Fluvial system restoration – case study: river Tua

Dissertação para obtenção do Grau de Mestre em Engenharia do Ambiente, Perfil de Engenharia de Sistemas Ambientais

The purpose of this thesis is to provide river basin managers with a framework for river restoration. To that end, it presents and discusses the relevant information on the current condition of the river Tua, in northern Portugal, and establishes what can be done to restore the river basin in order to protect the most important drainage basin's functions and ecosystems. It is intended that this thesis will serve as an example of the application of current knowledge on freshwater restoration which can be emulated by future managers in their efforts to restore this, or any water body they wish to. To this purpose, the thesis analyzes demographic data on the municipalities of the Tua drainage basin. It discusses literature and research on the subject of river restoration and important river processes in the following chapter, so as to introduce important theory concepts to have in mind when designing any restoration efforts. In its methodology, the techniques and data assessment tools used in the process of evaluating the river basin's conditions are described and defined, allowing interested managers to review and adapt to the specific needs of drainage basins anywhere. Finally, it presents a practical point-of-view intended to be applied on other freshwater bodies. The thesis includes the realization of an assessment physical characteristics and status of the Tua river reach, it splits up the drainage basin into several different sub-basins, for individual study, and, after a discussion of the conclusions drawn from the assessment for the whole drainage basin, it presents arguments for choosing the sub-sections which present the highest risk to the drainage basin and, as such, require priority action. This section also includes a presentation of the arguments in support of specific techniques to be put into place, given the specific needs of the sub-basin and the restoration goals for the entire drainage basin.