Driven by the need to protect water resources and achieve water security, while at the same time sustain economic development, research under the decision support methods for a sustainable water environment topic of WATERS Network will increase understanding, integration and management of key stages of the water environment/human interface.  This includes both biogeochemical and human factors for change, and their associated risks and uncertainties.  The term “water security” is interpreted and used in the broadest sense for the purposes of this discussion.  Factors include sustainable extraction and sufficient quality for drinking water, agricultural and ecosystem uses; water treatment and supply systems; equitable allocation from a socio-economic perspective; wastewater collection, treatment and reuse; stormwater management systems; reservoir and river systems; mitigation of natural disasters; and prevention, remediation, and impact reduction of human caused disasters.  Additional factors that will need to be considered as this component of the WATERS Network matures include climate as a large-scale driver, and socio-economic conditions as a decision driver (Minciardi et al., 2006).

A key aspect of the WATERS Network interplay with the human impacted water environment is managing change and complex water resources infrastructure systems toward secure and sustainable development.  Intelligent water environment infrastructure systems (Woldt and Dahab, 2006) and adaptive management (Gunderson and Holling, 2002) approaches have the great potential to lead to a secure and sustainable human/water environment interface and provide a framework to underpin critical policy decisions on the allocation of resources to support socio-economic goals.

Water quality issues involving the provision of adequate and safe water for people, and proper wastewater treatment have always been, and will continue to be top priorities of federal, state and local governments.  This challenge is magnified many times when one considers the typical configuration, geographic distribution, and size of many communities on a worldwide and nationwide basis.  While there is a large scale trend toward mega-cities, and this trend will demand all of the potential benefits that WATERS Network can yield in terms of finding solutions to water infrastructure sustainability, there are still a great number of smaller communities and settlements that are challenged and will benefit greatly.

Challenges at the human/water environment interface can be grouped into six main categories including: 1) source water systems that include both surface and groundwater supply reservoirs; 2) water treatment, supply and distribution systems; 3) wastewater collection treatment and disposal/reuse systems; 4) stormwater collection and management systems; 5) rivers and reservoirs that support community progress such as transportation and energy demands; and 6) detection and remediation of contaminated waters.  Some of these challenges have been quantified in economic terms.  For example, it is estimated that in the U.S. alone, the difference between projected expenditures and the clean water / drinking water investment needs over the next 20 years is in the range of $72 billion to $229 billion, with a point estimate of $148 billion, if current spending and operation practices are maintained (USEPA, 2002).

Adaptive infrastructure management combines distributed sensor networks with predictive modeling to make better, more optimal, decisions within the complex space/time framework of the water cycle/community interface.  In this case, the decisions pertain to the short and long term management of key surface/groundwater reservoirs, water treatment and supply, wastewater collection and treatment, and stormwater infrastructure as related to community demands for sustained economic development.  The general idea is to use adaptive management approaches to enhance performance, extend capacity, respond to disasters, and increase the life expectancy of existing water-based infrastructure systems.  In the case of a water cycle/community interface, there are many factors (dimensions) that need to be considered simultaneously, in order to move toward more optimal management of the infrastructure that extracts water resources, treats, conveys, distributes, and then treats the wastewater generated as a result of beneficial use.  For example, if an integrated network is assembled in which water demand information (both real time and forecasted) is connected to model-based control systems for water reservoir/supply (Nickel et al., 2003), water treatment (Head et al., 2002; Haas, 2004), water distribution system (Biscos et al., 2002), and wastewater treatment infrastructure (Dochain and Vanrolleghem, 2001; Hamed et al., 2004), then this highly connected infrastructure will be able to adapt to projected demands and potential natural or man-made disasters.  This “water environment infrastructure flexibility” will allow for operations in a more efficient manner and/or minimize adverse impacts from potential disasters.