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Accueil du site → Doctorat → Allemagne → 2020 → Three-dimensional hydrodynamic and ecosystem modeling of warm-monomictic reservoirs (Maroon and Abolabbas, Iran) under the impact of 21st century climate change

University of Kassel (2020)

Three-dimensional hydrodynamic and ecosystem modeling of warm-monomictic reservoirs (Maroon and Abolabbas, Iran) under the impact of 21st century climate change

Zamani Gharehchaman, Behnam

Titre : Three-dimensional hydrodynamic and ecosystem modeling of warm-monomictic reservoirs (Maroon and Abolabbas, Iran) under the impact of 21st century climate change

Auteur : Zamani Gharehchaman, Behnam

Université de soutenance : University of Kassel

Grade : Doktor der Ingenieurwissenschaften (Dr.-Ing.) 2020

Résumé partiel
Lakes and reservoirs, as the endpoint of their upstream catchment, collect their water as the resultant of the hydrological and ecosystem processes and, thus, act as a gauge of their catchment’s management. Physical processes, e.g. stratification and mixing and propagation of density currents, are the main drivers of the biochemical factors in lakes and reservoirs and are prone to be altered and affected by climate change. Hydrodynamic models are the tools to simulate the behavior of the water body under various forcing conditions. In this dissertation, hydrodynamics and limnological processes of the Maroon reservoir and the planned Abolabbas reservoir in southwest Iran were studied in a physical (the former) and biochemical (the latter) respect using 3D hydrodynamic (and biochemical) modeling. We used two 3D models and compared them in capturing hydrodynamics of the Maroon reservoir, studied the role of the reservoir’s morphology in its hydrodynamics, simulated nutrients cycle of the nearby Abolabbas reservoir and have an insight about these processes in the Maroon reservoir and eventually identified and predicted the effects of different climate change scenarios on the Maroon reservoir’s hydrodynamics and thermal regime in the 21st century. This dissertation is presented, based on the perspectives mentioned above, in four individual research studies, which have been published or are in press as follows :
Chapter 1. Introduction The research on physical limnology and the concept of hydrodynamic modeling in lakes and reservoir are briefly introduced. The importance of climate change in limnology and its shown impacts on lakes and reservoirs in the literature are summarized, and finally the purpose and motivation of the research forming this thesis is presented.
Chapter 2. Comparison between two hydrodynamic models in simulating physical processes of a reservoir with complex morphology : Maroon reservoir Two 3D hydrodynamic models AEM3D and MIKE3 are compared in simulating hydrodynamics of the Maroon reservoir. The reservoir has a complex bathymetry with steep walls which makes it a good case for studying the performance of hydrodynamic models. The results indicated that the AEM3D model, by using a finite difference scheme with a purely z-level vertical discretization, shows better consistency with observations so that the AME and RMSE of the model remain below 1℃. The MIKE3 model showed overall higher errors from 56 to 130% larger than AEM3D and the level of error strongly depends on its vertical discretization method and the turbulence model. The lowest errors by MIKE3 were seen by the k-ε turbulence model with a hybrid z-sigma discretization, while the highest errors were generated by the sigma discretization. The stand-alone vertical mixing model in AEM3D model, used instead of the constant-eddy-viscosity or k-ε formulation, showed a better performance in modeling vertical mixing and wind mixed layer, which is another reason of observing better results by this model than MIKE3

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