HR: 0800h
AN: H11F-0347    [Abstracts]
TI: On the effects of triangulated terrain resolution on distributed hydrologic model response
AU: * Vivoni, E R
EM: vivoni@nmt.edu
AF: Department of Earth and Environmental Science, New Mexico Institute of Mining and Technology, 801 Leroy Place, Socorro, NM 87801 United States
AU: Ivanov, V Y
EM: viva@mit.edu
AF: Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139 United States
AU: Bras, R L
EM: rlbras@mit.edu
AF: Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139 United States
AU: Entekhabi, D
EM: darae@mit.edu
AF: Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139 United States
AB: Distributed hydrologic models based on triangulated irregular networks (TIN) provide a means for computational efficiency in small to large-scale watershed modeling through an adaptive, multiple resolution representation of complex basin topography. Despite previous research with TIN-based hydrology models, the effect of triangulated terrain resolution on basin hydrologic response has received surprisingly little attention. Evaluating the impact of adaptive gridding on hydrologic response is important for determining the level of detail required in a terrain model. In this study, we address the spatial sensitivity of the TIN-based Real-time Integrated Basin Simulator (tRIBS) in order to assess the variability in the basin-averaged and distributed hydrologic response (water balance, runoff mechanisms, surface saturation, groundwater dynamics) with respect to changes in topographic resolution. Prior to hydrologic simulations, we describe the generation of TIN models that effectively capture topographic and hydrographic variability from grid digital elevation models. In addition, we discuss the sampling methods and performance metrics utilized in the spatial aggregation of triangulated terrain models. For a 64 km2 catchment in northeastern Oklahoma, we conduct a multiple resolution validation experiment by utilizing the tRIBS model over a wide range of spatial aggregation levels. Hydrologic performance is assessed as a function of the terrain resolution with the variability in basin response attributed to variations in the coupled surface-subsurface dynamics. In particular, resolving the near-stream, variable source area is found to be a key determinant of model behavior as it controls the dynamic saturation pattern and its effect on rainfall partitioning. A relationship between the hydrologic sensitivity to resolution and the spatial aggregation of terrain attributes is presented as an effective means for selecting the model resolution. Finally, the study highlights the important effects of terrain resolution on distributed hydrologic model response and provides insight into the multiple resolution calibration and validation of TIN-based hydrology models.
DE: 1818 Evapotranspiration
DE: 1821 Floods
DE: 1836 Hydrologic budget (1655)
DE: 1860 Runoff and streamflow
DE: 1866 Soil moisture
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting