1. Pärnu Bay study area Are Kont Valdeko Palginõmm Hannes Tõnisson
Ülo Suursaar
Agnes Anderson
Acknowledgements:
BONUS BaltCoast project has received funding from BONUS (Art 185), funded jointly by the EU and [national funding institution acknowledgements, as appropriate].

2. Design Step
Pärnu Bay study area including City of Pärnu and Valgeranna summer resort

3. Vulnerability of Pärnu to 2.1 m storm surge

4. Define the administrative boundaries for the Virtual System
Pärnu County:
City of Pärnu
Rural municipalities:
Varbla
Tõstamaa
Audru
Tahkuranna
Häädemeeste
Kihnu

5. Define the linkages between the ESE components
Environmentally sensitive area under growing human pressure
Shallow bay and low-lying coast
Sea-level fluctuations caused by windstorms associated with occasional ice attacks
Extensive floods, erosion of sandy beaches and shoreline changes

6. Define the linkages between the ESE components
Valuable natural resources providing a number of ecosystem services and being a driving force for economic growth
Public beaches and warm seawater in summer associated with relevant infrastructure
The Pärnu Bay has a considerable importance in fisheries. Over 80% of the coastal fishing in Estonia is connected with this region
The bay is an important spawning ground and an area of development of juvenile fish for many species

7. Define the linkages between the ESE components
Marine spatial planning of the Pärnu Bay is under developing
The marine spatial planning should be harmonized with the existing coastal plannings

8. What external hazards are there?
Occasional, extreme storm events in autumn or early winter
Such storms may cause storm surges of 2-3 m height in the practically tideless Pärnu Bay

9. What external hazards are there?
Concurrent impacts are:
inundation of low-lying urban and coastal areas
damage of critical infrastructure
coastal erosion
siltation of navigation channels
secondary pollution from re-suspended bottom sediments and storm debris

10. What external hazards are there?
The impacts of extreme storms are usually track- dependent:
travelling from west to northeast, the cyclone must retain a great deal of its strength
the track must pass Estonia about km north, which yields local SW-W winds with sustained speeds up to m/s
pre-elevated (by up to cm) mean Baltic Sea level as a result of preceded stormy period or a series of successive cyclones

11. Describe the state of the system and knowledge gaps
Large-scale topographic, geological, soil, vegetation, etc. maps
Profiles, reports and results of different kind of natural studies
Hydrodynamics of Pärnu Bay has been measured and modelled and the results are related to the records of meteorological stations and tide gauges

12. Describe the state of the system and knowledge gaps
Initiated by the Ministry of the Environment, a preliminary risk assessment in case of storm surges and floods has been done and the areas at risk have been mapped.
After the last extreme storm in January 2005, a lot of measures have been taken:
improve the rescue service system
inform the people in advance about possible hazards
change the regulations considering constructing in the areas at risk

13. Describe the state of the system and knowledge gaps
We do not have any socio-economic models for the study area
We do not know quantitatively the reactions to extreme events in the economic and social spheres

14. Pärnu Bay study area conceptual model
Compensation by
insurance companies
City of Pärnu
Valgeranna
Natural hazard – storm surge
Inundation of city center
Erosion of sandy beach
Damaged dwellings,
infrastructure,
tourist facilities
Problems with sewage
system, water quality
Disturbances in
transport and
communication
Loss of sunning and
swimming area
Lost profit from
tourist service
Inundation of
Audru polder
Responses and adaptations
Raising of awareness,
warning of people
Health and rescue
services
Regulations of
constructing in
areas at risk
Changes in coastal and
marine spatial planning
Conservation of
breeding ground for
waterfowl
Facilitation of natural
tourism and playing golf
Siltation of
navigation
channel

15. Most important impacts are: 1
Most important impacts are: Inundation of the City – affected people, infrastructure and real estate 2. Rapid sediment re-distribution - Erosion (damage and loss of infrastructure) and accumulation (again damage to infrastructure – siltation of harbour channels)

16. Inundation of the City (what happened, current situation):
Maximum event (2005 storm Gudrun) 8 km2 of the City Under the water (over 25%);
Sea level up to 275 cm (Critical level is only 160 cm)
Damaging events are expected at least once in years (without climate change);
775 houses were affected
300 people were evacuated
1 casuality

17. Inundation of the City (What is the future):
Inundation level up to 400 cm (in perfect storm scenario) by year 2100 (sea-level rise according to RCP stronger storm), which is over 1 m over the current max;
1/10 year inundation is expected to cover 4.85 km2 (15% of the City, 600 people affected);
1/100 year inundation is expected to cover 7.1 km2 (21% of the City, 3800 people affected);
1/1000 year inundation is expected to cover km2 (31% of the City, 8500 people affected - 21% of the City population) ;

18. Inundation of the City (Actions taken):
Estonian Water Act, Chapter 51 on the assessment and management of flood risks. Based on this, the document “The preliminary assessment of flood risks” has been compiled and approved by the Ministry of the Environment in 2012;
only densely populated areas are regarded as risk areas, in Pärnu region these are the city of Pärnu and densely populated areas in Audru Municipality, in the village of Papsaare;
for these areas, maps with a different likelihood have been compiled (from 1 time per 10 years up to 1 time per 1,000 years) which are available at the respective map application of the Land Board.
emeregncy act re-newed (For the whole Estonia);

19. Inundation of the City (Actions taken):
Emergency commission established (Pärnu county) and action procedure and diferent actions for diferent flood levels;
First response (sandbags for smaller events to protect lower buildings);
Preliminary closure of streets that will be affected (no additional problems with extreme-event-adventure tourists);
Affected infrastructure, dwellings and tourist attractions is calculated for diferent events – 37 km of steerts will be Under the water;
Insurance companies have ordered their own inundation maps, more detailed than public ones and not only for densely populated areas

20. 275 cm above mean sea-level

21. Inundation of the City (Gaps and solutions):
Informing inhabitants is not up the task yet (there is storm warning and prediction of flood level but information is not translated to „normal people language“) – Solution?;
it is known what buildings and infrastructure are affected in case of different flood levels, however, for most of them, there is no plan how to protect these and how to compensate the costs, number of public buildings (over 20% of 1/10 year inundated buildings are public buildings) will be also affected – Solution?!
no clear future plans for increasing sea-level and resulting increase in flood levels – Solution?;
Clear and throughout information (also for less densely inhabited areas) on flood levels belongs to insurance companies only – how to inform public? Urgent need for delivering such an information to public

22. Rapid sediment re-distribution (Current state)
Rapid erosion in neighbouring municipalities;
Loss of high-valued recreational sandy beaches;
Damage to tourism infrastructure (no sandy beaches, destruction of trees and adventure track, damage to the tourism facilities (Lottemaa, etc.);
Siltation of the harbour channel from Port of Pärnu (most important harbour in the region, 4th biggest cargo harbour in Estonia t/year);

23. Rapid sediment re-distribution (Actions taken)
Small-scale projects to build dunes (increaisng natural protection, reducing sediment flow to harbour channel)
Local coastal protection measures (often hard protection), however, often dangerous and causing undesirable effect;
No general action plan, lack of co-ordination, lack of general thinking.

24. Rapid sediment re-distribution (Future)
Increasing erosion from neighbouring municipalities;
Increasing damage to buildings and infrastructure;
Loss of sandy beaches;
Lost profit from recreation service
Increased pressure to Pärnu beaches;
Increasing costs of harbour channel maintenance (dredging).

25. Rapid sediment re-distribution (Gaps and solutions)
No general plan for coastal protection - land and sea actions are planned separately in Estonia
Nourishement of the beaches with material from harbour channel dredging (problems with sand quality? Legislation restriction? Cost?)
More extensive dune building, who is paying? Loss of sea- view?;
No more local hard defence measures, what happens with the existing ones?;

26. Small scale questions
Drinking water – mostly groundwater, away from inundation area, well protected from floods – may affect land subsidence? Problems with some smaller wells near to the coast with increasing sea-level;
Sewage treatment system – out of order during inundations = affecting bathing water quality ->impact to tourism – solution? Water is anyway with poorest quality along the Estonian coast, however, good for fish (rich in nutrients), etc.;
Impact on public transport (during inundation and impact of erosion) - 6 buslines will be affected.
Future access to low-lying harbour region and storing areas?

27. Data and Methods
What strategy did you choose for the simulation modeling?
Numerical modeling in the Pärnu Bay area has mainly been and is still used in hydrodynamical research
This research has been closely related to the records of meteorological observation
A multidisciplinary approach has been developed in order to combine the effects of climatic forcing on hydrodynamics and geomorphic shore processes

28. Data and Methods
What strategy did you choose for the simulation modeling? In the current project, many different kind of large-scale maps (topographic, geological, hydrological, soil, vegetation, land cover, areas at risk, etc.) from different times can be used together with the reports of specific investigations and the results of numerical modeling

29. Data and Methods
Which models were chosen?
2D hydrodynamic model (Gulf of Riga – Väinameri area; incl. Pärnu Bay). With this model, a number of sea level and flow hindcast studies as well as sensitivity experiments of extreme conditions have been carried out
Modeling system composed of WRF atmosphere model (fed by MIROC5 reanalysis and local weather data) and FVCOM ocean model will be used to hindcast historic extreme surge events in the Pärnu Bay as well as the meteorological and hydrological parameters of similar storms under future climate conditions
GIS has been used in monitoring, mapping and spatial planning, and can be used also in the current project

30. Problem scaling No