Coastal flood risk Poland
The Polish coastline
The 500 km long Polish coastline is situated along the Baltic Sea, a non-tidal, semi-enclosed and shallow body of brackish water. Exchange of water through the Danish Straits is the primary regulator of water levels in the basin. Most of the coastline is a spit- and barrier-type coast, with dunes ranging in height from less than 2 up to 49 m. Sections of cliffs make up ca. 18 % of the entire coastline length. Behind the dunes, coastal plains with occasional depressions (down to 1.8 m below mean sea level) are usually observed. The Polish Baltic Sea coast is not densely inhabited: only 2.8% of Poles reside in municipalities with direct access to the sea (17).
The Baltic Sea is practically non-tidal; tidal range is 6 cm for the Polish coast. … Two basic shore types exist: dunes and barrier beaches, and cliffs. Cliffs comprise about 100 km of the coastline and are cut into Pleistocene sediments (1). Poland’s coast can be split into three different areas reflecting major physiographic and economic differences along the Polish coast (1):
- Area I mainly covers the Odra Estuary (and the conurbations of Szczecin and Swinoujscie).
- Area II encompasses the western and central-eastern dunes, cliffs, and the open sea barrier beaches (including the Hel Peninsula).
- Area III covers the Vistula Delta (and the conurbations of Gdansk, Sopot, and Elbag).
Global sea level rise
For the latest results: see Europe Coastal floods
For the latest results: see Europe Coastal floods
Sea level rise Baltic Sea near Polish coast
Measurements of sea level changes made in Świnoujście belong to the longest series of measurements made in the world. At this location a trend of 0.4 mm per year was observed during 1811-2006, accelerating to 1.0 mm per year during 1947-2006 (19). This rate rises moving eastward: Kołobrzeg (central part of the Polish coast) recorded an increase of 0.5 mm during 1901–2006 and 1.4 mm during 1947–2006, while in Gdansk (eastern coast), 1.6 mm increase was observed during 1886–2006 and 2.5 mm during 1947–2006. The difference is largely due to uneven isostatic movement of the crust (17): the Polish coast is subject to the glacial isostatic adjustment, which causes a yearly uplift by about 0.4-0.5 mm (18). Satellite altimetry reveals that the rise in water levels is mostly uniform in the southern Baltic Sea. It amounted to 3.2 mm per year between 1992 and 2016, a pace very similar to the world ocean average, which was 2.9 mm per year during 1992-2016 (20).
A relative sea level rise of 45-65 cm by 2100 is probable for Poland. … Subsidence is limited, reaching up to 1 mm/y locally (5).
Vulnerabilities - Flood risk - Trends in the past
In the Baltic region, the intensification of coastal erosion, flooding, and the frequency and severity of storm conditions has been observed since the 1970s (3), although this may well represent natural variability as found in northwestern Europe (4). … In recent years an intensification of changes in atmospheric circulation in the Baltic has been observed, which has resulted—inter alia—in the increase of northwesterly storm intensity and frequency (1).
Vulnerabilities - Flood risk- Future projections
Risk assessment 2017
Storms surges are an important factor shaping the Polish coast. Extreme water levels depend largely on the volume of water flowing in from the North Sea. Long-lasting storm surges, even though relatively insignificant at the coast, can cause a flood along estuaries dozens of kilometres inland. Across the whole region, however, flood defences protect the lowest areas, particularly around river mouths and coastal lakes, while dunes and cliffs protect the rest of the coast (17).
A high-resolution assessment has been made of possible social and economic impacts of storm surges and inundation of land caused by sea level rise in Poland. In this assessment it was assumed that flood defences will not fail and all land gets inundated lying below the assumed water level, as long as there is a direct connection with the source of flood. For future sea level rise a low, medium and high-end projection was assumed (related to the so-called RCP2.6, RCP4.5 and RCP8.5 scenarios of climate change). In these scenarios, water levels rise gradually to 28, 53 and 98 cm by 2100 relative to 1986-2005 levels (17).
According to the assessment the impacts of sea level rise will be much smaller than indicated in previous studies because previous studies (1,9) did not include current flood defences. For instance, 1 metre sea level rise would directly affect ‘only’ 20,000 inhabitants and €2.3 bln of assets (0.6% of GDP, in 2011 prices). However, coastal flood risk in this area is determined by storm surges on top of sea level rise, and the frequency of coastal floods will increase substantially due to sea level rise. 1 metre sea level rise will triple the number of inhabitants and assets in the 100-year flood zone, and the damage by a 100-year flood event could increase from €1.5 bln (0.4% of 2011 GDP) under current conditions to €4.6 bln (1.2% of 2011 GDP) with 1 metre sea level rise. Flood hazard concentrates in the Vistula and Odra rivers’ mouths, encompassing approximately 75% of the total flooded area in all scenarios. The costs of economically optimal flood defences would increase from 0.39% of GDP at current conditions to 0.49-0.67% of GDP under the sea level rise scenarios of the assessment (17).
Still, on an annual basis the costs of adapting flood defences to future sea level rise are relatively small. Even for the 2090s under the high-end scenario of sea level rise these costs are ‘only’ a quarter of current annual investments on dikes (relative to GDP), and only 7% of annual disaster relief spending in Poland. In fact, storm surge hazard will be even less than projected in this assessment: an actual overtopping of flood defences would mostly cause inundation of a much smaller area than indicated here, since the peak of the surge lasts only a short period of time (17).
It is estimated that a sea level rise of 0.6 m without any actions may result in losing around 120 km2 of the land due to coastal erosion, whereas 2,200 km2 can be flooded by storm floods. This will be the direct threat for 300,000 people and indirectly for another 1.7 million people due to floods, erosion and land falls (2). The total cost of land loss due to sea level rise may be nearly US$30 billion plus some US$18 billion at risk of flooding, while the cost of full protection is US$6 billion (at 1995 prices) (1). The expected effect of the so-called climatic conditions on the coastal zone of the Baltic Sea will intensify already observed phenomena such as (2):
- coastal erosion (loss of deposits on the foreshore and higher instability of cliffs);
- storm floods and river swells;
- intrusion of salty waters to aquifer levels;
- increase of groundwater level;
- eutrophication (growth of algae) in the Gdańska Bay;
- overflows over coastal protection constructions.
Economic impacts of sea level rise for Europe
The direct and indirect costs of sea level rise for Europe have been modelled for a range of sea level rise scenarios for the 2020s and 2080s (8). The results show:
- First, sea-level rise has negative economic effects but these effects are not particularly dramatic. In absolute terms, optimal coastal defence can be extremely costly. However, on an annual basis, and compared to national GDP, these costs are quite small. On a relative basis, the highest value is represented by the 0.2% of GDP in Estonia in 2085.
- Second, the impact of sea-level rise is not confined to the coastal zone and sea-level rise indeed affects landlocked countries as well. Because of international trade, countries that have relatively small direct impacts of sea-level rise, and even landlocked countries such as Austria, gain in competitiveness.
- Third, adaptation is crucial to keep the negative impacts of sea-level rise at an acceptable level. This may well imply that some European countries will need to adopt a coastal zone management policy that is more integrated and more forward looking than is currently the case.
Adaptation strategies - Infrastructure measures
For the city of Gdansk, different technical solutions to decrease the vulnerability have been reported, including the construction of reservoirs, flood dykes, polders, dry reservoirs and bypasses (7). In the Vistula Delta, where Gdansk is located, agricultural productivity is high and full protection is required consisting of improving existing dikes, and constructing new dikes and storm and flood prevention facilities. It is estimated that 107 and 280 km of new dikes must be constructed under 30 cm sea level rise by 2100 and 1 m sea level rise by 2100, respectively; the lengths of dikes to be improved are 243 and 324 km for the same scenarios. The total protection costs for all protection measures in the whole coastal zone of Poland could amount to 6 billion dollar.
Adaptation strategies - Contingency planning
Disaster prevention, preparedness, response and recovery should become even more of a priority for Member States (6).
Adaptation strategies - The costs of adaptation for the EU
Both the risk of sea-level rise and the costs of adaptation to sea-level rise in the European Union have been estimated for 2100 compared with 2000 (9). Model calculations have been made based on the IPCC SRES A2 and B1 scenarios. In these projections both flooding due to sea-level rise near the coast and the backwater effect of sea level rise on the rivers have been included. Salinity intrusion into coastal aquifers has not been included, only salt water intrusion into the rivers. Changes in storm frequency and intensity have not been considered; the present storm surge characteristics are simply displaced upwards with the rising sea level following 20th century observations. The assessment is based on national estimates of GDP.
The projections show that without adaptation (no further raising of the dikes and no beach nourishments), the number of people affected annually by coastal flooding would be 20 (B1 scenario) to 70 (A2 scenario) times higher in 2100 than in 2000. This is about 0.05 - 0.13% of the population of the 27 EU countries in 2010 (9).
Without adaptation, damage costs would increase roughly by a factor of 5 during the century under both scenarios, up to US$ 17×109 in 2100. Total damage costs would amount to roughly 0.04% of GDP of the 27 EU countries in 2100 under both scenarios. Damage costs relative to national GDP would be highest in the Netherlands (0.3% in 2100 under A2). For all other countries relative damage costs do not exceed 0.1% of GDP under both scenarios (9).
Adaptation (raising dikes and beach nourishments in response to sea level rise) would strongly reduce the number of people flooded by factors of 110 to 288 and total damage costs by factors of 7 to 9. In 2100 adaptation costs are projected to be US$ 3.5×109 under A2 and 2.6×109 under B1. Relative to GDP, annual adaptation costs constitute 0.005 % of GDP under B1 and 0.009% under A2 in 2100. Adaptation costs relative to GDP are highest for Estonia (0.16% under A2) and Ireland (0.05% under A2). These results suggest that adaptation measures to sea-level rise are beneficial and affordable, and will be widely applied throughout the European Union (9).
The references below are cited in full in a separate map 'References'. Please click here if you are looking for the full references for Poland.
- Pruszak and Zawadzka (2008)
- Ministry of the Environment and the National Fund for Environmental Protection and Water Managementof the Republic of Poland(2010)
- Dziadziuszko and Jednoral (1988), in: Pruszak and Zawadzka (2008)
- WASA Group (1998), in: Pruszak and Zawadzka (2008)
- Pruszak (2000), in: Pruszak and Zawadzka (2008)
- Commission of the European Communities: Green paper (2007)
- Staudt (2006), in: Walraven and Aerts (2008)
- Bosello et al. (2012)
- Hinkel et al. (2010)
- Cazenave et al. (2014)
- IPCC (2014)
- Watson et al. (2015)
- Yi et al. (2015)
- Church et al. (2013), in: Watson et al. (2015)
- Shepherd et al. (2012), in: Watson et al. (2015)
- Church et al. (2013), in: Watson et al. (2015)
- Paprotny and Terefenko (2017)
- Peltier et al. (2015), in: Paprotny and Terefenko (2017)
- Wiśniewski et al. (2011), in: Paprotny and Terefenko (2017)
- NOAA (2016), in: Paprotny and Terefenko (2017)