Remote Sensing at the Service of Wetlands Mapping: A Case of the Lower Loukkos Complex (North-West Morocco)

Abstract

Despite their highly recognized ecological values and ecosystem services, approved by the scientific community, wetlands are in perpetual degradation and their global spatial extension in significant regression. The conservation and sustainability of such ecosystems begins with their monitoring and delimitation. This study aims to develop an approach using open access remote sensing data to make this delineation. Applied to the coastal wetland complex of the lower Loukkos in the Mediterranean area, the methodology followed a two-step process. Firstly, it predicted the spaces favourable for water accumulation conditions, and secondly, it identified the presence of water and its response on the soil and vegetation. The approach was based on a theoretical modelling adopting the potential, existing, efficient wetland (PEEW) approach. The recordings from Sentinel sensors served as the basis for calculat - ing indices Beven-Kirkby Index (BKI), Buffer zone Index (BZI), Normalized Difference Moisture Index (NDMI), Normalized Difference Vegetation Index (NDVI) and Modified Normalized water difference index (MNDWI) to pre-locate and model potential wetland areas (PW). Photointerpretation was used to map the existing wetland areas (EW). The estimated area of wetlands in the lower Loukkos region is 379 km 2 for potential areas identified from topographic data and the hydrographic network, 120 km 2 for areas dominated by wetlands detected by remote sensing of water bodies , vegetation and soil moisture, and 33 km 2 for natural wetlands identified by photo-inter - pretation. As a result, the area of current wetlands is only about 9.5% of their theoretical past extent. The validity of this method was confirmed through a comparison of the results with field investigations and hydromorphic traits in soil surveys, as well as external soil mapping data, showing an 84% concordance.