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Universitat Potsdam (2012)

Analyzing and modelling of flow transmission processes in river-systems with a focus on semi-arid conditions

Cunha Costa, Alexandre

Titre : Analyzing and modelling of flow transmission processes in river-systems with a focus on semi-arid conditions

Wassertransferprozesse in Flusssystemen mit einem Schwerpunkt auf semi-ariden Bedingungen

Auteur : Cunha Costa, Alexandre

Université de soutenance : Universitat Potsdam

Grade : Doctor rerum naturalium (Dr. rer. nat.) in der Wissenschaftsdisziplin Hydrologie 2012

Résumé partiel
One of the major problems for the implementation of water resources planning and management in arid and semi-arid environments is the scarcity of hydrological data and, consequently, research studies. In this thesis, the hydrology of dryland river systems was analyzed and a semi-distributed hydrological model and a forecasting approach were developed for flow transmission processes in river-systems with a focus on semi-arid conditions. Three different sources of hydrological data (streamflow series, groundwater level series and multi-temporal satellite data) were combined in order to analyze the channel transmission losses of a large reach of the Jaguaribe River in NE Brazil. A perceptual model of this reach was derived suggesting that the application of models, which were developed for sub-humid and temperate regions, may be more suitable for this reach than classical models, which were developed for arid and semi-arid regions. Summarily, it was shown that this river reach is hydraulically connected with groundwater and shifts from being a losing river at the dry and beginning of rainy seasons to become a losing/gaining (mostly losing) river at the middle and end of rainy seasons. A new semi-distributed channel transmission losses model was developed, which was based primarily on the capability of simulation in very different dryland environments and flexible model structures for testing hypotheses on the dominant hydrological processes of rivers. This model was successfully tested in a large reach of the Jaguaribe River in NE Brazil and a small stream in the Walnut Gulch Experimental Watershed in the SW USA. Hypotheses on the dominant processes of the channel transmission losses (different model structures) in the Jaguaribe river were evaluated, showing that both lateral (stream-)aquifer water fluxes and ground-water flow in the underlying alluvium parallel to the river course are necessary to predict streamflow and channel transmission losses, the former process being more relevant than the latter. This procedure not only reduced model structure uncertainties, but also reported modelling failures rejecting model structure hypotheses, namely streamflow without river-aquifer interaction and stream-aquifer flow without groundwater flow parallel to the river course.

Mots Clés : Trockenflüsse , Transferverluste in Flüssen , Hochwasservorhersage , Unsicherheitsanalyse , hydrologische Modellierung — Dryland Rivers , Channel Transmission Losses , Flood Forecasting , Uncertainty Analysis , Hydrological Modelling

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Page publiée le 6 juin 2012, mise à jour le 1er décembre 2018