smart sensors and the environment
Key text
This topic is sponsored by the ARC Research Network on Intelligent Sensors, Sensor Networks and Information Processing.
Monitoring reef systems or catchments for environmental change can be a big job; sometimes too big for humans to handle without a bit of technological assistance. Now that assistance is increasingly available in the form of smart sensors.
Monitoring threats to the reef – the need for smart sensors
How do you manage a unique natural resource like the Great Barrier Reef when it's threatened on so many fronts? Coral bleaching caused by rising water temperatures due to climate change, is possibly the biggest and most immediate threat.
(image: Great Barrier Reef Marine Park Authority
But then there's also coral disease; sediment, fertiliser and pesticide pollution from mainland run-off; and the growing spectre of acidification. The reef ecosystem is already susceptible to the effects of climate change; pollution only makes the problem worse. Each of these threats comes from a different source, operates at a different scale and interacts in a variety of ways.
Appropriately managing the many challenges confronting the reef requires reliable and timely information on its changing environment. Where are sea temperatures rising? How fast are changes happening? Where are excess nutrients and sediment coming from? Is it a gradual process or do they come in pulses following heavy rain? Are there any changes in the reef environment prior to an outbreak of coral disease?
But perhaps the bigger question is how do you collect the information to answer these questions? And don't forget, the Great Barrier Reef is a very big place covering 300,000 square kilometres and made up of a network of around 3000 reefs. Environmental monitoring may be needed continuously at multiple locations and over long periods. Deploying an army of scientists is out of the question in terms of budget and resources. Remote sensing by satellite can be useful but often doesn't provide the required level of detail. For example, satellite images can only reveal water surface temperatures at resolutions of a kilometre or more. This does not provide sufficient detail to investigate the cause of damaging events such as coral bleaching. Measurements at smaller scales and at various depths are needed to better understand the nature of bleaching events.
Detail is one thing, being able to see changes in real-time throughout the reef would also help researchers and environmental managers to preserve this environmentally and economically important asset. And the only way this can be realistically achieved is by deploying networks of sensors over the reef to monitor its many processes.
And that's exactly what is happening. Sensors of all shapes and sizes are being deployed across the Great Barrier Reef to monitor different processes. The monitoring is being likened to covering the Great Barrier Reef with a digital skin, enabling scientists and managers to pick up real-time information about the reef.
This may be the way of the future for all forms of environmental management, be it catchment management, bushfire risk management, agriculture or monitoring invading pests (Box 1: Environmental applications of smart sensor technology). When the task involves understanding environmental changes over large or multiple spatial scales, sometimes in areas where humans are few and far between, then smart sensor networks may be the answer.
Sensors getting 'smarter'
Humans have been using environmental sensors for centuries. For example, consider the rain gauge. All over the world we have been putting out a variety of rain-collecting vessels that can accurately tell us how much rain has fallen at any particular location. Rainfall is one of the most important environmental variables around but, as sensors go, the traditional rain gauge is not very 'smart'. It collects information but it can't do anything with that data, and it needs regular checking. What's more, data collected at one location may not reflect what's happening elsewhere.
A traditional rain gauge is a good reliable sensor but it's passive. It collects, you record. In recent decades automated weather stations have been developed that have the capacity to collect meteorological data automatically – 24 hours a day, seven days a week – and then transmit that information to a central location. While these stations are much 'smarter' than the old passive rain gauge, weather stations are expensive and you can only set up so many.
But all that is changing as an exciting mix of nano-engineered materials, miniaturised computers and rapid wireless communications is giving rise to a new generation of environmental sensors. These new sensors are smaller, cheaper and more versatile than anything we've seen before and their deployment in intelligent, interacting networks (Box 2: Intelligent sensor networks) is opening up a new age of environmental monitoring.
These new sensors will be able to process information they collect and adapt to changing conditions. They'll be able to measure an amazingly wide range of environmental variables, and they'll be able to share this information with a network of sensors. And because they'll be smaller and cheaper, we'll be able to build more of them and create networks with a greater coverage than has ever been possible before.
The nuts and bolts of a smart sensor
Smart sensors come in all shapes and sizes, detect many different things and process the data they collect in different ways.
The name 'smart' or 'intelligent' sensor relates to a sensor's ability to detect information of interest (eg, a sudden change in water temperature), process the data it collects, communicate with other sensors and have some capacity to adapt to changes in the environment.
To be 'smart' there's a basic set of components that a sensor can use. The first component is the unit that senses or measures some environmental variable. This variable might be sound, light, temperature, pressure, magnetic field or some chemical compound, or a combination of variables (eg, temperature and pressure).
Next, our sensor needs some capacity to process the raw data being collected, and this is usually done through its own tiny computer processor. Combined with this processing capacity is also the ability to store this information in its computer memory and only transmit information of interest.
The sensor needs to be able to communicate with other sensors so the data it collects and the information it processes can be passed through a network of sensors to a central computer. For maximum convenience this communication may be wireless; if so, the sensor also needs some form of radio transmitter.
requirements that make a sensor smart. On top of this, however, it'll
also need a power supply to drive these processes.
The challenge now is to refine the developing smart sensor technology.
Making more of smart sensors
Like many areas of emerging technology, the science of smart sensors and smart sensor networks is strongly multidisciplinary in nature. It may involve electrical, mechanical and materials engineers as well as biologists and chemists. In addition, putting together smart sensor networks needs good information technology skills and interpreting collected information involves statistics and network modelling expertise. To help bring these people together, the Australian Research Council (ARC) has established the ARC Research Network on Intelligent Sensors, Sensor Networks and Information Processing (or ISSNIP).
Provides details of smart sensor research being conducted through ISSNIP.
(Australian Research Council, Australia)
ISSNIP is developing smart sensor solutions for the environment, defence, security, transportation and health monitoring. Some of the many fascinating applications of the research conducted through ISSNIP are the development of navigation systems for aircraft based on the visual systems of bees, sensors to detect drugs, helping unmanned aerial vehicles find targets and facial recognition for security systems.
Research on ways to improve smart sensors is advancing on many fronts. This includes development of more sensitive detectors, smarter communication between sensors and more efficient ways of processing information by sensors and sensor networks.
Internationally, the push is on to develop smaller and cheaper sensors. How small can a sensor become? Well, believe it or not, researchers are working on smart sensors, referred to as 'smart dust', that are the size of grains of sand.
Monitoring the Great Barrier Reef
Research trials like those being conducted on the Great Barrier Reef are an important way to refine smart sensor technology for a range of applications. Once established, smart sensor networks that provide access to real-time information about the reef will be valuable tools for its management.
Provides interactive maps with up-to-date information from sensor sites around the World, including Australia.
(Microsoft® Research, USA)
The Great Barrier Reef Ocean Observing System will see the installation of sensor networks across seven Great Barrier Reef sites. Wireless sensor networks, for example, are being tested at Davies Reef. They involve the placement of a number of environmental sensors that measure temperature, salinity, light and oxygen. The information from some of these sensors is presented in an easy to use web-based format via SensorMap.
There's also a wireless sensor network being installed in Nelly Bay at Magnetic Island. This network consists of temperature sensors vertically positioned below the ocean surface 2 metres apart. The network will beam back temperature information to a base station real-time to help understand upwellings and their impact on the productivity
of the Great Barrier Reef. Another sensor is also being deployed there to measure
wave frequency.
(image: ISSNIP)
Scientists and environmental managers need detailed, real-time information about the reef environment if they are going to fully understand the processes occurring there. Eventually smart sensor networks across the reef will be providing some of the answers so that it can be better protected against pollution and climate change.
Boxes:
1. Environmental applications of smart sensors
2. Intelligent sensor networks
Related Academy Links
Wireless but not clueless
Coral bleaching – will global warming kill the reefs?
External sites are not endorsed by the Australian Academy of Science.
Posted December 2008.