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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.
11

GIS baserad kartering av urbana ekosystemtjänster : Fallstudie av Bomhus, Gävle

Eriksson, Tim, Jansson, David January 2018 (has links)
Bevarande av ekosystem överlag men i synnerhet i urbana miljöer är en viktigfaktor för att främja människors hälsa, eftersom de bidrar medekosystemtjänster (EST). EST är de funktioner ekosystem har som på någotvis förbättrar miljön för oss människor. Urbaniseringen, som det senasteårhundrandet ökat dramatiskt ser inte ut att avta. Det är också urbaniseringensom är den drivande kraften för markanvändningsförändringar, vilket är detstörsta hotet mot de urbana EST. Att planera rätt bebyggelse på rätt plats ärdärför av största vikt om utbudet och produktionen av de urbana EST inte skaminska eller försvinna. Kunskap om vilka tjänster som produceras, var deproduceras samt i vilken omfattning de produceras kan underlätta förplanerare och beslutsfattare att fatta bättre och mer välgrundade beslut.Syftet med denna studie var att undersöka vilken kapacitet en stadsdel medblandad bebyggelse och markanvändning har att producera de fyra mestkarterade reglerande EST. Målet var att analysera, värdera och karterautbudet av tjänsterna: temperaturreglering, luftrening, flödesreglering ochvattenrening. Studien är en fallstudie av stadsdelen Bomhus i Gävle där vi medfjärranalys av satellitbilder och GIS identifierade vilka marktäcken fanns iområdet. Marktäckena tilldelades sedan ett värde utifrån hur mycket debidrog till varje tjänst. Värdena baserades dels på befintlig forskning ochlitteratur och dels på kunskapen från två tillfrågade experter inom området.Resultatet visar att Bomhus har en hög kapacitet att producera de undersöktatjänsterna, speciellt tjänsterna temperaturreglering och luftrening. Till stordel beror det på att Bomhus har stora ytor av de högt värderademarktäckesklasserna barrskog, vatten och lövskog. Barrskog som visade sigvara den näst största klassen och täckte ca 20% av studieområdet var även denklass som fick högst värde. Våtmark som var den klart minsta klassen men somfick näst högst värde tillsammans med vatten ansågs därför som extra känsligoch bör skyddas vid exploatering. Öppen mark med vegetation som däremotvar den största klassen samtidigt som den erhöll det lägsta värdet ansågs därförsom mest lämplig för exploatering. / Preserving of ecosystems generally but more specifically ecosystems in urban environments is an important factor with regards to human health. Because ecosystems provide us with ecosystem services (ESS). ESS are the functions ecosystems have that in any way improves the environment for humans. Urbanization which over the last decade has increased rapidly, does not seem to decrease. It is also urbanization that is the driving force of land use changes, which is the biggest threat to urban ESS. Planning the right type of development at the right location is crucial to ensure that the supply and production of urban ESS will not decrease or be lost. Knowledge of which services that are produced, were they are produced and to what extent they are produces could facilitate for planners and decision makers to make better and more informed decisions.The aim with this study was to examine what capacity a district with mixed housing and land use has to produce the four most commonly mapped regulating ESS. The goal was to analyse, evaluate and map the supply of the regulating services: temperature regulation, air purification, water regulation and water purification. The study is a case study of Bomhus, Gävle where we with remote sensing of satellite images identified the different land covers in the study area. Each land cover where assigned a value based on how much they contributed to each service. The values were partly based on previous research and partly on the knowledge of two experts in the field of study.The results show that Bomhus has a high capacity to produce the examined services, especially temperature regulation and air purification. This is mostly because Bomhus has large areas of the highly valuated land covers, coniferous forest, water and deciduous forest. Coniferous forest which were the second biggest land cover class covering almost 20% of the study area were also the land cover that got the highest value. Wetlands which was the smallest land cover class and got the second highest value along with water is therefore, considered to be most vulnerable land cover and should be protected from exploitation. Open land with vegetation however, that was the biggest land cover class and received the lowest value was considered to be most suitable for exploitation.
12

Undersökning av tidigt varningssystem för algblomning : -en studie genom vattenkvalitetsmätningar med EXO2 sond, fjärranalys och vattenprovtagning / Investigating early warning system for algal blooms : -a study by in situ measurement of water quality using the EXO2 probe, remote sensing and water sampling in Stora Ullfjärden, Håbo kommun

Löf, Harald January 2021 (has links)
Algal blooms can pose a serious threat to humans and animals in lakes used for drinking water and recreation in the bloom contains toxin producing cyanobacteria. Early warning of impending algal blooms requires systems with high temporal resolution. Cyanoalert from Brookman Geomatics is such a system that uses remote sensing satellites from the Eu Copernicus program to supervise amongst others chlorophyll in water systems.Measurements of chlorophyll are studied in this project to identify water quality parameters and conditions affecting the reliability. Biweekly sampling is conducted during the spring of 2021 obtaining chlorophyll data from profile measurements using water sampling a calibrated multiparameter probe. Water samples are then used as accurate reference for satellite measurement comparison.The water samples showed low levels of chlorophyll, turbidity, and pH in the beginning of the sampling in March. During the sampling period the levels rose until reaching a maximum during algae bloom in the end of May. The bloom was preceded by rising water temperatures and the formation of a thermocline and rising pH levels that could be used as suitable indicators for imminent bloom formation.Obtained data and governing effects were analyzed by multivariate regression (PLSR). VIP-plots showing that turbidity had the largest influence on the projected chlorophyll and thereby the measured chlorophyll levels. Also, Secci depth was identified as having strong influence. This indicates that high turbidity is a factor causing accuracy of chlorophyll measurements to deteriorate.A proposed warning system for algal blooms should use remote sensing satellites for detecting chlorophyll and turbidity combined with in situ sensors for the surveillance of water temperature, phycocyanin and pH.
13

Plantdiversitet på svenska slåtterängar : En GIS-analys med kulturella perspektiv

Gartz, Mira January 2015 (has links)
High plant species diversity depends on a landscape that provides enough habitual space, functional connectivity and heterogeneity. Habitat destruction and land use change is recognized as the biggest threat to biodiversity of today. The Swedish landscape has not only undergone dramatic changes in land-use the last 60 years, it also contains some of the last fragments in Europe of the highly valuable hay-meadows. Many of the Swedish hay-meadows are considered to hold high ecological values and are protected by Natura 2000 regulations. Yet there are no systematic conservation strategies for the hay-meadows and most of the work is done by volunteers. This study aims to further investigate how the surrounding landscape affects the total plant species richness on Swedish hay-meadows. A local scale GIS-analysis on landscapes surrounding 21 hay-meadows across two time steps was carried out. The historical land-use was compared with the present landscapes and with species data from the same areas. Results show that the forest cover has grown almost 12% in 60 years. There is a negative correlation between forest and the plant species richness of both time steps. The total area of arable fields has dropped 19%, although no statistical correlation with the plant species richness of either time step was found. The ex-arable fields of 1950 however, did show a negative impact, both alone and together with open pasture. Open pasture has decreased 17%, although no statistical correlation was found between this land-cover category and plant species richness. The overall results indicate that the historical land-use on the local scale is of greater importance on the current plant species richness than present land-use. This should be considered within landscape planning and when designing conservation strategies. / En hög plantdiversitet är beroende av ett landskap som erbjuder tillräckligt stora habitat, funktionell konnektivitet och heterogenitet. Habitatförlust och förändrad markanvändning utgör det största hotet mot biodiversitet idag. Det svenska landskapet har inte bara förändrats dramatiskt de senaste 60 åren, det innehåller också några av Europas sista fragment av de mycket värdefulla slåtterängarna. Många av de svenska slåtterängarna är upptagna i Natura 2000-områden. Trots detta finns inga systematiska bevarandestrategier för dessa slåtterängar och arbetet hänger mestadels på volontärer. Den här studien ämnar bidra till en ökad förståelse för hur omgivande landskap påverkar plantdiversiteten på svenska slåtterängar. GIS-analyser av lokala landskap som omger 21 svenska slåtterängar har utförts. Nedslag vid två tidpunkter har gjorts; år 1950 och 2015. Genom digitalisering av kartor från 1950-talet har arean av marktyper kunnat beräknas och sedan jämföras med dagens markanvändning och artdata i samma områden. Resultaten visar att den totala skogsarealen har ökat med 12% sedan 1950-talet och det finns negativa samband mellan både den historiska och den nutida skogsarealen och artrikedomen på ängarna. Arean av åkermark har minskat med 19% i de undersökta områdena, men inga samband med artrikedomen kunde finnas. Däremot visade det sig att den före detta åkermark som fanns på 1950-talet påverkar dagens artrikedomen negativ, både som ensam oberoende variabel och tillsammans med öppen mark. Öppen mark har minskat med mellan 17% och 24%, men inga samband mellan denna landskapskategori och plantdiversiteten fanns. De sammanställda resultaten indikerar att den historiska markanvändningen på lokal skala har större påverkan på dagens plantdiversitet än den nutida markanvändningen. Detta bör tas i beaktande vid utformande av bevarandestrategier och vid fysisk planering.
14

Construction of a solid 3D model of geology in Sardinia using GIS methods

Tavakoli, Saman January 2009 (has links)
<p><p>Abstract</p><p>3D visualization of geological structures is a very efficient way to create a good understanding of geological features. It is not only an illustrative way for common people, but also a comprehensive method to interpret results of the work. Geologists, geophysics engineers and GIS experts sometimes need to visualize an area to accomplish their researches. It can show how sample data are distributed over the area and therefore they can be applied as suitable approach to validate the result. Among different 3D modeling methods, some are expensive or complicated. Therefore, such a methodology enabling easy and cheap creation of a 3D construction is highly demanded.</p><p>However, several obstacles have been faced during the process of constructing a 3D model of geology. The main debate over suitable interpolation methods is the fact that 3D modelers may face discrepancies leading to different results even when they are working with the same set of data. Furthermore, most often part of data can be source of errors, themselves. Hence, it is extremely important to decide whether to omit those data or adopt another strategy. However, even after considering all these points, still the work may not be accurate enough to be used for scientific researches if the interpretation of work is not done precisely. This research sought to explain an approach for 3D modeling of Sedini platform in Sardinia, Italy. GIS was used as a flexible software together with Surfer and Voxler. Data manipulation, geodatabase creation and interpolation test all have been done with aid of GIS. A variety of interpolation methods available in Surfer were used to opt suitable method together with Arc view.</p><p>A solid 3D model is created in Voxler environment. In Voxler, in contrary to many other 3D types of software there are four components needed to construct 3D. C value as 4<sup>th</sup> component except for XYZ coordinates was used to differentiate special features in platform and do gridding based on chosen value. With the aid of C value, one can mark layer of interest to identify it from other layers.</p><p>The final result shows a 3D solid model of the Sedini platform including both surfaces and subsurfaces. An Isosurface with its unique value (Isovalue) can mark layer of interest and make it easy to interpret the results. However, the errors in some parts of model are also noticeable. Since data acquisition was done for studying geology and mineralogy characteristics of the area, there is less number of data points collected per volume according to the main goals of the initial project. Moreover, in some parts of geological border lines, the density of sample points is not high enough to estimate accurate location of lines.</p><p>The study result can be applicable in a broad range of geological studies. Resource evaluation, geomorphology, structural geology and GIS are only a few examples of its application. The results of the study can be compared to the results of similar works where different softwares have been used so as to comprehend pros and cons of each as well as appropriate application of each software for a special task.</p><p> </p><p> </p><p><em>Keywords: GIS, Image Interpretation, Geodatabase, Geology, Interpolation, 3D Modeling</em></p><p> </p><p> </p></p><p> </p>
15

Making remote sensing bankable - cold climate SODAR and meteorological mast intercomparison

Engblom Wallberg, Ian January 2010 (has links)
The value of an easy to install, accurate, far-reaching measurement instrument is easily understood when dealing with setting up and monitoring wind power parks. However the use of remote sensing equipment when doing this is a subject of much discussion amongst professional experts and scholars. This is especially the case when the environmental conditions are difficult, such as areas with complex terrain or cold climate (or both), for example forested, hilly or mountainous regions in north Europe and North America. The remote sensing technology SODAR provides for detailed 3-dimensional datasets, but need a skilled analyst to make sure the measurements are realistic. This thesis is aimed at verifying the accuracy of the SODAR wind measuring equipment at two potential wind power parks in Sweden. It has been done by comparing the wind speed, wind direction and turbulence measured by an AQ Systems AQ500 Wind Finder SODAR to the wind speed, wind direction and turbulence measured by in situ anemometers mounted in nearby meteorological masts. The comparison was made by calculation of statistical parameters such as correlation and root mean square error. The results of this investigation shows that the differences in the measured quantities are site specific and that i t‟s very difficult to distinguish between differences arising from ambient conditions, the measurement method and the method of calculating comparable values. It is clear, however, that conditions such as temperature, inhomogeneous fetch and wind speed are contributors to the observed discrepancies. When compensating for these various sources of error; such as eliminating data from malfunctioning equipment, icing conditions, mast wake and forest flow disturbance, the SODAR wind speed data shows a very high correlation with the mast anemometer data, giving a correlation coefficient of around 0.90 – 0.95. / Värdet av ett mätinstrument som är lätt att installera, noggrant och som kan mäta högt upp i troposfären är lätt att inse när man har att göra med att installera och övervaka vindkraftparker. Det har dock funnits en debatt om huruvida fjärranalytiska mätningar är tillräckliga för sådana ändamål i expert- och akademikerkretsar. Debatten spetsas ytterligare till då omgivningarna är svåra, exempelvis i områden med komplex terräng eller kallt klimat (eller både och), till exempel skogbeklädda, kulliga eller bergiga områden i norra Europa och Nordamerika som är aktuella för exploatering av vindkraft. Det fjärranalytiska redskapet SODAR förser exploatören med detaljerade tredimensionella datasamlingar, men kräver en erfaren och skicklig analytiker för att verkligen verifiera att mätresultaten är realistiska och tillförlitliga. Detta examensarbete har som mål att verifiera noggrannheten hos SODAR-utrustning vid två potentiella vindkraftparker i Sverige. Det har gjorts genom att jämföra vindhastighet, vindriktning och turbulens mätt med en AQ Systems AQ500 Wind Finder SODAR med vindhastighet, vindriktning och turbulens mätt med anemometrar i närbelägna meteorologiska mätmaster. Jämförelsen gjordes genom att beräkna statistiska parametrar som korrelation och standardavvikelse. Resultatet av undersökningen visar att skillnaderna i de uppmätta storheterna är specifika för varje mätplats och att det är mycket svårt att särskilja bidragen till skillnaderna mellan omgivande förhållanden, mätmetoder och beräkningsmetoder. Det står dock klart att förhållanden så som temperatur, inhomogen omgivande skrovlighet på anloppssträckan och vindhastigheten i sig själv bidrar till de observerade skillnaderna i mätresultat. Kompenseras felaktig och störd data bort så visar vindhastigheten mätt med SODAR en mycket god korrelation med mastanemometerdata, med en korrelationskoefficient omkring 0,90 – 0,95.
16

Classification of Points Acquired by Airborne Laser Systems

Ruhe, Jakob, Nordin, Johan January 2007 (has links)
During several years research has been performed at the Department of Laser Systems, the Swedish Defense Research Agency (FOI), to develop methods to produce high resolution 3D environment models based on data acquired with airborne laser systems. The 3D models are used for several purposes, both military and civilian applications, for example mission planning, crisis management analysis and planning of infrastructure. We have implemented a new format to store laser point data. Instead of storing rasterized images of the data this new format stores the original location of each point. We have also implemented a new method to detect outliers, methods to estimate the ground surface and also to divide the remaining data into two classes: buildings and vegetation. It is also shown that it is possible to get more accurate results by analyzing the points directly instead of only using rasterized images and image processing algorithms. We show that these methods can be implemented without increasing the computational complexity.
17

Using GIS-based Multi-criteria Analysis for holiday resort site selection in Weihai, China

Liu, Meichen, Xia, Xiaolin January 2011 (has links)
Nowadays, GIS techniques have been widely used in every walk of life. Owing to the rapid urban growth, it is of importance to plan and develop the cities in a reasonable and scientific way. As a result, optimum sites of different constructions should be considered to make full use of land resources and optimize urban structure. Although the traditional field-survey method is important, GIS-based multi-criteria analysis (MCA) provides a more reasonable and scientific way in site selection issue. Weihai, our study area, is one of the fastest developing coastal cities in China. Owing to the rapid urban expansion, Weihai government municipality planned to develop the Poyu town into a new district with multifunctions. In consideration of its advantages in natural resources and geographic position, a holiday resort is proposed. In the aim of applying GIS-based MCA in site selection, this thesis would present an experiment to select the optimal site for a holiday resort with the help of GIS techniques. The data used in this project is a satellite image and digital elevation data of Poyu town. The satellite image has been digitized to obtain the current land use map, based on which constraint maps and factor maps have been made to make preparation of multi-criteria analysis. Finally, the multi-criteria analysis model has been made. The weights for multi-criteria analysis are obtained from the advice of experienced people in Weihai Planning Bureau and also earlier studies on the site selection. There are three sets of weights based on three themes that have been used in this project. The three themes which were fruit-picking theme, seascape and seafood theme as well as leisure and recreation theme were decided based on the results of the questionnaire. Through the discussions of the results, a final selected site for the holiday resort was determined. It includes the optimal site for the main part focusing on both fruit picking theme and leisure and recreation theme and also the optimal site for an accessory part focusing on seascape and seafood theme. The final section concludes the general project work, its perspectives and the function of GIS-based MCA in site selection.
18

Classification of Points Acquired by Airborne Laser Systems

Ruhe, Jakob, Nordin, Johan January 2007 (has links)
<p>During several years research has been performed at the Department of Laser Systems, the Swedish Defense Research Agency (FOI), to develop methods to produce high resolution 3D environment models based on data acquired with airborne laser systems. The 3D models are used for several purposes, both military and civilian applications, for example mission planning, crisis management analysis and planning of infrastructure.</p><p>We have implemented a new format to store laser point data. Instead of storing rasterized images of the data this new format stores the original location of each point. We have also implemented a new method to detect outliers, methods to estimate the ground surface and also to divide the remaining data into two classes: buildings and vegetation.</p><p>It is also shown that it is possible to get more accurate results by analyzing the points directly instead of only using rasterized images and image processing algorithms. We show that these methods can be implemented without increasing the computational complexity.</p>
19

Skatta beståndsålder och ståndortsindex via flygbilder / Estimate the age of a tree stand and site index using aerial footage

Häggblad, Erik, Arvidsson, Claes January 2019 (has links)
Hållbart skogsbruk kräver kunskap om skogens tillstånd i nutid samt tänkbara framtida åtgärder. Syftet med studien var att undersöka om det via digitala flygbilder var möjligt att skatta trädålder och SI på beståndsnivå, samt med vilken precision det kan utföras.Endast tall- och/ eller grandominerade bestånd, valdes i Vetlanda och Nybro kommun. Flygbilderna bearbetades av Foran Sverige AB med hjälp av ett program framtaget av Spacemetric AB.De fältinventerade beståndens data jämfördes med medianvärden från de skattade trädhöjderna, vilka matades in i en formel, konstruerad för att göra en kurvanpassning mot de nya höjdutvecklingskurvorna.Metoden för framtagning av höjdvärden via bildmatchning bör förfinas, t.ex. bör laserskanningen bidra med högre precision. Endast mindre delar av landet har mer än en skanningstidpunkt med laser, metoden kräver minst två höjdvärden i serie.Syftet med studien anses uppfyllt, dock hade studien tjänat på en bättre metod för att sålla bort felaktiga data innan analys. Generaliserbarheten är god på liknande bestånd, vidare studier krävs för att kunna påvisa en användarbarhet i olika typer av bestånd, där även olika skötselvarianter bör vägas in.
20

Miljöhänsyn i skogsbruket – Tolkning, tillämpning och mätbarhet : Fältstudie och fjärranalys av avverkningar i Trosa kommun

Sandin, Axel January 2023 (has links)
Retention forestry is a key measure in Swedish forestry policy to combine a clearcutting regime and sustainability goals regarding forest biodiversity. The aims of increasing industrial production from forestry and to protect the environment is equally prioritized in the Swedish forestry legislation. Freedom for landowners is a cornerstone in Swedish forestry policy. This position is heavily debated among activists and scholars and is politically questioned, especially from the European Commission which challenges the Swedish position. This study investigates how Swedish landowners interpret and practice retention in forestry, discussed through a theoretical framework of political ecology. Logged areas from 2020 in Trosa municipality in Sweden was investigated through field work and remote sensing through NDVI-analysis. Retention was practiced in all the logged areas, but the measures and level of retention varied greatly. The method can be used for different purposes at different seasons. If production and environment is equally prioritized as the legislation requires is questioned.

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