Ryszard B. Zeidler

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.

Continental shorelines : climate change and integrated coastal management

Abstract Two continental shorelines, of Poland and Vietnam, are presented in the context of their vulnerability to climate change, present and planned response strategies and steps toward integrated coastal management (ICM). The two cases illustrate a broad realm of possible effects and actions facing continental shorelines. The climate change issue is primarily centered around sea level rise in Vietnam but has been expanded to other domains in Poland. General ICM issues are treated under the action plan Vietnam ICM 2000, 1 and a central Vietnam coast at Hue is considered for its ICM potentials. GIS-aided techniques are employed in both countries to solve vulnerability problems and prepare for ICM. Sea-level rise scenarios, 10 cm (SLR1) and 30 cm (SLR2) by the year 2030, and 30 cm (ASLR1) and 100 cm (ASLR2) by the year 2100, are assumed as boundary conditions (along with some wind climate changes) for the entire Polish coast. Over 2200 km 2 and 230 000 people are found vulnerable in Poland, and the total cost of land at loss due to ASLR2 is presently re-assessed at nearly US

CLIMATE CHANGE VULNERABILITY AND RESPONSE STRATEGIES FOR THE COASTAL ZONE OF POLAND

30 billion (plus some US

DEPTH OF CLOSURE AND SEABED VARIABILITY PATTERNS

18 billion at risk of flooding), while the cost of full protection reaches US

SEDIMENT TRANSPORT IN VARIOUS TIME SCALES

6 billion. Growing prices urge for prompt protection actions. Physical and socioeconomic development scenarios are examined and the coastal data input is provided for other Polish climate-change studies that are under way, thus adding to the cross-sectoral dimension. With 1-m sea-level rise in Vietnam, 17 million people will be subject to annual flooding, of which over 14 million are in the Mekong Delta provinces. About US

BEACH GROUND-WATER OSCILLATIONS

17 billion of capital value will be lost by annual flooding, which is about 80% of the yearly GDP. In the 30-year development scenario, the capital value lost will be close to US

SEA LEVEL RISE AND COAST EVOLUTION IN POLAND

270 billion, which would be even higher than the projected GDP at that time; the damage increases faster than the GDP. Major low-lying areas will be subject to increase in flooding: and, if no additional protection measures are taken, about 40 000 km 2 will be flooded annually.

WIND- AND SEA LEVEL-INDUCED SHORE EVOLUTION IN POLAND

Four accelerated sea level rise scenarios, 30 and 100 cm by the year 2100, and 10 and 30 cm by the year 2030, have been assumed as boundary conditions (along with some wind climate changes) for the entire Polish coast, under two recent programmes completed in 1992 and 1995. Three adaptation strategies, i.e., retreat, limited protection and full protection have been adopted and compared in physical and socio-economic terms. Over 2,200 km2 and 230,000 people are found vulnerable in the most severe case of 100-cm rise by 2100. The total cost of land at loss in that case is estimated at nearly 30 USD billion (plus some 18 USD billion at risk of flooding), while the cost of full protection reaches 6 USD billion. Particular features of vulnerability and adaptation schemes have been examined as well, including specific sites and the effects of not only sea level rise but also other climate change factors, and interactions with other climate change studies in Poland. Planning of coastal zone management facing climate change can be facilitated by the use of a GIS-supported coastal information and analysis system. An example of the application of such a system for a selected Polish coastal site is shown to illustrate the most recent smaller-scale research activities undertaken in the wake of the overall assessment of the vulnerability to climate change for the entire Polish coastal zone.

NEARBED SEDIMENT CONCENTRATION FROM TRACER STUDIES

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.

VERTICAL VARIABILITY OF COASTAL SEDIMENT TRANSPORT

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.