Master thesis
https://hdl.handle.net/2077/59931
2024-03-28T10:44:22ZFROM SPACE TO THE SUBSURFACE. Examining Relations Between Vegetation Indices and Local Groundwater Storage.
https://hdl.handle.net/2077/79088
FROM SPACE TO THE SUBSURFACE. Examining Relations Between Vegetation Indices and Local Groundwater Storage.
Antonsson, Gustav
This study aimed to examine the relationship between vegetation indices, NDVI and NDWI, and groundwater levels in the county of Kalmar, utilizing correlation and regression analysis. Further, by examining related geospatial features the study aimed to interpret the statistical outcomes to identify significant temporal and spatial patterns. Data used involved NDVI, NDWI, derived from Sentinel 2 level-1C imagery, as well as groundwater measurement. The data was presented in time series showing bi-weekly maximum values, extending over different ranges between 2015 and 2022. Additionally, data related to land cover, soil type, topographic location, distance between groundwater and ground surface have been observed and compared between measurement stations to create a framework for interpretation.
While few definite patterns have emerged, results of the study provided notable observations from performed analysis. Results showed varying strengths of correlations over the measurement stations studied, for both indices in relation to groundwater levels, with strongest correlation generally found after three-month time-lag of vegetation indices. NDVI showed positive correlation, indicating high NDVI values correlating with low groundwater levels and vice versa. NDWI over most stations showed negative correlation, indicating high NDWI values indicating high groundwater levels. Also, while soil type and median groundwater depth were features that provided notable findings when analyzed separately in relation to found correlations, combining several features make patterns less certain. Results of this study show variation in correlation being due to variations in local geospatial features.
Future studies should more extensively and separately examine the effect of geospatial features related to vegetation and groundwater correlation. The use of different remote sensing data sources such as Sentinel 2 level-2A and Radar could present a more informative result. Also, addressing more careful data collection, seasonal focus and use of visualization. The addition of precipitation data could further be used to provide more detail in explaining the relationship between vegetation and groundwater.
2023-11-06T00:00:00ZExploring Urban Land Cover Changes and the Effect on Nocturnal Air Temperature Dynamics in Helsingborg - A temperature modeling made with TAPM
https://hdl.handle.net/2077/78706
Exploring Urban Land Cover Changes and the Effect on Nocturnal Air Temperature Dynamics in Helsingborg - A temperature modeling made with TAPM
Bäck, Amanda
In light of increasing global temperatures, urban areas face growing challenges related to heat
stress. Alterations in land cover (LC) within cities contribute to changes in the intra-urban
climate, predominantly driven by the replacement of vegetated surfaces with impermeable
materials. These changes affect the thermal properties of urban environments, exacerbating
the Urban Heat Island effect. Understanding the impact of land cover changes (LCC) on
urban climate necessitates the use of remote sensing, pre-trained deep learning models, and
temperature modeling techniques.
This study focuses on assessing land cover changes in the Helsingborg urban area from 2004
to 2020 through image classification utilizing a pre-trained deep learning model.
Furthermore, it investigates the influence of LCC on nocturnal air temperature using the
three-dimensional prognostic air pollution and meteorological model, The Air Pollution
Model (TAPM). Specifically, the analysis centers around the 2018 heatwave in Sweden,
aiming to evaluate TAPM's ability to differentiate between various land cover types and
identify temperature patterns within the Intra-Urban Heat Islands. The deep learning model
achieved an overall accuracy exceeding 90%, revealing a decline in grass surfaces and an
increase in areas covered by buildings and trees. TAPM's temperature modeling, based on the
land cover classifications, demonstrated distinct temperature variations at a 100 x 100-meter
local scale. Additionally, it indicated a higher proportion of areas with elevated nighttime
temperatures (>18°C), posing potential health risks during heatwave events akin to the
summer of 2018
2023-10-09T00:00:00ZTHE FIRST ACTIVE ACID SULFATE SOIL FOUND OUTSIDE THE BALTIC BASIN, IN VISKA VALLEY WEST COAST OF SWEDEN
https://hdl.handle.net/2077/78536
THE FIRST ACTIVE ACID SULFATE SOIL FOUND OUTSIDE THE BALTIC BASIN, IN VISKA VALLEY WEST COAST OF SWEDEN
Bergström, Johanna
Acid sulfate (AS) soils are naturally formed but are responsible for environmental problem
due to its low pH. Drainage of active AS soils can lead to mobilization of harmful metals and
a severe pH drop in nearby aquatic environments, which in turn may harm the ecological
conditions. Most AS soil in Sweden has been found mainly along the northeast coast, and this
area has received much research attention. A few discoveries have also been made in
Mälardalen and Skåne. Recently, during a geological survey by the Geological Survey of
Sweden (SGU) in the Viska Valley in Halland, old drilling profiles were found that showed
sulfide-rich layers that hinted about the possible existence of AS soil. Focusing on the Viska
Valley, this project aims to investigate the existence of AS soil in southwestern Sweden and
find clues about its formational environment. Electrical Resistivity Tomography’s (ERT)
suitability was evaluated as a method for locating AS soil on the west coast, and the ERT data
was compared to the old drilling profiles. This study together with another master thesis
study in Falkenberg was carried out during September 2019 to June 2020 in collaboration
with SGU. Sampling sites were determined based on the old drilling data and SGU’s soil
map. Samples were collected by using an Edelmann drill and brought to the laboratory for
oxidation and further analyses, including grain-size distribution, metal-, sulfur- and organic
content. Two ERT-measurements were made along one of the drilling profiles. This study is
the first that proves the existence of AS soil outside the Baltic basin. In two areas of the
valley, AS soil was found, one which was active and one potential, both in post-glacial gyttja
clay covered by floodplain sediments. The gyttja clay is believed to have formed during the
Tapes transgression when the valley consisted of a fjord-like bay, protected from wind and
currents with saltwater input from Kattegat. The data from the ERT measurements displayed
anomalies where the AS soil was found, but the information is not sufficient to determine
with certainty whether the layer of AS soil is present. However, the study made
simultaneously in Falkenberg showed more optimistic results with the ERT, which suggests
that it may be an appropriate method with different electrode spacing and a larger number of
measurements. This study only covers a small area of the Viska Valley, and most likely it is
possible to find more AS-soil in the area as well on the entire west coast in areas that were
below the highest coastline.
2023-09-15T00:00:00ZManaging Domestic Wells in Sweden. Investigating the role of domestic wells in ensuring a reliable drinking water supply and assessing their vulnerability to climate change
https://hdl.handle.net/2077/78392
Managing Domestic Wells in Sweden. Investigating the role of domestic wells in ensuring a reliable drinking water supply and assessing their vulnerability to climate change
Stenfelt, Alice
Domestic wells provide drinking water for a significant proportion of the population in
Sweden, especially in rural areas where public water supplies are not available (Drage,
2022; Hjerne et al., 2021). Domestic wells typically lack regulation (Gunnarsdottir
et al., 2020; Stoll et al., 2011), with owners being responsible for maintaining and en suring water safety (Socialstyrelsen, 2008). Examining individual drinking water sup plies is crucial for sustainable development, given their heavy reliance on groundwater
sources (Maxe, 2007). Recent studies on climate change impacts have emphasized
groundwater-related concerns (Stoll et al., 2011). Therefore, it is imperative to con duct research, plan, and manage domestic water sources to enhance national drinking
water security and reduce vulnerability to disruptions. Domestic wells are particularly
vulnerable to changes in groundwater quality and quantity, which can lead to water
scarcity, affecting a significant portion of the population (Rodhe et al., 2006).
In order to address the study’s aim of examining the current state of domestic well
management by municipalities and contributing to the understanding of drinking water
and domestic wells, especially in terms of their vulnerability to climate change impacts,
an online survey was distributed to all municipalities in Sweden. Additionally, four
semi-structured interviews were conducted with representatives from municipalities
and County Administrative Boards. Thematic analysis was performed on the collected
data to gain insights into the opportunities and challenges municipalities face in their
efforts to achieve sustainable objectives and ensure universal access to clean water.
The study reveals that domestic wells in Sweden have not yet received specific attention
from authorities, and comprehensive regulations addressing issues such as water qual ity and quantity deficiencies are lacking. Nonetheless, the survey indicates a growing
recognition of the need to address these challenges, particularly in southern municip alities and areas with scarce groundwater resources. This highlights the urgency of
promoting sustainable water management and achieving sustainable drinking water
solutions in regions heavily reliant on groundwater.
2023-08-28T00:00:00Z