| 1. |
- Berndtsson, Ronny, et al.
(författare)
-
Drivers of changing urban flood risk : A framework for action
- 2019
-
Ingår i: Journal of Environmental Management. - : Elsevier. - 0301-4797 .- 1095-8630. ; 240, s. 47-56
-
Tidskriftsartikel (refereegranskat)abstract
- This study focuses on drivers for changing urban flood risk. We suggest a framework for guiding climate change adaptation action concerning flood risk and manageability in cities. The identified key drivers of changing flood hazard and vulnerability are used to provide an overview of each driver's impact on flood risk and manageability at the city level. We find that identified drivers for urban flood risk can be grouped in three different priority areas with different time horizon. The first group has high impact but is manageable at city level. Typical drivers in this group are related to the physical environment such as decreasing permeability and unresponsive engineering. The second group of drivers is represented by public awareness and individual willingness to participate and urbanization and urban sprawl. These drivers may be important and are manageable for the cities and they involve both short-term and long-term measures. The third group of drivers is related to policy and long-term changes. This group is represented by economic growth and increasing values at risk, climate change, and increasing complexity of society. They have all high impact but low manageability. Managing these drivers needs to be done in a longer time perspective, e.g., by developing long-term policies and exchange of ideas.
|
|
| 2. |
- Eklund, Lina, et al.
(författare)
-
Cropland changes in times of conflict, reconstruction, and economic development in Iraqi Kurdistan
- 2016
-
Ingår i: Ambio: a Journal of Human Environment. - : Springer Science and Business Media LLC. - 0044-7447. ; 45:1, s. 78-88
-
Tidskriftsartikel (refereegranskat)abstract
- The destruction of land and forced migration during the Anfal attacks against the Kurds in Iraq in the late 1980s has been reported to have severe consequences for agricultural development. A reconstruction program to aid people in returning to their lands was launched in 1991. To assess the agricultural situation in the Duhok governorate during the pre-Anfal (A), post-Anfal (B), reconstruction (C), and present (D) periods, we mapped winter crops by focusing on inter-annual variability in vegetation greenness, using satellite images. The results indicate a decrease in cultivated area between period A and B, and a small increase between period B and C. This supports reports of a decline in cultivated area related to the Anfal campaign, and indicates increased activity during the reconstruction program. Period D showed a potential recovery with a cropland area similar to period A.
|
|
| 3. |
- Hasan, Abdulghani, et al.
(författare)
-
On generating digital elevation models from liDAR data – resolution versus accuracy and topographic wetness index indices in northern peatlands
- 2012
-
Ingår i: Geodesy and Cartography. - : Vilnius Gediminas Technical University. - 2029-6991 .- 2029-7009. ; 38:2, s. 57-69
-
Tidskriftsartikel (refereegranskat)abstract
- Abstract Global change and GHG emission modelling are dependent on accurate wetness estimations for predictions of e.g. methane emissions. This study aims to quantify how the slope, drainage area and the TWI vary with the resolution of DEMs for a flat peatland area. Six DEMs with spatial resolutions from 0.5 to 90 m were interpolated with four different search radiuses. The relationship between accuracy of the DEM and the slope was tested. The LiDAR elevation data was divided into two data sets. The number of data points facilitated an evaluation dataset with data points not more than 10 mm away from the cell centre points in the interpolation dataset. The DEM was evaluated using a quantile-quantile test and the normalized median absolute deviation. It showed independence of the resolution when using the same search radius. The accuracy of the estimated elevation for different slopes was tested using the 0.5 meter DEM and it showed a higher deviation from evaluation data for steep areas. The slope estimations between resolutions showed differences with values that exceeded 50%. Drainage areas were tested for three resolutions, with coinciding evaluation points. The model ability to generate drainage area at each resolution was tested by pair wise comparison of three data subsets and showed differences of more than 50% in 25% of the evaluated points. The results show that consideration of DEM resolution is a necessity for the use of slope, drainage area and TWI data in large scale modelling. Global change and GHG emission modelling are dependent on accurate wetness estimations for predictions of e.g. methane emissions. This study aims to quantify how the slope, drainage area and the TWI vary with the resolution of DEMs for a flat peatland area. Six DEMs with spatial resolutions from 0.5 to 90 m were interpolated with four different search radiuses. The relationship between accuracy of the DEM and the slope was tested. The LiDAR elevation data was divided into two data sets. The number of data points facilitated an evaluation dataset with data points not more than 10 mm away from the cell centre points in the interpolation dataset. The DEM was evaluated using a quantile-quantile test and the normalized median absolute deviation. It showed independence of the resolution when using the same search radius. The accuracy of the estimated elevation for different slopes was tested using the 0.5 meter DEM and it showed a higher deviation from evaluation data for steep areas. The slope estimations between resolutions showed differences with values that exceeded 50%. Drainage areas were tested for three resolutions, with coinciding evaluation points. The model ability to generate drainage area at each resolution was tested by pair wise comparison of three data subsets and showed differences of more than 50% in 25% of the evaluated points. The results show that consideration of DEM resolution is a necessity for the use of slope, drainage area and TWI data in large scale modelling.
|
|
| 4. |
- Mandere, Nicodemus, et al.
(författare)
-
Tropical Sugar Beet Land Evaluation Scheme : TSBLES: Development, validation and application under Kenyan conditions
- 2010
-
Ingår i: GeoJournal. - : Springer Science and Business Media LLC. - 0343-2521 .- 1572-9893. ; 75:2, s. 215-228
-
Tidskriftsartikel (refereegranskat)abstract
- In Kenya the government is promoting diversification of crops to embrace high value crops and drought resistant crop varieties in efforts to reduce poverty in rural areas. Sugar beet is one of the crops considered as an option in this context and it is therefore important to increase knowledge about the potentials in the country for cultivating this crop. Sugar beet trials conducted in Nyandarua and Butere Mumias Districts of Kenya have shown that the crop yields are comparable to those obtained in traditional sugar-beet cultivation regions of Europe. Since sugar beet yield is affected by climate and soils, the results of Nyandarua and Butere Mumias sugar beet trials are not adequate to propose that comparable yields can be obtained elsewhere in the country and other tropical regions. Physical land evaluations assessing the potentials and constraints for sugar beet production are therefore essential. The objectives of this study was to develop a Tropical Sugar Beet Land Evaluation Scheme (TSBLES) that can aid assessment of the suitability of different areas in the tropics for sugar beet cultivation; and to test this scheme for an assessment of suitable sugar beet zones and land areas in Kenya. The development of the scheme was based on various literature sources and expert judgment on sugar beet requirements, and a Tropical Sugar Beet yield prediction Model. The TSBLES accounts for physical conditions of land i.e. climatic, edaphic and topographic conditions. According to the assessment results 27% of the land area in Kenya is suitable for sugar beet cultivation. Of this area, 5% is highly suitable, another 5% is moderately suitable and 17% is marginally suitable. Most of the highly suitable land area is concentrated in Rift Valley, Central and Nyanza provinces. The Rift Valley has the highest share of the suitable land area.
|
|
| 5. |
- Mandere, Nicodemus, et al.
(författare)
-
Tropical sugar beet land evaluation scheme: development, validation and application under Kenyan conditions
- 2010
-
Ingår i: GeoJournal. - : Springer Science and Business Media LLC. - 1572-9893 .- 0343-2521. ; 75:2, s. 215-228
-
Tidskriftsartikel (refereegranskat)abstract
- In Kenya the government is promoting diversification of crops to embrace high value crops and drought resistant crop varieties in efforts to reduce poverty in rural areas. Sugar beet is one of the crops considered as an option in this context and it is therefore important to increase knowledge about the potentials in the country for cultivating this crop. Sugar beet trials conducted in Nyandarua and Butere Mumias Districts of Kenya have shown that the crop yields are comparable to those obtained in traditional sugar-beet cultivation regions of Europe. Since sugar beet yield is affected by climate and soils, the results of Nyandarua and Butere Mumias sugar beet trials are not adequate to propose that comparable yields can be obtained elsewhere in the country and other tropical regions. Physical land evaluations assessing the potentials and constraints for sugar beet production are therefore essential. The objectives of this study was to develop a Tropical Sugar Beet Land Evaluation Scheme (TSBLES) that can aid assessment of the suitability of different areas in the tropics for sugar beet cultivation; and to test this scheme for an assessment of suitable sugar beet zones and land areas in Kenya. The development of the scheme was based on various literature sources and expert judgment on sugar beet requirements, and a Tropical Sugar Beet yield prediction Model. The TSBLES accounts for physical conditions of land i.e. climatic, edaphic and topographic conditions. According to the assessment results 27% of the land area in Kenya is suitable for sugar beet cultivation. Of this area, 5% is highly suitable, another 5% is moderately suitable and 17% is marginally suitable. Most of the highly suitable land area is concentrated in Rift Valley, Central and Nyanza provinces. The Rift Valley has the highest share of the suitable land area.
|
|
| 6. |
- MZOBE, Pearl, et al.
(författare)
-
Dissolved organic carbon in streams within a subarctic catchment analysed using a GIS/remote sensing approach
- 2018
-
Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 13:7
-
Tidskriftsartikel (refereegranskat)abstract
- Climate change projections show that temperature and precipitation increases can alter the exchange of greenhouse gases between the atmosphere and high latitude landscapes, including their freshwaters. Dissolved organic carbon (DOC) plays an important role in greenhouse gas emissions, but the impact of catchment productivity on DOC release to subarctic waters remains poorly known, especially at regional scales. We test the hypothesis that increased terrestrial productivity, as indicated by the normalized difference vegetation index (NDVI), generates higher stream DOC concentrations in the Stordalen catchment in subarctic Sweden. Furthermore, we aimed to determine the degree to which other generic catchment properties (elevation, slope) explain DOC concentration, and whether or not land cover variables representing the local vegetation type (e.g., mire, forest) need to be included to obtain adequate predictive models for DOC delivered into rivers. We show that the land cover type, especially the proportion of mire, played a dominant role in the catchment's release of DOC, while NDVI, slope, and elevation were supporting predictor variables. The NDVI as a single predictor showed weak and inconsistent relationships to DOC concentrations in recipient waters, yet NDVI was a significant positive regulator of DOC in multiple regression models that included land cover variables. Our study illustrates that vegetation type exerts primary control in DOC regulation in Stordalen, while productivity (NDVI) is of secondary importance. Thus, predictive multiple linear regression models for DOC can be utilized combining these different types of explanatory variables.
|
|
| 7. |
- Mzobe, Pearl N., et al.
(författare)
-
Dissolved organic carbon (DOC) export from subarctic areas analyzed using a GIS/remote sensing approach
- 2016
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Subarctic ecosystems are predicted to experience the fastest responses to climate change on the planet, with dramatically altered vegetation patterns, frost dynamics and hydrological flow paths. The resulting change in dissolved organic carbon (DOC) export to river systems is poorly known, but reports of rising DOC in northern surface waters have led to widespread speculations on a possible climate-induced freshwater ‘brownification’. In this study we explore the possibility of using the Normalized Vegetation Difference Index (NDVI) together with easily available topographical indices to model the DOC release into first-order streams, focusing on a subarctic area of Sweden (Stordalen) with discontinuous permafrost. We utilise earth observation data in predicting changes in DOC export, and further combine these efforts with distributed modeling of hydrological flow paths to generate maps of stream DOC in a palsa landscape. Our preliminary results point to a largely unexplored potential of using GIS and Remote Sensing analysis to reconstruct and project the DOC export from subarctic catchments and its response to climate change.
|
|
| 8. |
- Nilsson, Hampus, et al.
(författare)
-
Dynamic spatio‐temporal flow modeling with raster DEMs
- 2022
-
Ingår i: Transactions in GIS. - : Wiley. - 1467-9671 .- 1361-1682. ; 26:3, s. 1572-1588
-
Tidskriftsartikel (refereegranskat)abstract
- A user-friendly high-resolution intermediate complexity dynamic and spatially distributed flow model is crucial in urban flood modeling. Planners and consultants need to improve the accuracy of floods and estimation of risks. A new flow model will serve as a rapid tool to improve identification of these. This article provides a detailed explanation of a model based on a multiple flow algorithm. Model testing was performed on selected urban and rural areas. Additionally, a sensitivity analysis is conducted to analyze functionality. The model includes basic hydrological processes and is therefore less complex than fully physical models. The data needed to set up and run the new model include spatially and temporally distributed basic geometric and hydrologic variables (i.e., digital elevation model, precipitation, infiltration, and surface roughness). The model is implemented using open-source coding and can easily be applied to any selected area. Outputs are water volumes, depths, and velocities at different modeling times. Using GIS, results can be visualized and utilized for further analyses. The test, applied in urban as well as rural areas, demonstrates its user-friendliness, and that the estimated distributed water depths and water velocity at any time step can be saved and visualized.
|
|
| 9. |
- Persson, Andreas, et al.
(författare)
-
Modelling flow routing in permafrost landscapes with TWI : an evaluation against site-specific wetness measurements
- 2012
-
Ingår i: Transactions in GIS. - : Wiley. - 1467-9671 .- 1361-1682. ; 16:5, s. 701-713
-
Tidskriftsartikel (refereegranskat)abstract
- In northern peatlands the thawing of permafrost increasing the active layer depth and changing the hydrology may lead to feedbacks in the climate system through changes in the biogeochemistry of carbon. We are examining this association on the Stordalen peatland complex in subarctic Sweden by analyzing a DEM derived from LiDAR-data and the calculated TWI. The DEM, with a spatial resolution of 1 m, and the TWI are evaluated against two seasons of water level measurements from 30 sites in the peatland. The TWI is calculated with a form-based flow routing algorithm which produces a natural flow routing pattern. In permafrost wetlands the topography is the major driver and is very important even though its magnitude is low. Site-specific wetness (SSW) measurements from the sites were compared with the different peatland types that occur in the study area, i.e. fen, internal fen and palsa. The results showed a strong correlation between the TWI and the palsa. The TWI was better at describing general patterns than site-specific hydrology. The evaluation of spatial patterns of TWI against SSW reveal the resolution required to develop the technique to be useful for climate change studies.
|
|
| 10. |
- Persson, Andreas, et al.
(författare)
-
Spatial Influence of Topographical Factors on Yield of Potato (Solanum Tuberosum L.) in Central Sweden
- 2005
-
Ingår i: Precision Agriculture. - : Springer Science and Business Media LLC. - 1385-2256 .- 1573-1618. ; 6:4, s. 341-357
-
Tidskriftsartikel (refereegranskat)abstract
- This study has evaluated the sampling density for creation of high-resolution digital elevation models (DEMs) for precision agriculture purposes. The relationships between yield and topographical factors were investigated in a study area located in the central Sweden province of Dalarna. The DEM data sampling was carried out with a RTK-GPS system. A dense sampling scheme was employed and data was divided into two for both interpolation and validation. Kriging interpolation was used for DEM generation. From the DEM, topographical parameters were extracted and topographical indices were estimated. The indices were calculated with slope length and its vertical and horizontal components. The drainage area for a point of interest and the relationship of this area to the total drainage area were also estimated. The relationship of yield and the topographical parameters and indices was investigated usingboth circular and spatial statistics. A spatial regression was used to calculate a model for the relationship. Up to 20% of the yield could be explained in the final model for one of the fields.
|
|
