Monitoring and Quantification of Floating Biomass on Tropical Water Bodies. GI_Forum 2014 – Geospatial Innovation for Society|

Abstract

Water hyacinth, or Eichhornia crassipes (Mart.) Solms, is an invasive and free floating water plant, native to South America that has often been marked as one of the world’s worst invasive aquatic species. It grows into large dense vegetable carpets that block sun energy transmission into shallow waters or even the lake bottom. This study focuses on two different water bodies in the tropical/subtropical zone, where water hyacinth infestation is already an issue. A parallel research approach was chosen in order to compare regional results with regards to operability and suitability of the chosen method. The first area studied is the southeastern area of the Inle Lake in Central Myanmar, and the second region is the Winam Gulf on Lake Victoria in Kenya. The Winam Gulf has been clogged by Eichhornia crassipes for decades, in contrast to a few reports about Water hyacinth infestation on the Inle lake waters. As in many other countries in the tropics, the current local monitoring and control measures of invasive aquatic vegetation in Myanmar and Kenya mostly rely on simple observations and mechanical methods. The monitoring and quantification of spatialtemporal variation of floating vegetation using satellite images has been tested in many approaches as being useful for analysing the spatial extent and temporal abundance of the macrophytes on tropical water bodies (SCHOUTEN 1999 et al., ALBRIGHT 2004 et al., NASA 2007, LANEVE 2010 et al., WINSTANLEY 2011 et al. ). The objective of the presented study was to test a multi-sensor approach, combining several remote sensing methods at two different locations, with particular ecological and land use systems, in order to detect and monitor floating biomass, and assess the abundance and quantity of Eichhornia crassipes and similar floating macrophytes using MERIS, MODIS and Landsat 7-ETM imagery. The successful multi sensor approach resulted in temporal spatial patterns of floating biomass, enabling transformable quantifications for the detected floating biomass. The quantified and harvestable biomass can be used further as a permanent source of bioenergy, or a resource for a chemical process named Hydrothermal Carbonization (HTC), converting biomass into an alternative energy source (hydrochar) or into solid or liquid fertilizer (LIBRA et al. 2011)