The effects of different hillslope dynamics - controlled by lithology - on the hydrologic response of real catchments are addressed in this work. The analysis is based on the concept of kinematic dispersion (Saco and Kumar, 2004), whose role in enhancing or counteracting the geomorphological dispersion has been poorly understood. Some issues in particular have remained unexplored, including specifically (i) the role of both geomorphological and kinematic components in determining the total dispersion, also as function of basin scale, (ii) the fraction of dispersion introduced by the hillslope-channel lengths correlation and (iii) the effects of kinematic dispersion on the scaling properties of peak flows. The approach adopted is the link-based one given by the width function, which allows to identify the effective values of geomorphologic, hillslope-borne and channel-borne kinematic dispersion for real cases, taken within the major sub-basins of the Upper Tiber River (central Italy). Specific conditions determining whether different dispersion mechanisms reinforce or counteract are sought through theoretical developments and numerical investigations. We find the existence of a scaling behaviour for the geomorphological dispersion with drainage area. On the contrary, based on the analysis of effective lag times and travel time variances, kinematic dispersion doesn’t show a clear simple scaling, and this breaks the scaling behaviour of the total catchment dispersion. Implications for the scaling behaviour of peak discharges are also addressed. We find that different flow dynamics related to the hillslope component of transport breaks the scaling behaviour of the maxima of the width function with drainage area (Veitzer and Gupta, 2001) whose exponent is found in our study area to approach 0.5 with a very good determination coefficient. The peaks of the Instantaneous Unit Hydrographs plotted against the drainage area appear, on the contrary, more disperse. This hints that hillslope dynamics strongly affect the possibility of transferring information on the peak floods statistics from one basin to another, even for neighbouring catchments.
DI LAZZARO, M. (2009). Effects of the hillslope-born kinematic dispersion on the scaling of peak floods. In 2009 AGU Fall Meeting RESEARCH ABSTRACTS. WASHINGTON : American Geophysical Union.
Effects of the hillslope-born kinematic dispersion on the scaling of peak floods
DI LAZZARO, MICHELE
2009-01-01
Abstract
The effects of different hillslope dynamics - controlled by lithology - on the hydrologic response of real catchments are addressed in this work. The analysis is based on the concept of kinematic dispersion (Saco and Kumar, 2004), whose role in enhancing or counteracting the geomorphological dispersion has been poorly understood. Some issues in particular have remained unexplored, including specifically (i) the role of both geomorphological and kinematic components in determining the total dispersion, also as function of basin scale, (ii) the fraction of dispersion introduced by the hillslope-channel lengths correlation and (iii) the effects of kinematic dispersion on the scaling properties of peak flows. The approach adopted is the link-based one given by the width function, which allows to identify the effective values of geomorphologic, hillslope-borne and channel-borne kinematic dispersion for real cases, taken within the major sub-basins of the Upper Tiber River (central Italy). Specific conditions determining whether different dispersion mechanisms reinforce or counteract are sought through theoretical developments and numerical investigations. We find the existence of a scaling behaviour for the geomorphological dispersion with drainage area. On the contrary, based on the analysis of effective lag times and travel time variances, kinematic dispersion doesn’t show a clear simple scaling, and this breaks the scaling behaviour of the total catchment dispersion. Implications for the scaling behaviour of peak discharges are also addressed. We find that different flow dynamics related to the hillslope component of transport breaks the scaling behaviour of the maxima of the width function with drainage area (Veitzer and Gupta, 2001) whose exponent is found in our study area to approach 0.5 with a very good determination coefficient. The peaks of the Instantaneous Unit Hydrographs plotted against the drainage area appear, on the contrary, more disperse. This hints that hillslope dynamics strongly affect the possibility of transferring information on the peak floods statistics from one basin to another, even for neighbouring catchments.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
