Hannes Tõnisson

Coastal Damages on Saaremaa Island, Estonia, Caused by the Extreme Storm and Flooding on January 9, 2005

Abstract A cyclone known as Gudrun in the Nordic countries developed above the North Atlantic and traveled over the British Isles, Scandinavia, and Finland on January 7–9, 2005. As a result of high initial levels of the Baltic Sea, the fast-traveling cyclone with a favorable trajectory and strong SW–W winds created a record high storm surge (275 cm) in Pärnu, as well as in many other locations along the west Estonian coast. The January storm induced clearly visible changes in the development of shores and the dynamics of beach sediments over almost all of Estonia. The precondition for the profound changes observed from this storm—which has been observed in connection with some previous major storms—was a combination of the absence of protecting ice cover in the sea, relatively high sea level for a long period before the storm, and a very intensive storm surge taking place over the background of the already elevated sea level. Strong storm waves combined with the high sea level caused substantial changes in the coastal geomorphology of depositional shores on Saaremaa Island, Estonia. The most exceptional changes occurred in the areas that were well exposed to the storm winds and wave activity—for instance, in Kelba, where the high rate of erosion (<3000 m3) resulted in the elongation of a spit by 75 m. Our conclusion is that the January 2005 storm caused significantly larger changes to the depositional shores in west Estonia than the cumulative effects of ordinary storms over the preceding 10–15-year period.

Observation and analysis of coastal changes in the West Estonian Archipelago caused by storm Ulli (Emil) in January 2012

ABSTRACT Tõnisson, H., Suursaar, Ü., Rivis, R., Kont, A. and Orviku, K., 2013. Observation and analysis of coastal changes in the West Estonian Archipelago caused by storm Ulli (Emil) in January 2012. The study analyzes the meteorological parameters, hydrodynamic conditions and coastal changes at three practically tideless locations on Saaremaa Island caused by storm Ulli (sustained wind speed 20 m/s, gusts 28 m/s) which struck the Estonian coast on 4 January 2012. It was the last and the most influential storm of a series of storms which began on November 2011. Wind and sea-level data from nearby meteorological and hydrological stations were used to provide the forcing data for hydrodynamic study. Wave hindcast was performed using a semi-empirical SMB-type wave model. Shorelines, scarp positions and beach profiles were measured in August 2011, and again during each of storm Berit (in November) and storm Ulli (in January). Local storm surge height reached 1 m, significant wave height (Hs) was up to 2.8 m, the combined sea level and Hs reached 3.65 m, and local wave run-up reached 3.2 m during Ulli. At Cape Kiipsaare, recession of the sandy scarp reached 9 m (at the rate of nearly 1m per hour). The loss of sand was approximately 4–5 m3 per 1 m of shoreline. Erosion occurred on the shores exposed to the prevailing wind direction while accumulation was recorded on the leeward side of the spit. Erosion mostly occurred at the elevations between 1–3 m. Although the winter 2011/12 included a series of influential storms, nearly two-thirds of coastal erosion during the winter 2011/2012 was caused by storm Ulli, which featured the highest sea levels.

Multi-scale analysis of wave conditions and coastal changes in the north-eastern Baltic Sea

ABSTRACT Suursaar, Ü., Alari, V., Tõnisson, H., 2014. Multi-scale analysis of wave conditions and coastal changes in the northeastern Baltic Sea. In: Green, A.N. and Cooper, J.A.G. (eds.), Proceedings 13th International Coastal Symposium (Durban, South Africa), Journal of Coastal Research, Special Issue No. 70, pp. 223–228, ISSN 0749-0208. Temporal variations of shoreline changes have been analyzed and interpreted in three differently exposed Estonian coastal sections. Using coastline contours that have been recorded frequently over the last twelve years, as well as recently digitized aerial photographs, orthophotos and old topographic maps (some of them dating back to 1900), all overlaid in the Mapinfo software, areal changes over different sub-periods were calculated. To explain the shoreline changes, two different wave modelling approaches were used and mutually compared. Both the BaltAn65+ reanalysis (an ERA-40 refinement) forced SWAN model hindcast (1965–2005) and the point model runs (1966–2012), locally and independently calibrated against extensive wave measurements in these coastal study sites, confirmed specifically higher (and increasing) intensity of coastal processes in the westerly exposed study sites, and a decrease in northerly exposed sites. Some common quasi-periodic cycles with high stage approximately in 1985–1995, and probably also from 2007 can be found. However, the role of a few randomly occurring extreme winter storms (such as in 1967, 2005, 2007 and 2012) was often decisive within the sub-periods.

Natural Development and Human Activities on Saaremaa Island (Estonia) in the Context of Climate Change and Integrated Coastal Zone Management

The coastal zone is a crucial environment that is experiencing pressure from a wide variety of different agents and interests. Many sandy beaches high in recreation value are suffering from increasing erosion, and the shoreline is receding in these areas despite of tectonic land uplift. Sediment deficit is evident in many places. One key problem in recent decades has been a rapid increase in the number of holiday houses built as close as possible to the seashore. Unlike in the Nordic countries, where major coastal settlement expansion took place after WWII, almost the entire coast of Estonia was, until 1991, proclaimed a Soviet border zone in which activities were strongly restricted. A revival in coastal land use and a rapid increase in coastal settlement have occurred over the last 15–20 years. This paper focuses on Climate Change impacts, natural and artificial changes on the coast of Saaremaa Island associated with increasing pressure and conflicting interests. We also examine the advantages and disadvantages of existing legislation regulating land use within the Estonian coastal zone in the context of integrated coastal zone management. The paper ends with an outlook.

Changes on coasts of western Estonia and Russian Gulf of Finland, caused by extreme storm Berit in November 2011

The study is analyzing the meteorological parameters, hydrodynamic conditions and coastal changes caused by extreme storm known as Berit, which travelled across the Baltic Sea from 27th to 29th of November in 2011. Wind speed on West Estonian islands reached to 19,7 m/s (gusts 29 m/s), 20,4 m/s on the northern coast (gusts 27 m/s) and 15 m/s (gusts 20 m/s) on the Russian Gulf of Finland coast. Sea level at Pärnu reached to 110 cm, 142 cm at Narva-Jõesuu and +190 cm near St Petersburg (outside from the Flood Protection Facility). Shorelines, scarp positions and beach profiles were measured at the end of summer in several sites along Estonian coast and Russian Gulf of Finland coast. Two researchers spent the whole duration of the storm in Harilaid Peninsula and recorded changes in shoreline, scarp positions and beach profiles. Wave run-up and sea-levels were also recorded. All the measurements were carried out using DGPS with the accuracy of 1 cm in vertical and horizontal scale. Russian study site was measured a few days after the storm. In order to assess variations in forcing conditions during the storm a wave hindcast was performed using a SMB-type wave model. Calibrated against the field measurements, the model is forced by wind data, and it calculates significant wave parameters for a chosen location. Significant wave height 1.5 km off the Kelba study site was 2.8 m and maximum waves reached to 4.4 m. The first results indicate that 1.5 m high sandy scarp in Cape Kiipsaare receded up to 4 m. The loss of sand was ca 6 m3 per 1 m of shoreline. The speed of recession was around 0.6 m/h during the peak of the storm. The length of gravel-pebble spit at Kelba increased and new gravel ridges in the proximal part reached to 2.8 m. In the Russian part of the eastern Gulf of Finland as a result of storm and flood the scarp up to 2 m high was formed along 15 km of dunes of the northern coast (Komarovo, Repino). It was the first strong erosion event observed after extreme dunes damage during autumn 2006-winter 2007.

Regional Environmental Sensitivity Index (RESI) Classification of Estonian Shoreline (Baltic Sea)

ABSTRACT Aps, R.; Tõnisson, H.; Suursaar, Ü., and Orviku, K, 2016. Regional Environmental Sensitivity Index (RESI) Classification of Estonian Shoreline (Baltic Sea). In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 972 - 976. Coconut Creek (Florida), ISSN 0749-0208. Despite improving navigation safety measures, there is a growing risk of accidental oil spills and associated oil pollution on the Baltic Sea, an area which has been designated as a Particularly Sensitive Sea Area by the International Maritime Organization. Environmental Sensitivity Index (ESI) maps have been an integral component of oil-spill contingency planning and response in the United States since 1979, serving as a quick reference for oil spill responders. The ESI ranks shoreline into 10 classes in relation to sensitivity, natural persistence of oil, and ease of clean-up. Some countries outside the US have adopted the ESI approach to classify their own shorelines for similar oil spill contingency planning, the resulting maps being referred to as Regional Environmental Sensitivity Index (RESI) maps. However, problems arise when applying the classification system. This article highlights the difficulties of applying the standard ESI classification to the Estonian shoreline and suggests a potential RESI classification scheme for Estonia that would divide cliff shores among sensitivity classes 1 and 5, with most of them into class 5, the designation for those that are the most difficult to clean up (mixed sediments on the beach and no access from the land). An Estonian RESI map layers are integrated into the SmartResponse Web - an analytical tool for emergency response and recovery that is used to combine the information related to the accident, development of an oil spill and information on environmental sensitivity of the Baltic Sea shoreline. The SmartResponse Web enables the identification and dynamic assessment of environmental risks as a continuous process for purposes of determining best practices for reducing or even eliminating the risks, and it is used by the Estonian oil spill response authorities for contingency planning, training and in emergency situation.

Retreat rate of cliffs and scarps with different geological properties in various locations along the Estonian coast

ABSTRACT Orviku, K., Tõnisson, H., Kont, A., Suuroja, S. and Anderson, A., 2013. Retreat rate of cliffs and scarps with different geological properties in various locations along the Estonian coast. Recently reported increased water depths and greater wave heights, perhaps associated with increased storminess, are likely to lead to more active changes, such as increased beach erosion, faster shoreline migration and sediment redistribution. A coastal environment particularly sensitive to the impact of sea-level rise is that of highly erodible cliffs and scarps. As structures are often built close to such formations, it is important to determine the retreat rate of cliffs and scarps. Among other things, knowing the retreat rate can help regulators plan coastal protection measures and can help property owners decide where to place their structures to avoid damage. The principal objective of the current study is to find and analyze the retreat rate of cliffs and scarps in several locations along the Estonian coast. Variable geological conditions, exposure to the sea and human influence are considered. The study was carried out in five different locations along the Estonian coast representing different geological properties, variable human influence and hydrodynamic conditions. Aerial photographs, orthophotos, RTK-GPS, leveling survey and archive data was used to measure the changes on the edges of the scarps and cliffs. It was found that the fastest rate of retreat appears on the location where the softest sediments are exposed to the roughest wave conditions – in Cape Kiipsaare. Here the yearly scarp-line retreat reached over 7 m/y (17 m3/y per meter of shoreline) which is faster than the fastest retreat rate of soft cliffs recorded anywhere else, but still two times lower in terms of the eroded volume of sediments.

Changing natural and human impacts on the development of coastal land cover in Estonia

ABSTRACT Antso, K., Kont, A., Palginõmm, V., Ratas, U., Rivis, R. and Tõnisson, H. 2013. Changing natural and human impacts on the development of coastal land cover in Estonia. The structure of coastal land cover in Estonia is variable and shows considerable differences from site to site. The diverse geomorphology of the seashores is one of the key factors causing different velocity and magnitude of changes while the countrys history of settling the coast has also shaped the character of land cover. The main objectives of the current paper are: 1) to give an overview of land use and the trends of development of land cover pattern in different parts of the Estonias coast; 2) to analyze the relationships of natural and man-induced processes and their cumulative impact on the evolution of coastal land cover pattern in Estonia. The current paper focuses mainly on changes in land cover in agricultural areas and on small islands. In predominating agricultural coastal areas, the traditional open landscape of fields and grassland in the beginning of the 20th century has been replaced by woodland and grassland with shrubs by the start of the 21st century. Expansion of reed beds in the areas of former seashore grasslands is another striking phenomenon. The evolution of the landscapes on small islands is strongly dependent on the character of their formation and is well reflecting the relationships of vegetation, topography and moisture conditions. Cessation of traditional land use, rapid increase in coastal population and expansion of built-up areas in recent decades, together with higher storm activity, create stresses on the coast that threaten both nature and man.

Past extreme events recorded in the internal architecture of coastal formations in the Baltic Sea Region

ABSTRACT Vilumaa, K.; Tõnisson, H.; Sugita, S.; Buynevich, I.V.; Kont, A.; Muru, M.; Preusser, F.; Bjursäter, S.; Vaasma, T.; Vandel, E.; Molodkov, A., and Järvelill, J.I., 2016. Past extreme events recorded in the internal architecture of coastal formations in the Baltic Sea region. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 775–779. Coconut Creek (Florida), ISSN 0749-0208. The postglacial uplift and transgressive-regressive phases of the Baltic Sea have affected the formation and displacement of sandy accumulation forms in the region. The dune-ridge complexes preserve a geological record of past sea-level fluctuations, coastal evolution, and extreme events, and offer insights into major driving mechanisms. This study aims to improve methodologies for identifying different storm signatures in coastal deposits using examples from Estonia and Latvia. The paleo-beach ridges are typically covered by aeolian sand, and the inter-ridge swales are mostly filled with organic sediments. Ground-penetrating radar surveys corroborate distinct textural patterns in sand layers underneath the ridges and swales. In the ridges, sharp seaward-dipping reflections represent storm scarps. The ridge sequences without dipping reflections suggest either aeolian origin or longshore transport; smaller sandy ridges, which are buried under peat layers, reflect prolonged, calmer phases. Compound dunes with ridges in their cores indicate major coastal events or shifts in atmospheric conditions that would have exposed wide sand areas to wind and facilitated dune development. This study demonstrates that the aeolian processes and changes in storminess have played an important role in the genesis of ridge-swale complexes in the Baltic Sea Region.

Incorporating dynamic factors to the Environmental Sensitivity Index (ESI) shoreline classification - Estonian and Spanish examples

ABSTRACT Aps, R., Tõnisson, H, Anfuso, G., Perales, J.A., Orviku, K., Suursaar, Ü. 2014. Incorporating dynamic factors to the Environmental Sensitivity Index (ESI) shoreline classification - Estonian and Spanish examples. In: Green, A.N. and Cooper, J.A.G. (eds.), Proceedings 13th International Coastal Symposium (Durban, South Africa), Journal of Coastal Research, Special Issue No. 70, pp. 235–240, ISSN 0749-0208. Oil transportation is growing in the Baltic Sea area and especially in the Gulf of Finland where it will reach approximately 180–200 million tons a year by 2020. Growing oil transportation is considerably contributing to the risk of accidental spill-related shoreline oiling. This paper focuses on amending the Environmental Sensitivity Index (ESI) related shoreline classification to local conditions by dynamically changing the categorization of the shoreline in terms of its susceptibility to spilled oil caused by extreme meteorological events. This takes into consideration a number of natural physical factors. The paper presents the results of two European case studies: the Estonian shoreline of the Gulf of Finland (Baltic Sea), and the Spanish coast of the Gibraltar Strait. Susceptibility to spilled oil of some categories of the Estonian shoreline (sandy shores, till shores and gravel shores) occasionally changes over time from low to high sensitivity and back; especially conditioned to the influence of heavy storms. The studies carried out in Spain revealed a well recognizable indirect proportionality between foreshore slope and the tidal range. At many locations, the dynamic morphological characteristics of the beach appeared to be largely determined by contouring and specific conditions that are modifying the initial ESI related categorization of the sandy beaches concerned. The novelty of this work is in attempt to move from the standard ESI related, and locally adapted, static shoreline classification towards more dynamic shoreline monitoring based on characterization of the elements sensitive to oil pollution on shorelines.