Hel Peninsula is located in the south Baltic Sea, in the west part of the Gulf of Gdańsk (see Fig. 1). The Peninsula separates the outer waters of the Gulf of Gdańsk from its inner part where the harbours of Gdańsk and Gdynia are situated. These harbours are sheltered by Hel Peninsula against the wave impact from the northern sector (as well as from north-east in the case of Gdynia harbour). Hel Peninsula shores on the open sea side are most exposed to wave attack from N-E sector. The Puck Bay, located SW from the shores of Hel Peninsula, constitutes the westernmost inner part of the Gulf of Gdańsk (Fig. 1).
Inhabited permanently by about 10 000 people, Hel Peninsula is visited by more than 1 million tourists every year. With the area of about 32 km², the Peninsula has the population density of ca. 313 inhabitants per square kilometre which is much more than the average in Poland (123 persons/km² in 2011). The seasonal increase of number of people on Hel Peninsula leads to many conflicts between local stakeholders, e.g. between ecologists and representatives of tourism-related business. The communication of Hel Peninsula towns and villages with Władysławowo located at the Peninsula root is provided by one road and one railway line which not only serve tourists and the local inhabitants, but are also the only supply lines for numerous institutions and companies situated there.
Observed for tens of years, coastal erosive phenomena constitute a serious threat to the supply lines and other objects located in the vicinity of the shoreline. Therefore, protection of the seashore of Hel Peninsula is extremely important and absolutely necessary. The protection used to be based on a groyne system, stretching along a 10 km long shore segment from the Hel Peninsula root. The groynes were constructed in 1946-1969 as timber palisades, each about 60 m long, spaced from each other by about 90 m. They were intended to mitigate erosion on the lee side of the harbour of Władysławowo, the breakwaters of which had disturbed the natural longshore sediment flux. Because of unsatisfactory efficiency of the groynes, artificial beach nourishment was implemented in the eighties of the 20th century. The nourishment has been carried out till now and slightly mitigated the erosive processes at the site. The groynes, coexisting with artificial beach fills, are subject to gradual damage manifested by loss of piles at various sections of the structures. The above mentioned coastal protection system is supplemented by a seawall at the lee side of the Władysławowo harbour and light revetments (the gabion structures built into artificial dunes).
On the strength of the Act of Parliament of Republic of Poland (28 March 2003) on establishment of long-term ‘Coastal Protection Programme’, the safe maintenance of Hel Peninsula shores ought to be provided by a system of sediment bypassing at the harbour of Władysławowo and artificial beach nourishment along the shore segment stretching 23.5 km south-eastwards from Władysławowo. Aside from application of the shore protection measures, the above mentioned Parliamentary Act, together with the Governmental Directive (29 April 2003) on determination of the width of the coastal technical/protective belt, recommends coastal monitoring and research aimed at identification of the most threatened shore segments. These activities are carried out by the Maritime Office in Gdynia (the governmental authority responsible for coastal management, among other things), often supported by a few other governmental entities (for instance the Institute of Meteorology and Water Management – IMGW) and scientific institutions, including the Institute of Hydro-Engineering of the Polish Academy of Sciences (IBW PAN). The coastal research is a basis for the nourishment interventions along specified shore segments, identified as the ones being most vulnerable to erosion. Till now, the nourishment operations, although rather extensive and costly, have proved to be satisfactory, ensuring protection of Hel Peninsula coast against erosion and flooding.
The Baltic Sea has been experiencing the growth of storminess in winter over the recent decades. The wave impact superimposes on the accelerated sea level rise, particularly dangerous to some segments of the Polish coast, including its east part, comprising the Gulf of Gdańsk and Hel Peninsula. Future wave and sea level scenarios determined on the basis of the global climatic scenarios indicate that hydrodynamic conditions in the south Baltic will become more severe in 21st century, particularly in the period from 2081 to 2100. A discussion among coastal managers and engineers arises to which degree the observed climate changes will affect hydrodynamic processes directly influencing coastal morphodynamics. At present, the lithodynamic equilibrium of the open sea shores of Hel Peninsula basically depends on the artificial beach nourishment. A question appears if the technical and financial means described in the respective Polish legal regulations will turn out to be sufficient in the anticipated new circumstances.