HR: 0800h
AN: H11F-0356    [Abstracts]
TI: Effects of initialization conditions in distributed hydrological response: spatio-temporal dependencies on rainfall forcing, watershed topography and soils.
AU: * Noto, L V
EM: valerio@idra.unipa.it
AF: Dipartimento di Ingegneria Idraulica ed Applicazioni Ambientali, Universita' di Palermo, Viale delle Scienze, Palermo, 90128 Italy
AU: Ivanov, V Y
EM: viva@mit.edu
AF: Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139 United States
AU: Bras, R L
EM: rlbras@mit.edu
AF: Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139 United States
AB: Numerical experiments with hydrological models show that the initial conditions are important in modeling the rainfall-runoff response at the event scale. However, it is still largely unknown how the influence of initialization states is related to land-surface characteristics such as catchment topography and soils. Similarly, different rainfall forcings may lead a variety of dependencies of the hydrologic response on antecedent wetness conditions. We investigate the influence of the initial states on the short-term hydrologic estimation to characterize the integral effects of topography and soils across a range of precipitation rates using a physically-based, distributed-parameter hydrological model tRIBS (TIN-based Real-time Integrated Basin Simulator). The tRIBS model accounts for the processes of rainfall interception and evapotranspiration with the continuous soil moisture accounting, lateral moisture transfer in the unsaturated and saturated zones, and runoff routing. In the discussed study, we assume that the groundwater significantly controls the initial conditions of the basin and, therefore, that the mean water table depth is the primary initialization variable. Initialization of the soil moisture distribution in the unsaturated zone is thus assumed to be uniquely related to the water table position. Two case studies have been developed. The first one considers a synthetic 2-D planar hillslope for which the effects of different initializations are studied for various slope magnitudes and soil types subject to different rainfall rates and durations. The second one is based on the real basin, Baron Fork (OK), for which the topography and soil/landuse types are fixed while different initial water table positions and synthetic rainfall events are used. The study focuses on the analysis of dynamic and time-integrated links between the catchment land-surface descriptors and a number of key hydrologic variables controlling the basin response. A variety of spatially-lumped, e.g. runoff types comprising the outlet streamflow, and spatially distributed variables, e.g. the root zone soil moisture, are used to examine the transition of the dominant response mechanisms, the basin areas of higher sensitivity, and the contributing factors to the dissipation of the initialization effects. The discussed cases demonstrate the interplay between different hydrological processes leading to a complex structure of effects that initialization states impose on the basin response.
DE: 1821 Floods
DE: 1860 Runoff and streamflow
DE: 1866 Soil moisture
DE: 1878 Water/energy interactions
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting