Abstract
Hydrological predictions in ungauged basins (PUB) are highly uncertain. This is caused by
incomplete process understanding, heterogeneity of the land surface and subsurface, spatiotemporal variability in the driving forces, inadequate model structure and scaling issues. This paper discusses a theory for hillslope scale subsurface flow travel time distributions, and
presents ideas for an associated suite of models, that resolves this problem by combining new
insights into the driving hydrological mechanisms, the use of auxiliary data that is readily
available such as runoff chemistry and hillslope topography, with efficient mathematical tools
such as dimensional and similarity analysis. Our discussion starts from two basic observations:
1) hillslopes act as the main filter between rainfall and stream flow. The hydrological behavior
of hillslopes is to a large extent controlled by the form (geomorphology) and internal hydraulic
structure (soil properties) of these hillslopes. 2) current, fully distributed, physically based,
hydrological models are limited in their applicability because of inherent problems (mainly
parameter uncertainty and inadequate process representation) associated with such a model
setup. On the other hand, much auxiliary data such as stream chemistry, high-resolution
topography, and soil maps could provide useful insights into the dominant hydrological
processes, water and solute residence times, and spatial patterns of controlling parameters. This data, while readily available for many catchments, is currently not fully exploited within
hydrology. Our final goal is to construct a hydrological theory of travel time distributions that is
1) respecting the internal structure of landscapes, as observed, 2) has a simple model
structure to avoid the curse of dimensionality, 3) uses auxiliary information to constrain water
flow pathways and reduces the problem of parameter uncertainty, and 4) provides measures of
hydrological similarity that assists regionalization..
Original language | English |
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Title of host publication | VIIth IAHS Scientific Assembly, Foz do Iguaçu, Brazil, 3-9 April 2005 |
Place of Publication | Foz do Iguaçu, Brazil |
Pages | np |
Publication status | Published - 2005 |