Cities explore the future of urban stormwater

Hurricane Harvey brought more than fifty inches of rain that submerged thirty percent of Harris County, Texas. A storm of this caliber would have devastating impacts on any city, however, Houston’s aging infrastructure and expansive areas of impermeable pavement left it uniquely exposed. The city of Houston is situated only fifty feet above sea level on old swampland, forty miles from the coast.

The city’s stormwater drainage system is composed primarily of a series of natural bayous (slow moving rivers) and man-made channels that divert runoff out of the city and into the Galveston Bay. Many of the city’s bayous are inadequate to handle normal rainfall, much less a major hurricane. “The main bayou through downtown, Buffalo Bayou, is pretty much still a dirt mud channel like you would have seen 100 years ago,” says U.S. Geological Survey hydrologist Jeff East.

Additionally, Houston’s lack of zoning regulations further exacerbated the cities flood vulnerability. Houston, a rapidly growing city of nearly 2.4 million residents, does not require builders to use flood mitigation techniques such as permeable pavement and green areas to better absorb rainwater, or retention ponds for runoff. As a result, the city has expansive areas or pavement and impervious surfaces “that make it extremely difficult for the water to drain into the soil. Instead, it runs into the bayous and, in this case, into people’s homes,” says Sam Brody, a professor at Texas A&M, Galveston.

In response to the changing weather patterns across the country, cities such as Chicago have turned to green infrastructure as a way to work alongside the traditional infrastructure to more effectively manage stormwater under these conditions.

Need for a New System

Chicago has the largest wastewater capture quarry, water treatment facility, and water treatment plant in the world. However, Chicago still continues to experience significant flooding from stormwater runoff. In the past five years, there have been approximately 181,000 claims totaling over $753 million in flood-related property damage.

Brenna Berman, Chicago’s chief information officer, says that the city is, “still getting the same amount of rain annually that we got [in the past] but it’s coming at a different rate than it once did. However, we’re getting rain more quickly, rain for a shorter period of time, most likely due to global warming.” Therefore, the same solution does not work the same in every location.

A Greener Solution?

In response, Chicago has been installing green infrastructure to hold and treat stormwater. Currently, Chicago is in the midst of a five-year, $50-million plan towards creating ten million gallons of stormwater storage in hopes of reducing stormwater runoff by up to 250 million gallons per year. Permeable pavement has been installed in bike lanes and alleys, which allows for water to be soaked into the ground rather than flowing into the sewer system. Additionally, there are bioswales, tree pits, and infiltration planters, which are areas of vegetation and soil collecting and filtering stormwater that prevent flooding and allow cleaner water to enter the sewer system. Although there are a number of green infrastructure solutions available, there is not much data available regarding which types work best and how well they are working. That’s where City Digital comes in.

City Digital, a partnership of companies based at University of Illinois’ UI LABS, heads the pilot project which combines sensors and cloud computing as an innovative solution to stormwater runoff. The project aims to develop the next generation of sensing and monitoring tools for green stormwater infrastructure. The partnership is comprised of large, multinational companies including Microsoft, ComEd, Siemens, Accenture, Tyco, and HBK Engineering, as well as academic institutions such as the University of Illinois, Illinois Institute of Technology, Northwestern University, and Argonne National Laboratory.

These companies, universities, and the City of Chicago are collaborating together to identify and solve large-scale infrastructure challenges in order to develop solutions that can be broadly commercialized.

How it Works

Beginning in August of 2016, City Digital has been installing low cost sensors and innovative software tools throughout the city in order to monitor and evaluate the city’s current green infrastructure.

The ultimate goal of this smart green infrastructure monitoring is to create a system of sensors that combines weather information with surface and groundwater monitoring to evaluate the amount of water present, whether or not it is entering the green infrastructure, and what the water undergoes once it enters the infrastructure. Additionally, the system will measure the pH levels and the temperature of the water. Above the ground, the sensors work to monitor the weather conditions, such as precipitation amounts and air pressure levels. Below ground, the sensors monitor soil moisture, chemical absorption rates, and water quality to determine if the infrastructure is managing the water as intended.

The data collected by the sensors is then communicated via cellular network into an analytics platform. There, the effectiveness of the various green-infrastructures can be monitored in real time. As of this past spring, there are six sites throughout Chicago that are transmitting more than 20,000 streams of real time data that translate into site specific recommendations for green infrastructure being built in the future.

Ultimately, the purpose is not only to determine if the green-infrastructure is working, but where and when certain types of green infrastructure are most effective. Specifically, whether the green infrastructure is preventing rainwater from entering the sewer system and what green designs work best for different types of rain and lengths of the storm.

Supporters of the pilot project urge that smart green infrastructure monitoring can be a low-cost alternative to traditional monitoring. Joshua Peschel, one of the key players of the Chicago pilot project says, “the traditional way of monitoring stormwater infrastructure, if done at all, is with expensive measurements that are often very sparse in space and time. This project seeks to fill the data gaps by adding unique measurement techniques and intelligence to these new green streets in Chicago.”

By providing innovative, low cost monitoring for green infrastructure, the pilot project is changing the way not only Chicago, but cities all over the world address stormwater issues. The pilot project is designed to create a pathway to commercialization so that successful pilots can easily and directly be extended throughout other areas of Chicago and even further to other cities both nationally and globally.

A Nationwide Concern

Pollution generated by urban stormwater runoff is not limited to Chicago. According to Larry Levine, a senior attorney in the Natural Resource Defense Council’s water program, “Stormwater runoff is one of the largest water pollution issues facing the U.S. today.” While Chicago’s stormwater project stemmed from concerns regarding flooding, other cities across the country are turning to green infrastructure to solve serious pollution issues that are destroying important natural waterways.

In Seattle, Washington the Green Duwamish River faces many threats to its health and sustainability due to pollution from stormwater runoff. In the Puget Sound region bordering the river, like many other regions in the U.S., was largely developed without stormwater controls due to lack of information and understanding of the harmful effects of polluted runoff. As a result, polluted runoff threatens the salmon, economy, and health of the communities that depend on the viability of the Green Duwamish River. Specifically, uncontrolled stormwater runoff from surrounding developed lands can cause flooding, erosion, and toxic contamination. In response, King County, who manages the area, is aiming to implement a similar green infrastructure to Chicago’s stormwater pilot project.

Other cities across the country such as Philadelphia, New York, and Portland have also been implementing stormwater projects over the past few years with federal funding. Further, Levine notes that these stormwater runoff control projects address the key issue of nonpoint source pollution (“NPS”) in the Clean Water Act. While it is relatively straightforward to regulate point source polluters such as a manufacturer releasing chemicals into a river, it is increasingly difficult and costly to regulate NPS because it comes from many diffuse sources.

States report that NPS is the most significant single source of water pollution in the country. However, with rise of green infrastructure and stormwater control programs across the country, a much-needed remedy to NPS could be on the horizon.


Although the likelihood of a storm like Hurricane Harvey hitting Houston again is slim, what will continue to plague and pose the most severe threat to the area is stormwater. Without a change in infrastructure, as seen in the Chicago Pilot, the city will continue to face devastating impacts from average rainwater runoff.

Alicia Garcia

Image: A “green rooftop” – An example of green infrastructure that can help naturally divert, collect, and filter stormwater. Pixabay user StockSnap, Creative Commons. Chicago Storm Water Pilot Project


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