Green Infrastructure And Its Effects On Flood Mitigation In The Greater Tucson, Arizona Metro
Presenter: Kevin Dyer1
Co-Author(s): -
Advisor(s): Dr. Hoshin Gupta
1Department of Hydrology and Atmospheric Sciences, University of Arizona
Tucson, Arizona has long struggled with the effects of flooding during its annual monsoon season and winter rains. Tucson continues to grow outward and encroach on its surrounding desert in the Santa Cruz River Basin, which worsens flooding. This sprawl brings new impermeable land in the forms of new roads, buildings, and parking lots, etc. which contributes to further water runoff. To alleviate these issues local agencies and environmental NGOs have introduced green infrastructure (GI) to certain flood prone areas. Green infrastructure is an approach to water management that aims to restore and protect the natural water cycle through changes in land use. Here in Tucson, it often means planting trees, creating retention and detention basins, and generally removing impermeable surfaces whenever possible. The goal of this study was to determine the effectiveness of these green infrastructure projects in flood mitigation. Three watersheds across Tucson were examined for their flood response. Estimates for 10-, 25-, and 50-year storm rainfall totals were taken from the NOAA ATLAS 14 Point Precipitation Frequency Estimates for the centroid of each watershed tested. Importing this data as well as data provided by the Pima County Flood Control District onto QGIS, the FLO-2D plugin utilizes the Natural Resources Conservation Service (NRCS) Curve Number Method to estimate the amount of precipitation that becomes runoff and the amount that infiltrates the soil. Each of the three watersheds were run twice in each precipitation condition (10-, 25-, and 50- year storms). The first run was under existing conditions with green infrastructure in place, while the second run simulated the same area with the green infrastructure removed. Precipitation excess, the proxy used for flooding in this study, was compared across trials to determine the overall effectiveness of green infrastructure in mitigating floods across Tucson, AZ.