An Approach to Delineate Groundwater Bodies at Risk: Seawater Intrusion in Liepaja (Latvia)

Groundwater quality in coastal areas is frequently affected by seawater intrusion as a consequence of intensive water consumption. To achieve "good chemical status" of a groundwater body according to Water Framework Directive the effects of saline or other intrusions should not be observed. Groundwater pumping in former decades has caused a significant seawater intrusion into confined aquifer in Liepaja and has led to deterioration of relatively wide coastal area of the third largest city in Latvia. However, the area affected by seawater intrusion is a small part of groundwater body F1 which overall chemical status is good. Thus, no specific management measures have been applied to explore and control seawater intrusion. A political decision was made to delineate the area affected by seawater intrusion as new groundwater body at risk- F5. This study demonstrates simple approach for delineation of groundwater bodies at risk in coastal areas. Delineation process was based on chloride concentration gradient along the well profile and gradient based buffers. Finally, the worst-case scenario was selected for delineation of boundaries.