Cole Jermyn

Date of Award


Document Type



Environmental Resources Engineering

Thesis Advisor

Charles Kroll

Thesis Advisor

Stephen Shaw


NEXRAD, precipitation


This study examines precipitation and streamflow patterns in watersheds in the Bronx, New York and Baltimore, Maryland to analyze runoff ratios, the ratio of runoff to precipitation, across varying levels of urbanization. i-Tree Hydro was also utilized to assess its effectiveness at modeling urban hydrology. NEXRAD precipitation data and USGS streamflow measurements were used to calculate monthly average runoff ratios for five watersheds of varying land cover characteristics. This data, supplemented by weather station data from BWI Airport, was also used to run the i-Tree Hydro model. Streamflow predictions from this model were used to calculate average monthly runoff ratios for comparison to the above estimates. Both the watershed-specific NEXRAD precipitation data and the BWI Airport precipitation data were used to calculate runoff ratios and run i-Tree Hydro. With both datasets, differences were shown between the runoff ratios of the watersheds with the greatest and least percentages of tree cover during summer months, indicating the importance of tree cover as a valuable resource for reducing runoff during high warmer months when evapotranspiration is high. This could be particularly valuable in cities susceptible to heavy precipitation in the summer months, such as Baltimore. At these sites, the i-Tree Hydro model was shown to take into account land cover, while underestimating the effect of seasonal changes on ET and subsequent runoff ratios.