Abstract
Abstract. In active tectonic regions with large-magnitude storms, it is still difficult to predict stormflow responses by distributed runoff models from the catchment properties without a parameter calibration using observational data. This paper represents an attempt to address the problem. A review of observational studies showed that the stormflow generation mechanism was heterogeneous and complex, but stormflow responses there were simply simulated by a single tank with a drainage hole when the stormflow-contribution area was spatially invariable due to the sufficient amount of rainfall supply. These results suggested such a quick inflow/outflow waveform transmission was derived from the creation of a hydraulic continuum under a quasi-steady state. General conditions necessary for the continuum creation were theoretically examined by a sensitivity analysis for a sloping soil layer. A new similarity framework using the Richards equation was developed for specifying the sensitivities of waveform transmission to topographic and soil properties. The sensitivity analysis showed that saturation-excess overland flow was generally produced from a soil layer without any macropore effect, whereas the transmission was derived mainly from the vertical unsaturated flow instead of the downslope flow in a soil layer with a large drainage capacity originated from the macropore effect. Both were possible for the quick transmission, but a discussion on the soil-layer evolution process suggested that an inhibition of the overland flow due to a large drainage capacity played a key role, because a confinement of the water flow within the soil layer might be needed for the evolution against strong erosional forces in the geographical regions. The long history of its evolution may mediate a relationship between simple stormflow responses and complex catchment properties. As a result, an insight into this evolution process and an inductive evaluation of the dependences on catchment properties by comparative hydrology are highly encouraged to predict stormflow responses by distributed runoff models.
Highlights
The prediction of runoff response to rainfall is a basic hydrological aim
Many distributed runoff models have been developed, but it is still difficult to predict stormflow responses in catchments with no observational data used for the parameter calibration and to predict responses to storms of larger magnitude than have ever been observed even in catchments with observational data
This idea was originally based on individual observational results on stormflow responses and their mechanisms, and the review suggested that HC under QSS played a key role in the production of these responses
Summary
The prediction of runoff response to rainfall is a basic hydrological aim. It is still difficult to estimate hydrographs in response to hyetographs without a parameter calibration using previous observational data (Sivapalan et al, 2003). There are many reasons for this, but the most essential one is the difficulty in detecting the main properties of a catchment that control its runoff responses (Betson and Ardis, 1978). Most physically based distributed runoff models assume that the surface topography is the controlling factor Some hillslope observations, especially in active tectonic regions, do not indicate the dominant effects of topography. This incompatible observational result is attributable to the dominant function of underground pathways, including
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