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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Stream monitoring using near-infrared spectroscopy of epilithic material

Persson, Jan January 2007 (has links)
The European Union Water Framework Directive (WFD), with initiatives to manage surface water resources, has increased the need for fast and inexpensive methods for monitoring conditions in streams. The objective of this thesis is to assess the potential of near-infrared spectroscopy (NIRS) of epilithic material to become such method. NIRS, which is a technique that is commonly used in industry for process monitoring and quality control of products, registers the chemical properties of organic material on a molecular level. Epilithic material, i.e. the layer of dead and alive material that covers stone surfaces in streams, is continuously influenced by the stream water that flows over it, and it has the potential to integrate chemical and biological conditions over time. The temporal integration is a significant factor, since conditions in streams can change within hours or days. The thesis consists of two published papers. In the first paper a new sampler for epilithic material, the Stone Brusher, was described and the performance evaluated. The Stone Brusher is designed to take qualitative or semi-quantitative samples of epilithic material from stones at 7–50 cm water depth. The epilithic material is dislodged from the stone surface with a rotating brush enclosed in a chamber, and the material is drawn up directly into the sample bottle with an air-cylinder. The operator takes a sample quickly and without putting hands into the water. The sampler is made of plastic, stainless steel and aluminium and weighs 3.1 kg. It is designed to meet the demand for standardized sampling for research and environmental monitoring and to improve working conditions for sampling personnel. The equipment allows sampling from surfaces of bedrock and large stones that cannot be lifted from the bottom. Using data of near-infrared spectroscopy and diatom analyses, this new sampler was evaluated in comparison to the toothbrush method, a primitive method which is the current standard in EU. The results indicate that the Stone Brusher reduces sampling variability compared with the toothbrush method. In the second paper, the Stone Brusher was used to collect epilithic material from 65 sites (42 uncontaminated and 23 contaminated) from streams in the widespread mining area called the Skellefte-district in Västerbotten, northern Sweden, in order to test the hypothesis that impact on the epilithic material caused by emissions from mining and mining-related industries can be detected using NIRS. The epilithic material was filtered onto glass fibre filters, measured by NIRS, and the results were modelled using Principal Component Analysis (PCA). The NIRS approach was evaluated by comparing it with the results of chemical and diatom analyses of the same samples. Based on PCA, the NIRS data distinguished contaminated from uncontaminated sites and performed slightly better than chemical analyses and clearly better than diatom analyses. Of the streams designated a priori as contaminated, 74 % were identified as contaminated by NIRS, 65 % by chemical analysis and 26 % by diatom analysis. Unlike chemical analyses of water or of epilithic material samples, NIRS data reflect biological impacts in the streams. Given that, and the simplicity of NIRS-analyses, further studies to assess the use of NIRS of epilithic material are justified. NIRS has the potential to become a fast method for screening in regions where large numbers of streams occur to find impacted streams or as a routine method for temporal monitoring in selected streams for early detection of environmental impact, similar to process monitoring in industry.
42

Managing agricultural nutrient leaching within the EC Water Framework Directive in Sweden

Bratt, Anna-Lena January 2003 (has links)
Agricultural management practices geared towards reducing nutrient leaching are in focus for the research presented in this thesis. Critical measures for reducing diffuse pollution from the agricultural sector depend on decisions of individual farmers. It is useful to take stock of what different stakeholders are actually doing to reduce nutrient leaching and analyze their reasoning before defining a new administrative process. Stakeholder perceptions about potentials and problems concerning management of agricultural practices are analyzed with a systems approach using various analytical methods, and put in relation to the implementation of EC Water Framework Directive in Sweden. The methods used include surveys, focus group interviews, model comparison, sensitivity analyses and analyses of climate change implications. The results indicate a general positive attitude among stakeholders towards the main characteristics of the newly introduced directive. They also reveal that a move towards a pro-active process was perceived as an additional positive factor for the improvement of water quality, where specific activities and measures are carried out according to planning based on local assessments. The respondents pointed out that a national approach would put necessary pressure on local politicians to define environmental objectives and provide resources to fulfil them. The current findings indicate that decision making for farmers is a complex procedure and that the different factors need to be addressed in order to obtain a change in agricultural practices. Consistent legislation that is clear about power and rights is fundamental for cooperation to function when volunteerism and enthusiasm are absent. Environmental and socio-economic conditions change constantly, and administration has to be flexible to be able to adapt. Having access to and being able to use relevant data is only one important factor for stakeholder involvement. To give farmers the opportunity to further develop production towards reduced nutrient losses, appropriate information provided in all the right arenas is crucial.
43

Många bäckar små, blir det bättre då? : En studie om den småskaliga vattenkraftens för- och nackdelar ur ett miljöperspektiv

Östlund, Simon January 2014 (has links)
Idag står vi inför flera miljöproblem som exempelvis klimatpåverkan och förlust av biologisk mångfald. Vattenkraften är en förnybar energikälla som kan producera el med låga utsläpp av växthusgaser. Sverige har en lång tradition av att utnyttja vattnet som energikälla och har det senaste århundradet byggt ut en majoritet av de svenska vattendragen med vattenkraftverk. Idag står vattenkraften för nästan hälften av Sveriges elproduktion och bidrar till Sveriges låga utsläpp av växthusgaser. Samtidigt anses vattenkraften påverka den biologiska mångfalden och vattendragen negativt. Av ungefär 2100 kraftverk står de 200 största för över 90 % av elproduktionen. Det finns alltså ett stort antal småskaliga kraftverk som bidrar med en liten del elproduktion samtidigt som de riskerar att påverka vattendragen negativt. Syftet med den här studien var att undersöka om elproduktionen från småskalig vattenkraft är försvarbar sett till dess miljöpåverkan. Studien använde en kvalitativ metod baserad på semi-strukturerade intervjuer med följande intressenter inom småskalig vattenkraft: Svensk Energi, Svensk Vattenkraftförening, Energimyndigheten, Havs- och Vattenmyndigheten, Naturskyddsföreningen, Sportfiskarna samt Älvräddarna. Resultaten visade att småskalig vattenkraft är en billig och etablerad energikälla, den kan bidra med kulturella värden, den är lokalt producerad och konsumerad som kan ge en ökad stabilitet till elnätet samt minska distributionsförluster. Nackdelarna visar att småskalig vattenkraft saknar några av de viktigaste funktionerna som storskalig vattenkraft kan bidra med: reglering av elnätet samt möjlighet att lagra vatten som kan användas vid behov. Vidare kan småskalig vattenkraft anses ha en stor negativ påverkan på vattendragen och den biologiska mångfalden. Potentialen för småskalig vattenkraft kan också anses vara lägre än för övrig förnybar energi samtidigt som utvecklingen går långsammare. Lagstiftning, tillstånd och elcertifikatsystemet har även identifierats som faktorer som inte hjälper situationen för miljön i vattendragen. Behoven av att producera förnybar el från småskalig vattenkraft kan anses vara lägre än behovet av att värna om vattendragen och den biologiska mångfalden för att nå Sveriges miljökvalitetsmål och EU:s vattendirektiv. Det finns utrymme för att minska elproduktionen från småskalig vattenkraft och ändå nå miljöpolitiska mål om förnybar energi och vattenmiljö. Slutsatsen är att elproduktionen från småskalig vattenkraft inte är försvarbar sett till dess miljöpåverkan och att man bör undersöka möjligheten att ta bort de allra minsta kraftverken med störst miljöpåverkan. Det har också framkommit att det saknas ordentliga styrmedel för att främja biologisk mångfald och vattenmiljöer samt att synen på småskalig vattenkraft som miljövänlig bör ifrågasättas. / Today we face many environmental problems such as climate change and biodiversity loss. Hydropower is a renewable energy source that can produce electricity with low greenhouse gas emissions. Sweden has a long tradition of using water as an energy source and has during the past century built hydropower in a majority of the Swedish rivers. Today, hydropower accounts for nearly half of Sweden's electricity production and contributes to Sweden's low greenhouse gas emissions. But hydropower also affects biodiversity and water bodies negatively. Of the approximately 2100 hydropower plants in Sweden, 200 accounts for over 90% of the electricity production. Thus there are a large number of small-scale hydropower plants that contribute to a small portion of the electricity while they are liable to affect streams negative. The purpose of this study was to investigate whether electricity from small-scale hydropower is justifiable in terms of its environmental impact. The study used a qualitative method based on semi-structured interviews with the following stakeholders: Swedenergy, Swedish Hydropower Association, Swedish Energy Agency, Swedish Agency for Marine and Water Management, Swedish Society for Nature Conservation, Swedish Anglers’ Association and River Savers Association Sweden. The results showed that small-scale hydropower is a cheap and established energy source, it can also contribute with cultural values, it is locally produced and consumed that can give greater stability to the electricity grid and reduce distribution losses. The disadvantages show that small-scale hydropower lacks some of the key features that large-scale hydropower can provide: the regulation of the electricity grid and the ability to store water that can be used if necessary. Furthermore, small-scale hydropower is considered to have a major negative impact on streams and biodiversity. The potential for small-scale hydropower could also be considered lower than for other renewable energy while developing more slowly. Legislation, permits and electricity certificate system has also been identified as factors that do not help the environmental situation in streams. The need to produce renewable electricity from small-scale hydropower can be considered lower than the need to protect streams and biodiversity to reach Swedish environmental quality objectives and the Water Framework Directive. There is scope for reducing electricity production from small-scale hydropower and still achieve environmental policy objectives on renewable energy and streams and biodiversity. The conclusion is that electricity production from small-scale hydropower cannot be justified in terms of its environmental impact and that there is a need to examine the possibility of removing the smallest hydropower plants with the greatest environmental impact. It is also stressed that there is a lack of proper incentives to promote biodiversity and aquatic environments and that the view of small-scale hydropower as environmentally friendly should be questioned.
44

The impact of point source pollution on an urban river, the River Medlock, Greater Manchester

Medupin, Cecilia January 2017 (has links)
The River Medlock is a small (22km) urbanised river, and is one of the five main tributaries which forms part of the River Irwell Catchment in Greater Manchester, UK. The river has a legacy of pollution from the 18th century and continues to be affected by anthropogenic factors including point source pollution from waste water treatment works (WwTWs) and combined sewer overflows (CSOs). In order to investigate the impact of CSOs and the WwTWs on the river hydrology, water quality and ecology of the lower largely urbanised reach, data sets were obtained from the Environment Agency and from direct sampling of the river. Load estimations from continuous discharge records from the river's gauging station plus estimates of sub-catchment area indicate the lower sites, classified as a "highly modified water body" and downstream of treatment works had had a higher load of discharge and phosphate-P linked to point sources and episodic discharges. Short term, continuous monitoring revealed that CSOs were active during high velocity, but increased concentrations of nutrients post high velocity indicate WwTW effects and possibly diffuse sources. This project reveals that the WwTW are a major source of phosphate-P and that the impact of CSOs on the river quality is short-lived and depends on the degree of precipitation. Other parameters indicate good water quality although the benthic macroinvertebrate community is degraded as a result of episodic increases in the quantity of water destabilising the river bed. Therefore, pollution from the CSOs, the WwTW and rapid changes in discharge are the reasons for the river's failure to conform to EU's requirements of the Water Framework Directive.
45

ANALYSIS OF MONITORING NETWORK SPATIAL AND TEMPORAL REDUCTION AND THEIR CONSEQUENCES ON THE ECOLOGICAL CLASSIFICATION IN THE SCOPE OF WATER FRAME DIRECTIVE

Abramic, Andrej 15 May 2013 (has links)
La Directiva Marco Europea del Agua es la norma legislativa más importante que ha establecido la Comisión Europea, en materia de aguas, y constituye un importante avance para lograr una gestión sostenible del agua. Esta norma exige que todas las aguas, alcancen en el 2015 un status bueno e indica los pasos a seguir para conseguirlo, mediante el establecimiento de objetivos ecológicos y medioambientales en las mismas. Para concretar estos objetivos, la DMA ha establecido un sistema de indicadores biológicos, hidro-morfológicos y fisicoquímicos que determinan la calidad ecológica de las diferentes masas de agua. Para proporcionar una clasificación ecológica de las masas de agua costeras en la Comunidad Valencia existe una red de monitoreo costera que analiza la biomasa de fitoplancton, de forma indirecta a partir de la clorofila a. En las mismas, se establece la calidad de las aguas costeras en base al valor del percentil 90 del total de mediciones de clorofila a recogidas en sucesivas campañas mensuales durante un período de 5 años. Se ha considerado la posibilidad de reducir el número de campañas realizadas a lo largo del año y la posibilidad de reducir el número de estaciones revisadas en cada campaña y que consecuencias lleva esta reducción por estado ecológico. Los resultados del estudio exploratorio para la reducción temporal, muestran que una reducción no controlada en el número de campañas realizadas a lo largo del año en las aguas costeras valencianas, puede producir alteraciones impredecibles en su clasificación ecológica. Un estudio conjunto de las series pluviométricas, de oleaje, salinidad y clorofila a, para los tres climas marítimos presentes en las aguas costeras valencianas, ha permitido observar que el equilibrio trófico de los ecosistemas, en esta zona, depende tanto de la influencia antropogénica como de factores medioambientales determinados por la estacionalidad e irregularidad del clima. En base a ello, se han definido tres tipos de ecosistema / Abramic, A. (2011). ANALYSIS OF MONITORING NETWORK SPATIAL AND TEMPORAL REDUCTION AND THEIR CONSEQUENCES ON THE ECOLOGICAL CLASSIFICATION IN THE SCOPE OF WATER FRAME DIRECTIVE [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/28851 / Palancia
46

Surface irradiance estimations on watercourses with remote sensing data

Wessollek, Christine, Karrasch, Pierre, Kautz, Marie-Luise 13 August 2020 (has links)
The vegetation in the riparian zone of a watercourse in fluences the water state with multiple factors, first via direct substance discharge and secondly via shadow casting on the water surface. Shadowing directly regulates the solar radiant energy arriving at the water surface. Solar radiation input to aquatic environments is the most important abiotic factor for aquatic flora and fauna habitat development. Thus, to adequately asses the ecological state of water courses it is necessary to quantify the solar surface irradiance E (W=m2) arriving on the water surface. When estimating the solar surface irradiance the complex coherence between incoming solar radiation, atmospheric in uences, and spatial-temporal geometries need to be investigated. This work established a work flow to compute the solar surface irradiance for water bodies using different remote sensing data. The work flow was tested on regional level for a section of the river Freiberger Mulde, Saxony, for the year 2016. Product of the calculations is a map visualising the annual sum of the solar surface irradiance (kWh=m2) arriving on the Freiberger Mulde water surface and the surrounding terrain. Based on these information bio-hydrological issues can be further examinated.
47

Etablierung Entscheidungshilfesystem

Naumann, Sandra, Kurzer, Hans-Joachim 22 April 2010 (has links)
Zur Umsetzung der Ziele der EU-Wasserrahmenrichtlinie sind in Sachsen bis 2015 für Gewässereinzugsgebiete entsprechende Maßnahmen zur Erreichung bzw. Sicherung eines guten Gewässerzustandes durchzuführen. Für die hierzu erforderliche integrierte Planung und Entscheidungsfindung auf Einzugsgebietsebene stellen Entscheidungshilfesysteme den daran beteiligten Akteuren (Flächennutzer, -besitzer, Fachbehörden usw.) die technische Unterstützung bereit. Am Beispiel des überwiegend landwirtschaftlich genutzten Fließgewässereinzugsgebietes der Jahna (Sächsisches Lösshügelland) wurde ein Entscheidungshilfesystem entwickelt und erprobt. Es umfasst zum einen Werkzeuge zur Analyse der Belastungen der Oberflächengewässer und des Grundwassers durch Nährstoffaustrag (z.B. Modell Stoffbilanz) bzw. durch Wassererosion (Modell EROSION 3D). Zum anderen bietet das Entscheidungshilfesystem verschiedene Modelle und Verfahren an, mit deren Hilfe stoffaustragsmindernde landwirtschaftliche Maßnahmen ausgewählt und hinsichtlich ihrer Wirksamkeit abgeschätzt werden können. Ergänzend dazu wurde ein computergestützter Maßnahmenkatalog zur Unterstützung bei der Auswahl stoffaustragsmindernder Maßnahmen im Bereich Landwirtschaft erstellt. Die Priorisierung der verschiedenen Maßnahmenalternativen unter Berücksichtigung ökologischer und ökonomischer Ziele wurde beispielhaft mit Hilfe der Nutzwertanalyse durchgeführt.
48

Determination of bank structures and river width variations using remote sensing data

Karrasch, Pierre, Hunger, Sebastian 08 August 2019 (has links)
The European Water Framework Directive commits the member states to achieve the good ecological status for all waterbodies. For this purpose on the level of the national states monitoring programs are established with the aim to verify the actual status by means of regular surveys. Already in the past remote sensing data in conjunction with methods of geospatial data analysis revealed the added value in terms of monitoring strategies regarding the European Water Framework Directive. Depending on the type of data they can be used for example for the determination of several parameters of rivers and streams. The present analyses show how it is possible to determine the parameter of width variation of small and medium rivers based on digital orthophotos. Because this parameter strongly depends on the geometric quality of the riverbank line, its determination is given particular attention. It turns out that mainly riparian vegetation has a large impact on the visibility of the riverbank line. In a multi-stage process different methods for the identification of affected areas are developed with the aim to reconstruct the true riverbank line in a second step. Finally these data form the basis for the determination of river width variations.
49

Průzkum a hodnocení ekologického stavu vodních toků při zohlednění evropských standardů. Aplikace v modelovém povodí Rolavy. / Ecological survey and assessment of streams within European Standards. Application in the Rolava River basin.

Beranová, Zuzana January 2011 (has links)
This thesis deals with implementation of Water Framework Directive (2000/60/EC) in the Czech Republic. The study area was the Rolava River basin in the Ore Mountains (northwest of Bohemia). The ecological status assessment was applied to both - the main stream and relevant tributaries. Available hydrobiological and hydrochemical data enhanced with the field hydromorphological survey using the Hydroecological monitoring (HEM, Langhammer, 2007) were applied in this thesis. Results of the field survey were compared with two ecomorphological methods: LAWA-FS (LAWA, 2000) and EcoRivHab (Matoušková, 2003, 2007). As a final result, it was found out the water body on upper course of the Rolava River achieved good ecological status. Water body on lower course of the Rolava River and of the tributary the Nejdecký Brook were classified as not achieving good ecological status. The Rolava catchment has very specific conditions and huge potential to achieve the good status in the future.
50

Simulation of vegetation and relief induced shadows on rivers with remote sensing data

Karrasch, Pierre, Hunger, Sebastian 06 September 2019 (has links)
Rivers are the lifelines of our environment. For this reason they are always in the focus of environmental studies. For the assessment of the ecological status of rivers the member states of the European Union have developed different monitoring programs and approaches. The shadowing of a river affects the temperature of the water and also the energy balance of the water body. Therefore changes in temperature also in uence the biological and chemical status of rivers and lakes. The main objective of this study is the simulation of the shadowing of a section of the river Freiberger Mulde for a full year. This ensures that effects of different sun positions over the year (azimuth, elevation) and also local topography conditions in the close environment of the river section are taken into account. For all analyses a digital surface model and a digital elevation model with a geometric resolution of 2 m is available. The result of this simulation is a raster layer which represents the theoretical annual hours of shadowing of the river section. The results indicate a decrease of illumination of partly more than 80 %. In future this information can be expanded by means of further affecting factors such as the consideration of the phenological status of deciduous trees in the riparian zone.

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