Watershed Surface Characteristics and Storm Distribution Impactson Low-order Urban Stream Hydrology Response

This research observed and modeled rainfall-runoff processes for six ungauged low-order urban watersheds within the Louisville Metro area, KY for a variety of storm distributions. We collected rainfall/runoff event field data while surface biophysical data in the form of gridded elevation, landcover and soil type were also collected and processed for each watershed. These datasets enabled an adjustment of Green-Ampt infiltration loss and NRCS unit-hydrograph transform method time parameters to simulate runoff using the HEC-HMS rainfall-runoff model. Results indicated that impervious cover and watershed shape/hydraulic length most strongly influenced hydrograph responses, while positive-skew storm distributions resulted in higher peak runoff output. Modeling output suggested that while some calibration was required as a function of surface characteristics, the methods employed may allow other ungauged low-order watersheds to be modeled and assessed in terms of hydrologic response to various storm scenarios.