IEEE COMMUNICATIONS MAGAZINE (ACCEPTED) 1 Cyber-Physical Systems for Water Sustainability: Challenges and Opportunities Zhaohui Wang, Michigan Technological University Houbing Song, West Virginia University David W. Watkins, Keat Ghee Ong, and Pengfei Xue, Michigan Technological University Qing Yang, Montana State University Xianming Shi, Washington State University Abstract—Water plays a vital role in the proper functioning of the Earth’s ecosystems, and practically all human activities, such as agriculture, manufacturing, transportation, and energy production. The proliferation of industrial and agricultural activ- ities in modern society, however, poses threats to water resources in the form of chemical, biological, and thermal pollution. On the other hand, tremendous advancement in science and technology offers valuable tools to address water sustainability challenges. Key technologies, including sensing technology, wire- less communications and networking, hydrodynamic modeling, data analysis, and control, enable intelligently wireless networked water Cyber-Physical Systems (CPS) with embedded sensors, processors, and actuators that can sense and interact with the water environment. This article will provide an overview of water CPS for sustainability from four critical aspects: sensing and instrumentation, communications and networking, computing, and control, and explore opportunities and design challenges of relevant techniques. I. WATER SUSTAINABILITY Water is the lifeblood of the planet. Safe and abundant water resources are critical to all three dimensions of sustainability: social, economic, and environmental. Given its close linkage to a number of key global challenges, including population growth, industrialization, and climate change, water sustain- ability is of critical importance for sustainable development in the modern world. Achieving water sustainability, in turn, requires achieving universal access to safe drinking water, sanitation and hygiene; improving the efficiency of water use for economic purposes; strengthening equitable, participa- tory and accountable water governance; improving wastewater management and protecting water quality; and reducing the risks of natural and human-induced water-related disasters. In industrialized nations, fresh water resources — ground water, lakes, rivers, and streams — must meet a number of (sometimes competing) water use needs, including domestic, commercial, industrial, agricultural, and energy generation. In addition, sustainability requires that water withdrawals and consumption for human uses do not compromise aquatic ecosystems. Although water is a renewable resource, water availability and water quality may not be sufficient for desired water uses and ecosystem functioning. Deficits, or scarcity, may occur at seasonal time scales and at geographic scales ranging from community water systems to regional river basins and groundwater aquifers. In addition to overuse or scarcity, water resources are facing many other severe challenges, including contamination, aging infrastructure, lack of data for informed decision making, weak public awareness of water challenges, and inefficient water management strategies. Many of these challenges are due to global change issues, such as population growth, economic development and climate change, which are expected to increase in the foreseeable future. Given these critical and persistent water resources chal- lenges, we advocate “green 1 ” applications of the information and communications technology (ICT) to help achieve water sustainability [1]. To this end, green ICT can provide many benefits, including improved water quality, more effective emergency response, and increased public awareness of en- vironmental challenges. We envision technologies including communications and networking, sensor technology, hydrody- namic modeling, data analysis, and human-centered decision support systems to enable intelligently networked water Cyber- Physical Systems (CPS). This article will explore opportunities and design challenges of CPS for promoting water sustainablil- ity, including sensing and instrumentation, communications and networking, computing, and control. Given the diversity of water sustainability challenges, techniques discussed in this article could be further tailored to specific application requirements. II. WATER CYBER-PHYSICAL SYSTEMS Cyber-Physical Systems (CPS) are intelligently networked systems with embedded sensors, processors and actuators that are designed to sense and interact with the physical world (including human users), and support real-time, guaranteed performance in safety-critical applications, as defined in a CPS Vision Statement published in 2012 by the Federal Network- ing and Information Technology Research and Development (NITRD) Program’s CPS Senior Steering Group. The interplay between the “cyber” and “physical” elements among the CPS is critical: sensing, networking, computing, and control need to be deeply integrated in every component of CPS, and the CPS components must be inter-operable with a concerted design. Just as the Internet transformed the way people interact with information, CPS is transforming the way people interact with engineered systems and promoting sustainability. 1 Here “green” indicates the application of ICT to address environmental sustainability challenges.