ESRIG-EES colloquium: Samer Elshehawi, PhD student at IVEM

Title: Natural Isotope illustrate groundwater control over mire types in Slitere National Park, Latvia.

By: Samer Elshehawi, PhD student at IVEM.

Summary:
Slitere National Park in Latvia is home to rich fens with many endangered and threatened plant species. This study aimed to address how the hydrological systems affect vegetation biodiversity in the mire systems of the park: the base-rich inter-dune mires and extremely base-rich calcareous fens. Groundwater samples from these areas were collected for measurements of ion composition and natural isotopes of C, H and O. Also, we simulated groundwater flow paths from the highest local topographical point (a nearby sandy plateau) to the sea, and calculated the residence times of these groundwater flows. The results show that the inter-dune mires are supplied by a mixture of local and regional groundwater systems. The groundwater supply at one of the inter-dune mires was dominated by local groundwater flow from adjacent dunes, but we also detected a small input of calcareous water. This dominance by local groundwater may have resulted from the presence of drainage ditches and a small stream that drains into the Baltic Sea. In contrast, the extremely base-rich fens were found to be solely dependent on regional groundwater flows, which likely discharge at the plateau foothills due to presence of fault structures. Thus, the mires in Slitere National Park are not as pristine as previously thought. Drainage activities might have affected the original hydrological flow paths. Further research on the extent of these changes is recommended to preserve the endangered species and high biodiversity of these fens. Also, tracing the origin of groundwater flows might require further investigation into the larger landscape beyond the plateau.