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www.hydrol-earth-syst-sci-discuss.net/4/983/2007/
doi:10.5194/hessd-4-983-2007
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under a Creative Commons License.
Controls on runoff generation and scale-dependence in a distributed hydrologic model
1Department of Earth and Environmental Science, New Mexico Institute of Mining and Technology, Socorro, NM 87801, USA
2Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
3Center for the Environment, Harvard University, Cambridge, MA 02139, USA
Abstract. Hydrologic response in natural catchments is controlled by a set of complex interactions between storm properties, basin characteristics and antecedent wetness conditions. This study investigates the transient runoff response to spatially-uniform storms of varying properties using a distributed model of the coupled surface-subsurface system, which treats heterogeneities in topography, soils and vegetation. We demonstrate the control that the partitioning into multiple runoff mechanisms (infiltration-excess, saturation-excess, perched return flow and groundwater exfiltration) has on nonlinearities in the rainfall-runoff transformation and its scale-dependence. Antecedent wetness imposed through a distributed water table position is varied to illustrate its effect on runoff generation. Results indicate that transitions observed in basin flood response (magnitude, timing and volume) can be explained by shifts in the surface-subsurface partitioning. An analysis of the spatial organization of runoff production also shows that multiple mechanisms have specific catchment niches and can occur simultaneously in the basin. In addition, catchment scale plays an important role in the distribution of runoff production as basin characteristics (soils, vegetation, topography and initial wetness) are varied with basin area. For example, we illustrate how storm characteristics and antecedent wetness play a dramatic role in the scaling properties of the catchment runoff ratio.
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Notice on Discussion StatusCitation: Vivoni, E. R., Entekhabi, D., Bras, R. L., and Ivanov, V. Y.: Controls on runoff generation and scale-dependence in a distributed hydrologic model, Hydrol. Earth Syst. Sci. Discuss., 4, 983-1029, doi:10.5194/hessd-4-983-2007, 2007. Bibtex EndNote Reference Manager XML
