Mud and mangroves in Suriname: Multi-decadal analysis of a mud-dominated coast using earth observations

Abstract

Mudbanks are pertinent features that can be found along the 1,500-km long coastline of the Guianas. These mostly subtidal banks migrate from the mouth of the Amazon River in Brazil, along the coasts of French Guiana, Suriname and Guyana to the Orinoco Delta in Venezuela. When present the protect the coasts against incoming waves and simultaneously provide a source of sediment for coastal expansion and consequential mangrove colonization. Due to the alternating phases of erosion and expansion, that can last up to 10 – 15 years, is remains difficult to implement long-term coastal management strategies in the Guianas. This is especially true for coastal protection, nature conservation, CO2 storage and the development of agriculture and aquaculture. The limited accessibility of the coastal zone and the challenge to demarcate mudbanks in satellite observations make it difficult to differentiate between natural changes and those caused by mudbank migration, human interference or the impact of climate (change). Satellite observations offer the potential to improve future predictions, accurately analyse indicators of changes in mangrove forests and timely detect coastline changes on local- to regional scales. In this thesis a remote-sensing workflow was developed to utilize the spatial and temporal resolution of the complete Landsat satellite data archive since 1986 for the detection of mudbanks and associated coastal changes. This information was used to quantify the effect of mudbanks on local scale for the purpose of coastal management. We show that on average 32 m/yr coastal expansion occurs when mudbanks are present and 4 m/yr of erosion when absent. Large spatial- and temporal variations however highlights the importance variable mudbank footprints, caused by currents and waves, for the duration of coastal protection and natural changes that occur in mangrove forests.