oa Managing Residential Development in Karst Landscapes, Perth Metropolitan Area, South Western Australia

As the business and administration centre for the resource rich state of Western Australia, population growth in the Perth Metropolitan region has been consistently greater than the national average. the metropolitan area is located on the Swan Coastal Plain, a stretch of land which lies between the Indian Ocean and the Darling Scarp. Much of this region forms part of a karst belt which runs along the west Australian southern coast to 20 km inland. the belt is comprised of one main geological unit, the Tamala Limestone which is typically a soft porous rock that is highly susceptible to dissolution, with karst weathering often resulting in the development of sinkholes, open voids and caves.<br>Due to its geological setting, the pressure of new developments and the subdivision of land within the Perth Metropolitan region pose a risk with geohazards typical of karst environments. Urbanisation such as roads, buildings and construction can often acts of catalysts for karst formation by altering the flow of rain water runoff, applying increased loads on the surface, and increased vibrational noise. Urbanisation of karst environments presents a number of challenges for urban planners and engineers with structural failure of buildings and infrastructure a reality. This poses the question: How to manage urban development in karst landscapes in Western Australia’s fastest growing residential area?<br>This paper will present a number of case studies undertaken in residential developments in the Perth region detailing how geophysical methods have been used to map the limestone bedrock and identify karstic formations of potential risk. Ground penetrating radar and seismic methods have proven to be an affective combination of techniques over this environment with the sand dominant subsurface providing excellent transmission of radar wave energy and the basic two layer sand and limestone strata providing a distinct seismic refractive interface.