The EOMORES spatial planning services provide insight concerning water quality distribution for a number of spatial planning purposes. Two relevant cases are considered below:

• determining the most representative locations for in situ monitoring in order to identify the most suitable spots for bathing;
• monitoring dredging events and properly assessing their consequences.

Monitoring and Bathing Water Locations

What is the problem?

The spatial distribution of algae and cyanobacteria blooms can vary significantly. However, standard in situ samples are generally taken either in the middle of the lake or next to platforms or jetties – despite the fact that such locations may not be as representative of the entire water body. Bathing locations tend to be situated on shores with sandy beaches or close to cities or access roads, and often face south for maximum sun exposure. From a public health perspective, however, bathing locations should not be situated in areas where cyanobacterial scums frequently occur, since such scums may contain high concentrations of toxins.

How does EOMORES address it?

Satellite-based maps, incorporating long time series of data (multi-annual), indicate the average spatial distribution of parameters such as chlorophyll and cyanobacterial pigment over specific areas. Patterns of distribution are determined through combined hydrodynamic-water quality models.

Such long-term spatial information can be used to determine locations representative of the water body as a whole in order to optimise in situ sampling, as well as to identify the safest zones for future bathing locations.

EOMORES in action: Monitoring Chlorophyll-a distribution over lake Paterswoldsemeer (the Netherlands)

Dredging

What is the problem?

Dredging can have an environmental impact when the dredged material from lakes or from the seabed is excavated from the bottom of the water body, transported to the surface and stored, or when such materials overflow from the dredger. Sediment released into the water body in these ways is spread out by currents and thus increases the turbidity over a larger area. Depending on the sediment quality, dredging events can have multiple negative effects on the environment, for example, by affecting light penetration and nutrient conditions in the aquatic ecosystem, or by releasing harmful substances present on the water floor.

How does EOMORES address it?

Increased turbidity caused by dredging is often visible in optical satellite images. This allows the monitoring of the exact direction and length of the plume. EOMORES provides synoptic satellite mapping and high-frequency in situ monitoring of water turbidity before and after dredging.

EOMORES forecasting models can estimate the evolution of plumes resulting from dredging activities, taking into account the specificities of the analysed water system. This information can be useful in anticipating where and when the most critical impacts from dredging on the environment are to be expected, and are hence relevant for environmental assessments or for planning  in situ sampling following dredging events.

A dredging event identified by Tarkka –service by SYKE. Increased water turbidity caused by dredging in the Finnish coastal area, near the city of Rauma, is clearly visible in the Sentinel 2 provided images. Before the dredging (image on the left), the waters appear darker on the satellite images. The dredged locations are marked with red circles on the two other images and the event clearly affects water turbidity as demonstrated by the change in water colour. Sediment material that is lost during the dredging spread with water currents first to the South-West (middle image) and a few days later to the North-East (image on the right).