991 resultados para Urban River Corridor


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Urban Regeneration. A challenge for Public Art, supposed the start of a trend of critical thought related to the topics of Public Art, Urban Regeneration and Urban Design. This trend agglutinated around the Public Art Observatory that, still today, develops its activities.The book gathers a series of critical proposals organized in the chapters " Art and Design in/for Public Space ", " Forms and Representations of Public Art/Public Space. The Producer/User Dilemma " and " Public Art / Cities in Competition: Strategies, Bridges and Gateways ", with the participation of, among others, Sergi Valera, Ray Smith, Martí Peran, Ian Rawlinson, Chaké Matosian, Enric Pol, J. Hyatt, J. Gingell or T. Bovaird.

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The Rock Island Centennial Bridge spanning the Mississippi River between Rock Island, Illinois and Davenport, Iowa was opened to traffic on July 12, 1940. It is a thoroughly modern, four-lane highway bridge, adequate in every respect for present day high speed passenger and transport traffic. The structure is ideally situated to provide rapid transit between the business districts of Rock Island and Davenport and serves not only the local or shuttle traffic in the Tri-City Area, but also heavy through motor travel on U.S. Highways 67 and 150. The Centennial Bridge is notable in several respects. The main spans are box girder rib tied arches, a type rather unusual in America and permitting simplicity in design with pleasing appearance. The Centennial Bridge is the only bridge across the Mississippi providing for four lanes of traffic with separation of traffic in each direction. It is a toll bridge operating alongside a free bridge and has the lowest rates of toll of any toll bridge on the Mississippi River. It was financed entirely by the City of Rock Island with no obligation on the taxpayers; there was no federal or state participation in the financing. But perhaps the most outstanding feature of the new bridge is its great need. A few remarks on the communities served by the new structure, the services rendered, and some statistics on cross-river traffic in the Tri-City Area will emphasize the reasons for constructing the Centennial Bridge.

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In May 2011, very heavy rains combined with above average snowpack caused reservoirs throughout the Upper Missouri River basin to swell. The river carried more water in May and June than it does in an average year. The six Iowa counties bordering the river—Fremont, Harrison, Mills, Monona, Pottawattamie and Woodbury—suffered from major flooding which persisted throughout the spring and summer. On June 2, Governor Terry Branstad issued a Proclamation of Disaster Emergency for the six impacted counties. The Iowa Homeland Security and Emergency Management Division (HSEMD) activated the State Emergency Operations Center (SEOC) on June 10 to coordinate State, Federal, private sector, and voluntary agency preparedness and response activities in the affected area. The severity and duration of the flooding presented operational challenges for the SEOC and its partner agencies, which were further complicated by severe weather. The flooding forced the SEOC to conduct simultaneous response and recovery operations for an usually long period of time. The Missouri River floods caused major economic losses in Western Iowa. As a result of these economic losses, President Barack Obama issued a Major Disaster Declaration (FEMA-1998-DR) which made six counties eligible for Federal Public Assistance. The disaster declaration was subsequently amended on October 18, making five counties eligible for Federal Individual Assistance.

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The Missouri River floods of 2011 will go down in history as the longest duration flooding event this state has seen to date. The combination of above normal snowfall in the upper Missouri River basin followed by the equivalent of nearly one year’s worth of rainfall in May created an above normal runoff situation which filled the Missouri River and the six main reservoirs within the basin. Compounding this problem was colder than normal temperatures which kept much of the snow pack in the upper basin on the ground longer into the spring, setting the stage for this historic event.

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Seit den 1990er Jahren werden zunehmend nachhaltige Quartiere realisiert. Dabei besteht häufig eine beachtliche Diskrepanz zwischen den Zielen, die von den beteiligten Akteuren angestrebt werden, deren Umsetzung (Realisierungsphase) und deren Erhalt auf Dauer (Nutzungsphase). Es stellt sich folglich die Frage, auf welche Weise die Projektqualität im Sinne einer nachhaltigen Quartiersentwicklung verbessert werden kann. Diese Projekte sind jedoch enorm komplex aufgrund der großen Interdisziplinarität und Interdependenz ihrer Ziele sowie der vielschichtigen Akteursstrukturen. Sie stellen daher be-sonders hohe Anforderungen an die Projektsteuerung. Das konkrete Ziel dieser Arbeit besteht darin, die Bedeutung einer Prozesssteuerung im Sinne von Urban Governance zur Realisierung und zum Erhalt nachhaltiger Quartiere zu untersuchen. Damit soll einen Beitrag zur Förderung einer nachhalti-gen Stadtentwicklung geleistet werden. Die Arbeit stützt sich auf ein umfassendes theoretisches Fundament zum Thema Governance, wobei die relevanten Elemente für den Kontext nachhaltiger Quartiere herausgearbeitet werden. Die Hypothesen prüfen die Bedeutung der Schlüsselcharakteristika von Urban Governance (Kooperation, Partizipation, Verhandlungen) für die Projektqualität während der Realisierungs- und Nutzungsphase. Eine erste empirische Untersuchung wurde an zwanzig europäischen nachhaltigen Modellquartieren vorgenommen. Stärken und Schwächen aus der Perspektive der Nachhaltigkeit werden analysiert, deren Ursachen identifiziert und Handlungsoptio-nen aufgezeigt. Die Erkenntnisse zeigen die Notwendigkeit einer Verbesserung der Projektsteuerung während der Realisierungs- und der Nutzungsphase. Auf der Grundlage dieser Erkenntnisse wird ein umfassender Ansatz zur empirischen Untersuchung von Urban Governance im Kontext nachhaltiger Quartiere entwickelt. Dieser beruht auf dem akteurzentrierten Institutionalismus und den Merkmalen der Urban Governance. Anhand dieses Ansatzes wird mithilfe von Experteninterviews der Realisierungsprozess des nach-haltigen Quartiers Kronsberg (Hannover) analysiert. Betrachtet werden dabei die beteiligten Akteure und ihre Handlungso-rientierungen, die verwendeten Schlüsselinstrumente sowie aufgetretene Divergenzen zwischen Akteuren und deren Auswirkungen auf die Projekt- und Prozessqualität. Eine Vertiefung relevanter Themenfelder wird anhand der Fallstudie Neu-Oerlikon (Zürich) vorgenommen. Diese empirische Arbeit zeigt, dass eine Prozesssteuerung im Sinne von Urban Governance im Vergleich zu einer klassis-chen hierarchischen Steuerung eine notwendige aber nicht hinreichende Bedingung zur Verbesserung der Projektqualität nachhaltiger Quartiere darstellt. An konkreten Beispielen wird herausgearbeitet, dass der Mehrwert einer solchen Steuerung nur unter bestimmten Voraussetzungen erzielt werden kann: In manchen Situationen ist die Steuerungsform Kooperation und die Interaktionsform Verhandlung in ihrer Wirksamkeit zur Sicherung der Projektqualität begrenzt und hierarchische Interventionen sind notwendig. Nicht ein bestimmtes Steuerungsmodell per se ist geeignet, sondern es kommt auf den Ein-zelfall an: auf die Akteursstruktur, die individuellen und institutionellen Handlungsorientierungen der Akteure und deren Ver-haltensweisen, die Rahmenbedingungen und die Ausgestaltung des Urban Governance-Prozesses. Wenn die Spielregeln dieses Prozesses von den Akteuren nicht wirklich angenommen und gelebt werden, dominieren individuelle und institutio-nelle Akteursinteressen zu Lasten der Projektqualität. Ferner zeigen die Untersuchungen, dass die Partizipation der zukünftigen Quartiersnutzer in der Praxis häufig unzureichend ist. Dies führt zu Einbußen in der Projektqualität. Entscheidend ist auf jeden Fall, dass mindestens ein Akteur, in der Regel die öffentliche Hand, präsent ist, der die Definition anspruchsvoller Nachhaltigkeitsstandards, deren Umsetzung und deren Erhalt sichert sowie die notwendigen Rahmenbedingungen dafür schafft. Diese Arbeit belegt darüber hinaus, dass der Erhalt der Projektqualität während der Nutzungsphase (Faktor Zeit) bisher un-zureichend beachtet und in die Projektplanung einbezogen wird. Gerade dieser Aspekt bestimmt aber, ob das Quartier auch auf Dauer dem Nachhaltigkeitsanspruch gerecht werden kann! Tatsächlich handelt es sich um einen fortlaufenden Prozess, der nicht mit der Einweihung des Quartiers abgeschlossen ist. Vor diesem Hintergrund werden relevante Handlungsfelder beschrieben und die Notwendigkeit der langfristigen Fortsetzung einer Steuerung im Sinne von Urban Governance bzw. der Herausbildung einer Urban Governance-Kultur aufgezeigt. Aus den empirischen Erhebungen werden Erfolgs- und Risikofaktoren für Urban Governance-Prozesse während der Realisierungs- und der Nutzungsphase abgeleitet. Ferner werden bisher vernachlässigte Handlungsfelder (langfristiges Umwelt-management, ökologische Finanzierungsformen, urbane Landwirtschaft, Umweltkommunikation, etc.) eruiert. Die Berücksichtigung dieser Erkenntnisse ist unerlässlich für eine Verbesserung der Projektqualität nachhaltiger Quartiere. ---------------------------------------------- Gouvernance urbaine et quartiers durables: Entre intensions et mise en oeuvre --- Résumé --- Depuis les années 90, la thématique des quartiers durables a gagné en importance, même si leur développement s'est avéré difficile. Le décalage entre les objectifs, leur mise en oeuvre et le projet tel qu'il est vécu par ses habitants est souvent important et nécessite d'être réduit. Un quartier durable est par nature un projet complexe, aux objectifs ambitieux situé à la croisée de multiples champs disciplinaires, mobilisant de nombreux acteurs aux intérêts divergents. De plus, chaque projet, du fait des ses spécificités, requiert un pilotage adapté. L'objectif principal de la recherche vise à analyser la nature du pilotage du processus de conception, de réalisation et d'exploitation des quartiers durables. Ses résultats ont pour ambition de contribuer à optimiser et promouvoir le développement urbain durable. Le fondement théorique de la recherche se base sur le concept de gouvernance urbaine, adapté au contexte particulier de la gouvernance des quartiers durables. La gouvernance urbaine, au sens où nous l'entendons, est un mode de pilotage basé sur la coopération entre les acteurs publics et privés. Les hypothèses centrales du travail testent la portée et les limites des caractéristiques-clefs de la gouvernance urbaine (coopération, participation, négociation), ainsi que l'importance de la notion de pérennité pour la qualité du projet. Dans un premier temps, nous avons analysé vingt quartiers durables modèles européens et identifié leurs atouts et leurs faiblesses en termes de durabilité, ainsi que leurs divers modes de pilotage. Les enseignements tirés de ces exemples révèlent la nécessité d'améliorer le pilotage des projets. Dans un deuxième temps, nous avons élaboré une grille d'analyse fine fondée sur l'approche institutionnelle des acteurs et les caractéristiques-clefs de la gouvernance urbaine. En nous appuyant sur cette grille, nous avons analysé le processus de conception et de réalisation du quartier durable de « Kronsberg » (Hanovre) à l'aide des éléments suivants : les acteurs (avec leurs intérêts et objectifs propres), les instruments d'aménagement du territoire, les modes de pilotage, les zones de divergence et de convergence entre les acteurs, ainsi que leurs impacts sur le processus et le projet. Dans un troisième temps, les hypothèses centrales ont été testées sur le quartier de « Neu-Oerlikon » (Zurich) afin d'approfondir et d'élargir les enseignements tirés de celui de « Kronsberg ». Les résultats des analyses mettent en évidence le fait qu'un pilotage de projet selon le modèle de la gouvernance urbaine est certes une condition nécessaire mais non suffisante pour améliorer la qualité du projet. De plus, la valeur ajoutée de la gouvernance urbaine n'est valable qu'à certaines conditions. En effet, la coopération et la négociation peuvent même, dans certaines situations, réduire la qualité du projet ! Le principal enseignement de la recherche révèle qu'il n'y a pas de mode de pilotage idéal, mais que la qualité d'un projet dépend d'une multitude de facteurs, tels que les constellations d'acteurs, leurs intérêts personnels et institutionnels, les conditions cadres et les « règles du jeu » de la gouvernance urbaine. Si les « règles du jeu » en particulier ne sont pas réellement appropriées par l'ensemble des acteurs, les intérêts et les comportements personnels ou institutionnels prédominent au détriment de la qualité du projet. De même, si la participation des futurs usagers à l'élaboration du projet de quartier durable n'est pas assurée, tant la qualité du projet que sa pérennité en pâtissent. Nous avons également constaté que la présence d'un acteur (en règle générale les autorités publiques) qui veille à la définition d'objectifs ambitieux en matière de développement durable et à leur application constitue un apport essentiel à la qualité du projet. En outre, la recherche met en évidence les carences dans le suivi et le maintien à long terme des qualités de durabilité de la phase d'exploitation des projets de quartiers durables analysés. Dans la phase d'exploitation, le degré de coopération diminue généralement et les modes de fonctionnement et de pilotage sectoriels se mettent en place au détriment de la qualité du projet. Cela confirme la nécessité de poursuivre le processus de pilotage selon le modèle de la gouvernance urbaine au-delà de la phase de réalisation des projets. La recherche précise les enjeux des champs d'action de la phase d'exploitation (domaine encore peu étudié) et démontre la pertinence du mode de pilotage préconisé. Enfin, les analyses permettent d'identifier des facteurs de réussite et de risque susceptibles d'influencer les systèmes de gouvernance urbaine, ainsi que les enjeux des domaines de la durabilité encore négligés (agriculture urbaine, gestion environnementale dans la durée, comportement des usagers, financement équitable, etc.). La prise en compte de ces enseignements est essentielle à l'amélioration de la gestion de futurs projets de quartiers durables. ---------------------------------------------- Urban Governance and Sustainable Neighbourhoods: A Contribution to a Lasting Sustainable Development --- Abstract --- Since the 1990s, sustainable neighbourhoods have become an increasingly important topic. However, their development has proven to be difficult. There is an often considerable gap, which must be reduced, between the initial goals, the way they are implemented and how the project is finally inhabited. A sustainable neighbourhood is inherently a complex project, with ambitious goals that lie at the intersection of multiple disciplines, involving numerous stakeholders with diverging interests. Moreover, each project, due to its specific characteristics, requires an adapted steering. The main goal of this research is to analyse the nature of the steering process during the planning, realisation and use of sustainable neighbourhoods. The results aim to contribute to the promotion of sustainable urban development. The theoretical foundation of this research is based on the concept of urban governance, adapted to the particular context of sustainable neighbourhoods. Urban governance is understood in this work, as a mode of project steering based on the cooperation between public and private stakeholders. The central hypotheses of this work test the importance and the limits of the key characteristics of urban governance (cooperation, participation, negotiation) as well as the importance of continuity for the project quality. To begin with, we surveyed and analysed twenty exemplary European sustainable neighbourhoods and identified their strengths and weaknesses in terms of sustainability, as well as their diverse steering modes. The lessons learned from these examples reveal the need to improve the projects' steering. Secondly we elaborated a detailed framework for analysis founded on stakeholder-centred institutionalism and the key characteristics of urban governance. By systematically applying this framework, we analysed the planning and implementation process of the sustainable neighbourhood "Kronsberg" (Hannover). Our focus was on the following dimensions: the stakeholders (with their particular interests and goals), the instruments of spatial planning, the steering modes, the points of divergence and convergence amongst the stakeholders, as well as their impacts on the process and on the project. The final step was to test the core hypotheses on the neighbourhood "Neu-Oerlikon" (Zürich) in order to broaden the lessons learned from "Kronsberg". The results of the analysis highlight the fact that an urban governance type project steering is certainly a necessary but insufficient condition to improve the project quality. Moreover, the added value of urban governance is only valid under certain conditions. In fact, cooperation and negotiation can even in certain situations reduce the project's quality! The main lesson of this research is that there is not an ideal steering mode, but rather that the quality of the project depends on numerous factors, such as the stakeholder constellation, their individual and institutional interests, the general conditions and the "rules of the game" of urban governance. If these "rules of the game" are not really appropriated by all stakeholders, individual and institutional interests and behaviours predominate at the expense of the project's quality. Likewise, if the future users' participation in the project development is insufficient, both the project's quality and its continuity suffer. We have also observed that the presence of a stakeholder (in general the public authorities) who ensures the definition of ambitious goals in terms of sustainable development and their implementation is crucial for the project's quality. Furthermore, this research highlights the deficiencies in the follow-up and long-term preservation of the sustainability qualities in the neighbourhood projects which we have analysed. In the use phase, the degree of cooperation generally diminishes. Attitudes and project management become more sectorial at the expense of the project's quality. This confirms the need to continue the steering process according to the principles of urban governance beyond the project's implementation phase. This research specifies the challenges that affect the use phase (a still neglected area) and shows the relevance of the recommended steering mode. Finally, the analyses also identify the success and risk factors that may influence urban-governance systems, as well as the challenges of still neglected fields of sustainability (urban agriculture, long-term environmental management, user behaviour, fair funding, etc.). Taking into account these outcomes is essential to improve the management of future sustainable-neighbourhood projects.

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Urban places attract most highway travel because more people are to be per acre in urban places than elsewhere. In the beginning of highway development the objective was to provide an all-weather road for the rural people to get to town and back to their farms, but there was no consideration of getting motor vehicles through the town to the opposite side. With the development of intercity travel, it soon became apparent that travel through the urban areas would have to be given consideration along with the travel to and from the urban areas. This consideration led to the urban bypass, a provision in highway location whereby the traveler may get to the opposite side of the urban area without going through it, or at least not through the central business district. Bypasses, although highly desired by the through travelers, were not welcomed by local business interests on the basis that the community would suffer a reduction in retail trade. Some discussion of the pros and cons of bypasses and their consequences as observed from experience will shed light upon this type of local highway. The bypass report summaries in this document were based on interviews with businessmen and community leaders of cities that have actually experienced firsthand the impacts of a highway bypass. Several of the studies were conducted by newspaper reporters, city council members and residents of Iowa cities.

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The purpose of this Interstate Corridor Plan (plan) is to provide the Iowa Department of Transportation (Iowa DOT) with an initial screening and prioritization of interstate corridors/segments. This process evaluates the entire interstate system, independent of current financial constraints, using a select group of criteria weighted in terms of their relative significance. The resulting segments would then represent those areas that should be considered for further study (e.g., environmental, design, engineering), with the possibility of being considered for programming by the Iowa Transportation Commission. There was a dominant theme present in conversations with those department stakeholders who have a keen interest in the product of this planning effort. A statement that was often heard was that staff needed more information to help answer the question, “Where do we need to be looking to next, and when?” There was a strong desire to be able to use this plan to help populate that initial pool of candidate segments that would progress towards further study, as discussed below. It was this theme that framed the need for this plan and ultimately guided its development. Further study: As acknowledged at the beginning of this section, the product of this planning effort will be an initial screening and prioritization of interstate corridors/segments. While this initial screening will assist the Iowa DOT in identifying those areas that should be considered for further study, the plan will not identify specific projects or alternatives that could be directly considered as part of the programming process. Bridging the gap between this plan and the programming process are a variety of environmental, design, and engineering activities conducted by various Iowa DOT offices. It is these activities that will further refine the priority corridors/segments identified in this plan into candidate projects. In addition, should the evaluation process developed through this planning effort prove to be successful, it is possible that there will be additional applications, such as future primary system highway plans and statewide freight plans.

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Many states are striving to keep their deer population to a sustainable and controllable level while maximizing public safety. In Iowa, measures to control the deer population include annual deer hunts and special deer herd management plans in urban areas. While these plans may reduce the deer population, traffic safety in these areas has not been fully assessed. Using deer population data from the Iowa Department of Natural Resources and data on deer-vehicle crashes and deer carcass removals from the Iowa Department of Transportation, the authors examined the relationship between deer-vehicle collisions, deer density, and land use in three urban areas in Iowa that have deer management plans in place (Cedar Rapids, Dubuque, and Iowa City) over the period 2002 to 2007. First, a comparison of deer-vehicle crash counts and deer carcass removal counts was conducted at the county level. Further, the authors estimated econometric models to investigate the factors that influence the frequency and severity of deer-vehicle crashes in these zones. Overall, the number of deer carcasses removed on the primary roads in these counties was greater than the number of reported deervehicle crashes on those roads. These differences can be attributed to a number of reasons, including variability in data reporting and data collection practices. In addition, high rates of underreporting of crashes were found on major routes that carry high volumes of traffic. This study also showed that multiple factors affect deer-vehicle crashes and corresponding injury outcomes in urban management zones. The identified roadway and non-roadway factors could be useful for identifying locations on the transportation system that significantly impact deer species and safety and for determining appropriate countermeasures for mitigation. Efforts to reduce deer density adjacent to roads and developed land and to provide wider shoulders on undivided roads are recommended. Improving the consistency and accuracy of deer carcass and deer-vehicle collision data collection methods and practices is also desirable.

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For almost 75 years, the Grand Avenue Viaduct (known today as the Gordon Drive Viaduct) has been a familiar feature of Sioux City's urban landscape. With the exception of bridges over the Mississippi River, the Grand Avenue Viaduct is Iowa's longest grade separation as well as its longest bridge. For nearly a mile, from the eastern suburbs west to the central business district, the viaduct carries Gordon Drive and the city route of U.S. 20 over the Floyd River valley, which includes the remnants of the city's famed stockyards and the South Bottoms neighborhood, as well as a maze of railroad tracks and the present channel of the Floyd River. Constructed in 1937 and known simply as "The Viaduct" to local residents, the massive structure is as fundamental to Sioux City as were its stockyards just a few decades ago.

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Depth profiles were sampled at different locations throughout Lake Geneva on a monthly and seasonal basis over the course of 2 years and analysed for their stable hydrogen and oxygen isotope compositions. The isotopic compositions indicate an isotopic stratification in the metalimnion during summer and fall. This is related to mixing of Rhône River water, which in summer is dominated by snow and glacier melt waters, and lake water, with the latter having a homogenous isotopic composition. The observed interflow layer is 7-15 m thick and can be traced by the distinct stable isotope composition of the water for about 55 km throughout the lake as well as into shallow bay regions. Depth of the interflow layer close to the Rhône River mouth is similar to those previously described based on echo-soundings and turbidity profiles of sediment dispersion. In contrast to previous descriptions of the interflow within Lake Geneva, the stable isotope compositions allow for direct, natural tracing of the Rhône River water even in cases where the turbidity and conductivity measurements do not indicate such an interflow. In addition, the method allows for a quantification of the Rhône River and lake water in the interflow with the fraction of Rhône River water within the interflow estimated to be up to 37% in summer. The isotopic composition further indicates different vertical mixing processes within the two lake basins of Lake Geneva, related to the density gradients and local stability within the water column. The method may be applicable to other lakes in catchments with large differences in the topography as water that originates from high altitudes or glaciers has a distinct oxygen and hydrogen isotope composition compared to other sources of water originating at lower altitudes and/or from direct precipitation over the lake. Stable isotope measurements thus improve the understanding of the circulation of water within the lake, which is fundamental for an evaluation of the water residence times, dissolved pollutant and nutrient transport as well as oxygenation.

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The 1935 Iowa-Illinois Memorial Bridge is being documented at this time to fulfill the requirements of the Memorandum of Agreement regarding the removal of the Iowa-Illinois Memorial Bridge and the Iowana Farms Milk Company Building for the proposed improvements to Interstate 7 4 in Bettendorf, Iowa, and Moline, Illinois.1 The 1959 twin suspension bridge will be removed as well, but it was determined to be ineligible for the National Register of Historic Places. Discussion of the history of the 1959 twin span is included, however, in the current report as part of the overall history of the Iowa-Illinois Memorial Bridge. Fieldwork for the documentation occurred in November 2009 and October 2010 (Fig. 1). Limitations on photography included limited shoreline access on the Illinois side, making good views of the bridge from the south somewhat challenging. Also, photographs on the bridge deck were not possible because of interstate traffic and prohibitions on pedestrian traffic. Within the last few years, online primary sources have proliferated, along with historical materials regarding the Iowa-Illinois Memorial Bridge. Sources available online for this report included numerous historical photographs, as well as historical Davenport, Iowa, and U.S. newspapers that document the bridge planning and construction. Additional primary source material was found at the University of Iowa Libraries, the State Historical Society of Iowa in Iowa City, the Bettendorf Public Library, the Richardson-Sloane Special Collections Center at the Davenport Public Library, and the Iowa State University Special Collections in Ames.

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Defining the limits of an urban agglomeration is essential both for fundamental and applied studies in quantitative and theoretical geography. A simple and consistent way for defining such urban clusters is important for performing different statistical analysis and comparisons. Traditionally, agglomerations are defined using a rather qualitative approach based on various statistical measures. This definition varies generally from one country to another, and the data taken into account are different. In this paper, we explore the use of the City Clustering Algorithm (CCA) for the agglomeration definition in Switzerland. This algorithm provides a systemic and easy way to define an urban area based only on population data. The CCA allows the specification of the spatial resolution for defining the urban clusters. The results from different resolutions are compared and analysed, and the effect of filtering the data investigated. Different scales and parameters allow highlighting different phenomena. The study of Zipf's law using the visual rank-size rule shows that it is valid only for some specific urban clusters, inside a narrow range of the spatial resolution of the CCA. The scale where emergence of one main cluster occurs can also be found in the analysis using Zipf's law. The study of the urban clusters at different scales using the lacunarity measure - a complementary measure to the fractal dimension - allows to highlight the change of scale at a given range.

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Fish passage at artificial barriers is necessary for the conservation of healthy fish stocks. The first barrier that migratory fish encounter when ascending the Ebro River is the Xerta Weir, where a pool-type fishway was constructed in 2008. From 2007 to 2010, boat electrofishing surveys were conducted in the Ebro River downstream of the Xerta Weir to assess the potential pool of species that could use the fishway. Nine native and 12 exotic species were captured, the latter comprising 62 % of the relative abundance and 70 % of the biomass. A combination of video recording, electrofishing and trapping was used to assess the effectiveness of the fishway in facilitating the passage of fish. Eight species were detected using the fishway, of which five were native (Liza ramada, Anguilla anguilla, Barbus graellsii, Gobio lozanoi and Salaria fluviatilis) and three exotic (Alburnus alburnus, Cyprinus carpio and Rutilus rutilus). Only L. ramada used the fishway in substantial numbers. The rate of fish passage was the highest from June to August and decreased afterwards. The effectiveness of the fishway might be lowered by areas of turbulence within the fishway and by distraction flows from a nearby hydropower station