A colorful illustration of people walking on and alongside a path through green grass and giant flowers. The people are wearing gas masks.

Human Behavior, Climate Risk and the Food-Water-Energy Nexus

Y.C. Ethan Yang works with a team of researchers incorporating data on human behavior into a climate-risk modeling framework to improve resilience of critical water, food and energy systems.

Story by

Lori Friedman

Photography by

Illustration by Masha Krasnova-Shabaeva

Can human beings and the natural environment find a way to coexist?  Deteriorating U.S. infrastructure coupled with extreme weather events―and other effects of climate change―have heightened the stakes involved in achieving such harmony. While technological advances may help mitigate negative impacts, peaceful coexistence may depend on what actions humans are willing to take.

That’s why Y.C. Ethan Yang, a civil and environmental engineer working on issues at the food-water-energy nexus, incorporates data on human behavior into the computer modeling he uses to help improve the resilience of our life-sustaining systems.  Such data, however, can be hard to come by.

“We can measure the rainfall, we can measure the temperature, etcetera―but the human behavior data is really, really difficult to get,” says Yang. “I actually work with a lot of social scientists as well as psychologists to try to figure out the best way to incorporate their data into our models in order to simulate human behavior better.”

Almost all of our systems are interdependent, explains Yang, citing the interdependency of the water and energy sectors as an example.

“When we generate power, no matter the source, we need water for cooling purposes,” he explains. “So, the energy sector depends on the water sector in order to function. We also need energy to treat our raw waters for drinking purposes, and to send treated water from the treatment plant to homes and businesses. So, the water sector depends on the energy sector too.”

An adverse event in one system, explains Yang, can cause “a cascade event.”

Houston, We Have a Problem

The February 2021 power crisis in Texas offers a case in point. Unexpected low temperatures caused by a series of severe winter storms produced a massive electricity generation failure. This, in turn, led to shortages of water, food and heat. Regions unaccustomed to extreme heat, like states and cities in the Northeast, are also subject to the possibility of multi-system breakdowns.

We actually use the models to simulate this: What’s the risk that we might face, especially under the climate change impact conditions?” says Yang. “And then we try to identify what kinds of policies can be implemented or actions taken to mitigate this kind of cascade effect.”

Yang and his group are working with Houston Advanced Research Center (HARC) and the University of Houston on a project designed to increase the resilience of the Houston area’s energy systems. The team is developing a modeling framework that advances systems-level understanding of the impacts of climate change on electrical power infrastructure with support from an Alfred P. Sloan Foundation research grant.

Illustration of green growht on a modern building surrounded by water and dirt, with people wandering around it

Called the Pythias framework, the model will analyze the impact of climate risks such as extreme weather events, accelerating temperatures and water scarcity on power systems. Pythias will integrate that information with complex physical and socioeconomic models, and a state-of-the-art decision-making model to arrive at a novel approach to power system planning and management. The goal is to address how climate change will affect the long-term planning and management of power systems and needed steps to mitigate climate-related risks.

Yang will bring his expertise in agent-based modeling and will lead that part of the effort. An agent-based model simulates the actions and interactions of autonomous agents―individuals or groups of individuals―in order to understand the behavior of a system and what governs its outcomes. The HARC-led project will try to understand the ability of individual actors within the system to adapt to external conditions and make internal changes to the system to cope with potential hazards or respond to their consequences.  The “agents,” in this case, are the power-generation companies.

As more extreme weather events are anticipated, municipalities are trying to “expect the unexpected” and plan now for better resilience and reliability under changing conditions.

Urban Flooding: Too Much Water All at Once

While the Houston project is largely focused on improving the resilience of energy systems, most of Yang’s work is focused on water.

One such project, funded by an NSF CAREER Award, is in its first of five years and focuses on addressing challenges closer to home. Yang and his team are working with Bethlehem Township, Pa., the most flood-prone municipality in the Lehigh Valley region, on a framework to help mitigate urban flooding. This work could become a model for other municipalities in the region and across the country.

According to a recent report by the Center for Disaster Resilience at the University of Maryland, flooding caused by excessive stormwater runoff in developed areas where the water doesn’t have anywhere to go is widespread and costly―and, perhaps, an even greater challenge than extreme flooding events.

“The reason we have these stormwater flooding issues is not because we don’t have drainage systems―we do,” says Yang. “The problem is that too much water is coming down at the same time and our system cannot handle it. So, the solution is actually to try to delay that timing a little bit to avoid flooding."

Bethlehem Township’s government is looking to do just that. Part of that effort is a program that encourages homeowners to implement low-tech, low-cost measures such as rain barrels, which capture rainwater from a homeowner’s roof to be used later, and rain gardens, which are collections of shrubs, perennials, and flowers planted on a natural slope that  temporarily hold and soak in rainwater runoff.  While the township looks to implement a stormwater fee to residents and issue credits to those who undertake mitigation efforts, Yang and his team will survey and interview local residents to assess their willingness to participate in such a program in exchange for reduced stormwater fees. 

Yang will again use an agent-based modeling approach to simulate both the natural process of how rainfall generates runoff and the location of potential flood zones within the township, as well as property owners' behavior, in order to design a flood mitigation program that works.

“Sometimes the models show good results, but the most challenging part is convincing people to take action,” says Yang.

Building a “Smart,” Resilient Campus

A group of Lehigh undergraduate students is working with Ethan Yang on a stormwater mitigation project designed to help the campus achieve one of the goals outlined in Lehigh’s Sustainability Strategic Plan 2030: develop a Stormwater Management Plan (SMP) by the end of 2021 that identifies green infrastructure and low-impact development (LID) projects, and provides guidelines for the design team to help mitigate stormwater runoff impacts and treat rainwater as a resource rather than as a waste product. 

The students and Yang will work toward upgrading the existing green infrastructure on campus, such as several water retention basins designed to collect rainwater and delay its release into the city’s drainage system. Their first project aims to achieve a better understanding of the effectiveness of the water retention basin on Lehigh’s Goodman campus. Step one is to install several “smart” sensors at the facility in order to obtain real-time measurements. This will have the additional benefit of testing the custom sensors that Yang and the students are building.

Our idea is: So, we have these basins, but we don’t really know how they function, how much water they collect, how long they can delay the stormwater drainage and how much water we should be releasing for maximum impact,” says Yang. “We won’t know these details unless we install our sensors up there to do the measuring.”

Some of the students will be working on the project as part of the Campus Sustainable Impact Fellowship, a partnership between the Office of Creative Inquiry and the Office of Sustainability to provide students with hands-on experiential learning through campus sustainability projects. Part of the 2030 strategic plan is to utilize the campus as a living laboratory to advance campus sustainability.

Sustainability is at the heart of Yang’s efforts, and the frameworks he builds are designed to provide the information that institutions and governments need to determine how best to upgrade existing facilities to improve their resilience.

Adds Yang: “Our team wants to ask them: Are you thinking about upgrading the facilities that you have now in order to improve their resiliency and reliability? Maybe an event won’t happen for the next 20 or 50 years, but it’s a risk management issue. Are you willing to invest in something now to prevent future problems?”

Story by

Lori Friedman

Photography by

Illustration by Masha Krasnova-Shabaeva

Related Stories

Alan W. Pense

Remembering Alan W. Pense, Former Lehigh Provost and Vice President of Academic Affairs

Pense, who rose through the ranks from professor to provost, was a renowned figure in the world of metallurgy research and education.

Keith Moored examine bio-inspired robots

Lehigh-led Interdisciplinary Research Team Wins Prestigious $7.5M DOD Award

Keith Moored, associate professor of mechanical engineering and mechanics, will lead the team in conducting research to develop fast and efficient schools of bio-inspired underwater vehicles.

University Center in spring

Lehigh Achieves Gold Rating in 2022 STARS Report for Second Straight Year

In the report's operations category, Lehigh scored 66% higher than the average of reporting peer institutions.