Monitoring the coastal zone using earth observation: application of linear spectral unmixing to coastal dune systems in Wales

Abstract

Coastal sand dune systems across temperate Europe are presently characterized by a high level of ecological stabilization and a subsequent loss of biological diversity. The use of continuous monitoring within these systems is vital to the preservation of species richness, particularly with regard to the persistence of early stage pioneer species dependent on a strong sediment supply. Linear spectral unmixing was applied to archived Landsat data and historical aerial photography for monitoring bare sand (BS) cover dynamics as a proxy for ecological dune stabilization. Using this approach, a time series of change was calculated for Kenfig Burrows, a 6-km 2 stabilized dune system in South Wales, during 1941-2014. The time series indicated that a rapid level of stabilization had occurred within the study area over a period of 75 years. Accuracy assessment of the data indicated the suitability of medium-resolution imagery with an RMSE of <10% across all images and a difference of <3% between observed and predicted BS area. Temporal resolution was found to be a significant factor in the representation of BS cover with fluctuations occurring on a sub-decadal scale, outside of the margin of error introduced through the use of medium-resolution Landsat imagery. This study demonstrates a tractable approach for mapping and monitoring ecologically sensitive regions at a subLandsat pixel level.

Tropical Wetland (TropWet) Mapping Tool: The Automatic Detection of Open and Vegetated Waterbodies in Google Earth Engine for Tropical Wetlands

“…The reflectance of a pixel can be conceptualised as a linear combination of the reflectance of all subpixel components (known as endmembers), weighted by abundance [41,72]. LSU uses this concept Remote Sens.…”

“…For instance, linear spectral unmixing (LSU) is a simple, yet effective approach for determining the proportion of spectrally distinct land cover types within a pixel. The main drawback of this approach is that it requires accurate delineation of land cover endmembers (pure spectra that is uniquely associated with that land cover type), which is typically done through manual delineation [41].…”

Surface composition of debris-covered glaciers across the Himalaya using spectral unmixing and multi-sensor imagery

“…Spectral unmixing routines have been used in glaciology to some extent, i.e. for retrieval of snow grain size or to derive fractional snow covered areas from MODIS or Landsat (Painter, 2003;Painter et al, 2009;Sirguey et al, 2009;Veganzones et al, 2014;Rosenthal and Dozier, 1996), to map clean glacier areas or snow (Painter et al, 2012;Cortés et al, 2014), lakes (Zhang et al, 2004) and vegetation (Ettritch et al, 2018;Song, 2005;Xie et al, 2008). However, their use for mapping the surface of debris-covered glacier tongues has not been thoroughly exploited.…”

The influence of the agricultural management systems in the maintenance of the biodiversity in benefit of the Phyto sanity control

“…Several coastal dune systems have become increasingly vegetated in recent decades, for example in Africa [28], United Kingdom [43], Europe [12], China [56], Australia [7] and in Brazil [35] is not different. Santa Catarina Island is located in southern Brazil.…”