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sur le développement des zones arides et semi-arides

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University of New South Wales (1994)

Rainfall runoff modelling in an arid zone small catchment

Telvari, Abdolrassoul

Titre : Rainfall runoff modelling in an arid zone small catchment

Auteur : Telvari, Abdolrassoul.

Université de soutenance : University of New South Wales

Grade : Doctor of Philosophy thesis 1994

The study is aimed at investigation and modelling of transmission losses throughout an arid zone catchment, and the inclusion of these losses in realistic modelling outflow from the catchment. This research is different to the many previous studies of transmission losses reviewed in the thesis, which have only considered these losses within individual channel reaches. In addition, small runoff plots were used to give direct estimates of rainfall excess hydrographs for inputs to each of the sub-areas of a runoff routing model, rather than the indirect estimates based on runoff from the catchment outlet that are usually necessary. Therefore the model then incorporates specific allowance for the channel transmission losses. Initial losses and the continuing loss rate were first derived for all runoff events in the runoff plots. The results were supported by field infiltration measurements. Based on the rainfall and runoff data collected from the 4 Km$\sp2$ catchment and from the three 25 m$\sp2$ runoff plots located within it, a regression equation was developed for estimating transmission losses. The maximum potential loss was evaluated in the field by determining the volume and porosity, and hence the capacity of the channel bed materials. Simulated hydrographs were calculated by six versions of the runoff routing model WBNM, which was modified to make different allowance for transmission losses. One of the modified models shows a good fit with the observed hydrographs. Even though this model was physically based, it would still be difficult to extend its application to similar ungauged arid catchments, due to lack of available data and/or accuracy of the rainfall and runoff data. Several subsidiary investigations are described. These include the method for conversion of the raw data of runoff to hydrographs, a method to estimate the rating curve for an ungauged spillway, investigation of the soil surface hydraulic properties and a study for generalising the plot data within the entire catchment.

Subject words : Rain and rainfall Mathematical models • Runoff Mathematical models


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