Dear Sama,

This is complex question. If saline water (effects of soil flooding on plants) is concerned, then input of water from sea vs. input from rain is most important. If the question is soil salinity, then evapotranspiration will eventually lead to concentration of salt in soils, leading to increased level of salt above that in seawater.

Sincerely,

Gederts

Sama good to knwo that you are working in marshes. The salinity is certainly affected by freshwater input and evaporation. But it is also very much affected by seawater intrusion and the activities that are going on in adjacent waters. The salanity in Gulf which mixes with the upstream water in marshes vary between 3.9 - 4.5% within the northern 150 km. Intrusion of this water can have a huge influence on salinity within marshes. 

Dear Sama,

This is complex question. If saline water (effects of soil flooding on plants) is concerned, then input of water from sea vs. input from rain is most important. If the question is soil salinity, then evapotranspiration will eventually lead to concentration of salt in soils, leading to increased level of salt above that in seawater.

Sincerely,

Gederts

It is not easy to have a general answer to this question. The best way to know is to collect the water sample along the saline intrusion site over the time for analysing the salt content/ EC parameter, and then using some mathematical models for the their water time resident trends.

Regards,

Tuan

Dear Sama, 

Are  you're in a continental and "closed" context ? Do you know the ratios of the solutes elements coming into your marshes? Are you located upper Bassorah town or downwards under influence by sea tides ? You may have an idea of the concentration of your water by evaporation using environemental isotopes or tracers : You  may ave some information about D or 180 in water in your marshes ? Regards,  Olivier 

very interesting, well currently the tidal effect from the Gulf does not reach the marshes due to several geological and anthropogenic activities downstream. i manage to calculate the evapotrasporation, which is the deference between water input and output divided by area.   also i calculated the residence time/day of each marsh and i found that the % of salinity due to residence time increase in the three marshes were 12%. 19, and 91.5%. any idea on how can i incorporate these findings in to the subject of fresh water salinization?

If there is no tidal influence in these marshes, then salinity would be a function of the balance between freshwater inflows,outflows and ET. In the Everglades there also is submarine groundwater discharge into marshes in the dry season, which could happen in your marshes if they are close to the coast, even if they do not have a direct coastline to experience tides.

You're right that longer the residence time of water in a marsh, greater would be ET loss and hence an increase in salinity. However,  note that the flow paths in marshes can have a lot of spatial variation due to vegetation resistance. This leads to very different residence times -- in an open channel between two clumps of vegetation the res time could be like half hour while it maybe be a week just a foot away in a dead zone that is sheltered by the veg. So the residence time of a marsh is really an average with possibly high variation. Do you have salinity data from the marsh ? Also, are you looking at salinity from the perspectoive of what an individual wetland plant faces, or are you modeling the whole marsh salt balance ?

When the residence time is long, salts will settle and form deposit. With the evapotranspiration, the salinity will increase because concentrated. The wetland physiology can be disturbed as microflore in the roots may die of increased salinity (osmoregulation disturbances).

D.E. Musibono