Designing Resilient Networks in the Water Sector in an Uncertain Climate

Disaster resilience has been defined as “the ability to plan and prepare for, absorb, recover from, and more successfully adapt to disruptive events” (NRC, 2012). Critical infrastructures are the backbone of modern, interconnected economies. The disruption of key systems and essential services - such as telecommunications, energy or water supply, transportation or finance - can cause substantial economic, social and environmental damage. Emerging and systemic threats intensify the challenge of making a compelling case for water sector infrastructure financing that addressing complex risks-witness the unanticipated release of toxics during the Hurricane Harvey in Houston, and loss of communication and relief networks after Hurricane Maria in Puerto Rico. Lack of reliable and sustainable access to safe drinking water and sanitation persists as a global challenge, as do challenges of water quantity and quality for agriculture and ecosystems, and closely-related issues of water resource management investment. Understanding the degree, form, and severity of climate risks facing water management and planning is necessary to achieve sustainable resource management and development goals for energy, food production, sanitation and supply, and ecosystems. Traditional risk management methods center upon the abilities to prevent, absorb the impact of, and/or withstand threats usually characterized as discrete events. Unfortunately, this approach can give rise to new vulnerabilities, as systems become more exposed and sensitive, and with less capacity to adapt to unexpected events. Additionally, infrastructure improvement effort needs to explicitly address the potential for creating new vulnerabilities.

Resilience is an objective related to how systems perform under stress encompassing the ability of a disaster-impacted locale to recover quickly. In climate of changing extremes two major challenges persist:

• little understanding of critical infrastructure dependencies and the potential for cascading impacts associated with system disruptions, and
• building standards have not yet evolved to include designs, tools and practices and capable of enhancing the resilience of interdependent systems

Expeditiousness of system functionality recovery is crucial to avoiding the costs associated with delays, temporary services, and secondary losses. The close interconnectedness of water systems with other critical infrastructure such as energy, point to substantial potential for cascading failures and compounding losses if thresholds are crossed, disruptions occur. Time horizons, temporal and spatial uncertainty, externalities and policy misalignments all confound implementation of resilient designs even in the face of clear long-term economic benefits. Tools and methods to conduct resilience assessment under a changing climate are emerging, such as tiered approaches to layering resilience strategies and UNESCO/USACE Climate Risk–Informed Decision Analysis (CRIDA). These tools and approaches are intended to facilitate institutional climate adaptation mainstreaming by supplementing the standard engineering design cycle, however barriers to impactful and innovative financing that address efficiency vs buffers still exist. Much work remains on how to consider risk and resilience in tandem and trade-offs in order to identify optimal allocations of resources. Planning and preparing for recovery of water system functions can mitigate the risk of secondary losses. In the context of water sector financing, buying down risk has diminishing returns and resources for improvement are limited. Given the realities described above about systemic threats and emerging risk, it is important to recognize the limitations of traditional risk management and reliability planning. While some of these risks can be managed, i.e., the probability and consequence of their occurrence can be characterized to provide clear signals about how to reduce them, others will remain uncertain. To realize the aspirations for resilience, there is much work that needs to be done to create a knowledge-base of how to assess and enhance the resilience of built systems and to explore pragmatic mechanisms to compel its creation. We will evaluate the barriers and case for resilient vs risk-based approaches and draw lessons to provide a business case for investment in resilience in the water sector. The paper will further outline the challenges and benefits of resilience-based planning for critical infrastructure, and approaches to measuring resilience in complex water systems and the networks that support them.