ØKOSAT

The ØKOSAT project aims to enhance Norwegian water monitoring and focuses on developing a system to track water quality in lakes and coastal areas, utilizing parameters like chlorophyll-a, secchi depth and turbidity. The project will employ satellite data and software tools to monitor water quality and climate change impacts, such as increased phytoplankton levels and changes in light attenuation.

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Bjørnafjorden, Norway’s widest fjord, located in Vestland county. European Union, Copernicus Sentinel-2 imagery

Water quality monitoring with satellite

Overview

Satellite data in water quality monitoring

The main object of the project is to develop a system for using satellite observations as an additional data source for the monitoring of lakes and coastal water bodies of Norway. The plan is that parameters that can be provided by the satellites, such as chlorophyll-a concentration, turbidity and secchi depth can be monitored yearly in a majority of the 8000 waterbodies concerned. This will give a more precise classification of the ecological status of Norwegian water bodies. Satellite observations will also be an important tool for monitoring the effect of climate change in lakes and coastal waters, where it is expected to affect the water quality parameters.

Adaptation to the ecological status classification system

Classification of ecological status is an important basis for the River Basin Management Plans following the EU Water Framework Directive. The more frequent observations and the areal coverage of the water bodies made possible by satellites, will increase the precision of the classification. Use of satellite observations means that a different sampling method will be used. Therefore, some challenges are raised that the water authorities need to address, e.g. Can we use the same classification system as for in situ data? And for water bodies where there are in situ data available, how should they be combined with the satellite-generated data in the classification? The national classification systems based on in situ data are intercalibrated between the European countries and the use of satellite-based methods would therefore need to be coordinated in the same manner to ensure similarities between the EU countries.

With a large amount of data available a renewed infrastructure is needed to manage the enlarged amount of monitoring data and provide the users with the relevant results. The data processing and QC need to be automatized and the national data bases for storing of monitoring and status classification data need to be updated. The system should be flexible and be able to adapt and include updates of the satellite data, improvements of algorithms as well as including of new data, such as hyperspectral measurements etc. The project is also developing such a structure for a long-term use.

Application site(s)

All Norway

Data

Satellite

Sentinel-2 A and B
Sentinel-3 A and B
Landsat

Other

In situ data:

chlorophyll-a concentration,
salinity,
secchi depth,
turbidity,
Coloured Dissolved Organic matter (CDOM),
Total Suspended Matter (TSM)
water colour

👉 These in situ data were gathered for the most monitored Norwegian lakes and coastal stations between 2016-2022. Satellite observations from both Sentinel-2 and Sentinel-3 from the same monitoring stations, using a set of algorithms developed for water quality parameters, were compared with the in situ data.

Results based on Sentinel-2 are more promising for lakes, as the higher resolution provides more data.
Sentinel-3 water quality products work well for most coastal waters.
Different algorithms are needed for different lake types (i.e. humic, eutrophic, turbid, clear)
Current development of a routine based on the lake’s optical characteristics (Optical Water Types, OWT) are used for selecting the proper algorithms for specific lakes and to define which lakes that are not optimal for monitoring by remote sensing.

◀︎ Turbidity derived from the OLCI sensor (Ocean and Land Colour Instrument) from the Sentinel 3A satellite over the largest lake in Norway; Lake Mjøsa on 1 September 2023. © Contains modified Copernicus Sentinel 3A data 2023 processed by Brockmann Consult and the Norwegian Institute for Water Research, NIVA.

Results - Final product(s)

The project will deliver water quality data for lakes and coastal waters in Norway (chlorophyll a, Secchi disc depth, turbidity Satellite monitoring may deliver a more comprehensive dataset on these parameters and from a large number of waterbodies which we would not be able to sample with traditional in-situ methods.

Based on these parameters the project will deliver a method which contributes with parameters to the classification of ecological status of Norwegian lakes and coastal waterbodies and improve the basic data flow to the classification process. According to the roll-out plan the tool will be implemented during 2026.