Dear Maria,

this seems to be an interesting case. However, without a topographic (hypsometric) layer and spatial scale it is difficult to judge. The northern stream appears to be a tributary, right? The western inflow from what you call a eutrophicated "bay" likewise appears to be a tributary, albeit likely to a lesser extent than the northern one, I suppose? It would also be helpful to know whether there are tidal forces involved (coming from the eastern access to the sea). I suspect that flow velocities are fairly low in the central "bay" you are concerned with. How far away is the sea from your eastern "point source"? Would be good to have more contextualizing information.

With best wishes,

Julius

Dear Julius Riese

Thank you for your answer!

It's quite hard to distinguish in this area what's tributary and what's not, as it's a coastal area, an inner archipelago. However, the northern stream is generally considered to be a main stem. The western eutrophicated bay is a flad (as they usually call such coastal lagoons in Finland). The characteristics of a flad are usually that they are under some kind of protection because of their unique ecosystem and the "entrance" to the flad is usually very narrow and very shallow (however inside a flad it's usually 2-8m deep).

As you can see on the maps, this flad is connected to the other bigger bay (fjärden) through a small ditch that goes through wetlands. The coordinates of the central bay of interest are 59°58'00.9"N 23°40'09.7"E.

There is basically no tide in that area of the Baltic sea. The central bay is something like 9-14km from the open sea (areas of the outer archipelago) depending on what route to choose through all these islands.

Basically, we have made a GAM analysis for that area based on our other parameters, and we have a predicted "normal level" for turbidity and a map, which shows SD from that normal level for every occasion (approx. 6 occasions during the non-ice period). So, basically, we were thinking about if it's possible to understand which source has a greater influence on this high positive SD turbidity in the bay and to which spatial extent. Like the spatial influence of a "point-source pollution". We have lots of high-resolution data, so we were thinking that probably it's possible indirectly calculate the strength and direction of influence. Kind of to draw the area where this particular point of pollution has influence, and where it stops having significant influence, being too diluted. But now thinking more about it, it seems that it's not really possible to predict such things without knowing velocities.

All the best,

Maria

🤔 Want to calculate the influence of three different sources of water intake on a bay? Here are some steps you can take:

💧 Identify the three different sources of water intake and their respective flow rates. This information can be obtained from water suppliers or regulatory agencies.

🌊 Collect data on the current water quality in the bay, including parameters such as temperature, salinity, dissolved oxygen, and nutrient levels.

🧮 Use a water quality model or simulation software to predict the impact of each water source on the bay's water quality. These models can help to estimate factors such as nutrient loading and dissolved oxygen depletion.

📊 Compare the results of each simulation to determine the relative influence of each water source on the bay's overall water quality.

🌟 Keep in mind that water quality is a complex issue influenced by many factors beyond just the three sources of water intake. The results of your calculations may need to be interpreted in the context of other environmental factors impacting the bay.

Dear Maria,

many thanks for these extended explanations and the excellent cartographic material. This seems to be a very interesting area. It is difficult for me to judge from afar, but I agree with you that without knowing the volume/rate of flow-through/discharge at your three points and/or the flow velocities there, it would be difficult to assess the relative influence of the three inlets on the central bay/fjärden. But if you're out and about on boats there anyway and have already collected lots of other data, it shouldn't be too difficult to estimate flow-through rates by combining stream velocities (should be easy to measure) with a rough bathymetry at your three points.

Very interesting :-)

Julius

Dear Maria, you can use analysis of variance (one-way analisys of variance), with 3 gradations of factors (difference sourses) (A, B, C). The result will be the influence of each factor, especially A, B, and C. The interaction 1st order of factors AB, AC, and BC, and the interaction 2nd order of factors ABC.

Hi Maria, you can use mass balance calculations, using the biogeochemical values as a reference. Regarding the latter, if you have geochemical analysis of heavy elements and isotopes you can have very precise information.