• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 19
  • 10
  • Tagged with
  • 29
  • 13
  • 12
  • 7
  • 6
  • 5
  • 5
  • 5
  • 5
  • 5
  • 5
  • 5
  • 5
  • 5
  • 4
  • 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.
1

Inverkan av dikning av sulfidjordar på metallkoncentrationer i havssediment : En studie av hur metallhalten i havssediment i Gumbodafjärden (Norra Sverige) har förändrats över tid

Thomas, Jacob January 2016 (has links)
Acid sulphate soils cover all around the world an area of approximately 170 000 km2. The soils can cause huge acidification problems for streams and lakes due to increasing concentration of hydrogen ions which will increasing the mobilization of heavy metals. This can result in huge complications for species living in the polluted water. The aim with this study was to see what kind of impact the ditching activity in a catchment area affected by sulfide soils have when it comes to the leaching of heavy metals and Al. This was studied by investigate the distribution of 27 different elements (such as heavy metals, trace metals, nutrient etc) and LOI in a 2,14 m long marine sediment core from a bay situated in the county of Västerbotten. The catchment area from the stream which has it outflow at the bay are predicted to be affected by the acid sulphate soils in a high extent. Furthermore the spatial distribution of the elements in the bay was studied, this was made by compare the results from two sediments samples taken by a HTH corer from two different locations. The results made it clear that some element highly correlated to each other followed a trend similar to the ones of Sulphur and LOI. The concentration for the elements (As, Cu, Fe, Mn, Ni, Pb och Zn) was also compared by the Canadian guidelines which indicate that As and Fe had concentration that can cause severe negative effects for biota in the water. The conclusion made from this study indicate that the majority of the elements are affected by the LOI fluctuations due to the high positive or negative correlation to LOI. Therefore the highest concentration of elements such as Al, Co, Cu Mn, Ni and Zn which will be leached by acid sulphate soils are in this situation instead caused by LOI. However there occur some trends when the ratio between S/LOI and other heavy metals sharply  increase, this could be seen as a sign of an effect caused by acid sulphate as a results of ditching activity.
2

Bestämning av dagvattenflöden i Knivstaåns avrinningsområde / Determination of stormwater flows in the Knivsta river drainage area

Boholm, Per January 2012 (has links)
The purpose of the thesis was to map the hydraulic load on the Knivsta river from stormwater runoff, and build a platform for further studies of pollution loads on the rivers ecosystems. New residential areas are planned to be built in Knivsta municipality and it will have an impact on stormwater flows to Knivsta river. To examine the impact this will have, simulations were made in the area as it stands today and after expansion work. The work includes calculation of flows from the populated areas but also from the catchment area around it consisting of woodlands and fields. Because of expected climatic changes which may affect rainfall, the simulations have been performed with different return periods for rainfall data. Return periods of 1, 2, 10 and 50 years were chosen to get a result that reflects the current situation but also a possible climate change that would give rise to much greater rainfall.Simulation results showed that stormwater runoff would increase by 11 percent if new residential areas were built in the drainage area. Return times of rain had profound implications for the amount of runoff. A 50-year rainfall generated 7.6 times as much stormwater runoff for 1 hour as a 1-year rainfall and the amount of flooded water increased significantly as more and more pipes were flooded.In the simulations no consideration was taken to water already present in the system, only to water which is supplied through the storm water runoff. To get a better picture of flood risk and flows in the pipe system, additional analyses of flows and cross-sectional area of Knivsta river and flowing ditches are required. An analysis of the pipeline system in the detailed plans for the new areas should be done when these plans are available. Without these detailed plans, it is difficult to determine how the newly built areas will affect the pipes and ditches in the vicinity that the water must pass on the way to the recipient.
3

Transport och upptag av makronäringsämnen i ytvatten : Vilka faktorer påverkar transport och upptag av makronäringsämnen i ett mindre avrinningsområde? / Transport and uptake of macronutrients in surface water : What factors affect transport and uptake of macronutrients in a small catchment?

Svensson, Erika January 2021 (has links)
The availability of nutrients is the foundation of our ecosystems both on land and in the sea. The processes that control the surplus of nutrients and the biogeochemical cycle are linked to several important environmental issues and therefore important to know. At present, there is an excess of nutrients in our waters, mainly due to anthropogenic activities such as agriculture, emissions from operations or forestry. The abundance of nutrients leads to an overproduction of plant and zooplankton, which in turn creates problems such as oxygen deprivation, impaired depth of vision, changes in species composition and thus also changes in the structure of ecosystems. This study aims to increase the knowledge of which factors affect how nutrients are transported from land to sea. The focus is on the transport and uptake of macronutrients in a smaller catchment area with little anthropogenic influence. The study is based on analytical results from sampling surface water in the Forsmark area located on the coast of Uppland. The starting point has been to investigate how the availability of dissolved nitrogen, phosphorus, carbon and silicon differs in Lake Bolundsfjärden, its inflow and outflow, as well as which key factors control the mobility and transport of nutrients in the catchment area.  The study has been carried out by analysing data from previous samplings in the area. The sampling has been carried out by SKB (Svensk kärnbränslehantering AB) for approximately 20 years as part of their research on nuclear fuel disposal. Relevant parameters from the sampling results were compiled and have been statistically analyzed through Spearman's correlation tests as well as Wilcoxon signed ranked tests. The key factors that have a major impact on the uptake and transport of nutrients are temperature, alkalinity, and pH. These parameters are part of the biogeochemical cycle and vary with the seasons of a temperate climate. Silicon, nitrogen and phosphorus co-vary with several seasonal parameters, while the DOC content in surface water is only indirectly affected by the seasons mainly in the form of precipitation and snowmelt.  Over the past two decades, the annual nutrient flow has remained relatively stable for phosphorus and silicon, while nitrogen and DOC show rising trends, a likely explanation being ongoing climate change with more extreme weather.
4

Geomorfologisk kartläggnng av Kungsbäckens avrinningsområde

Sjö, Maria, Tähtikivi, Annelie January 2006 (has links)
<p>År 2015 ska alla avrinningsområden i EU-länderna vara fastställda. Anledningen till detta är att år 2000 trädde ett vattendirektiv i kraft. Syftet med direktivet är att skapa en helhetssyn för vattenresurserna i Europa och för att få en enhetlig och övergripande lagstiftning. I Sverige har SMHI redan bestämt vattendelare och avrinningsområden för ett stort antal områden i landet, men i och med direktivet har det blivit ett krav. En helhetssyn på vattenresurser tillsammans med kunskaper om geologi är en förutsättning för en hållbar utveckling och ett effektivt tillvaratagande av naturresurserna. Inom samhällsplaneringen spelar geologin en tämligen betydande roll. Vid exempelvis planering av nya bostadsområden är det av stor vikt att veta markens egenskaper.</p><p>Syftet med detta examensarbete var att fastställa Kungsbäckens avrinningsområde samt att göra en geomorfologisk undersökning av området. Arbetet syftade även till att redogöra för några fluvialmorfologiska förekomster kring del av Kungsbäcken - från utloppet vid Gavleån vid Stora Vall till viadukten vid Regementsvägen. Genom att utföra studien som en kombination av naturgeografi och GIT påvisas möjligheterna att utföra olika typer av analyser och beräkningar utifrån de naturresurser som finns i ett område och den moderna tekniken. Vidare kommer resultatet från denna studie att delges SMHI. De kan därmed få nytta av materialet när de, på uppdrag av Naturvårdsverket, skall utföra en kartläggning av Kungsbäckens avrinningsområde.</p><p>För att möjliggöra en geomorfologisk kartläggning av Kungsbäckens avrinningsområde och fastställa dess gränser studerades initialt tillgängligt material såsom tidigare studier, litteratur, terrängkarta, jord- och bergartskartor samt flygfotografier. Vid genomförandet av fastställningen av områdets gränser nyttjades bland annat SMHI:s tidigare gjorda gränser, en av oss gjord analog analys, utifrån tryckta terrängkartan 13H SV samt en flödesmodellering av en i studien gjord höjdmodell över området. Därefter gjordes fältstudier till tre stycken områden med osäkra områdesgränser, vilka framkom av ovan nämnda analyser. Med hjälp av flödesriktningsinstrument och okulär besiktning kunde gränserna då fastställas. Även fältstudier av geomorfologiskt intresse har utförts, såsom studie av ändmoräner och hällar.</p><p>Med hjälp av genomförda fältstudier, analyser, digitalisering och litteraturgranskning har gränserna för Kungsbäckens avrinningsområde bestämts samt beräknats till en area av 105,4 km2. Områdets geomorfologiska kartläggning har resulterat i en karta där de olika förekomsterna finns redovisade (se bilaga 1, karta i A3-format). Förutom detta finns olika begrepp och naturfenomen beskrivna i rapporten samt nyttan med denna typ av studie.</p> / <p>In year 2000, the EU Water Framework Directive was adopted and by 2015, all European watersheds have to be established. The purpose with the directive is to create an overall view over the water resources in Europe and to get a comprehensive legislation. SMHI in Sweden has already established a few watersheds around the country. An overall view of the water resources together with knowledge of the geology is a requirement to a sustainable development and an effective taking care of the nature resources. Within the physical planning, the geology knowledge is very important. For example, it is vital to know the quality of the ground when planning new building complexes.</p><p>The purpose with this bachelor thesis was to establish the watershed of Kungsbäcken and to do a geomorphologic survey of the area. The thesis also aimed to describe some of the fluvial morphologic presences, in a part of Kungsbäcken, i.e. from the outflow to Gavleån at Stora Vall, to the viaduct at Regementvägen.</p><p>By doing the study as a combination of physical geography and GIT, the possibilities to do different types of analyses and calculations, on the basis of the nature resources in an area and the modern technique are pointed out. Furthermore, the result from this study will be given to SMHI. The result may be of benefit to SMHI, when mapping the watershed of Kungsbäcken later on.</p><p>To make the geomorphologic survey of the watershed and to establish the boundaries of it, literature, earlier studies in the area, terrain- , rock, - soil maps and aerial photos were studied. Moreover, out of date-boundaries established by SMHI were used, together with an analogue analysis, based on the printed terrain map 13H SV. We also used a flow model, based on a digital elevation model over the area. The study also contained field trips. Three areas with uncertain boundaries were studied and with flow direction instruments and ocular examination, the boundaries were established. Field trips of geomorphologic interest were also made, like studies of recessional moraine and roch moutonnée.</p><p>By field trips, analyses, digitizing and literature perusal, the boundaries of the watershed of Kungsbäcken has been established and the area is 105.4 km2. The result of the geomorphologic survey of the area can be seen in a map (appendix 1). Apart from that, concepts and nature phenomena are also described in the report along with observations of the benefits of studies like this one.</p>
5

Geomorfologisk kartläggnng av Kungsbäckens avrinningsområde

Sjö, Maria, Tähtikivi, Annelie January 2006 (has links)
År 2015 ska alla avrinningsområden i EU-länderna vara fastställda. Anledningen till detta är att år 2000 trädde ett vattendirektiv i kraft. Syftet med direktivet är att skapa en helhetssyn för vattenresurserna i Europa och för att få en enhetlig och övergripande lagstiftning. I Sverige har SMHI redan bestämt vattendelare och avrinningsområden för ett stort antal områden i landet, men i och med direktivet har det blivit ett krav. En helhetssyn på vattenresurser tillsammans med kunskaper om geologi är en förutsättning för en hållbar utveckling och ett effektivt tillvaratagande av naturresurserna. Inom samhällsplaneringen spelar geologin en tämligen betydande roll. Vid exempelvis planering av nya bostadsområden är det av stor vikt att veta markens egenskaper. Syftet med detta examensarbete var att fastställa Kungsbäckens avrinningsområde samt att göra en geomorfologisk undersökning av området. Arbetet syftade även till att redogöra för några fluvialmorfologiska förekomster kring del av Kungsbäcken - från utloppet vid Gavleån vid Stora Vall till viadukten vid Regementsvägen. Genom att utföra studien som en kombination av naturgeografi och GIT påvisas möjligheterna att utföra olika typer av analyser och beräkningar utifrån de naturresurser som finns i ett område och den moderna tekniken. Vidare kommer resultatet från denna studie att delges SMHI. De kan därmed få nytta av materialet när de, på uppdrag av Naturvårdsverket, skall utföra en kartläggning av Kungsbäckens avrinningsområde. För att möjliggöra en geomorfologisk kartläggning av Kungsbäckens avrinningsområde och fastställa dess gränser studerades initialt tillgängligt material såsom tidigare studier, litteratur, terrängkarta, jord- och bergartskartor samt flygfotografier. Vid genomförandet av fastställningen av områdets gränser nyttjades bland annat SMHI:s tidigare gjorda gränser, en av oss gjord analog analys, utifrån tryckta terrängkartan 13H SV samt en flödesmodellering av en i studien gjord höjdmodell över området. Därefter gjordes fältstudier till tre stycken områden med osäkra områdesgränser, vilka framkom av ovan nämnda analyser. Med hjälp av flödesriktningsinstrument och okulär besiktning kunde gränserna då fastställas. Även fältstudier av geomorfologiskt intresse har utförts, såsom studie av ändmoräner och hällar. Med hjälp av genomförda fältstudier, analyser, digitalisering och litteraturgranskning har gränserna för Kungsbäckens avrinningsområde bestämts samt beräknats till en area av 105,4 km2. Områdets geomorfologiska kartläggning har resulterat i en karta där de olika förekomsterna finns redovisade (se bilaga 1, karta i A3-format). Förutom detta finns olika begrepp och naturfenomen beskrivna i rapporten samt nyttan med denna typ av studie. / In year 2000, the EU Water Framework Directive was adopted and by 2015, all European watersheds have to be established. The purpose with the directive is to create an overall view over the water resources in Europe and to get a comprehensive legislation. SMHI in Sweden has already established a few watersheds around the country. An overall view of the water resources together with knowledge of the geology is a requirement to a sustainable development and an effective taking care of the nature resources. Within the physical planning, the geology knowledge is very important. For example, it is vital to know the quality of the ground when planning new building complexes. The purpose with this bachelor thesis was to establish the watershed of Kungsbäcken and to do a geomorphologic survey of the area. The thesis also aimed to describe some of the fluvial morphologic presences, in a part of Kungsbäcken, i.e. from the outflow to Gavleån at Stora Vall, to the viaduct at Regementvägen. By doing the study as a combination of physical geography and GIT, the possibilities to do different types of analyses and calculations, on the basis of the nature resources in an area and the modern technique are pointed out. Furthermore, the result from this study will be given to SMHI. The result may be of benefit to SMHI, when mapping the watershed of Kungsbäcken later on. To make the geomorphologic survey of the watershed and to establish the boundaries of it, literature, earlier studies in the area, terrain- , rock, - soil maps and aerial photos were studied. Moreover, out of date-boundaries established by SMHI were used, together with an analogue analysis, based on the printed terrain map 13H SV. We also used a flow model, based on a digital elevation model over the area. The study also contained field trips. Three areas with uncertain boundaries were studied and with flow direction instruments and ocular examination, the boundaries were established. Field trips of geomorphologic interest were also made, like studies of recessional moraine and roch moutonnée. By field trips, analyses, digitizing and literature perusal, the boundaries of the watershed of Kungsbäcken has been established and the area is 105.4 km2. The result of the geomorphologic survey of the area can be seen in a map (appendix 1). Apart from that, concepts and nature phenomena are also described in the report along with observations of the benefits of studies like this one.
6

GIS-baserad beräkning av urbana delavrinningsområden : Utveckling av en objektorienterad metod

Berg Lissel, Maria January 2016 (has links)
The aim was to identify geographical areas of concern in the process of catchment delineation in urban areas in geographic information systems, GIS. The aim was also to develop a new method for the delineation in order to address identified problems. The calculations of the catchment areas are important for subsequent hydraulic modeling, which is performed in order to properly design storm water systems capable of handling the storm water. An object oriented method was developed that took into account the identified, problematic factors in the infrastructure and buildings of the urban area. An alternative algorithm for the preprocessing of the digital elevation model, DEM, was tested to see how the results would differ from a current method for catchment delineation with another algorithm for the preprocessing of the DEM. The two different algorithms for DEM preprocessing were used before the same procedure of catchment delineation was performed on the DEMs in ArcGIS. The delineated catchments from the two different preprocessing algorithms along with the object oriented method, were evaluated against reference catchment areas manually plotted by hydraulic modeling specialists. The object oriented method showed a higher correlation to the reference than the topographic methods for the most important target parameters when performing well. However the object oriented method has to improve in precision and efficiency if it is to be used for the calculations. The catchment delineation methods with different DEM preprocessing algorithms yields different results. For the DEM preprocessing, an algorithm from Whitebox GAT seemed to performed better in flat areas and in areas where the storm water lines have been lowered into the DEM, than the ArcGIS method did. However the combination of Whitebox GAT and ArcGIS resulted in some problems with the catchment delineation and hence the combined method has to be refined in order to be used.
7

Avrinningens variation i det boreala landskapet : - en fallstudie i Strömsjöliden

Boström, Erik January 2015 (has links)
No description available.
8

Transport of organic chlorine through soil : A study of organic chlorine in soil water from a catchment in northern Sweden

Söderholm, Simon, Karlsson, Rebecka January 2008 (has links)
<p><p>Chlorine is an element commonly found in the environment of our planet, in the atmosphere, the earth crust and the oceans. Chlorine occurs in two forms, inorganic chloride (Cl<sub>in</sub>) and organically bound chlorine (Cl<sub>org</sub>), also called organochlorine. For a long time, the organic halogens (among them the organic chlorine) had been considered as produced only by human activities. However, the research of the recent decades suggests a considerably amount of naturally produced organic chlorine in soil and water. Through the research, a hypothesis have emerged, suggesting that there occur a formation of organic chlorine in the top soil layer where chloride is consuming, while the organic chlorine is degrading on deeper soil levels, causing a release of chloride. The study in this thesis attempts to explore the transportation of organic chlorine through soil. 49 soil water samples were collected at three transects, S04, S12 and S22, nearby a stream in northern Sweden and analysed for Cl<sub>org</sub>, using an AOX-analyser. The results suggest a decrease in concentrations of Cl<sub>org</sub> by soil depth for transects S04 and S12. The study also indicates that concentrations of Cl<sub>org</sub> are decreasing with increasing distance from the stream, where the highest mean concentration was found in the organic matter-rich riparian transect S04. Further conclusions are that the spring flood and changes in groundwater level may influence the concentrations of Cl<sub>org</sub>.</p></p> / <p><p>Ämnet klor är vanligt förekommande på vår planet och finns både i atmosfären, jordskorpan och världens oceaner. Klor uppträder i två olika former: oorganisk klorid (Cl<sub>in</sub>) och organiskt bundet klor (Cl<sub>org</sub>). De organiska halogenerna (bland vilka organiskt klor ingår) har under lång tid ansetts härstamma från enbart antropogena källor. De senaste decenniernas forskning har dock tytt på en naturlig produktion av organiskt klor i mark och vatten. Genom denna forskning har en hypotes tagit form som föreslår en bildning av organiskt klor i de övre marklagren, där klorid binds, medan det i djupare marklager sker en nedbrytning av det organiska kloret vilket medför ett frigörande av klorid. Denna studie syftar till att studera transporten av organiskt klor genom mark. 49 stycken markvattenprover insamlades vid tre provpunkter (S04, S12 och S22) på ett avrinningsområde i norra Sverige och analyserades med hjälp av ett AOX-instrument. Resultaten tyder på en minskning av Cl<sub>org</sub> med ökande markdjup för provpunkterna S04 och S12. Studien visar även en minskning i koncentration av organiskt klor med ökande avstånd till vattendraget, där den högsta medelkoncentrationen återfanns i provpunkten S04 som ligger nära bäcken och är rik på organiskt material. Vidare slutsater är att vattenflödena under vårflod samt variasionen i grundvattennivå har en påverkan på koncentrationerna av Cl<sub>org</sub>.</p></p>
9

Grön infrastruktur och ökade vattenflöden : Mellankommunal samverkan för att stärka gemensam klimatanpassning inom avrinningsområden

Ljungberg, Felix January 2020 (has links)
No description available.
10

Hur substrat och avstånd från vatten påverkar strandvegetation vid Ölmans avrinningsområde / Effects of substrate and distance from the stream on riparian vegetation in the Ölman watershed

Johansson, Julia January 2020 (has links)
Avrinningsområden är landområden där det ofta finns förutsättningar för stor biologisk mångfald. År 2017 var ett område som undersöktes Ölmans avrinningsområde, där man dokumenterade och räknade antal individer av de olika växtarter som fanns på olika avstånd från vattnet, samt de olika vegetationstypernas procentuella täckning av marken. Det här är en undersökning som, i hopp om att ge en bättre förståelse för vegetationszonering vid vattendrag, försöker upptäcka huruvida det finns en skillnad i artmångfald och artfördelning på två olika substrat och på tre olika avstånd från vattnet vid Ölmans avrinningsområde i Värmland, Sverige. Alla data som användes i undersökningen hade redan samlats in i juli 2017. Analysen skedde under hösten 2018. Resultaten påvisade inget samband mellan substrat och artmångfald och artfördelning. Avståndet från vattnet hade inte heller någon inverkan på artmångfald och artfördelning. Ölmans avrinningsområde är påfallande litet, vilket med sannolikhet påverkar förekomst av naturlig zonering – eller en brist därav. Det finns också flera andra biotiska och abiotiska faktorer som kan påverka växtlivet, såsom pH-värden i vattnet och jorden, mänsklig påverkan, påverkan från djur, och så vidare. Att enbart känna till grovleken på det underliggande substratet ger inte tillräckligt med information för att tillåta dragande av några definitiva slutsatser gällande vegetationsstrukturen. / Watersheds are areas of land that often have the prerequisites for great biological diversity. In 2017 one area being examined was the Ölman watershed, where different plant species were accounted for, both by species and amount of individuals, on different distances from the water, as well as the percentage of ground coverage of different types' of vegetation. This is a study that, in an attempt to better understand vegetation zones along rivers and streams, tries to discover whether there is a statistically significant difference between the species diversity and species distribution on two different substrates and three different distances from the water of the Ölman watershed in Värmland, Sweden. All data used for the study were collected in July 2017 and analysed in autumn 2018. The results showed no relationship between substrate and species diversity or species distribution. The distance from the water did not have any effect on the species diversity or species distribution either. The Ölman watershed is quite small, which is likely to affect the presence of natural zoning – and the lack thereof. There are also several other biotic and abiotic factors that can influence plant life, such as pH of the water and soil, human and animal interference, etc. Only knowing the coarseness of the substrate does not provide enough information to be able to draw any definite conclusions on the vegetation structure.

Page generated in 0.102 seconds