smart sensors and the environment

Box 1 | Environmental applications of smart sensors

Catchment monitoring and management

One of the big environmental challenges of our time is managing freshwater in an age of climate change. Sensor networks can be used to help manage this precious resource by continuously monitoring water quality and water flow into catchment areas that are often remote and broad-ranging. The resulting information can also be combined with other sensor networks monitoring soil condition to assist with the fair and efficient distribution of water for irrigation, as well as for management of the surrounding environment.

For example a sensor network is proposed for a North Queensland catchment that empties into a reef system. This network will provide information about the effects of nearby land use on the immediate catchment environment and in the adjacent reef system.

Similar technology could also provide early warning of flash flooding. Indeed, networks of smart sensors have already been deployed in a river for just this purpose in the UK by researchers at Lancaster University. Some of the sensors measure pressure from below the waterline in order to determine depth. Others monitor the speed of the river flow. Each sensor node is smaller than a human fist and powered by batteries and solar panels. Each is also accompanied by a computer unit about the size of a packet of chewing gum, which contains a processor about as powerful as those found in modern mobile phones.

When do plants need a drink?

And it’s not just catchment managers who are interested in monitoring water. If farmers could take the guesswork out of when their crops and pasture plants need water they could make their operation a lot more efficient. Scientists at CSIRO have been investigating the installation of wireless sensor networks over farms to measure soil moisture to determine the most effective irrigation for a particular field.

Researchers at the University of Colorado have taken water monitoring on farms one step further. They have developed clip-on sensors the size of a fly's wing that are attached to plant leaves during the growing season. The sensor monitors moisture content and chemical signatures that can indicate when the plant is undergoing water stress. The chemical signs, such as an increase in salt and sugar content in the cells, occur much earlier than physical signs, such as drooping leaves.

Because of its tiny size, the sensor can only transmit a signal about half a metre away to the next sensor. The signal passes along the network to a base station and is then transmitted to the farmer’s computer, which analyses the data. The result is either emailed to the farmer (for example, ‘turn irrigation on now’) or may even switch on the water for the farmer. The system is expected to save up to 40 per cent of water use.

Preparing for bushfires

Every Australian city is vulnerable to bushfires, and as our urban zones increasingly extend into bushland areas it’s a problem that’s only growing. Low cost sensor networks set up around our cities could monitor local moisture levels, humidity, wind-speed and direction. Integrating this information with satellite imagery and long term weather forecasting would enable better understanding of fire risks and bushfires as they develop. And such information could prove invaluable in planning a coordinated disaster response or providing early warning to high-risk areas.

Listening for invading toads

Cane toads have been spreading across northern Australia for decades but it’s always been difficult to monitor the invasion front because it’s so large and is often in unpopulated areas. Smart sensors are now being trialled in an attempt to better monitor when the noxious toad first enters a region. Researchers at the University of NSW together with National ICT Australia have developed wireless sensor nodes consisting of an acoustic sensor, a micro-processor and a wireless communication unit. Each sensor picks up toad or frog calls and relays them to a microserver that also forms part of the network. The microserver receives the data, determines whether a cane toad is present and then relays this information back to a central control room. The system is being progressively trained to distinguish different frogs and so far can recognise the calls of up to nine frog species from northern Australia. By making the data collection automatic with wireless transmission of the results, pest management has become more feasible across remote and widespread areas.

Box
Box 2. Intelligent sensor networks

Related sites
Plants tell sensor when they need a drink (News in Science, Australian Broadcasting Corporation, 23 July 2007)
Tracking cane toads from the sofa (News in Science, Australian Broadcasting Corporation, 12 July 2005)
Future farms (ABC Rural, Australian Broadcasting Corporation, 1 February 2007)
Water catchment flow monitoring (ISSNIP, Australia)

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Posted December 2008.