| This dissertation covers two interrelated topics, flood hydrology and precipitation climatology. The first portion of this dissertation examines the hydrology of extreme floods in two distinct settings: agricultural watersheds of the Great Plains of eastern Nebraska and urbanizing watersheds in the Milwaukee, Wisconsin metropolitan region. In each setting, empirical analyses of extreme flood response are carried out based on high-resolution (1 km, 5 minutes) rainfall fields derived from WSR-88D (Weather Surveillance Radar - 1988 Doppler) radar reflectivity observations and high time resolution (15–60 minutes) USGS (United States Geological Survey) discharge observations. High-resolution rainfall observations are used to characterize the space-time variability of flood-producing rainfall in terms of storm structure, storm motion and magnitude of rainfall rates. Hydrologic analyses examine the controls of runoff production and the role of drainage network structure for extreme flood response. The organization of warm season convective systems is shown to play an important role in the scale-dependent flood response of both agricultural and urbanizing watersheds.; The second portion of the dissertation concerns the climatology of warm season precipitation in the United States east of the Rocky Mountains. Analyses are based on a national composite reflectivity dataset derived from the observations from the WSR-88D radar network in United States, covering the 5-year period from 1996 through 2000. Analyses center on characterization of spatial and temporal heterogeneities of warm season precipitation. The focus of these analyses is the geographic, seasonal, diurnal and interannual variations of warm season rainfall and their relationship to land-ocean boundaries and topographic variation. The results of the analyses are generally consistent with past studies, but provide additional insights to terrain controls of rainfall heterogeneities and to the diurnal cycle of warm season rainfall. |
