Ryszard B. Zeidler

Abstract

It is widely taken for granted that the climate is changing worldwide, partly on account of anthropogenic eiTects. The impact on Polish coast of the accelerated sea level rise (ASLR) due to the intensifying greenhouse effect has been tackled under IPCC auspices (Zeidler 1992). Regional climate change for the Baltic Sea is discussed first, with particular emphasis on recent findings for sea level (mean and extrema) and storm intensity. Examination of trends and statistical distributions for sea level datasets, revised and updated for the Polish coast, has partly confirmed some earlier conclusions drawn for mean sea level showing a trend about 20 cm per 100 years. For the maximum sea levels the rising trend is about two times smaller. More thought is being given to the general problem of land (primarily arable) degradation due to extended landward penetration of sea water due to ASLR. Long-term coastline change is analysed on the basis of routine topographic and bathymetric data collected at the PAS Institute of Hydro-Engineering IBW PAN Coastal Research Station, situated some 75 km from Gdansk. Following that analysis, we are postulating a large-scale model basing on conservation laws for sediment volume, the shore profile equilibrium (the Dean profile), dispersion terms between coastal cells, and linkage between wave energy dissipation and shore transformation. Assessment of coast vulnerability to ASLR (Zeidler 1992) has been summarized to identify the potential hazards. The Polish "Study Area" under IPCC 'Common Methodology* has been defined as the area within which the physical eiTects of the accelerated sea level rise (ASLR) over the next century could be felt. The inland boundaiy of the study area was chosen as the + 2.5 mm contour. In summary, the area endangered under ASLR1 and ASLR2 is very substantial — 2230 km2 both flooded permanently and at risk (flooded periodically). The area losses under ASLR 1 and ASLR2 are respectively 672 and 948 km2. The length of roads Hooded is 400 km and 564 km in the two cases, in addition to 35 and 126 km of railways, 300 and 415 km of primary power lines, and 26 bridges. The population to be evacuated in advance amounts to 142,690 (urban) and 92,150 (rural), thus 234,840 in total. Various protection techniques are proposed to avoid loss of land. Flood protection in the Lower Vistula River has been described in a comprehensive monograph published by IBW PAN (Makowski 1993).

Keywords: climate change; sea level rise; shore protection; coastal management; Poland's coast vulnerability to sea level rise

Ryszard B. Zeidler, Institute of Hydro-Engineering, Polish Academy of Sciences, Gdansk