The purpose of this study was to examine the possibilities of creating a trail near the town of Alingsås in southern sweden, preferably a round trip connecting all the 5 nature reserves that lies near town. The aim was to investigate the potential of an easily passable trail using mainly existing roads and trails, that at the same time, would pass many interesting nature areas around the town that could give the visitor nature experiences. Another aim was also to examine if there was any area fitting to create a shorter trail, about 10 kilometres long.   The passability of trails connecting some of 42 pre-marked areas was studied together with examination of the nature types and the experience these gave in terms of natural and cultural experiences.   The results showed that many trails east of the town was hard to pass and gave a low amount of experiences due to heavy forestry. But a few areas contained very high nature and culture experiences instead. Some passages through town gave good experiences but passages through industrial areas was also needed. Areas with good experiences was found south and southwest of the town.   A proposal of a 35 kilometre trail connecting the 5 nature reserves was made, outruling some of the studied areas, but still having areas with good experiences. Passability studies showed that it was mostly easy to walk. Areas southwest of Alingsås was recommended for a shorter trail.

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Cette thèse est une partie du projet ONEMA pour le dimensionnement des passes à poissons et pour l’amélioration de la continuité écologique des cours d’eau. Ce travail s’est concentré sur les passes à poissons naturelles qui présentent des avantages de coût et paysager. Il s’agit d’un écoulement à forte pente autour des blocs (macro-rugosités) régulièrement repartis en quinconce avec des grands nombres de Froude. Les conditions hydrodynamiques sont alors très diverses, et peuvent être franchissables par un nombre élargi d’espèces de poisson. Ce mémoire présente les travaux réalisés à l’Institut de Mécanique des Fluides de Toulouse (IMFT). Afin d’étudier l’écoulement dans ces passes, on va mener des expériences sur des canaux réduits ainsi que des simulations numériques à l’aide du modèle Telemac 2D. L’objectif est de mieux connaître la structure de l’écoulement en fonction des conditions hydrauliques et géométriques comme le nombre, la forme et la taille des macro-rugosités. Plus particulièrement, la compréhension de l’interaction de phénomènes physiques généralement étudiés séparément, tels que le passage en régime torrentiel, l’interaction de sillage ou l’écoulement autour de macro-rugosités, a été recherchée. Des relations hauteur-débit ont été établies permettant une aider au dimensionnement des passes naturelles. Elles fournissent des critères de franchissement comme les vitesses maximales, la puissance dissipée ou la hauteur d’eau minimale. Pour atteindre une description plus locale de l’écoulement, des mesures de Vélocimétrie Acoustiques Doppler ont été conduites. Elles ont aussi permis de définir la plage de validité du modèle numérique 2D (Telemac). Ce modèle a alors était utilisé pour extrapoler les critères de franchissement pour des configurations non testées expérimentalement. Finalement, les connaissances sur l’écoulement ont été synthétisées pour définir des préconisations générales de dimensionnement. La précision des relations établies en laboratoire a pu aussi être vérifiée sur des passes réelles. L’hydrodynamique de ces passes est maintenant suffisamment connue pour savoir si un poisson peut remonter le courant et se reposer. Il restera à s’assurer que leur attractivité soit bonne et que des phénomènes liés aux échelles de longueurs de la turbulence ne présentent un obstacle au franchissement. / This thesis is supported by an ONEMA project for the design of fishways and improve ecological continuity of rivers. This work focused on nature-like fish passes that have cost and landscaped appearance advantages. There is a steep flow around the blocks (macro-roughness) regularly distributed in a staggered configuration with large Froude numbers. The hydrodynamic conditions are sufficiently different to be passable by an expanded number of fish species. This thesis presents the work carried out at the Institute of Fluid Mechanics of Toulouse (IMFT). To study the flow in these passes, experiments are conducted on physical models and numerical simulations using the Telemac 2D model. The goal is to better understand the flow structure based on hydraulic and geometric conditions such as the number, shape and size of macro-roughness. In particular, we considered the interaction of physical phenomena usually studied separately such that the passage in supercritical regime, the interaction of wake or flow around macro-roughness. The stage-discharge relationships were established to assist in the design of nature-like passes. They provide criteria useful for passability such as maximum speeds, power dissipation or minimal water height. To reach a local description of the flow measurements with an Acoustic Doppler Velocimeter were conducted. They also helped to define the valid range of the 2D model. This model was then used to extrapolate passability criteria for untested experimental configurations. Finally, the knowledge on flow has been synthesized to define general recommendations sizing. It has also been able to verify on real scale passes, the accuracy of the relations established in the laboratory. The hydrodynamics of these passes is now sufficiently described to know if a fish can swim upstream and rest. It will remain to ensure that their attractiveness is good and that phenomena related to the turbulence length scales do not present an obstacle to the fish passage.

General and special public use of roads Abstract Subject matter of this thesis is general and special public use, whose object are roads. Institutes relating to public use of roads, such as charging for general use, restriction of general use and possible means of use, are analysed in this thesis. Focus is also put on the newest changes in this field and recent case law. The text also includes author's considerations de lege ferenda. The text itself, excluding introduction and conclusion, is divided into three chapters. In the first chapter institute of public use is analysed, especially its object and subject. Public use is also split into general and special. The second chapter offers general interpretation relative to roads, which are the object of public use. This interpretation deals with categorisation and defining aspects of each category of roads. Increased attention is paid to local roads in relation to their previous legislation, and also to private roads in public use due to the circumstances of their origin. The main part is included in the third chapter, which deals directly with general and special use of roads, as is legislated in Law no. 13/1997 Coll., on Land Communications (Road Act) and other legal regulations regulating limits of such use. This chapter is divided to subchapters on...