Collaborative Research: The Hydrology, Hydraulics and Hydrometorology of Flood Response in Urbanizing Drainage Basins

Princeton University, Princeton NJ

Investigators

Abstract

0208225 Smith The integrated hydrologic, hydraulic and hydrometeorological process that controls flooding in urbanizing drainage basins will be examined through analyses of flood response in the Baltimore metropolitan region. The science questions are: (1) How does the scale-dependent flood response of urban drainage basins depend on the space-time structure of rainfall for warm season systems of thunderstorms? (2) How does flood response vary with land-surface properties including impervious cover and structure of the urban drainage network? And (3) What is the relative role of changing channel/floodplain morphology due to urbanization, as compared with geologic controls of channel floodplain morphology, in determining the attenuation of flood waves? Questions 1 and 2 will be examined through hydrologic and hydrometeorological analyses of flood events in 24 drainage basins smaller than 200 km2 for 25-30 flood events during the period 1996-2003. Diagnostic analyses of rainfall and discharge observations for the flood events will be used in conjunction with model analyses to address questions 1 and 2. Hydrologic model analyses will be based on a distributed hydrologic model, the Network Model. Hydraulic analyses of flood wave propagation will be carried out for a subset of the 24 basins and will include 4 stream reaches, each with upstream-downstream pairs of stream gaging stations. The 2-d depth-averaged hydraulic model, TELEMAC, will be used for assessing hydraulic controls of flood response in urbanizing stream channels. The key observations used in this study are: (1) high-resolution (1 km, 5 minutes) radar rainfall estimates, (2) high-resolution (0.6 m contour interval) topographic data sets, (3) high-resolution (0.6 m grid, 0.15 m vertical resolution) topographic data sets derived from airborne radar, (4) high-resolution (1 m) representations of impervious cover, and (5) field-surveyed channel cross sections, longitudinal profiles and pebble counts.