Smart-Phone Robots Tweet Flow Dynamics Data in Real Time

A fleet of 100 smart-phone enabled floating robots was launched in the Sacramento River at Walnut Grove on May 9, 2012 to demonstrate new technology that transmits flow dynamics data in real time. These robots are part of the Floating Sensor Network project, a joint effort between the University of California Berkeley, the Lawrence Berkeley National Laboratories and the California Department of Water Resources (DWR). Data collected from the robots are integrated into Delta hydrodynamics models to predict where particles go in water. The project was funded in part by DWR, the Delta Science Program and the National Science Foundation.

“Our approach is to put a sensor into the river and let it float with the river so that it traces where the water moves as it goes through rivers and estuaries and deltas,” said Andrew Tinka, lead graduate student on the project. “We need to know where the water goes and we need to know how it carries things through the Delta. How it carries saltwater, how it carries pollution. We need to know these things so that we can make environmental management decisions about where the water should go and how we can manage the Delta.”

Data sent from the waterproof sensors are used to estimate and produce maps of water flow. The devices transmit information using the cellular phone network as well as short-range wireless radios. As the sensors are carried by the water, their GPS receivers keep track of their movement. This provides a snapshot of the direction and speed of the water at a point. The real time information from multiple sensors is combined to provide a ‘traffic map’ for the entire delta, showing the speed of water, how deep the water is, and how contaminated the water is.

Some of the robots even relay their results on Twitter, which means that their position is automatically “tweeted” so it can be followed in real-time.

“In the same way that using Android phones as the central unit of drifters is an innovative way to leverage the explosion of mobile phone technology for environmental monitoring, using a micro-blogging service like Twitter to follow the drifters is a natural way for people to “follow” where the robots are,” says Jon Beard, one of the students working on the project, who came up with the idea of Android and Twitter for the drifters.

The data are also integrated into delta hydrodynamics models in real time which will allow prediction of water movement several days into the future. This accurate understanding of currents in the Delta will help with understanding fish migration in the Delta.

This experimental deployment demonstrated the real-time data gathering capabilities of the robot monitoring flotilla-which can also be deployed rapidly in response to unanticipated events such as floods, levee breaches, and contaminant spills. The fleet was used to measure speed of water through broken levees, in an experiment conducted jointly with the Department of Homeland Security and the U.S. Army Corps of Engineers in Stillwater, Oklahoma. “One of the avenues explored by the project is the further development of this technology so it becomes almost ‘disposable,’ i.e. cheap enough that it can be deployed at will in emergency scenarios,” says Alexandre Bayen, associate professor at the University of California, Berkeley and the Principal Investigator of the project.

But why track water?

Water managers need to track the movement of water, salinity, and contaminants in complex networks of channels like deltas or estuaries. Whether in emergency situations such as a levee failure, flood, or contaminant spill, or for management efforts such as maintaining the freshwater channel in the Sacramento-San Joaquin Delta, it is important to understand where the water is going.

According to Bayen and his colleagues, the long-term vision of the project is to put California water online, to create a system that will enable water managers and scientists to visualize California’s water resources in real time, an innovation that will transform the management of scarce water resources in California and around the world.

The group’s next project is to deploy the drifters in Lake Tahoe, in collaboration with the University of California, Davis, to monitor the ecosystem of the lake.

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