Monitoring Dynamic Mangrove Systems in Suriname and Indonesia using Planet Lab Satellite Images and the Historic Satellite Data Archive (Google Earth Engine)
Mangrove ecosystems play a key role in protecting deltas and low-lying coasts against storms, waves and sea-level rise and mangroves create habitats for fish, birds, benthos and are a carbon sink. Mangrove thrives in brackish water of intertidal areas between sea and land in (sub)tropical regions.
Spotting mangrove ecosystems from above
Large areas of mangroves are already removed for aquaculture, agriculture, urban expansion, or infrastructure constructions but there are still pristine mangrove ecosystems in the world urgently needing protection. Such area are found in the Guianas (Suriname), Australia, Southern Africa and Asia.
To increase our scientific understanding of the complex mangrove coastal ecosystems we analyze timeseries of satellite images. These images became were coming available in 1984 and gained significantly in quality and frequency since 2000. From the timeseries we derive dynamics of ecosystems i.e. erosion of mangroves and colonization of mud flats by mangroves. These analyses provide insights the degree of decadal dynamics, the whereabouts of vulnerable locations, colonization and erosion speed and the various spatial patterns of colonization which are poorly understood. The LandTrendr algorithm ‘Landsat-based detection of trends in disturbance and recovery’ is applied to the timeseries of satellite images to extract information on the mangrove ecosystems.
Two study areas are selected having mangrove ecosystems but contrasting physical and ecological environmental settings. These areas are the coast of Suriname and the coast near Demak, Java in Indonesia. The Suriname ecosystem is driven by migrating mudbanks along the coast originating from the Amazon and this area knows relatively low pressure from human activities. The Java ecosystem is dominated by complex tidal systems and ocean currents and is at many locations disturbed by human activities for decades. The comparison of the two areas will yield insight in the behaviour of ecosystems and the effects of human pressure.
The figures below show some preliminary results for the Suriname case. The field photo shows the mangrove ecosystem at ‘Weg naar Zee’ north of Paramaribo in Suriname, where after severe erosion of the coast a ‘building with nature’ initiative is started to stimulate sediment deposition by the construction of levees and where mangrove seedlings are planted to stimulate colonization of the mud flats by mangroves.
The central figure shows a Google Maps satellite image of the Coppename coast in central Suriname showing the mangrove ecosystem and the high mud concentrations in the ocean water. The lower image shows some first results how the project used the LandTrendr algortihm to identify the mangrove ecosystem changes at the Copenmane coast in time intervals of three to four years between 2000 and 2018. One of the next step in the project is to apply the same methods to the coast of Java and to compare the different environmental settings of the study areas.
The figure below illustrates the mangrove colonication for this area between 2000 and 2018. Dark green: mangrove colonization from 2000 to 2004. Light green: 2004 to 2008. Yellow: 2008 to 2011. Orange: 2011 to 2014. Red: 2014 to 2018.
- Department of Physical Geography (Faculty of Geosciences, Utrecht University)
Steven de Jong, Gerben Ruessink, Job de Vries
- Department of Sustainable Development (Faculty of Geosciences, Utrecht University)
Pita Verweij, Anissa Triyanti
- Department of Biology (Faculty of Science, Utrecht University)
- Department of Estuarine & Delta Systems (NIOZ)
Tjeerd Bouma, Celine van Bijsterveld