Distrbuted Sensing Systems for Water Quality Assesment and Management

Abstract

The exponential progress of technology development, driven in many cases by Moore’s Law, has enabled the combination of sensing, computation and wireless communication in small, low-power devices that can be embedded directly in the physical environment. Recent research has resulted in several new classes of embedded networked sensing systems that can be rapidly distributed in the environment to study phenomena with unprecedented detail. Embedded networked sensing systems are transforming the way in which physical, biological and chemical changes are detected and quantified. These results are leading to new mechanistic understanding of the environment and, consequently, to new models and predictions for better assessment and management of environmental challenges.This white paper describes the emerging technologies used in distributed sensing systems and the opportunities these systems present for environmental management, and in particular, water quality protection. A team of faculty, students, and staff at the Center for Embedded Networked Sensing (CENS) wrote the report. CENS is a National Science Foundation sponsored Science and Technology Center, headquartered at the University of California, Los Angeles (UCLA). In addition to UCLA, the California Institute of Technology, the Riverside and Merced campuses of the University of California, and the University of Southern California are partners in the center. CENS is developing embedded networked sensing systems and applying this technology to critical scientific and social applications. The Foresight and Governance Project at the Woodrow Wilson International Center for Scholars edited and finalized this document for the U.S. Environmental Protection Agency’s Office of Water.This paper first briefly describes the potential applications of sensing systems to four common water quality management problems. This potential includes: (1) providing early warning for septic systems, (2) allowing for the trading of credits for non-point source runoff, (3) monitoring beach water quality, and (4) management of combined sewer overflows. Section 4 describes these scenarios in further detail.Section 1 provides an overview of sensors (i.e., the devices that convert environmental phenomena into an electronic response) and actuators (i.e., the devices that convert electrical signals into mechanical responses). Sensors have the potential to detect physical, chemical, biological, and radiation properties in the environment. A variety of sensors is currently available for networked environmental sensing, while others are still in early research and development phases. Physical sensors for water quality monitoring are generally the most field-ready and scalable to distributed applications, followed by chemical and then biological sensors. The costs for these sensors depend on the physical, chemical, or biological parameter of interest. Indicator sensors and event-triggering sampling can be used when direct detection sensors are not ready for field deployment. To more extensively detect environmental properties, even more sophisticated sensors and sensing strategies are needed, including: (1) hardening novel sensors types (such as lab-on-a-chip technology) to withstand harsh conditions for extended periods, and (2) devising integrated sensing systems for higher order observations, such as quantifying materials fluxes in the environment.Section 2 on Deployment Platforms discusses three new sensing system classes: static, mobile robotic, and mobile handheld. These sensing systems differ from traditional measurement systems in that sensors are attached to wireless radios that enable real-time communication of the data collected. For any particular situation, the best system class to use depends on the environment’s spatial and temporal variation. Among the three classes of sensing systems, mobile handheld systems are best used when the environmental phenomena of interest cover a broad area and do no