Natural and anthropogenic hazards

There are many natural and anthropogenic hazards to human life, health, livelihood, and property, and hazards that affect the natural environment. The hazards we encounter are influenced by the way we build cities, and where we build them, how we farm and mine, how we travel and where we go, and how we rearrange the distribution of life on the planet. Floods, fires, erosion and landslides, earthquakes, plant and animal invasions, storms and tsunamis, and changes in sea-level and atmospheric composition have been happening for millions of years. As they threaten the way we live, we want to understand their processes and negate or mitigate any negative consequences.

The Earth’s climate and landscapes are dynamic. Over millions of years, the planet has cooled and warmed, mountains have risen and been eroded away, and rivers have cut their way across continents, changed courses, flooded, and dried up. Life has evolved with the landscape. Plants and animals range in areas where the land and climate are suitable, and the distribution of species has changed as the Earth has changed. Plants and animals have evolved and become extinct, and they migrate across continents as environmental conditions change.

Humans also change the landscape. We build cities along rivers that supply water, and near fertile lands to grow our food. We develop agricultural and pastoral lands, relocating plant and animal species around the world to suit our needs, like sheep for meat and wool, and wheat for its grain. We develop mines and construct power stations to supply resources for our burgeoning population. Our rapid consumption of food, fuel, mineral, and fibre resources is hastening natural environmental change. Some of the conditions we are creating are hazardous to our health, livelihoods, property, lives, and to the natural environment that supports us.

BioCity@UniSA research includes geology, geomorphology, hydrology, urban and regional planning, biodiversity, engineering, materials, spatial sciences, construction, and surveying, to understand and plan for hazards. Research is focussed on reconstructing past events to understand change, biodiversity and land restoration, construction materials and engineering technologies to mitigate hazards, and using spatial sciences to predict and manage hazards.

Spatial science and hazard management

Using spatial information, such as Geographic Information Systems (GIS), we can model the likelihood of natural hazards occurring and the impacts of such hazards. This technique can be used to predict the effects of floods, tsunamis, fires, earthquakes, volcanic eruptions, landslides, and sea-level rise. We can predict the behaviour of such events and conduct risk assessment, looking at the chance of such an event as well as its consequences. We can then look to negate or mitigate their impacts on ourselves and the environment.
Rainfall patterns are complex and far from being fully understood. This complexity is compounded by global climate change. Flooding is a natural consequence of high rainfall events, but when it rains on cleared lands, both urban and agricultural, there is more runoff, it moves more quickly, and it takes more sediment with it. The effects of flooding can be mitigated by reducing development in flood prone areas, or through engineering solutions such as the construction of levee banks to divert potential floods. For example, flooding at Wilson’s Bog in Cleland Conservation Park near Adelaide has historically led to landslides. Such landslides would be hazardous to people and property in developed areas, but within a conservation park the damage is minimal.

In mountainous regions, slope instabilities and landslides are ever present threats. Remote sensing technologies are being used to gather data on land forms and land use to model the likelihood of landslide occurrence. To improve the accuracy of such predictions, research is focussed on new, very high spatial resolution remote sensing technologies, and improving our understanding of the conditions which lead to landslides.

Computer visualisations can be constructed in 2D, 3D, and 4D to show how landscapes will look in the future. In this way, hazards such as erosion can be modelled to understand their potential. Landscapes might also be visualised including events that increase the potential of hazards, or events that experience hazards, like increasing housing densities, vegetation clearance, and reduced river flows.

Researchers from BioCity@UniSA have had a significant impact on policy development for hazard management in South Australia. For example, Bushfire Hazard Zones have been redefined utilising GIS and fire modelling tools, and further research is being conducted into the performance of building materials during fires.

Environmental change, biodiversity, and land restoration

Environmental changes can take many forms. Changes in temperature affect both aquatic and terrestrial life. Aquatic life can be affected by water pollution, including an increase of nutrients or sediments. Terrestrial plants can be directly affected by soil contamination, such as heavy metals, and animals can be indirectly affected by consuming these plants.

Changes in biotic communities can occur with the introduction of a new species, such as an exotic weed. In such cases, GIS tools are being used to develop models of their preferred habitats, predict where future problem areas will be, and assist in the management of this hazard. BioCity@UniSA researchers are examining the use of remote sensing technologies to map weeds and inform weed management strategies. Research includes work on methods of discriminating between plant species, and on which spatial and spectral resolutions are the most appropriate and cost-effective to detect weeds.

Plants and animals can no longer migrate as environmental changes occur, because much of the landscape has been modified to suit human needs. For example, an endangered plant or animal species might be restricted to limited, fragmented habitat. If the environmental conditions change, such as a warming of the local climate, the location may no longer be a suitable. Often, species cannot migrate to more favourable locations because incompatible agricultural landscapes surround them. Furthermore, species can become extinct if one, chance hazard event, such as a fire or flood, occurs within their restricted range. An example of such a species is the critically endangered Gilbert’s Potoroo (Potorous gilbertii), with a wild population found only in Two Peoples Bay Nature Reserve in Western Australia.

Just as environments can be changed with negative consequences, so too can they be changed for positive outcomes. Land restoration involves human intervention to restore natural areas and natural processes. Prior to physical works, an understanding of the ecological, hydrological, geophysical systems in question is required. Research is designed to conclude with recommendations directing the works required to restore the landscape. These works might include earthworks and revegetation to reduce erosion and replace habitat, weed and pest control or removal, and the breeding and reintroduction of native species. Projects are often community based to increase participation, reduce costs, increase the sense of ownership, and improve the chances of success.