Encontrados 11 documentos, a visualizar página 1 de 2

Flood hazard mapping by integrating airborne laser scanning data, high resoluti...

The assessment and management of flood risks framework impose the mapping of flood hazard in potential flood risks areas. Floods in urban environments may happen due to rainfall extreme events and be exacerbated by saturated or impervious surfaces. Flood risk is greater in urban areas. (...)

Runoff and erosion at the micro-plot and slope scale in a small burnt catchment...

Wildfires can have important impacts on hydrological processes and soil erosion in forest catchments, due to the destruction of vegetation cover and changes to soil properties. However, the processes involved are non-linear and not fully understood. This has severely limited the understanding on the impacts of wildfires, especially in the up-scaling from hillslopes to catchments; in consequence, current models ...

Varrimento por laser: estado-da-arte e aplicações

Effect of the Resolution and Accuracy of DTM produced with Aerial Photogrammetr...

Wildfires are a common phenomenon in Portugal, affecting on average 100.000 ha of rural areas per year and up to 400.000 ha in dramatic years like 2003 and 2005. Wildfires can strongly enhance the hydrological response and associated sediment losses in recently burnt forest catchments and, thereby, negatively affect land-use sustain- ability of the affected terrains as well as ecosystem functioning of downstrea...

Hydrological and erosion response at micro-plot to -catchment scale following f...

Wildfires can have important impacts on hydrological and soil erosion processes, due to the destruction of vegetation cover and changes to soil properties. According to Shakesby and Doerr (2006), these wildfire effects are: i) much better known at small spatial scales (especially erosion plots) than at the scale of catchments; ii) much better studied with respect to overland flow and streamflow (and, then, espe...

Runoff and erosion in a small burnt catchment in central Portugal

Post-fire erosion is a major concern because of its potential effects on soil and water resources. Wildfire is frequently observed to increases soil erosion rates (Shakesby and Doerr, 2006). Many studies have emphasized the role of the partial or entire elimination of vegetation and ground cover (thereby exposing the mineral soil to direct impact of raindrops and overland flow) as a key factor in the increased ...

3D segmentation of forest structure using an adaptive mean shift based procedure

Plant communities display a vertical structure based on the size and growth pattern of the dominant species. To a large extent, this pattern, called vertical stratification, depends on the climatic zone. Vertical structure analysis consists in detecting the number of layers and their limits within a forest stand. So far, there is a lack of robust approaches applied to airborne laser scanning (ALS) data that pro...

Assessment of the performance of eight filtering algorithms by using full-wavef...

In this study the strengths and weaknesses of eight filtering algorithms are evaluated by using the mean, standard deviation and RMSE metrics. Seven of these algorithms are implemented in the freeware software ALDPAT (Airborne LiDAR Data Processing and Analysis Tools) and the eighth, known as the Axelsson filter, in the commercial software Terrascan. The referred metrics are calculated by using DTM of topograph...

Integration of Aerial Laser Scanning Data and CIR Images to Produce DTM in Urba...

Airborne Laser Scanning is an established technique to produce Digital Terrain Models (DTM). In spite of its widespread use, the extraction of a DTM in urban areas still poses problems because the filtering process often fails to separate some of the objects on the terrain surface from the terrain itself. This happens because only one kind of information – geometric information – is used in the process. To over...

The study of soil, hydrological, erosion and vegetation processes following wil...

The EROSFIRE-II project (PTDC/AGR-CFL/70968/2006) has as overall aim to predict soil erosion risk in recently burnt forest areas, including following common post-fire forest management practices. Although the project’s main focus is on onsite erosion processes, also the export of sediments out of small catchments is addressed. To this end, a study area of about 60 ha located near to the village of Colmeal (...