Urban Infrastructure and Water Management: What the USGS Studies

Managing the urban water cycle is a growing challenge for planners and regulators who must supply cities with clean drinking water. Sanitary sewers, and combined sanitary and storm sewers, carry wastewater to central treatment plants. Roads, parking lots and buildings speed stormwater into nearby streams, raising the risk of urban flooding and of damage to natural ecosystems, and these pressures will grow as cities expand and climate change is likely to shift rainfall patterns. Understanding the urban water cycle is key to managing water well and protecting people, infrastructure and urban streams, and the U.S. Geological Survey has the expertise to monitor, model and interpret it.

The Urban Landscapes Capability Team

The USGS has studied how urbanisation affects groundwater, surface-water quality, ecosystems and geologic resources across the country for more than a century. The Northeast Region's Urban Landscapes Capability Team shares that expertise at local, regional and national scales:

• continuous water-quality monitoring, to track trends and catch problems before a whole supply system is affected;
• groundwater monitoring and modelling in many kinds of aquifer, to assess pumping for public supply and dewatering of infrastructure (pumping groundwater to keep subways from flooding, for example);
• studying how groundwater and surface water respond to changes in water management;
• advanced geophysical equipment to assess damaged underground supply lines such as aqueducts, the potential for geothermal energy, and the capacity to store and recover grey water, and to guide new supply and wastewater lines in crowded areas;
• measuring water quality and quantity to judge how well stormwater control measures (SCMs), green infrastructure among them, work.

Water supply

Monitoring water quality and quantity is essential to safe, reliable drinking water. Contaminants such as sediment, nutrients, metals and chloride can compromise supplies and call for costly treatment. USGS scientists often work with water suppliers and towns to evaluate the whole supply system: not only the water, but the infrastructure that holds and carries it.

Wastewater

Without proper treatment, contaminants such as nutrients, organic and inorganic compounds, pharmaceuticals and personal care products, and pathogens can reach receiving waters, lowering water quality, causing mutations in aquatic life, and closing beaches. The effects of damaged or underperforming treatment plants, combined sewer overflows, and leaking or misconnected pipes are hard to pin down without a well-designed monitoring programme. With influent and effluent monitoring and contaminant-source tracking, the USGS supplies near real-time data that help managers judge how well treatment works and find infrastructure problems with sewer authorities.

Automated sampling of water entering and leaving a wastewater treatment plant, part of a regional water-quality assessment. Photographs by Tia-Marie Scott, USGS.

Stormwater

• Grey infrastructure, traditional engineering, moves storm runoff quickly from developed land to streams or estuaries.
• Green infrastructure, such as rain gardens and bioswales, reduces runoff and helps restore the natural water cycle by letting more water soak in and evaporate.

Both protect cities from flood damage and can, in some cases, reduce the contaminants in runoff. The USGS combines proven field methods with new technology to measure how well SCMs work at every scale, from the water and contaminant balance of a single rain garden to the combined effect of many measures across an urban catchment, helping managers meet local and state targets for reducing contaminants. Hydrologic and contaminant-loading models then extend what is learned in the field across the wider city: a calibrated model, for example, is predicting how much street cleaning could cut the sediment washed into nearby waters.

The Depth Integrated Sample Arm (DISA), centre, is new USGS technology for measuring sediment concentrations and loads truly. It suits "flashy" systems where sediment varies with flow and depth, such as storm sewers and tunnels (right) or streams that run only part of the time (left), and avoids the over-collection of settled sediment by a fixed-point intake, seen in the hydrograph and sample jars above. Photographs by William Selbig, USGS.

Examples of USGS urban infrastructure studies

• Urban watersheds in Maryland: discharge stations in several urban watersheds track effects on the urban water cycle and nutrient export.
• Resilience of critical infrastructure to flooding: where investments in green infrastructure could make the Baltimore region more resilient to stronger coastal storms, rising sea level and flooding.
• Rockland County, New York: an assessment of public water supplies, monitoring surface reservoirs, fractured bedrock and glacial aquifers along with sewer outfalls, to compare supply and treatment with likely demand.
• Southeast Expressway, Boston: how well three best management practices reduced suspended sediment and related constituents in highway runoff.

Working with the USGS

The team is committed to expanding studies of the infrastructure that carries drinking water, wastewater and stormwater, working with local, state, federal and Tribal agencies, nonprofits, universities and watershed groups. Jointly funded work is possible through the Cooperative Water Program.

Sources

• Shawn C. Fisher, Rosemary M. Fanelli and William R. Selbig, Urban Infrastructure and Water Management—Science Capabilities of the U.S. Geological Survey, USGS Fact Sheet 2016–3025, April 2016. https://doi.org/10.3133/fs20163025
• The photographs and figure are taken from the fact sheet's PDF. Its banner photograph (Creative Commons) and a photograph by the Bronx Council for Environmental Quality are not reproduced here.