1. Numerical modelling of sea water intrusion in coastal aquifer Main parameters Particle-size distribution Bulk density Hydraulic conductivity Transmissivity Storage coefficient Specific yield Effective porosity Hydrometeorological data (precipitation, evapotranspiration, mineralization etc.) Area of study Coastal area of Kaliningrad region

2. Numerical modelling of sea water intrusion in coastal aquifer Natural processes

3. Numerical modelling of sea water intrusion in coastal aquifer Increase in Vistula Lagoon’s mineralization

4. Numerical modelling of sea water intrusion in coastal aquifer Anthropogenic influence, spill of produced water in Vistula Lagoon

5. Transformation of ecosystems caused by produced water spill

6. Distribution of salinization in the area of produced water spill

8. Changes of soils physical properties under high mineralized water influence

9. Changes of seepage velocity in saltaffected soils

10. Mathematical Modeling in HYDRUS – 1D, Hydraulic Model Van Genuchten-Mualem

11. Comparison results of natural processes modelling for coastal areas (sand soils) with the literature data showed its similarity. Changes in Vistula Lagoon mineralization lead to small increase in groundwater salinization. There was a sharp rise of groundwater mineralization in case of modelling produced water spill in Vistula Lagoon. Moreover the verification of data with field experiments and literature data also showed the high rate of it relevance. The best way to evaluate changes is a comprehensive approach: use modelling, but always verify data with real measurements, experiments under field and laboratory conditions. Moreover, geochemical transformation of soils causing changes in soils structure as a result leads to decrease of seepage velocity. Thus, additional models, such as HYDRUS etc should be used in order to assess soils transformation more complex an in a proper way.