Nutrient Monitoring: Monitoring and Predicting the Impacts of Trees on Urban Stormwater Reduction

Science Center Objects

The effects of tree removal on the urban hydrologic cycle in order to measure the impact that trees have on stormwater runoff detention volume are being studied in two medium-density residential catchments in Fond du Lac, WI. A paired catchment statistical design and analysis of high-frequency measurements of storm event hydrographs and other monitoring data are being used to quantify stormwater discharge, soil moisture, aboricultural water consumption, and groundwater, both before and after tree removal.

Monitoring station for Urban Stormwater

Photographed is an urban stormwater monitor. 

(Public domain.)

Since 2018, USGS scientists have establish a baseline water budget for two medium-density residential catchments by measuring the hydrologic response of each catchment before ash trees are removed. Scientists have measured over 75 stormwater runoff events characterizing rainfall-runoff relations of the paired catchments before tree removal. During the winter of 2019/2020, approximately 60 percent of ash trees lining the street in one catchment will be removed, while the second catchment will remain unchanged. Changes in hydrologic response would be attributed to the sudden absence of trees, mostly through the loss of interception capability due to the loss of leaves, trunks, and stumps.

This project was funded under the Nonpoint Source Pollution Impacts on Nearshore Health Focus Area of the Great Lakes Restoration Initiative to collect data that will help assess the urban component of nonpoint runoff and determine the reduced amount of untreated runoff from urban watersheds. A website was created to provide a background of the project and description of the objectives and methods: https://www.usgs.gov/centers/wisconsin-water- science-center/science/monitoring-and-predicting-impacts-trees-urban

Aerial view of basins and trees

This is an aerial view of basins and tree locations in an urban area. 

(Public domain.)

Partners

This project involves cooperation from the University of Wisconsin- Madison, University of Wisconsin – Stevens Point, City of Fond du Lac, U.S. Forest Service, and U.S. Environmental Protection Agency.