| 1. |
- Earon, Robert, et al.
(författare)
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Groundwater Resources Potential in Hard Rock Terrain : A Multivariate Approach
- 2014
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Ingår i: Ground Water. - : John Wiley & Sons. - 0017-467X .- 1745-6584.
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Tidskriftsartikel (refereegranskat)abstract
- Groundwater resources are limited and difficult to predict in crystalline bedrock due to heterogeneity and anisotropy in rock fracture systems. Municipal-level governments often lack the resources for traditional hydrogeological tests when planning for sustainable use of water resources. A new methodology for assessing groundwater resources potential (GRP) based on geological and topographical factors using principal component analysis (PCA) and analysis of variance (ANOVA) was developed and tested. ANOVA results demonstrated statistically significant differences in classed variable groups as well as in classed GRP scores with regard to hydrogeological indicators, such as specific capacity (SC) and transmissivity. Results of PCA were used to govern the weight of the variables used in the prediction maps. GRP scores were able to identify 79% of wells in a verification dataset, which had SC values less than the total dataset median. GRP values showed statistically significant correlations using both parametric (using transformed datasets) and non-parametric methods. The method shows promise for municipal or regional level planning in crystalline terrains with high levels of heterogeneity and anisotropy as a hydrogeologically and statistically based tool to assist in assessing groundwater resources. The methodology is executed in a geographic information systems environment, and uses often readily available data, such as geological maps, feature maps and topography, and thus does not require expensive and time-consuming aquifer tests.
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| 2. |
- Shami, Siavash, et al.
(författare)
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Assessments of ground subsidence along the railway in the Kashan plain, Iran, using Sentinel-1 data and NSBAS algorithm
- 2022
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Ingår i: International Journal of Applied Earth Observation and Geoinformation. - : Elsevier. - 1569-8432 .- 1872-826X. ; 112
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Tidskriftsartikel (refereegranskat)abstract
- The 110-kilometer-long Qom-Kashan railway is one of the busiest lines in Iran, passing through the Kashan plain. The majority of Iran's plains have subsided in recent years as a result of uncontrolled groundwater extraction, and the Kashan plain is no exception. In this study, ground surface displacement in the Kashan plain region and its impact on the railway were investigated using New Small Baseline Subset (NSBAS) in up-down and east–west directions using descending and ascending Sentinel-1 data collected between 2015 and 2021. Our results indicate that the Kashan plain is subsiding more than 90 mm/year. The study of the local areas around the railway which passes through the study area revealed that the rate of vertical velocity in some locations reaches –23 mm/year, while the rate of east–west velocity is insignificant and is approximately ±2 mm/year. Additionally, a method for analyzing the railway's stability based on longitudinal profiles along the railway is presented. Our findings suggest that more than 60% of the railway line is subject to variable amounts of subsidence. Additionally, a region of approximately one kilometer of the railway has been classified as a risk zone due to relatively fast local deformation. After examining the effect of various factors, it was determined that uncontrolled groundwater extraction in agricultural areas contributed to the subsidence in this area. Our results show that the presented stability control approach in this study is highly reliable for creating hazard profiles for linear structures, such as railways.
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| 3. |
- Nickman, Alireza
(författare)
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Road disasters? Modeling and assessment of Swedish roads within crucial climate conditions
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- An efficient maintenance of roads to ensure high accessibility and durability of the transport capacity requires an understanding of how the hydrological response depends on both the road and the landscape characteristics. New methods and data were used to identify and explain interaction between roads and surrounding environment and their influence on hydrologic responses both in watershed scale and road-section scale. In the watershed scale, flood hazard probability was made with reference to the most influential physical catchment descriptors and road characteristics. Additionally, a physical based model was used to estimate the effect of road topography on the hydrological responses of 20 watersheds to storms with different intensities. A simple method was developed and discussed to address flood risk probability in the road-stream crossings concerning the correlation between the quantities of the physical catchment descriptors and occurrence/absence of flooding. The most influential factors in describing the probability of flooding along the roads were topographic wetness index, soil properties, road density and channel slopes. A detailed study of simulated flow duration curves showed differences between the 20 watersheds for three different storms based on topography with and without roads. An increase in peak flow and reduced time to pick occurred with existence of roads and increased storm intensity.In the road-section scale, an uncertainty-based simulation approach was used to identify the most influencing processes in controlling the dynamics of the groundwater level. A model (CoupModel) set up with four different geological stratifications was made to model two positions in a slope upstream of a road with drainage pipes and ditches. Results from the simulations indicate the significance of precipitation rate, road drainage and position in hillslope, and soil properties and stratifications in controlling groundwater levels. The same model was also applied to simulate soil moisture and temperature dynamics in two road sections by using groundwater and climate data. Porous media properties were obtained as statistical distribution function that provided the best performance of moisture and temperature dynamic in the road layers and underlying soil.
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| 4. |
- Alkaradaghi, Karwan, et al.
(författare)
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Landfill Site Selection Using GIS and Multi-criteria Decision-making AHP and SAW Methods: A Case Study in Sulaimaniyah Governorate, Iraq
- 2022
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Ingår i: Research Developments in Geotechnics, Geo-Informatics and Remote Sensing. - Cham : Springer Nature. ; , s. 289-292
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Konferensbidrag (refereegranskat)abstract
- Lack of land for waste disposal is one of the main problems facing urban areas in developing countries. The Sulaimaniyah Governorate, located in Northern Iraq, is one of the main cities of the country in the Kurdistan Region, covering an area of 2400 km2. Currently, there is no landfill site in the study region that meets the scientific and environmental requirements, and the inappropriate dumping of solid waste causes adverse effects to the environment, economic and urban aesthetic. To overcome this phenomenon, it is crucial to suggest a landfill site, even in countries that recycle or burn their waste to protect the environment. Landfill sites should be carefully selected taking into account all regulations and other restrictions. The integration of geographic information systems and the multi-criteria decision analysis were used in this study to select suitable landfill locations in the region. To this end, thirteen layers prepared according to their importance including slope, geology, land use, urban area, villages, rivers, groundwater, slope, elevation, soil, geology, road, oil and gas, land use, archaeology and power lines. Two different methods (simple additive weighting and analytic hierarchy process) were implemented in a geographical information system to obtain the suitability index map for candidate landfill sites, where all these conditions satisfied the scientific and environmental criteria adopted in this study. The comparison of the maps resulting from these two different methods demonstrates that both methods produced consistent results.
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| 5. |
- Haas, Jan, et al.
(författare)
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Remote sensing of bidecadal urbanization and its impact on ecosystem service in the yangtze river delta
- 2013
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Ingår i: Proceedings of Dragon 2 Final Results & Dragon 3 Kick-Off Symposium. - : ESA Communications. - 9789290922681 ; , s. 1-8
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Konferensbidrag (refereegranskat)abstract
- The degree of urbanization and resulting effects on Ecosystem Services is investigated in the Yangtze River Delta in China within a 20 year time frame from 1990 to 2010. A Random forest classifier is used to classify the Landsat mosaic from 1990 and the HJ-1A/B mosaic dating from 2010. Urban Land Index (UI) and Urban Expansion Index (UX) are used to represent the intensity and rapidity of urbanization. Post-Classification Change Detection is then performed and Ecosystem Service value losses for the land-cover classes water, wetland, forest and cropland that transitioned to urban areas are calculated according to a valuation scheme adapted to the Chinese market. The results showed that Yangtze River Delta experienced significant urbanization during 1990 to 2010. Urban areas increased alongside a major decrease in cropland resulting in a substantial loss of 4.2 billion CNY in Ecosystem Services.
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| 6. |
- Hammar, Arvid, 1986, et al.
(författare)
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Optical Tolerance Analysis of the Multi-Beam Limb Viewing Instrument STEAMR
- 2014
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Ingår i: IEEE Transactions on Terahertz Science and Technology. - 2156-342X .- 2156-3446. ; 4:6, s. 714-721
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Tidskriftsartikel (refereegranskat)abstract
- We report on an optical tolerance analysis of the submillimeter atmospheric multi-beam limb sounder STEAMR. Physical optics and ray-tracing methods were used to quantify and separate errors in beam pointing and distortion due to reflector misalignment and primary reflector surface deforma-tions. Simulations were performed concurrently with the man-ufacturing of a multi-beam demonstrator of the relay optical system which shapes and images the beams to their corresponding receiver feed horns. Results from Monte-Carlo simulations show that the inserts used for reflector mounting should be positioned with an overall accuracy better than 100 µm (~1/10 wavelength). Analyses of primary reflector surface deformations show that a deviation of magnitude 100 µm can be tolerable before deployment, whereas the corresponding variations should be less than 30 µm during operation. The most sensitive optical elements in terms of misalignments are found near the focal plane. This localized sensitivity is attributed to the off-axis nature of the beams at this location. Post-assembly mechanical measurements of the reflectors in the demonstrator show that alignment better than 50 µm could be obtained.
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| 7. |
- Johansson, John, 1982
(författare)
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Optical remote sensing of industrial gas emission fluxes
- 2013
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Mobile optical remote sensing techniques offer promising possibilities to quantify and geographically attribute local industrial gaseous emissions to the atmosphere. Studies have repeatedly shown that such emissions are often poorly understood, underestimated, and thereby not properly accounted for in emission inventories and regional atmospheric chemistry models, especially for emissions of VOCs. A better understanding and quantification of industrial VOC emissions is crucial for combating ground-level ozone, a serious problem facing most of the world's larger urban areas.This thesis presents results from a number of measurement campaigns primarily conducted in the area around Houston, Texas, USA, which has one of the world's largest concentrations of oil, gas and petrochemical industries. In the campaigns, the two flux measurement methods Solar Occultation Flux (SOF) and Mobile DOAS were used to quantify emissions of VOCs (alkanes and alkenes), SO2, NO2, and formaldehyde (HCHO) from the largest industrial conglomerates in the area.Measured emissions are compared to industry estimates reported to emission inventories, showing discrepancies of up to an order of magnitude for VOCs but not for SO2 and NO2. Emission factor models are used to estimate effects on VOC emissions of unrepresentative meteorological conditions during the measurement campaigns. These effects are determined to be too small to explain the discrepancies between measurements and reported emissions seen for VOCs.A plume chemistry model is applied to a number of cases where formaldehyde were detected together with significant amounts of alkenes in order to assess whether the formaldehyde could be explained as a secondary pollutant from the oxidation of alkenes. The results of the modeling shows that secondary emissions can only explain a small fraction of the measured formaldehyde flux in most cases, suggesting that most of the formaldehyde emissions measured from local sources were primary emissions. Secondary emissions are, however, still believed to be the largest source of formaldehyde further downwind from sources.
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| 8. |
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| 9. |
- Paul, Seema, et al.
(författare)
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Understanding hydrodynamic and climate effects on the transboundary Lake Victoria basin at a catchment scale
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Annan publikation (populärvet., debatt m.m.)abstract
- This study examines how hydrodynamic processes in the catchment area of Lake Victoria are affected by climate change. A methodology was developed using numerical modelling and long-term geospatial mapping methods to understand the influence of climate change on hydro-meteorological processes in Lake Victoria, utilising satellite and climatic data from 1900 to 2020. The methodology enables the examination of how hydrodynamic processes, like the inflow of water to the lake and responses to water level variations, are impacted by climate variables. The resulting model demonstrates the crucial interdependence between hydrodynamic processes and climatological factors. Long-term rainfall variation shows a linear positive correlation, which explains the increase in the lake’s overall water level. With respect to the bathymetry as well as the areal coverage, the presence of nutrients in the lake water helps to identify pollution patterns and water quality. Given the regional importance of shallow freshwater lakes across the world, Lake Victoria provides an exceptional case study and the study shows how numerical modelling can improve understanding of the relationship between the physical features of shallow lakes and their hydrodynamics. This includes analysing flow patterns, hydro-meteorological processes, transport of pollutants, and the impact of eutrophication. These factors are crucial in determining water levels and water quality, especially in face of climate change.
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| 10. |
- Darvishi, Mehdi, et al.
(författare)
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InSAR-based Ground Motion Service of Sweden: evaluation and benefit analysis of a nationwide InSAR service
- 2022
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Konferensbidrag (refereegranskat)abstract
- Space-geodetic techniques such as Global Navigation Satellite Systems (GNSS) and Syntenic Aperture Radar interferometry (InSAR) are powerful tools to measure and monitor ground surface motion. InSAR has widely been used for the detection and quantification of slow mass movements over the past three decades mainly at the local and regional scales. The high performance and millimeter-level measurement accuracy of radar satellite to provide a dense deformation map at different spatial and temporal resolutions are the key factors to think of using SAR data and InSAR technique as an efficient tool for geohazards motoring system at the nationwide scale.Sweden has recently joined to the countries having InSAR Ground Motion Service (GMS) at a nationwide scale. The InSAR service of Sweden, which will soon be freely available for users, provides the displacement time-series of measurement points for the entire country. The Swedish GMS project was started last year and is an ongoing collaboration between the Geological Survey of Norway (NGU) and several Swedish organizations (led by the Swedish National Space Agency (SNSA)). The InSAR-based GMS of Sweden has been generated by NGU using Sentinel-1 data (2015–2020) and the Persistent Scatterer Interferometry (PSI) technique. The web-based GMS of Sweden consists of ~1,5 billion time-series measurement points obtained from both descending and ascending satellite orbital modes.Currently, the Swedish GMS is under evaluation and validation phase and the given plan has been designed to assess the quality or validate the GMS products. We plan to conduct the data validation through two main phases: 1) a cross-comparison between InSAR measurement points and ancillary data such as GNSS, Corner Reflectors (CR), Electronic Corner Reflectors (ECR) and leveling data, and 2) assessment of tropospheric and ionospheric effects on InSAR measurement points. Specifically, we will evaluate different approaches and data for the InSAR tropospheric corrections, such as Very-Long-Baseline Interferometry (VLBI), Water Vapour Radiometry (WVR), and GNSS data at the Onsala Space Observatory (OSO).In the first phase of validation, leveling data collected in Gothenburg and Stockholm cities, mainly over the residential areas and public transport infrastructures compared to the corresponding InSAR measurements points (vertically converted) for a five-year period. The initial results present a high correlation between two sets of the vertical displacements. The same procedure will be performed for the Kiruna city where the mining activities resulted in adrastic urban land subsidence. Since the CRs and ECRs have recently been installed in different parts of Sweden, we do not have them as PS points in the current version of the GMS. Therefore, those CR-based measurement points will be used in future accuracy assessments. In the second phase, we investigated the effects of phase delay induced by troposphere on displacement time-series using two approaches, i.e., time-space filtering and using external data (e.g., atmospheric reanalysis data, GNSS, VLBI and Water Vapor Radiometer (WVR)). Recently, European GMS (EGMS) has been released and the Ortho displacement map is now available for users freely. We also evaluated and compared the EGMS-Ortho displacement map with our independent InSAR processing and GNSS data over the Kiruna.As the InSAR-based GMS can be used to monitor and identify the potential risk of geo-related hazards in Sweden, the society will directly benefit from the outcomes of this project. This open access product will help the stakeholders with decision support for prioritization of risk-reducing measures, and identification of the need for further investigations for areas in danger. The service could also assist municipalities and county administrative boards to have an update information regarding urban areas which are more prone to land subsidence and disruption urban infrastructure.
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