GEOMORPHOLOGICAL TRANSFER FUNCTION CALCULATED FROM DIGITAL ELEVATION MODELS FOR DISTRIBUTED HYDROLOGICAL MODELLING
✍ Scribed by ROGER MOUSSA
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 351 KB
- Volume
- 11
- Category
- Article
- ISSN
- 0885-6087
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✦ Synopsis
Recently, several attempts have been made to relate the hydrological response of a catchment to its morphological and topographical features using dierent hypotheses to model the eect of the drainage network. Several transfer functions were developed and some of these are based on the theory of a linear model, the geomorphological unit hydrograph. The aim of this paper is to present a methodology to automatically identify the transfer function, using digital elevation models for applications in distributed hydrological modelling. The transfer function proposed herein is based on the Hayami approximation solution of the diusive wave equation especially adapted for the routing hydrograph through a channel network. The Gardon d'Anduze basin, southern France, was retained for applications. Digital elevation models were used to extract the channel network and divide the basin into subcatchments. Each subcatchment produces, at its own outlet, an impulse response which is routed to the outlet of the whole catchment using the diusive wave model described by two parameters: celerity and diusivity functions of geometrical characteristics of the channel network. Firstly, a geomorphological unit hydrograph obtained by routing a homogeneous eective rainfall was compared with the unit hydrograph identi®ed by a lumped model scheme, then the distributed model was applied to take into account the spatial variability of eective rainfall in the catchment. Results show that this new method seems to be adapted for distributed hydrological modelling; it enables identi®cation of a transfer function response for each hydrological unit, here subcatchments, and then simulation of the contribution of each unit to the hydrograph at the outlet.