Channel Dynamics in Alpine and Lowland Streams Across Spatial and Temporal Scales: Grand Mesa, Western Colorado and Brazos River, Central Texas

Rivers and streams develop landform morphology in equilibrium with the flow of water and sediment through the channel. This dissertation examines features in fluvial systems with different geomorphic regimes; step-pool streams in Grand Mesa, western Colorado, USA and the meandering Brazos River, east-central Texas, USA. Grand Mesa streams are unique with headwaters located on one of the largest mesas in the world. Large reservoirs with regulated discharges drain into each stream. Significant differences were found for standard step-pool characteristics of step height, channel width and step wavelength between the streams of Grand Mesa and step-pool streams in mountain-peak alpine areas. The stage of channel evolution for step-pool streams shows the Grand Mesa channels as either approaching or having obtained an idealized channel form from distribution of energy within the system. Rates of lateral channel migration occurring along a section of the middle Brazos River from the late 1920s to 2008 were mapped using aerial photographs, planimetric maps, and fieldwork. Flow regulation has greatly altered the discharge and suspended sediment characteristics of the river. Peak flows occurred more frequently prior to regulation, impacting the rate and style of migration. Rates of channel migration prior to regulation averaged 13 (+/- 3) m/year whereas migration after regulation averaged 4 (+/- 3) m/year. Total channel migration ranged from 1.09 to 11.53 m/year with an average of 3.28 m/year. The results support the difficulty in predicting the magnitude of channel meandering for large rivers. Oxbow lakes are a major component of the fluvial system in lowland regions. After cutoff, the lake fills with sediment and requires an increasing river discharge to maintain a hydrologic connection. The relationship between the cutoff ratio, diversion angle and rate of sedimentation of twenty eight lakes located on the middle and lower Brazos River, central Texas, was examined. The time of cutoff was dated using historic maps and aerial photographs. Rates of sedimentation were determined using a digital elevation model and range from 0.02 to 0.4 meters per year. Field observations of river-to-lake connections with the rates of sedimentation determined a correlation between discharge events in the main channel and sediment deposited in the lake

River and Stream Power Assessment Report Including Culvert and Bridge Vulnerability Analysis: Deerfield River Basin, Massachusetts and Vermont

This geomorphic assessment of Deerfield River in western Massachusetts and southern Vermont has been prepared by Milone & MacBroom, Inc. (MMI) on behalf of the University of Massachusetts as part of its Farms, Floods, and FGM project, funded by the United States Department of Agriculture – National Institute of Food and Agriculture National Integrated Water Quality Program(USDA – NIFA NIWQP) program. This project is a broad-based geomorphic assessment of the Deerfield River and its adjacent riparian corridor to define its characteristics, processes, and management issues. The river channel is used extensively for hydroelectric power generation and recreation, with agricultural land uses on the floodplains. This river assessment focuses upon temporal river processes and resulting features rather than the more common assessment of local cross section forms and characteristics that change after annual floods. The Deerfield River has been found to be remarkably stable with moderate specific stream power (SSP) except in highly contracted segments, and the few large floodplains are more prone to sediment deposition rather than dynamic migratory channels or avulsions. In contrast, several larger tributaries have steep gradients and narrow confined valleys that lead to high stream power and dramatic geomorphic changes during floods. Consequently, the anticipated hydrologic effects of climate change will be more acute along the tributaries than the main stem. The second part of this project included developing a Geographic Information System (GIS)-based model to compute specific stream power and using the results to help predict culvert and bridge vulnerability of failure. This vulnerability screening tool uses remote sensing data and a regression equation to predict hydrology and channel reach slope and a prediction of channel and structure condition that is compared to a field inventory of culverts. The purpose of the vulnerability screen analysis is to help identify the potential for channel and structural risk at culverts due to erosion, sedimentation, debris, and flooding. Vulnerable structures can then be ranked by priority for subsequent on-site investigation. River Assessment Methodology is based on a hydro-morphology approach and employs fluvial assessment of watershed valley and river channel characteristics, an analysis of the Active River Area, an assessment of the equilibrium state and adjustments, and culvert/ bridge vulnerability analyses throughout the Deerfield watershed in Vermont and Massachusetts (HUC 01080203)

The third dimension in river restoration: how anthropogenic disturbance changes boundary conditions for ecological mitigation

The goals of the European Water Framework Directive changed the perspective on rivers from human to ecosystem-based river management. After decades of channelizing and damming rivers, restoration projects are applied with more or less successful outcomes. The anthropogenic influence put on rivers can change their physical parameters and result in a different morphological type of river. Using the Ammer River as an example, a comparison between applied systems of corridor determination based on historical maps and data; calculation of regime width; and the change in parameters and river typology are pointed out. The results showed (a) a change in stream power and morphology (b) great difference between the historical and the predicted river type and (c) that regulated rivers can have a near-natural morphology

Gefährdungsanalyse für morphodynamische Entwicklung bei Flussrenaturierung und naturnahen Hochwasserschutzkonzepten

In the course of river regulation, climate change and the EU WFD, new sustainable flood protection measures are developed which go hand in hand with natural river behaviour and ecological demands. However, inundation hazards are often accompanied by morphological response of the river which can cause severe consequences in addition. Thus, sustainable nature-close flood risk management calls for explicit consideration of fluvial dynamics in addition to inundation studies alone. In the dissertation, a new concept is developed for identification, analysis and assessment of local morphodynamic hazards which is adequate for planning optimisation of nature-close flood protection measures in gravel-bed rivers. The state of the art reveals the complex three-dimensional interactions among river geometry, flow, sediment transport and vegetation. To tackle this, the concept integrates a Risk Identification procedure based on a detailed hydromorphologic characterisation where Elements at Risk and potential hazards can be clearly detected. In the Hazard Analysis, a 1D/3D approach is developed for the computation of the three-dimensional hydraulic flow field including a physically based approach of flow resistance due to vegetation in order to account for mass and impulse transfer accurately. A semi-qualitative prognosis of the fluvial morphological response on the flow field is implemented including approaches for stability and sediment transport behaviour. For the estimation of longterm morphodynamic processes the use of regime equations is suggested. To support model outcomes, the concept includes sound calibration and validation procedures with field data as well as permanent checks for plausibility. The application of the concept to a case study in the Upper Rhine shows promising and plausible results for a complex, vegetated river section. The new procedure may contribute to sustainable nature-close flood protection and support planning optimisation.Im Zuge des Klimawandels und der EU-Wasserrahmenrichtlinie werden nachhaltige Hochwasserschutzkonzepte erforderlich. Allerdings ist es bislang aufgrund der komplexen Wechselwirkungen in natürlichen Fließgewässern mit Vegetation nicht möglich, die Wirksamkeit von naturnahen Maßnahmen in hoher räumlicher Auflösung bereits im Planungsstadium abzuschätzen. Der Hauptbeitrag der Arbeit liegt auf der Entwicklung einer Methode zur Identifikation, Analyse und Bewertung der Gefährdung durch morphodynamische Prozesse in kiesführenden Fließgewässern. Im Stand des Wissens werden die komplexen dreidimensionalen Wirkungszusammenhänge zwischen Flussgeometrie, Strömung, Sedimenttransport und Vegetation erläutert. Das neue Konzept umfasst zunächst die Phase der Risiko-Identifikation, in der die Hydromorphologie des Flusssystems charakterisiert und die Risikoelemente sowie potenziell gefährdende morphodynamische Prozesse ermittelt werden. In der Gefährdungsanalyse wird ein neuartiger gekoppelter 1D/3D-Modellansatz zur Simulation der Hydrodynamik entwickelt, der die Rauheitswirkung von Vegetation über einen physikalisch-basierten Ansatz berücksichtigt. Zur Abschätzung der morphodynamischen Reaktion werden für jedes Risikoelement geeignete analytische Stabilitätsansätze und ein neuer Ansatz zur Bestimmung des Transportverhaltens mitgeführter Sedimente herangezogen. Langfristige Betrachtungen werden mithilfe der Regimetheorie ermöglicht. Zentrale Bedeutung liegt auf der Kalibrierung und Validierung der verwendeten Methoden und der Prüfung der Ergebnisse auf Plausibilität durch Felddaten. Das Konzept wird anhand eines Fallbeispieles am Oberrhein überprüft. Es zeigt sich, dass es mithilfe der neuen Methode möglich ist, die morphodynamischen Prozesse in komplexen Fließgewässern mit Vegetation plausibel abzuschätzen. Das entwickelte Konzept kann einen Beitrag zur Wirksamkeit und Nachhaltigkeit von naturnahen Hochwassermaßnahmen leisten und zur Planungsoptimierung eingesetzt werden

A combined modelling approach for simulating channel–wetland exchanges in large African river basins

In Africa, many large and extensive wetlands are hydrologically connected to rivers, and their environmental integrity, as well as their influence on downstream flow regimes, depends on the prevailing channel–wetland exchange processes. These processes are inherently complex and vary spatially and temporally. Understanding channel–wetland exchanges is therefore, indispensable for the effective management of wetlands and the associated river basins. However, this information is limited in most of the river basins containing large wetlands in Africa. Furthermore, it is important to understand the links between upstream and downstream flow regimes and the wetland dynamics themselves, specifically where there are water resource developments that may affect these links (upstream developments), or be affected by them (downstream developments). Hydrological modelling of the entire basin using basin-scale models that include wetland components in their structures can be used to provide the information required to manage water resources in such basins. However, the level of detail of wetland processes included in many basin-scale models is typically very low and the lack of understanding of the wetland dynamics makes it difficult to quantify the relevant parameters. Detailed hydraulic models represent the channel-wetland exchanges in a much more explicit manner, but require relatively more data and time resources to establish than coarser scale hydrological models. The main objective of this study was, therefore, to investigate the use of a detailed hydraulic wetland model to provide a better understanding of channel–wetland exchanges and wetland dynamics, and to use the results to improve the parameterisation of a basin-scale model. The study focused on improving the water resource assessments modelling of three data-scarce African river basins that contain large wetlands: the floodplains of the Luangwa and Upper Zambezi River basins and the Usangu wetland in the Upper Great Ruaha River basin. The overall objective was achieved through a combined modelling approach that uses a detailed high-resolution LISFLOOD-FP hydraulic model to inform the structure and parameters of the GW Pitman monthly hydrological model. The results from the LISFLOOD-FP were used to improve the understanding of the channel–wetland exchange dynamics and to establish the wetland parameters required in the GW Pitman model. While some wetland parameters were directly quantified from the LISFLOOD-FP model results, others, which are highly empirical, were estimated by manually calibrating the GW Pitman wetland sub-model implemented in excel spreadsheets containing the LISFLOOD-FP model results. Finally, the GW Pitman model with the inclusion of the estimated wetland parameters was applied for each basin and the results compared to the available downstream observed flow data. The two models have been successfully applied in southern Africa, with the GW Pitman model being one of the most widely applied hydrological models in this region. To address the issue of data scarcity, during setup of these models, the study mainly relied on the global datasets which clearly adds to the overall uncertainty of the modelling approach. However, this is a typical situation for most of the data scarce regions of the continent. A number of challenges were, however, faced during the setup of the LISFLOOD-FP, mainly due to the limitations of the data inputs. Some of the LISFLOOD-FP data inputs include boundary conditions (upstream and downstream), channel cross-sections and wetland topography. In the absence of observed daily flows to quantify the wetland upstream boundary conditions, monthly flow volumes simulated using the GW Pitman monthly model (without including the wetland sub-model) were disaggregated into daily flows using a disaggregation sub-model. The simulated wetland inflows were evaluated using the observed flow data for downstream gauging stations that include the wetland effects. The results highlighted that it is important to understand the possible impacts of each wetland on the downstream flow regime during the evaluations of the model simulation results. Although the disaggregation approach cannot be validated due to a lack of observed data, it at least enables the simulated monthly flows to be used in the daily time step hydraulic model. One of the recommendations is that improvements are required in gauging station networks to provide more observed information for the main river and the larger tributary inflows into these large and important wetland systems. Even a limited amount of newly observed data would be helpful to reduce some of the uncertainties in the combined modelling approach. The SRTM 90 m DEM (used to represent wetland topography) was filtered to reduce local variations and noise effects (mainly vegetation bias), but there were some pixels that falsely affect the inundation results, and the recently released vegetation-corrected DEMs are suggested to improve the simulation results. Channel cross-section values derived from global datasets should be examined because some widths estimated from the Andreadis et al. (2013) dataset were found to be over-generalised and did not reflect widths measured using high-resolution Google Earth in many places. There is an indication that channel cross-sections digitised from Google Earth images can be successfully used in the model setup except in densely vegetated swamps where the values are difficult to estimate, and in such situations, field measured cross-section data are required. Small channels such as those found in the Usangu wetland could play major role in the exchange dynamics, but digitising them all was not straightforward and only key ones were included in the model setup. Clearly, this inevitably introduced uncertainties in the simulated results, and future studies should consider applying methods that simplify extractions of most of these channels from high-resolution images to improve the simulated results. The study demonstrated that the wetland and channel physical characteristics, as well as the seasonal flow magnitude, largely influence the channel–wetland exchanges and wetland dynamics. The inundation results indicated that the area–storage and storage–inflow relationships form hysteretic curves, but the shape of these curves vary with flood magnitude and wetland type. Anticlockwise hysteresis curves were observed in both relationships for the floodplains (Luangwa and Barotse), whereas there appears to be no dominant curve type for the Usangu wetlands. The lack of well-defined hysteretic relationships in the Usangu could be related to some of the difficulties (and resulting uncertainties) that were experienced in setting up the model for this wetland. The storage–inflow relationships in all wetlands have quite complex rising limbs due to multiple flow peaks during the main wet season. The largest inundation area and storage volume for the Barotse and Usangu wetlands occurred after the peak discharge of the wet season, a result that is clearly related to the degree of connectivity between the main channel and those areas of the wetlands that are furthest away from the channel. Hysteresis effects were found to increase with an increase in flood magnitudes and temporal variations in the wetland inflows. Overall, hysteresis behaviour is common in large wetlands and it is recommended that hysteresis curves should be reflected in basin-scale modelling of large river basins with substantial wetland areas. At a daily time scale, inflow–outflow relationships showed a significant peak reduction and a delayed time to peak of several weeks in the Barotse and Usangu wetlands, whereas the attenuation effects of the Luangwa floodplain are minimal. To a large extent, the LISFLOOD-FP results provided useful information to establish wetland parameters and assess the structure of Pitman wetland sub-model. The simple spreadsheet used to estimate wetland parameters did not account for the wetland water transfers from the upstream to the next section downstream (the condition that is included in the LISFLOOD-FP model) for the case when the wetlands were distributed across more than one sub-basin. It is recommended that a method that allows for the upstream wetland inflows and the channel inflows should be included in the spreadsheet. The same is true to the Pitman model structure, and a downstream transfer of water can be modelled through return flows to the channel. The structure of the wetland sub-model was modified to allow an option for the return flows to occur at any time during the simulation period to provide for types of wetlands (e.g. the Luangwa) where spills from the channel and drainage back to the channel occur simultaneously. The setup of the GW Pitman model with the inclusion of wetland parameters improved the simulation results. However, the results for the Usangu wetlands were not very satisfactory and the collection of additional field data related to exchange dynamics is recommended to achieve improvements. The impacts of the Luangwa floodplain on the flow regime of the Luangwa River are very small at the monthly time scale, whereas the Barotse floodplain system and the Usangu wetlands extensively regulate flows of the Zambezi River and the Great Ruaha River, respectively. The results highlighted the possibilities of regionalising some wetland parameters using an understanding of wetland physical characteristics and their water exchange dynamics. However, some parameters remain difficult to quantify in the absence of site-specific information about the water exchange dynamics. The overall conclusion is that the approach implemented in this study presents an important step towards the improvements of water resource assessments modelling for research and practical purposes in data-scarce river basins. This approach is not restricted to the two used models, as it can be applied using different model combinations to achieve similar study purpose

Publicationes Instituti Geographici Universitatis Tartuensis 110

Lifelong Learning ProgrammeAntti Roose: Progressing water geography discourses in the framework of the Erasmus seminar series - Silvia Piovan and Pierpaolo Faggi: The tradition of the European Seminar on Geography of Water in Padova: Experience in research and training - Leandro del Moral, Maria Fernanda Pita, Belén Pedregal, Nuria Hernández-Mora, Natalia Limones: Current paradigms in the management of water: Resulting information needs - Arvo Järvet: Morphological assessment of the quality of running water bodies for water management planning - Milada Matoušková and Kateřina Šmerousová: Hydromorphological reference condition of streams based on the European Water Framework Directive - Andrea Corsale and Giovanni Sistu: The changing relations among resources, communities and institutions in Sardinian wetlands - Franca Battigelli and Andrea Guaran: Drinking water(s) in Italy: Bottled, tap or kiosk water? - Levente Ronczyk, Szabolcs Czigány, Zoltan Wilhelm: Urban water damages in Pécs triggered by extreme weather events - Daniela Zlatunova and Panka Babukova: Flood risk assessment – a basis for sustainable spatial development. Case study: the Republic of Bulgaria - Chronicle of European seminars of water geography 2005–2014:Tartu 2005, Sevilla 2006, Sofia 2008, Udine 2009, Cluj-Napoca 2010, Cagliari 2011, Munich–Fischbachau 2012, Zadar 2013, Padova 201

Cottonwood Management Plan/Programmatic Environmental Assessment Proposed Implementation of a Cottonwood Management Plan Along Six Priority Segments of the Missouri River

The U.S. Army Corps of Engineers (Corps) proposes to preserve existing stands and reestablish new stands of plains cottonwood (Populus deltoides) at selected public/government lands along the Missouri River in accordance with the Cottonwood Management Plan (CMP). The Proposed Action is the implementation of the CMP. The goal of the plan is to be a living document that preserves, creates, or restores cottonwood habitats along the Missouri River and meets the requirements of the USFWS 2003 Amended Biological Opinion (BiOp) concerning the bald eagle (Haliaeetus leucocephalus). The principal immediate focus of the CMP includes measures in the following segments: • Segment 4: Garrison Dam to Lake Oahe Headwaters near Bismarck, North Dakota (RM 1389.9 – RM 1304.0) • Segment 6: Oahe Dam to Big Bend Dam (RM 1072.3 – RM 987.4) • Segment 8: Fort Randall Dam to Niobrara River (RM 880.0 – RM 845.0) • Segment 9: Niobrara River to Lewis & Clark Lake, including the Lake (RM845.0 – RM 811.1) • Segment 10: Gavins Point Dam to Ponca, Nebraska (RM 811.1 – RM 753.0) • Segment 13: Platte River mouth to Kansas City, Missouri (RM 595.5 – RM 367.5) The programmatic Environmental Assessment (EA) evaluated the potential impacts of cottonwood management along the Missouri River; however, site-specific environmental review, in the form of EAs, are anticipated in the future prior to implementation of the techniques suggested in the CMP in any segment