Zbigniew Pruszak

The analysis of beach profile changes using Dean's method and empirical orthogonal functions

Abstract Sea bottom changes in the cross-shore direction have been analysed. The cross-shore profile, as a major factor of beach configuration, has been presented schematically as a superposition of a basic curve reflecting the mean layout and slope of the shore given by Deans function y=A·χ 2 3 and superimposed various bars, troughs, berms, etc. depicting local characteristic features of the profile. The local features of the profile have been analysed by use of one- (1-D) and two-dimensional (2-D) empirical orthogonal functions. On the basis of field observations and measurements the parameter A has been presented as a function of time. Three time scales have been distinguished (short, seasonal and long-term) with respect to which more or less regular changes of the parameter A occur. The modified parameter A was applied to two different field sites, namly Lubiatowo, Baltic Sea (Poland) and Gold Beach, Black Sea (Bulgaria). It has been found that in extreme cases the parameter A can vary in time by a factor of two, or more, for the same grain size distribution.

Forced and self-organized shoreline response for a beach in the southern Baltic Sea determined through singular spectrum analysis

Abstract Temporal and spatial variations in shoreline position along the southern Baltic coast were investigated using singular spectrum analysis (SSA) with the overall aim to determine characteristic patterns in the shoreline response and whether these patterns displayed forced or self-organized behavior. The investigated beach is located at Lubiatowo on the Polish Coast and is mildly sloping with multiple bars having a median grain size of 0.22 mm, being typical for the coast in the southern Baltic Sea. Data on coastal morphology have been collected at Lubiatowo including (1) bathymetric surveys since 1987 twice a year to cover changes in the seabed (along 27 lines covering a longshore×cross-shore area of 2600×1000 m), and (2) beach topography surveys since 1983 every 4 weeks on the average, extending from the shoreline to the dune foot (along the same 27 lines). Furthermore, several dedicated field campaigns have been carried out at Lubiatowo, as well as measurements of deep-water wave properties since 1998. SSA was employed to the time series of shoreline position from all 27 survey lines. The analysis method demonstrated a large potential for detecting temporal patterns from fairly short and noisy time series with irregular sampling interval. In summary, three dominant patterns emerged jointly reproducing 70–90% of the overall variation in the data for the different survey lines. These temporal patterns were demonstrated to represent forced and self-organized components describing the variation in shoreline position. The forced components could be related to the mean properties of the wave climate, whereas the self-organized components were mainly influenced by particular events or features of the beach such as storm waves, storm surges, beach type (dune, cliff), and sediment characteristics.

Statistical properties of multiple bars

Abstract A natural, mild-slope, multiple-bar shore with a sandy bed (D 50 = 0.022 cm) at the Coastal Research Facility (CRF) Lubiatowo (Poland) is analysed. The bathymetric dataset consists of 81 cross-shore transects surveyed from 1964 to 1994. Correlations have been computed for couples of parameters of each bar and for the same parameters of different bars. The most significant correlations have been obtained for parameters of the innermost stable bar. Correlations of the same parameters of different bars decrease rapidly with the distance from shoreline. Further analysis has shown that water depths over consecutive bar crests increase similarly to the mean shore profile. Their change can be presented by a Dean-type function describing a new ‘bed equilibrium line’ for the envelope of bar crests. The line is directly coupled with breaker parameters. Hence a wave breaking criterion for multiple-bar profiles could be established. Wave breaking is put forth as a major factor of bar formation.

Potential Implications of Sea-Level Rise for Poland

Abstract Polands approximate 500-km coastline predominantly comprises sandy, low-lying beaches and populated coastal lowlands. They are exposed to a range of threats from recently observed intensified climate changes and anticipated accelerated sea-level rise. Sediment starvation is already indicated by the growing necessity for dune and cliff protection that has been exacerbated by sea-level rise. The current study is both a summary and extension of existing Polish studies, and analyses current and predicted influences of accelerated sea-level rise on the coast. First, the Polish coast was divided into three areas according to coastal and socioeconomic characteristics. Then, considering two scenarios of accelerated sea-level rise [(i) 30 cm/100 y and (ii) 100 cm/100 y], an analysis of the threats of land loss and flood risk was carried out, and economic and social costs and losses assessed. This analysis included two adaptation scenarios: retreat (do nothing) and full protection. These analyses show that the greatest impacts of accelerated sea-level rise would occur in the far-eastern and western regions of the Polish coast with lesser impacts along the central region. Threatened areas include the conurbation of Gdansk, the Zulawy polders, and the low-lying areas around the Szczecin Lagoon and the Odra river mouth. Because both the Szczecin Lagoon region and the Vistula River delta are of key importance for the Polish economy and are densely populated, a carefully planned response is required to manage these threats. STRESZORENIE: Polska, posiadaja c okolo 500 kilometrowej dlugości piaszczysty i na wielu odcinkach nisko poloz ony brzeg morski, w wyraźny sposob naraz ona jest na roz nego rodzaju zagroz enia wynikaja ce z nasilaja cych sie w ostatnich latach zmian klimatycznych oraz przyspieszonego wzrostu poziomu wody (ASLR) w morzu. Pojawiaja cy sie deficyt osadow wzmaga erozje linii brzegowej, wydm i klifow co przeklada sie na konieczność coraz szerszej ich ochrony. Niniejsza praca stanowi zarowno podsumowanie, jak i rozszerzenie dokonanych w Polsce studiow i analiz dotycza cych obecnego i przewidywanego wplywu ASLR na brzeg. Dokonuja c podzialu calego polskiego wybrzez a na trzy podstawowe, maja ce geograficzne i socio-ekonomiczne uwarunkowania, obszary (AREA I, II, III) oraz przyjmuja c dwa roz ne scenariusze przyspieszonego wzrostu poziomu morza (ASLR1-30 cm/100 lat oraz ASLR2-100 cm/100 lat) i zwia zane z nimi warunki brzegowe przeprowadzono analize zagroz enterenow, ryzyka ich chwilowego lub cze sciowego zalewania, a takz e wynikaja cych z tego tytulu kosztow i strat zarowno materialnych, jak i spolecznych. Analizy te zostaly wykonane w ramach dwoch podstawowych scenariuszy adaptacji, tj. opcji cofania sie (odsta pienia od ochrony) oraz wariantu pelnej ochrony zagroz onego brzegu i sa siaduja cych z nim terenow la dowych. Wykonane analizy wykazaly, iz najwie ksze zagroz enie utraty lub niszczenia terenow i zwia zane z tym koszty materialne i spoleczne wyste puje w dwoch rejonach polskiego wybrzez a. Pierwszy z nich znajduje sie we wschodniej cze sci polskiego wybrzez a i obejmuje gdanska aglomeracje oraz cze sc Z ulaw drugi natomiast zlokal-izowany jest na zachodnim krancu Polski, obejmuja c nisko poloz one tereny wokol Zalewu Szczecinskiego i w rejonie ujscia Odry. Z uwagi na duz e zagroz enie a jednoczesnie znaczna narodowa wartosc obu tych obszarow wymagaja one wzmoz onej uwagi i priorytetu w ochronie.

Vulnerability of Poland's Coast to Sea-Level Rise

Over the last decades, the Polish coast, about 500 km long and predominantly featured by sandy, low-lying beaches, has been exposed to various threats resulting from intensified climate change and Accelerated Sea-Level Rise (ASLR). This has manifested itself in the growing intensity of shoreline, dune and cliff erosion and by the increasing necessity of their protection. The current study is both a summary and an extension of the existing Polish studies and analyses on the present and predicted influence of ASLR on the coast. First, the Polish coast was divided into three basic area types (AREA I, II, III) according to their geographic and socio-economic background. Then, two different scenarios of accelerated sea-level rise (ASLR1 — 30 cm/100 yrs and ASLR2 — 100 cm/100 yrs) were assumed. After that threats of land loss and the risk of its temporary or partial inundation was analyzed in connection with the assessment of the material and social costs and losses. These analyses were made within the framework of two adaptation scenarios, i.e. retreat (do nothing) and full protection. The performed analyses have shown that the greatest threat of partial or full land loss and the associated material and social costs are expected to occur in two regions of the Polish coast. One of them is situated in the eastern sector of the Polish coast and covers the agglomeration of Gdańsk and the Żulawy polders. The other is located in the west and comprises low-lying areas around the Szczecin Lagoon and the vicinity of the Odra river mouth. These areas both require intensive care and protection efforts.

Past and current climate change

This section describes long-term observed climatic changes in atmospheric parameters. The focus is on surface climate conditions, but changes in atmospheric circulation are discussed as they often are behind climatic variability seen on regional and local scales. For a summary introduction on mean atmospheric states and conditions in the Baltic Sea Basin see Annex 1.2 with sections on the general atmospheric circulation (A.1.2.1), surface air temperature (A.1.2.2), precipitation (A.1.2.3), clouds (A.1.2.4), and global radiation (A.1.2.5).

Coastal Processes in the Red River Delta Area, Vietnam

The economy and life in Vietnam is associated with the existence and development of large river deltas, i.e. the Mekong Delta and the Red River Delta. The latter is located in the northern part of Vietnam and apart from thousands of square kilometers of the area, it includes more than 165 km of coastline as well. In this area, the seashore and the adjacent densely populated, low-lying regions are often subject to intense impacts from the river (floods) and the sea (typhoons, changes in sea level, currents, etc.) and therefore undergo substantial and dynamic changes and destructions. In the current study, one of the coastal segments that are most vulnerable to destruction in Vietnam is analyzed. A synthetic analysis of the available information was carried out first and then the modeling of wave climate, currents and sediment movement patterns in the nearshore zone was done. The formulation of a phenomenological model of sediment budget, adequate for the amount of available information, allowed for assessment of the existing sediment fluxes and their relations to morphodynamic processes taking place in the studied area.

WAVE CLIMATE AND LARGE-SCALE COASTAL PROCESSES IN TERMS OF BOUNDARY CONDITIONS

The present analysis, as a kind of case study, deals with the experimental research at two different coast sites of the South Baltic. The analysis of the driving forces caused by wave fields and so on, and the responses, like current circulations, sediment transport and morphological coastal changes, gave rise to the attempt of empirical description of environmental site-specific coastal features and their large-scale interactions. In the present study, the name “large-scale” refers to the processes having the longshore scale of the order of kilometres and the cross-shore scale of hundreds of metres. Time scales lie in the range from months, seasons up to a few or dozen or so years at most. The above investigations provide an insight into the specific hydro- and morphodynamical processes occurring in coastal zones of the Baltic Sea. These processes can be regarded as representative for other small seas.

DEPTH OF CLOSURE AND SEABED VARIABILITY PATTERNS

Detailed studies have been undertaken to assist in the design of major extensions to the port of Haifa. Both numerical and physical model studies were done to optimise the mooring conditions vis a vis the harbour approach and entrance layout. The adopted layout deviates from the normal straight approach to the harbour entrance. This layout, together with suitable aids to navigation, was found to be nautically acceptable, and generally better with regard to mooring conditions, on the basis of extensive nautical design studies.Hwa-Lian Harbour is located at the north-eastern coast of Taiwan, where is relatively exposed to the threat of typhoon waves from the Pacific Ocean. In the summer season, harbour resonance caused by typhoon waves which generated at the eastern ocean of the Philippine. In order to obtain a better understanding of the existing problem and find out a feasible solution to improve harbour instability. Typhoon waves measurement, wave characteristics analysis, down-time evaluation for harbour operation, hydraulic model tests are carried out in this program. Under the action of typhoon waves, the wave spectra show that inside the harbors short period energy component has been damped by breakwater, but the long period energy increased by resonance hundred times. The hydraulic model test can reproduce the prototype phenomena successfully. The result of model tests indicate that by constructing a jetty at the harbour entrance or building a short groin at the corner of terminal #25, the long period wave height amplification agitated by typhoon waves can be eliminated about 50%. The width of harbour basin 800m is about one half of wave length in the basin for period 140sec which occurs the maximum wave amplification.Two-stage methodology of shoreline prediction for long coastal segments is presented in the study. About 30-km stretch of seaward coast of the Hel Peninsula was selected for the analysis. In 1st stage the shoreline evolution was assessed ignoring local effects of man-made structures. Those calculations allowed the identification of potentially eroding spots and the explanation of causes of erosion. In 2nd stage a 2-km eroding sub-segment of the Peninsula in the vicinity of existing harbour was thoroughly examined including local man-induced effects. The computations properly reproduced the shoreline evolution along this sub-segment over a long period between 1934 and 1997.In connection with the dredging and reclamation works at the Oresund Link Project between Denmark and Sweden carried out by the Contractor, Oresund Marine Joint Venture (OMJV), an intensive spill monitoring campaign has been performed in order to fulfil the environmental requirements set by the Danish and Swedish Authorities. Spill in this context is defined as the overall amount of suspended sediment originating from dredging and reclamation activities leaving the working zone. The maximum spill limit is set to 5% of the dredged material, which has to be monitored, analysed and calculated within 25% accuracy. Velocity data are measured by means of a broad band ADCP and turbidity data by four OBS probes (output in FTU). The FTUs are converted into sediment content in mg/1 by water samples. The analyses carried out, results in high acceptance levels for the conversion to be implemented as a linear relation which can be forced through the origin. Furthermore analyses verifies that the applied setup with a 4-point turbidity profile is a reasonable approximation to the true turbidity profile. Finally the maximum turbidity is on average located at a distance 30-40% from the seabed.

SEDIMENT TRANSPORT IN VARIOUS TIME SCALES

A special reflecting wall 12 m long and 2.1 m high was built off the beach at Reggio Calabria, and 30 wave gauges were assembled before the wall and were connected to an electronic station on land. It was possible to observe the reflection of wind waves generated by a very stable wind over a fetch of 10 Km. The experiment aimed to verify the general closed solution for the wave group mechanics (Boccotti, 1988, 1989), for the special case of the wave reflection.Significant features on Wadden Sea wave climate are evaluated in respect of the state of the art. Main emphasis was laid on an analysis of the governing boundary conditions of local wave climate in island sheltered Wadden Sea areas with extensions being sufficient for local wind wave growth. Explanatory for significant wave heights a reliable parametrization of local wave climate has been evaluated by using generally available data of water level and wind measurements.