Helena Boniecka

Articles

Recent experience with and trends in the artificial nourishment of marine and lagoon beaches in Poland, with a particular focus on the Hel Peninsula

Helena Boniecka

Przegląd Geograficzny (2022) tom 94, zeszyt 1, pp. 31-57 | Full text
doi: https://doi.org/10.7163/PrzG.2022.1.2

Further information

Abstract:

Artificial beach nourishment is one of key methods preventing coastal erosion and flooding, acting in support of the maintenance of much-disturbed coastal environments and their much-desired recreational functions.

Beach fills have been implemented since the 1930s, though relevant conceptual studies in Poland were elaborated in the 1960s and 1970s. These summarised the worldwide experience focusing on the rational implementation of beach fills in Poland. Recommendations at that time included a maximisation of the use made of sand dredged from navigation channels and canals, with a view to this being used to nourish abraded beaches near ports.

In 1978, sand by-passing was implemented successfully at the Dźwirzyno and Rowy fishing harbors, with regular dredging of the approach channels and harbour canals being combined with the pumping of a water-sand mixture on the lee (eastern) side of breakwaters. These systems have remained operational through to the present day. The largest fills were generated in the 1994‑1996 period; being ca. three times greater than the volume of sand dumped offshore.

Between 1980 and 2014, 32.2 M m3 of sand were deposited along the Polish coast and lagoon shores. This offered partial compensation of the reduced nearshore sand deficit, and served to increase resilience of beaches and the backshore in the face of erosion and inundation, while also helping with the contamination of beaches due to uncontrolled emissions in the course of events of the latter type. More than half of the total fill volume was deposited along the offshore coast of the Hel Peninsula, where a comprehensive scheme for coastal protection was implemented between 1989 and 1995. The Peninsula, and particularly its root and central part, are among sites in Poland most vulnerable to erosion, often subject to catastrophic inundation threats.

Following Poland’s adoption of the Coastal Protection Act 2003 (see the Dziennik Ustaw Official Journal of Laws of 2016, item 678), fills became the most popular coastal‑protection measure. Between 2004 and 2014 this measure was resorted to predominantly along offshore stretches of the Hel Peninsula, and at beaches adjacent to open sea ports on their lee (eastern) sides (including harbours from Łeba along to Dziwnów).

Fills were also performed along the shores of the Gulf of Gdańsk, where erosion processes have accelerated in recent decades; and at the open-sea beaches near Jarosławiec, Ustronie Morskie and Niechorze. The latter installations operated in support of existing protection schemes. Comprehensive protection of the soft cliff between Rewal and Trzęsacz was also inaugurated, the background erosion tendencies ongoing their having coincided with anthropogenic activities causing disruption to local geodynamic processes. Since the time of adoption of the Coastal Protection Act, a total fill volume of 10.5 M m3 has been deployed, see Table 1. This represents about one-third of all the filling done from 1980 until 2014.

Many positive changes are to be identified along the open-sea coast of the Hel Peninsula, on which more than 17.5M m3 of sand were deposited in the years from 1989 through to 2014, cf. Table 1, Figs. 3, 4 and 5. The large fill volumes achieved during the first 5 years of implementation of the protection scheme along the Peninsula resulted in rehabilitation of the nearshore seabed to such an extent that follow-up re-nourishment only needed to assume a lesser intensity. Morphometric parameters along the nourished beaches allow for them to be classified as very highly resilient in the face of hydrodynamic forces.

Since erosion tendencies prevail in Poland’s coastal zones, any cessation of beach fills may result in a gradual loss depletion of the level of safety achieved. Thus, annual deposition of several hundred thousand m3 of sand along the offshore beaches of the Hel Peninsula continues to represent an absolute necessity if the current level of resilience is to be maintained.

Reduction of nearshore sand deficits by way of beach filling represents the only method of preventing negative beach responses. Re-nourishments are determined by hydrological and morphodynamic factors, and should gain incorporation into the protection actions being planned by coastal authorities. There can be no doubt that the experience acquired thus far can provide for successive optimisation of the method under consideration, with a view to level of protection efficacy being raised, even as respect for environmental sustainability is also achieved.

Keywords: sztuczne zasilanie, brzeg morski, erozja, deficyt osadów strefy brzegowej, kubatura osadów

Helena Boniecka [helena.boniecka@im.umg.edu.pl], Uniwersytet Morski w Gdyni, Instytut Morski