations and hence its needs. There are myriads of approaches in mitigating and managing these risks. This research project aims to investigate the contemporary risk management practices in mitigating flooding risk in buildings adjacent to the Swan River and bring them together as a holistic risk management approach. The findings of this research can be proposed to the Western Australian government to assist them in developing further policies in ensuring sustainable buildings fit for the future. At this point of writing, the research project is on its early stage of conducting literature review and designing the research methodology. It is intended to conduct a pilot survey, followed by case study approach of contemporary buildings adjacent to the Swan River to contextualize the research. This paper presents the current progress of this research

The role of vegetation in mitigating the effects of landscape clearing upon dryland stream response trajectory and restoration potential

Dryland rivers are recognized for limited research and high uncertainties with respect to understanding biogeomorphic processes. This study uses aerial photography, sediment analysis, palynology indicators and hydraulic modelling to investigate the role of riparian vegetation in influencing the response of systems to disturbance, the trajectory of channel evolution and the potential for management. The study focuses on cleared and uncleared sites in the Yerritup catchment, along the south coast of Western Australia, that occur along a transect with a consistent stream gradient and landscape topographic setting. Downstream reaches show no gross botanical change, but gradual sediment deposition across the floodplain of up to 40cm based on palynological and sedimentary indicators. Channel response in the cleared section by incision, widening and floodplain degradation began rapidly after land clearing, but is driven by large flood events. Degradation of riparian vegetation has significantly increased the sensitivity of the system. The cleared reaches have transformed from a low-capacity channel, under-adjusted to the prevailing flow regime, to the large present channel that is now over-adjusted to the predominantly low to moderate seasonal (occasional flood) flow regime. Modelling of pre-settlement erosive potential reveals that the entire system was naturally sensitive to change, and was primed to erode once riparian vegetation was removed. The trajectory of channel evolution and the role of riparian vegetation is examined in relation to undisturbed reaches in the system and an appreciation of the historical range of variability in geomorphic response. Analysis of the patterns of contemporary vegetation growth identify the potential to re-establish vegetation where it is elevated from saline baseflow. However, the system is assessed as being close to a threshold where restoration is no longer possible and remediation options become more limited as eco-hydraulic and hydrochemical changes continue