In the Netherlands, dredging operations in the lake Markermeer can be seen from space! RBINS scientists process satellite images and validate these images with measurements in the lake.
The Marker Wadden project aims to construct islands in the Markermeer, one of the largest freshwater lakes in Western Europe. These islands will improve the sedimentation in the lake, and will increase the extent of natural shorelines and wetlands. The reduction of sediment on the lake bed and in the water column will improve water transparency, will help to restore the aquatic food chain, and increase the abundance and diversity of plants and animals in the Netherlands.
Satellite images
The dredging operations in this lake can be seen from space! Images from the Sentinel-2A satellite were processed by RBINS scientist Quinten Vanhellemont using ACOLITE, a multi-sensor atmospheric correction and processor that has been developed in HIGHROCt, an FP-7 project of the European Commission. The figures show the Markermeer on April 21, 2016 during early dredging operations, on May 1st, 2016, when a large dredging plume is observed, and on May 11, 2016, when the first artificial island reached the water surface.
Quinten also derived suspended sediment concentration from these images using one of the near-infrared bands on Sentinel-2A. Resuspension by wind on the 21st of April causes high surface sediment concentrations (reaching 100 g/m³) in the western part of the lake. The dredging plume observed on the 1st of May reaches similar surface sediment concentrations of 100 g/m³, with reference concentrations around 20 g/m³ in the Markermeer. Surface sediment concentrations in the IJsselmeer (east of the Houtribdijk), are less than 10 g/m³. The colour of the dredging plume is different from the surrounding sediments due to the different sediment type in the lake bed.
Why is this interesting?
These kind of images will be used in the European project INFORM (FP7-SPACE) that will develop new products for inland water quality monitoring. The validated INFORM products will form a basis for future products to assess e.g. the implementation of the Water Framework Directive (WFD). INFORM developments will lead to recommendations for future earth observation missions taking into account requirements for inland water quality monitoring. This summer the products will be validated for the Markermeer by our scientist Dimitry Van der Zande.
