Water quality

Water quality mapping

HERMESS has developed a water quality mapping service, which retrieves water quality parameters from a variety of remote sensing data. Concentrations are retrieved in a two-step approach:

  1. Atmospheric correction using an algorithm suited for turbid water conditions enabling processing of shallow coastal waters.
  2. Application of a multi-spectral decomposition algorithm to estimate concentrations of chlorophyll-a, inorganic suspended matter and yellow substance.

Water quality parameters

  • total suspended matter (TSM) concentration
  • chlorophyll-a & phaeophytin-a (TCHL) concentration
  • inorganic suspended matter (ISM) concentration
  • transparency or attenuation depth

Multiple sensors
Water quality can be derived from a wide range of sensors. Oldest data can be retrieved from SeaWiFS, which was launched in 1993. A continuous series of image retrievals is possible including Terra Modia, Aqua MODIS and Envisat Meris. Most recent source of water quality information is Sentinel 2.

Data analysis
Based on this huge data set, information can be derived to support our users:

  • time series of WQ parameters and trend analysis
  • tidal and seasonal dependencies
  • distribution of WQ parameters and scatter plots of retrieved and in-situ measured WQ parameters.

Example
Maps of water quality can be used to support analysis of eco-system status. Monthly and seasonally averaged chlorophyll concentrations during the growing season are used to assess growth conditions for macro benthos.

Clients and partners
Coastal zone managers, dredging companies, port authorities, consultants, research institutes.
tsm_waddensea_2011_07

Average chlorophyll-a concentration July 2011 over the Dutch Wadden Sea based on Envisat MERIS data.