Mangrove Ecosystems in the Mekong Delta – Overcoming Uncertainties in Inventory Mapping Using Satellite Remote Sensing Data

Abstract

In the Mekong Delta of Vietnam, losses of mangroves have been especially severe over the last decades mainly due to clearing for shrimp farming leading to a land use con fl ict between mangrove silviculture and shrimp aquaculture. Following the law on rules for land use and natural resource utilisation for reforestation of mangrove forests (1999), shrimp farming-forestry enterprises (SFFEs) have therefore been established where shrimp are cultured together with mangroves in integrated farming systems whereby 60% of the farm area must be protected mangrove. Monitoring tools are therefore required to map the extent of mangroves and aqua- culture and to delineate the percentage of mangroves in mixed mangrove-aquaculture farms. Current methodologies in forest mapping and mangrove area estimation require a large amount of manual work. In addition, currently applied methodologies in base data acquisition and transformation into statistics or maps are varying. This is leading to different estimates of mangrove area of the same region in different statistical surveys. Similar problems arise for actual mangrove distribution maps which are generated based on different sources and methodologies. Precise and reli- able mangrove maps are of increasing importance, since changes in these ecosystems often occur rapidly. There is a growing demand for detecting and assessing changes especially in the context of climate change, sea level rise and related threats to coastal ecosystems. International organizations and government agencies in several countries are, for this reason, urgently implementing programs of mapping and monitoring to measure the extent of decline of these important ecosystems. Remote sensing enables large-scale, rapid, long-term, and cost-effective mapping and moni- toring of mangrove ecosystems and with that provides important information for resource inventory mapping, change detection, and monitoring aquaculture activities. It also supports various management requests, ecosystem evaluation, productivity measurement, water quality assessment, or disaster management.