Summary of Net Zero Urban Water from Concept to Applications: Integrating Natural, Built, and Social Systems for Responsive and Adaptive Solutions

Some major points of the article are:

• Multiscale and multidimensional decision support is needed to adapt the built environment toward a NZUW future, in view of natural and social system dynamics and constraints.
• To reach a NZUW target, an urban water system will need to implement adaptive and responsive solutions across building, district, and city and regional scales.
• Net zero water technologies have been demonstrated at the building scale and incentives have been adopted by several districts and cities. Implementation barriers exist at all scales and require a shift in policies, governance and management structures, and technological improvements for comprehensive adaption to the urban water system.
• Six areas of research gaps across the NZUW approach are identified in the article: (1) alternative water sources and retrofit, (2) distributed soft infrastructure, (3) surface and groundwater interactions, (4) treatment and management technologies, (5) public preference, and (6) policy and governance.
• NZUW has similarities with Integrated Urban Water Management, Water Sensitive Urban Design, and One Water concepts. The key differentiation between NZUW and these previous integrated urban water concepts is its overarching goals. While Integrated Urban Water Management emphasizes cost-effective infrastructure planning, NZUW expands the goal to achieving self-sufficiency. NZUW goes beyond One Water by providing a quantitative framework to assess the tradeoffs between multiple adaptation options.
• Overall, the resulting quantitative framework is a tool for making comprehensive decisions across multiple systems with various stakeholders to move our water systems towards NZUW. The system-wide framework represents the potential responses to acute shocks and chronic stressors, as well as the associated uncertainties, over a forecast time horizon. Using this information, the tradeoffs across the built, natural, and social systems can be evaluated for decision support. Example outcomes may include physical infrastructure retrofit, policy or governance changes, or inter-agency agreements for overall water management oversight.

Figure 1. NZUW is a progressive target across three scopes, including the potential for long-term net positive urban water outcomes.	Figure 2. The NZUW approach integrates complex interactions across three scopes and natural, built, and social systems.

The Full Article is Available Until February 17, 2021.