ABSTRACT Kjeld Rasmussen, Henrik Steen Andersen, Jens Grundtmann, Bjarne Fog and Lasse Møller-Jensen: The CHIPS System for Satellite Image Processing. Geografisk Tidsskrift, Danish Journal of Geography 94:xx-xx. Copenhagen, Dec. 1994.
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In this study we present the first findings of the potential utility of miniaturized Light and Detection Ranging (LiDAR) scanners mounted on Unmanned Aerial Vehicles (UAVs) for improving urban flood assessment at the local scale. This is... more
In this study we present the first findings of the potential utility of miniaturized Light and Detection Ranging (LiDAR) scanners mounted on Unmanned Aerial Vehicles (UAVs) for improving urban flood assessment at the local scale. This is done by generating high spatial resolution Digital Terrain Models (DTM) featuring buildings and urban microtopographic structures that can affect floodwater pathways (DTMbs). The accuracy and level of detail of the flooded areas simulated by a hydrologic screening model (Arc-Malstrøm), were vastly improved when DTMbs of 0.3 m resolution representing three urban sites surveyed by a UAV-LiDAR in Accra, Ghana, supplemented a commercially available 10 m resolution DTM covering the full catchment area of the region. The generation of DTMbs necessitated the effective classification of UAV-LiDAR point clouds using a morphological and a triangulated irregular network method for hilly and flat landscapes, respectively. The UAV-LiDAR enabled the identificatio...
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In this study, we present the first findings of the potential utility of miniaturized light and detection ranging (LiDAR) scanners mounted on unmanned aerial vehicles (UAVs) for improving urban flood modelling and assessments at the local... more
In this study, we present the first findings of the potential utility of miniaturized light and detection ranging (LiDAR) scanners mounted on unmanned aerial vehicles (UAVs) for improving urban flood modelling and assessments at the local scale. This is done by generating ultra-high spatial resolution digital terrain models (DTMs) featuring buildings and urban microtopographic structures that may affect floodwater pathways (DTMbs). The accuracy and level of detail of the flooded areas, simulated by a hydrologic screening model (Arc-Malstrøm), were vastly improved when DTMbs of 0.3 m resolution representing three urban sites surveyed by a UAV-LiDAR in Accra, Ghana, were used to supplement a 10 m resolution DTM covering the region’s entire catchment area. The generation of DTMbs necessitated the effective classification of UAV-LiDAR point clouds using a morphological and a triangulated irregular network method for hilly and flat landscapes, respectively. The UAV-LiDAR data enabled the...
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... perspectives above. Classical theoretical lines of thought will support the characteriza-tion of rural populations' livelihood strategies and adapt-ability and their vulnerability to exogenous and endogenous... more
... perspectives above. Classical theoretical lines of thought will support the characteriza-tion of rural populations' livelihood strategies and adapt-ability and their vulnerability to exogenous and endogenous stressors. The livelihood ...
Research Interests: Human Ecology, Economics, Coping Strategies, Coevolution, Livelihood, and 13 moreShifting Cultivation, Small islands, Satellite Imagery, Agricultural land use change, Local Community, Environmental Conditions, Natural Resource, Active Transport, Population dynamic, Questionnaire Survey, Driving force, Adaptive Resource Management, and agricultural land
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This study focuses on the use of Synthetic Aperture Radar (SAR) data for mapping the extent of flooding events. A small test area in the middle Senegal River valley in the western part of Sahel is studied. Four ERS2 SAR PRI scenes have... more
This study focuses on the use of Synthetic Aperture Radar (SAR) data for mapping the extent of flooding events. A small test area in the middle Senegal River valley in the western part of Sahel is studied. Four ERS2 SAR PRI scenes have been used in the analysis for delineation of flooded areas. Change images have been produced by using the latest non-flood image (August 1999) as reference and dividing the backscatter values in the subsequent images by the values in this reference image. When plotting the temporal evolution in backscatter for different surface types an unambiguous picture emerges. Six different classes were found to have a distinct backscatter pattern trough time, and can therefore easily be identified in the images. For each change image in the flood period, an automatic standard classification algorithm has been applied, and the resulting classes have been assigned water or land. The classification result for the first SAR image in the flood period (September 22) h...
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ABSTRACT Three different methods (local knowledge, aerial photos, and botanical investigations) were used to document changes in woody vegetation cover in the Sahelian part of Burkina Faso. Local people had observed a general decline of... more
ABSTRACT Three different methods (local knowledge, aerial photos, and botanical investigations) were used to document changes in woody vegetation cover in the Sahelian part of Burkina Faso. Local people had observed a general decline of woody plants that was most pronounced in valleys, and aerial photos supported this view. Local people also reported a lack of rejuvenation of many woody species, and this was confirmed by botanical data and size class distribution analysis. Together the three methods documented a diminution in density and diversity of the woody vegetation cover which, estimated from size class distributions, will continue in the nearest future. Some of the trees and shrubs that are most appreciated by local people are also sharply declining, and local societies are therefore faced with reductions in some of their most essential natural resources.
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Rapidly expanding cities are exposed to higher damage potential from floods, necessitating effective proactive management using technological developments in remote sensing observations and hydrological modelling. In this study we tested... more
Rapidly expanding cities are exposed to higher damage potential from floods, necessitating effective proactive management using technological developments in remote sensing observations and hydrological modelling. In this study we tested whether high resolution topographic data derived by Light and Detection Ranging (LiDAR) and Unmanned Aerial Vehicle (UAV) systems can facilitate rapid and precise identification of high-risk urban areas, at the local scale. Three flood prone areas located within the Greater Accra Metropolitan Area in Ghana were surveyed by a UAV-LiDAR system. In order to simulate a realistic flow of precipitation runoff on terrains, Digital Terrain Models (DTM) including buildings and urban features that may have a substantial effect on water flow pathways (DTMb) were generated from the UAV-LiDAR datasets. The resulting DTMbs, which had a spatial resolution of 0.3 m supplemented a satellite-based DTM of 10 m resolution covering the full catchment area of Accra, and ...
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This study focuses on the use of Synthetic Aperture Radar (SAR) data for mapping the extent of flooding events. A small test area in the middle Senegal River valley in the western part of Sahel is studied. Four ERS2 SAR PRI scenes have... more
This study focuses on the use of Synthetic Aperture Radar (SAR) data for mapping the extent of flooding events. A small test area in the middle Senegal River valley in the western part of Sahel is studied. Four ERS2 SAR PRI scenes have been used in the analysis for ...
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ABSTRACT Kjeld Rasmussen, Henrik Steen Andersen, Jens Grundtmann, Bjarne Fog and Lasse Møller-Jensen: The CHIPS System for Satellite Image Processing. Geografisk Tidsskrift, Danish Journal of Geography 94:xx-xx. Copenhagen, Dec. 1994.
Research Interests:
ABSTRACT The objective of this paper is through a case study from the southern highlands of Tanzania, to illustrate how the agricultural system has changed within a period from the mid-1950s to the early 1990s in response to both... more
ABSTRACT The objective of this paper is through a case study from the southern highlands of Tanzania, to illustrate how the agricultural system has changed within a period from the mid-1950s to the early 1990s in response to both endogenous and exogenous forces. The focus is primarily on the latest response at village level to the liberalization process within the agricultural sector in the early 19905. New methods, by which remote sensing data from high resolution sensors are used as primary input, are analysed in relation to monitoring and to evaluate rapid land use changes.
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Seasonal flooding characterizes many of Africa's major rivers, including the Nile, the Niger, the Volta, the Sene-gal and the Zambezi. The strong seasonal variation in dis-charge is controlled by rainfall in highland catchments.... more
Seasonal flooding characterizes many of Africa's major rivers, including the Nile, the Niger, the Volta, the Sene-gal and the Zambezi. The strong seasonal variation in dis-charge is controlled by rainfall in highland catchments. Many of the rivers cut through semi arid or arid areas, ...
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This study focuses on the use of Synthetic Aperture Radar (SAR) data for mapping the extent of flooding events. A small test area in the middle Senegal River valley in the western part of Sahel is studied. Four ERS2 SAR PRI scenes have... more
This study focuses on the use of Synthetic Aperture Radar (SAR) data for mapping the extent of flooding events. A small test area in the middle Senegal River valley in the western part of Sahel is studied. Four ERS2 SAR PRI scenes have been used in the analysis for ...