Fundação de Amparo a Pesquisa no Estado do Rio Grande do Sul / The sediment yield causes a number of problems, and among them stands out silting of rivers and reservoirs, and contamination of surface water. Sediments result from the processes of erosion, transport, storage and compression. They depend on the physical characteristics of the watershed, as well as soil use and land cover. To study the sediment yield of a river is important to estimate the amount and origin of the sediments transported and deposited in a watershed. Therefore, it is possible to obtain knowledge about the unit of study, which leads to better planning and use of water resources. From liquid and solid discharge measurements in a river section, and conducting a sedimentometrical balance in Vacacaí Mirim reservoir, located at Santa Maria, Rio Grande do Sul, Brazil, the objective of this research is to characterize the sediment yield of a small watershed. The methodology was based on two stages: the first one was about the sedimentometrical characterization of the study area, and it was carried out between January and November of 2014, with the continuous monitoring of flow and sediments in fluviossedimentometrical station João Goulart, whose laboratory samples were also characterized and had their sediment concentration determined; the second stage was about the execution of sedimentometrical balance in the reservoir with the help of HEC-HMS 4.0 modeling program. Sediment entries, storage and output were checked in Vacacaí Mirim reservoir, which influences the study area. The results for the hydrossedimentometrical monitoring were satisfactory, getting a key curve with determination coefficient of 0.96; sedimentometrical curves ranged from 0.93 to 0.98; concentration ratio between suspended sediment and turbidity was 0.84, being considered acceptable; particle size characteristics were predominantly silt, for suspended material, and sand, for dragged material. Balance calibration for sedimentometrical hydrologic model gave a Nasch-Sutcliffe between 0.13 to 0.53 and 0.44 in validation; about reservoir sediments balance, it was noted and therefore considered that all sediment that enters the reservoir is retained and more sediment is produced downstream thereof mouth of the river it reaches the watershed. / A produção de sedimentos ocasiona uma série de problemas, entre eles destacam-se assoreamento dos rios e reservatórios e contaminação das águas superficiais. Os sedimentos são resultado dos processos de erosão, transporte, depósito e compactação. Dependem das características físicas da bacia hidrográfica e do uso e ocupação do solo. Estudar a produção de sedimentos em um rio é importante para estimar a quantidade e a origem dos sedimentos transportados e depositados em uma bacia hidrográfica, podendo assim, obter conhecimento da unidade de estudo e realizar um melhor planejamento e aproveitamento dos recursos hídricos. O objetivo desta pesquisa é de caracterizar a produção de sedimentos de uma pequena bacia hidrográfica, a partir de medições de descarga líquida e sólida na seção do rio e realizar um balanço sedimentométrico no reservatório do Vacacaí Mirim no município de Santa Maria. A metodologia se baseou em duas etapas: primeira etapa foi à realização da caracterização sedimentométrica da área de estudo com o monitoramento contínuo das vazões e sedimentos na estação fluviossedimentométrica João Goulart no período de janeiro a novembro de 2014 e na determinação da concentração de sedimentos e caracterização das amostras em laboratório; a segunda etapa foi à realização do balanço sedimentométrico no reservatório com o auxílio do programa de modelagem HEC-HMS 4.0 onde foram verificados as entradas, armazenamento e saída de sedimentos no reservatório Vacacaí Mirim que influencia a área de estudo. Os resultados obtidos para o monitoramento hidrossedimentométrico foram satisfatórios, obtendo uma curva-chave com coeficiente de determinação de 0,96; as curvas sedimentométricas variando de 0,93 a 0,98; a relação da concentração de sedimentos em suspensão e a turbidez foi de 0,84 sendo consideradas aceitáveis; as características granulométricas do material em suspensão foi predominante o silte e para o material em arraste foi à areia. Para o balanço sedimentométrico a calibração hidrológica do modelo obteve-se um Nasch-Sutcliffe entre 0,13 a 0,53 e na validação de 0,44; as considerações observadas no balanço de sedimentos no reservatório foram que todo o sedimento que entra fica retido no reservatório e é produzido mais sedimentos a jusante do mesmo que chega até o exutório da bacia.

This thesis evaluates the effectiveness of several flood mitigation strategies for reducing peak discharges in the Upper Cedar River Watershed located in northeast Iowa. Triggered by record flooding in June 2008, the Iowa Watersheds Project was formed to evaluate and construct projects for flood reduction. The Upper Cedar was selected as a pilot watershed and a hydrologic assessment was performed to better understand its flood hydrology. Evaluation of different flood mitigation strategies was performed with HEC-HMS, a lumped parameter surface water model. The hydrologic model development is described and the model applications are analyzed. The HMS model was used in several ways to better understand the flood hydrology of the Upper Cedar River Watershed. First, the runoff potential of the basin was assessed to identify the primary runoff generation mechanisms. Areas with agricultural land use and moderately to poorly draining soils had the highest runoff potential. Following, the model was used to evaluate the impact of several flood mitigation strategies - increased infiltration through land use changes, increased infiltration through soil improvements, and added storage in the watershed to hold runoff temporarily and reduce downstream flood peaks - for different flood frequency events (the 10-, 25-, 50-, and 100-year, 24-hour design rain storms) and the June 2008 flood. Although each scenario is hypothetical and simplified, they do provide benchmarks for the types of reductions physically possible and the effectiveness of strategies relative to one another. In order to reduce the impacts of flooding in the Upper Cedar, a combination of projects that enhance infiltration and/or store excess runoff will be necessary.

En stor del av Sportfiskarnas arbete handlar om att återställa den ursprungliga morfologin i vattendrag efter påverkan av främst jordbruk. Sådana återställningar kan exempelvis göras genom att återföra rensat material i form av block och sten till vattendragen samt att rätade sträckor återmeandras. Syftet med sådana åtgärder är ofta att hålla kvar vattnet i landskapet och uppnå jämnare flöden i vattendragen, för att vårda eller bevara den naturliga biotopen. Inom det biotopvårdande arbetet utgörs en del av arbetet av att uppskatta de hydrauliska effekterna av aktuella åtgärder i vattendraget. I många scenarion tillämpas Mannings formel för att beräkna och uppskatta dessa effekter.   Det här projektet som utförs inom ramen för sportfiskarnas projekt Hydrologisk restaurering av Södertörns avrinningsområden, utreder vanliga biotopvårdande åtgärder och dess hydrauliska effekter genom upprättandet av hydrauliska flödesmodeller i HEC-RAS. De simulerade effekterna jämförs med beräknat resultat utifrån Mannings formel för att utreda värdet av upprättande av modell relativt de konventionella beräkningarna. Metodiken utgjordes av en mindre initial litteraturstudie följt av inmätningar av bottennivå och vattennivå i de aktuella flödessträckorna varpå flödesmodeller för respektive objekt upprättades. Flödessträckan i Hågaån utgjorde objektet för jämförelse mellan modell och konventionella beräkningar. Återmeandring visade sig vara den mest lämpade åtgärden för att erhålla en sänkt hastighet och ett ökat djup över en längre sträcka. Utplacering av sten i vattendraget kunde konstateras ha lokalt avgränsade effekter i form av ett mer turbulent flödestillstånd. Även ett ökat djup samt minskad hastighet kunde i varierande omfattning erhållas i sektioner med utplacerade stenar. De hydrauliska effekterna av den upprättade våtmarken speglas av en lokalt sänkt hastighet och minskat djup. Mannings formel visade sig generera mycket liknande resultat som modellen för åtgärden utplacering av sten. För återmeandring erhölls lite större skillnad i resultatet som troligtvis beror på felaktigheter i den geometriska beskrivningen av fårans tvärsnitt. Intressanta uppslag för fortsatta studier inom området är att jämföra resultat med inmätningar i fält efter utförd åtgärd samt att jämföra metoderna för fler olika objekt och scenarion. / A significant part of the work process at Sportfiskarna consists of restoring the original morphology of waterways after, mainly the influence of agriculture. Such restorations can be made, for example, by restructuring straightened waterways and it may also include replacing material, like blocks of stone, that has been removed from the waterways in the past. The purpose of such measures is often to retain the water in the landscape and achieve more moderate flow variations in the waterways to preserve and promote the natural biotope. This work includes estimating the hydraulic effects of intended measures in the waterways. In many scenarios, Manning’s formula is applied to calculate and estimate these effects.  This study is performed within the context of the ongoing project, Hydrological restoration of the catchment areas at Södertörn, run by Sportfiskarna. Common measures and their hydraulic effects are investigated through the establishment of hydraulic flow models in HEC-RAS. The simulated effects are compared with calculated results from using Manning’s formula to investigate the value of establishing a model compared to the conventional calculations. A minor initial literature study was performed followed by measurements of bottom- and water level in the investigated flow sections whereupon flow models for each object were established. Hågaån was chosen as the object for comparison between model and conventional calculations. Restructuring straightened waterways proved to be the most suitable measure to obtain a reduced speed and an increased depth over a longer distance. Replacing blocks of stone in the waterways could be observed to have locally delimited effects in the form of a more turbulent flow condition. Increased depth and reduced speed could also be obtained in the sections with replaced stones. The hydraulic effects of the established wetland are displayed in a locally reduced speed and reduced depth. Manning’s formula proved to generate very similar results as the model for the replacement of stones measure. For restructuring straightened waterways, a slightly larger difference was obtained in the result which is probably due to inaccuracies in the geometric description of the cross section in the waterway. Suggestions for further studies are to compare results with measurements in the field after the measure has been performed and also to compare the methods for several different objects and scenarios.

The master’s thesis deals with the hydraulic analysis of the water flow capacity for the flood flow on the river Litava in the river kilometres 11,550 – 18,315 using the HEC-RAS 5.0.5 specifically 1D-2D numerical model. On the basic of flood areas, depths and speeds the results were evaluated and subsequently was created own proposal flood protection.

The diploma thesis is focused on the proposal of systematic revitalization of the selected section of the Knínický brook in the cadastral area of Veverské Knínice. It is a straight, very deep channel due to technical adjustments in the past. The HEC-RAS program verifies the capacity of the channel for the Q100 flow. In this way, it was found that the channel has very high capacity so a new route with Q1 flow capacity was designed. Due to the height conditions, the design also included three boulder chutes. Subsequently, the vegetation accompaniment and bank stands were suitably supplemented.

Continuing development of the Virginia Tech campus is increasing downstream flooding and water quality problems. To address these problems, the University has proposed the construction of a stormwater management facility to control the quantity and quality of stormwater releases to Strouble Creek, a tributary of the New River. The overall goal of this project is to design a stormwater management facility proposed for the Virginia-Maryland College of Veterinary Medicine at Virginia Tech in Blacksburg, Virginia that will reduce present and anticipated downstream flooding and water quality problems. Specific objectives of the project are: * control of flooding in lower areas by reducing the peak discharge while disturbing existing wetlands as little as possible, * address removal of major NPS pollutants such as total phosphorus (TP), total nitrogen (TN), metals, organic compounds related to petroleum and gasoline, and suspended sediment (SS) from stormwater runoff, and * design of a dam system that is able to withstand all driving forces and constructed in accordance with governing regulations. The design requirement to limit wetland disturbance below one acre was maintained. The requirement set by officials of Virginia Tech is based on the Nationwide Permit 26 of the Wetland Regulations. An individual permit process is thus avoided. Considering this demand, however, the freedom of the stormwater management facility design was significantly restricted. Resulting from the previous restrictions mentioned, the facility will include two ponds in series - a lower, dry pond and an upper, wet pond. The stormwater management system is designed to reduce the peak discharge. The dry pond is designed to detain water only for a short period of time, as opposed to the wet pond which is designed to retain water, thereby maintaining a permanent pool of water, and to change the characteristics of runoff. The wet pond was chosen to be of an Extended Detention wetland type. Aspects such as the availability of suitable area and detention volume governed the decision to make use of this type of stormwater wetland. The constraint on a maximum possible water surface elevation due to the Veterinary School1s road embankment, which crest elevation is at 2023 ft, was considered in the design. The stormwater management facility was designed to meet water quantity control requirements and to address water quality benefits. Storm water management regulations intending to mitigate the adverse effects of land development to streams and waterways were met. Requirements to limit peak discharges from 2-year and 10-year events to existing discharge levels were achieved. Several outlet structures for each of the ponds were investigated. The structures proposed are a perforated riser/broad-crested weir for the wet pond and a proportional weir for the dry pond. They were chosen as a result of analyses on hydraulic performance, maximum water surface elevations, drawdown times, peak discharge rates, and pollutant removal capabilities. The average pollutant removal capability of 75% of TSS, 45% TP, and 25% TN for an extended stormwater wetland, as found in the literature, is expected to be lower for the proposed facility, since the wetland-to-watershed-area ratio is considerably smaller (0.22%) than the required minimum ratio of 1%. However, other suggested desirable parameter for extended detention wetland systems such as required treatment volume, effective flow path length, and dry weather water balance will be maintained. The structural design of the dams was based on experience and research data. The dams are designed to consist of two zones, shell and core. The core extends as a cutoff trench 4 feet below the ground surface. Additionally, toe drain trenches and anti-seep collars along the pipe where penetrating the dam will be placed to collect and reduce seepage, respectively. Special considerations toward seepage problems were taken into account for both dams by placing a cutoff trench and a toe drain trench. Note: The appendix of this project report contains four AutoCAD files, that can only be viewed using AutoCAD. / Master of Engineering

Hydrological extremes associated with climate change are becoming an increasing concern all over the world. Frequent flooding, one of the extremes, needs to be analyzed while considering climate change to mitigate flood risk. This study forecasted streamflow and evaluated the risk of flooding in the Neuse River, North Carolina considering future climatic scenarios, and comparing them with an existing Federal Emergency Management Agency (FEMA) flood insurance study (FIS) report. The cumulative distribution function transformation (CDF-t) method was adopted for bias correction to reduce the uncertainty present in the Coupled Model Intercomparison Project Phase 6 (CMIP6) streamflow data. To calculate 100-year and 500-year flood discharges, the Generalized Extreme Value (GEV) (L-Moment) was utilized on bias-corrected multimodel ensemble data with different climate projections. The delta change method was applied for the quantification of flows, utilizing the future 100-year peak flow and FEMA 100-year peak flows. Out of all projections, shared socio-economic pathways (SSP)5-8.5 exhibited the maximum design streamflow, which was routed through a hydraulic model, the Hydrological Engineering Center’s River Analysis System (HEC-RAS), to generate flood inundation and risk maps. The result indicates an increase in flood inundation extent compared to the existing study, depicting a higher flood hazard and risk in the future. This study highlights the importance of forecasting future flood risk and utilizing the projected climate data to obtain essential information to determine effective strategic plans for future floodplain management.

Dams are amongst the most important components of water resource systems. In many places the water regulated by and stored in dams is essential to meet the development objectives of water supply, flood control, agriculture (i.e. irrigation and livestock), industry, energy generation and other sectors. Previous studies (Gourbesvive, 2008) indicate that in the next 30 years water use will increase by 50% in the world. By 2025 about 4 billion people will live under conditions of severe water stress. Continuous deterioration in water quality in most developing countries is additional challenge. Therefore, development of priority water infrastructures and improvements of water management have essential and complementary roles in contributing to sustainable growth and energy reduction in developing countries like Sweden. One way of improving water management is through increasing the efficiency of utilization of dam reservoirs (Bosona, 2010). Reservoir operation is a complex task involving numerous hydrological, technical, economical, environmental, institutional and political considerations. There is no general algorithm that covers all type of reservoir operation problems. The choice for techniques usually depends on the reservoir specific system characteristics, data availability, the objectives specified and the constraints imposed. Goal of the mathematical modelling and simulation of a physical system is to provide the user with the relevant information used in design and/or management decision-making. However, in the absence of adequate foresight and planning for adverse impacts, past dam construction has often resulted in devastating effects for ecosystems and the livelihoods of affected communities. In this project with Hec-ResSim simulation model four reservoirs in Ore River Basin and 3 reservoirs in Lule River Basin in different location in Sweden are considered and by new operation rules, model is simulated. With consideration of two high floods event model is calibrated and new operation rules for flood control and hydropower melioration was rendered and suggested.

Water levels up- and downstream of dams are strongly affected by water levels in the reservoir as well as the discharge of the dam. To ensure that no harm comes to buildings, bridges or agricultural land it is important to ensure that the water level in the reservoir is adjusted to handle large floods. This report studies within what range the water level in the reservoir of the Yayangshan dam, located in Lixian River, can vary without causing any flooding downstream the dam or at the Old and New Babian Bridge located upstream the dam. By calculation of the designed flood, flood routing- and backwater computation, initial water level ranges in the reservoir have been set for the pre-flood, main flood and latter flood season for damages to be avoided. Due to the far distance between the dam site and the bridges, backwater effects had no influence on the limitations of the initial water level in the reservoir.

Emulsion polymerizations of vinyl acetate (VAc) were performed by fully or partially replacing poly(vinyl alcohol) (PVA) with renewable materials as protective colloids or by adding renewable materials, as additives or fillers, to the emulsions during or after polymerization. The purpose of the study was to increase the amount of renewable materials in the emulsion. A total of 19 emulsions were synthesized. Different recipes were used for the synthesis. The following renewable materials were studied; hydroxyethyl cellulose (HEC) with different molecular weights, starch and proteins. HEC and starch were used as protective colloids. Proteins were used as additives or fillers. Cross-linking agent A and Cross-linking agent B were used as cross-linking agents. A total of 26 formulations were pressed, either cold or hot. The synthesized emulsions were evaluated with respect to pH, solids content, viscosity, minimum film formation temperature (MFFT), glass transition temperature (Tg), particle size and molecular weight (Mw). The tensile shear strengths of the emulsions were evaluated according to EN 204 and WATT 91. It was possible to fully, or partially, replace PVA as protective colloid with renewable materials. It was also possible to use renewable materials as additives or fillers in the emulsions. The emulsions obtained properties that differed from the reference. Generally, emulsions with HEC as protective colloid showed lower viscosity and slightly higher MFFT, Tg and molecular weight than emulsions with PVA as protective colloid. Larger particle sizes than the reference were obtained for emulsions containing PVA combined with renewable materials. The emulsion with starch as protective colloid exhibited the largest particle size. 10 formulations passed the criteria for D2. The emulsions where PVA was fully or partially replaced with HEC or starch showed a water resistance similar to the reference (around D2). The addition of protein did not decrease the water and heat resistance compared to the reference. Addition of protein after polymerization increased the water resistance (D2) compared to addition during polymerization. Addition of cross-linking agents did not increase the water resistance further. Two formulations passed the criteria for D3. The emulsion in the first formulation had PVA as protective colloid and protein B was added during polymerization. The emulsion in the second formulation had HEC as protective colloid. To both of these emulsions, protein A was added after polymerization, as a filler, combined with Cross-linking agent B as cross-linking agent before hot pressing. The first formulation also showed a good heat resistance (passed the criteria for WATT 91).