Estonia - West-Estonian Archipelago

Description of study area

The West-Estonian Archipelago consists of about 1.500 islands in the Baltic Sea. Most of them are small in area; the two biggest are Saaremaa (2.672 km2) and Hiiumaa (989 km2). The main geomorphic features of Saaremaa's coastal zone reflect the preglacial relief, the last glacial phase and postglacial isostatic uplift. Coastal zone topography, sedimentary rocks (limestones and dolomites), unconsolidated deposits and offshore hydrology resulted in the formation of a diverse range of shore types. Each shore type responds to global climate change and concurrent vitalization of shore processes differently. There are smaller study sites in Saaremaa where detailed measurements and field experiments have been carried out. Shore processes and changes in shoreline position, contour and beach profiles have been examined in the study sites marked with violet color (Fig. 1). The study sites, which are painted yellow, indicate the areas of landscape ecological research and observations. Meteorological analysis is based on the observation data of three stations at Vilsandi, Sõrve and Kihnu. Sea-level fluctuations are measured by a mareograph at Ristna, Kõpu Peninsula, Hiiumaa Island. The map of zonation and proposed coastal zone land use is compiled for the whole coast of Saaremaa Island.

West-Estonian Archipelago
Figure 1: Location of study sites, meteorological stations and mareograph in west-Estonian archipelago

Latest results

Stormy period in January 2007

An extremely stormy period was recorded on 9 - 28 January 2007 with a peak on 14 - 15 January 2007 (Fig. 2). The highest mean wind speed was 23 m/s from SW and W. The recorded mean sea levels over the same period are shown in Fig. 3.

wind speed records
Figure 2: Mean wind speed in Vilsandi during the extremely stormy period 9-28 January 2007

sea level records
Figure 3: Sea level in Ristna during the extremely stormy period 9-28 January 2007

Recording Doppler Current Profiler (RDCP) measurements Dec 2006 - May 2007

Measurement of waves, currents (at several layers), turbidity and sea level near Kelba Spit, Saaremaa, using RDCP-600 (Recording Doppler Current Profiler) were carried out during a period of 20.12.2006-23.05.2007 (154 days, 1h interval). RDCP was deployed ca 2 km off the Kelba coast in order to study relationships between hydrodynamic situation (incl. storms) and coastal processes. Maximum wave heights over the entire measurement period are shown in Fig. 4.

wave height measurements
Figure 4: Maximum wave heights during the measurement period

Recent shoreline changes in Saaremaa study sites

The shoreline changes in a couple of study sites caused by a strong storm event in January 2007 are indicated in Figs 5 and 6.

shoreline changes
Figure 5: Shoreline changes in Kiipsaare study site in 2005 - 2007

shoreline changes
Figure 6: Shoreline changes in Kelba study site in 2005 - 2007

Recent changes in land cover in Harilaid study site, NW Saaremaa

The land cover pattern in Harilaid has been more or less stable during the last a couple of years since the extremely strong storm Gudrun in January 2005. In longer time span, since the 1930s until now major trends have been towards an increase of areas covered with forest and substantial reduction of grasslands (Fig. 7). The last strong storm in January 2007 triggered an intensive eolian process in sparsely vegetated areas (Fig. 8).

land cover changes
Figure 7: Major trends of changes in land cover pattern in Harilaid in 1933 - 2005

sparsely vegetated area - eolian process
Figure 8: Eolian sand covering formerly vegetated area after a strong storm in January 2007

Coastal zone planning in Saaremaa

A comprehensive map of sustainable land use considering possible impacts of climate change in the coastal zone of Saaremaa was compiled using a number of thematic map layers and GIS technique. A couple of examples are presented in Fig. 9 (areas affected by storm surge) and 10 (Harilaid Peninsula and surrounding areas).

Areas affected by storm
Figure 9: Areas affected by storm surge in Saaremaa

Spatial planning
Figure 10: Spatial planning of coastal zone in Saaremaa

Contact information:

Are Kont, Tallinn University, Institute of Ecology, +372 7376387

 

 © GTK, 2007