Cristina Ponte Lira

Sedimentological Analysis of Sands

This paper presents a practical sequence to study sand grains at the macroscopical scale. The approach consists of two mains phases, the recognition of the grains and the assessment of some of its characteristics. The method is validated on the dimensional features by comparison with a sieving procedure through the analysis of eight large sand samples of different locations.

Advances in Applied Remote Sensing to Coastal Environments Using Free Satellite Imagery

Remote sensing emerges as a very effective technique to capture the dynamics of the coastal system, as it provides a holist view of the system at a wide range of spatial and temporal scales. However, the recent thrive of these systems has led to a broad variety of sensors and data, which can difficult the choice of the optimal sensor for a practical application. In mesoscale coastal environment applications and considering the universe of the solutions, Landsat program arises as a good compromise between spectral, radiometric, spatial and temporal resolutions, combined with free data access, supported by an efficient data sharing platform. The capabilities of the Landsat program was recently extended with the launch of a new satellite – Landsat 8, with improved radiometric and spectral resolution, opening the door to new studies. This work describes the applicability of these images in four case studies that demonstrates the potentialities of the Landsat program in what concerns: (1) time coverage – long-term evolution of an ephemeral ebb delta island; (2) frequency of coverage – seasonal evolution of a short-lived beach; (3) radiometric resolution – shoreline detection and extraction; (4) spectral resolution – bathymetric data retrieval.

Automatic detection of landslide features with remote sensing techniques: Application to Madeira Island

The extreme rainfall event of February 20 ,2010 triggered a series of landslides and alluvium episodes with extensive life and material damages. The use of automatic detection of the landslides over satellite imagery allowed the identification and characterization of the affected areas, the mapping of the landslide features and the calculation of the displaced sediment volume. The study shows that the occurred landslides were shallow, being the basins of Ribeira Brava the most affected areas, with almost two thirds of the total identified landslide polygons.

Adding a temporal dimension to the RUSLE model: Application to the Portuguese west coast

Soil erosion by water is one of the main sources of sediment supply to the coastal zone and its quantification is a major issue in coastal management. The intensity of sediment delivery to the coast can be assessed by the RUSLE model, which is able to account the time-variability of the primary variables. This study evaluates the potential changes in soil erosion considering a time window framed from pristine conditions to the end of 21st century. Results show the robustness of this method in ranking the importance of each variable of the erosion system, not only in a predefined time window, but also in comparing changes between instantaneous pictures separated in time.