Acta geographica Slovenica, 46-2, 2006, 143-169 SLOVENIAN COAST SEA FLOODS RISK OGRO@ENOST SLOVENSKE OBALE ZARADI MORSKIH POPLAV Nata{a Kolega Standing on a flysch ridge Piran is relatively safe from sea floods with the exception of its lower-central part (photograph: Matev` Lenar~i~). Z izjemo osrednjega dela mesta je Piran zaradi lege na fli{nem hrbtu sorazmerno varen pred poplavami morja (fotografija: Matev` Lenar~i~). Nata{a Kolega, Slovenian coast sea floods risk Slovenian coast sea floods risk UDC: 556.166(497.4-14) COBISS: 1.01 ABSTRACT: Article gives a review of sea floods on Slovenian coast with emphasis on their formation, extent and consequences. Sea floods are occurring every year, but they vary in frequency and extent. Con-sequently, the damage caused by floods also varies. Sea floods rise with flood tides, strong south winds and drops in air pressure. They are more frequent in autumn and winter, but they occur in spring too. The article presents a complete review of sea floods from the beginning of measurements in Koper to pre-sent-day, an analysis of flooded regions and influence of climate changes on sea floods. KEY WORDS: sea, sea floods, flooded regions, hazard, coast, Slovenia. The article was submitted for publication on March 24, 2006. ADDRESS: Nata{a Kolega, B. Sc. Harpha sea, d. o. o. ^evljarska ulica 8, SI - 6000 Koper E-mail: natasa@harphasea.si Contents 1 Introduction 145 2 Methods 145 3 Causes of floods 145 3.1 Flood tides development impact factors 146 3.1.1 Wind and waves 146 3.1.2 Air pressure 146 3.1.3 Weather fronts 146 3.1.4 Coast shape 146 3.2 Sea level values during sea floods 147 4 Some data about floods between years 1963 and 2003 147 4.1 Flood and storm between 3rd and 5th November, 1966 147 4.2 Floods between 25th and 26th November 1969 147 4.3 Floods in years 1979, 1980 and 1982 148 5 Statistical analysis of sea flood data between years 1963 and 2003 148 6 Mapping of flood areas on the Slovenian coast 149 6.1 The surface of flood areas during extreme and yearly floods 149 6.2 Description of flood areas 150 6.2.1 Ankaran 150 6.2.2 Koper 153 6.2.3 Izola 153 6.2.4 Strunjan and Fiesa 153 6.2.5 Piran 153 6.2.6 Portoro` 154 6.2.7 Lucija 154 6.2.8 Se~a and Se~ovlje 154 6.3 Number of residents in exposed areas 154 6.4 Building plans in flooding areas 155 6.5 Influence of global warming on sea flooding 155 6.5.1 Analysis of map of flooding area, on eventual rise of sea level by 50 cm, because of global worming 155 7 Conclusion 156 8 References 157 144 Acta geographica Slovenica, 46-2, 2006 1 Introduction Sea floods are often on Slovenian coast. Their extent and inflicted damage are usually not large, but they pose a significant financial cost on some occasions. Sea floods happen because of flood tides, which are caused by some meteorological factors in com-bination with hydrological factors. There is a marked influence of strong south winds and drops in air pressure. Sea floods are most frequent in autumn and rather rare in spring. Systematic tide measurements begun in 1958, but the data are available only since 1963. They give us the opportunity for detailed analysis of sea floods and inflicted damage with the support of statistical met-hods. Using above mentioned data, observation and mapping methods, we made two maps of flooded regions. 2 Methods The main theoretical method used was a review of literature, consisting of articles about individual floods in the past, and records from measurements of a mareograph at a custom pier in Koper between 1963 and 2003. We used verbal sources (accounts by tenants of flooded areas) as well. Mapping of the flooded areas was made by analyzing less accurate older maps of flooded areas, a digi-tal relief model and verbal sources of people remembering the extent of particular floods in the past. Map of flooded area on Slovenian coast at extreme and yearly floods is based on digital aero photo »snaps«. Flooding areas where then determined by digitizin polygons, using the 25 by 25 metres digital relief model of Slovenia, for regions that are 0.0 m, 1.0 m and 2.0 m above sea level. These polygons were then overlaid on digital aerial photos. With that, we formed closed areas of stated heights above sea lev-els. Since the digital relief model is based on grid of 25 meters, we could not determine narrow coast areas, where the height changes substantially in an area of 25 by 25 meters. An example of such area is Piran, where the height quickly changes from a plane to the top of flysch cliff. That is why flood areas were determined by observations and interviewing people who have experienced floods. With the use of digital relief model, there is one another impediment: the values of height above sea are integer numbers (in meters) only, so one can not determine areas with height of 30 cm above sea level. The map of flooded area if the sea level rises by 50 cm is based on digital relief model to give it more plastic illustration. Map scale is smaller than the one used in map of flooded area for present sea levels, because these are only predictions. Map shows the flooded areas at 50 cm sea level rise. The rise of sea level for 50 cm is a prediction of sea rise due to global warming for 21st century. The amp was calculated using maps of flooded area at extreme and yearly floods and digital relief model. 3 Causes of floods Main cause of sea floods on Slovenian coast are flood tides; however, there are other factors which determine height of tides, such as wind, undulation, air pressure, Moon gravity and tide type, weather fronts and coast shape. Tide height and timing of the flood tides can be accurately anticipated and so it is pos-sible to anticipate floods too. Tides are alternating rising and decreasing of sea level, caused by moon and sun gravity (Kunaver in ostali 1996). It propagates as a long wave, causing periodic changes in sea level. Its rising is denominated as high tide and its decreasing as low tide. They alternate in approximately 6 to 6 and a half hours. When moon rotates around Earth, it literally changes the shape of the planet. When moon crosses the local meridian (this moment is denominated as moon upper culmination), it attracts masses of water and the sea level rises. At the same time, on the other side of the earth, we have the same event, with lower amplitude; it is denominated moon lower culmination. When moon rises or sets, we have low tide. That is at 90 degrees east and west from longitude where the tide is high and the moon is attracting the sea. Tides are also affected by sun which is very far from earth, but represents a notable factor because of its great mass. Its influence is less than one half of that of the moons. 145 Nata{a Kolega, Slovenian coast sea floods risk Tide amplitude is highest at new and full moon, when the sun and moon are in conjunction or oppo-sition (sun, moon and earth are aligned) and their influences adds up. The tide on this position is denominated spring tide. The tides are weakest at waxing and waning moon, when earth - moon direction forms a right angle with earth - sun direction, because their influence subtracts. This is period of neap tide (Robi~ in Vrhovec 2002). Tide amplitude greatly differs around the world, from some centimeters to over 20 meters. Average daily amplitude in Koper is around 60 centimeters and can increase greatly with influence of other fac-tors. Maximal difference between high and low tide in Koper was 286 centimeters in th period 1955-1997 (Robi~ in Vrhovec 2002). 3.1 Flood tides development impact factors 3.1.1 Wind and waves The rise and fall of sea level depend on the direction and strength of the wind. The winds from the north cause drops in sea level along Slovenian coast, because they push the water from the north Adriatic to the south. A strong north-east wind is called bora. On the other hand, the winds from the south cause a rise of sea level. Such constant wind blowing from south-east without gusts is called jugo. It usually indica-tes imminent worsening of the weather. Blowing from the south Adriatic to the north, it pushes the water towards Bay of Trieste. It can also cause high waves. »… The rise of the sea level because of moderate and long-lasting south-east wind can amount to around 25 cm, but the sea level can arise also over half of meter during very strong south-east wind especially in the autumn and the first half of the winter…« (Bernot 1983, 50). The sea often floods the lower parts of the coast during high tides. The waves are also a consequence of the wind and they have very important role on sea floods. The waves of the south-east wind jugo can reach the height of few meters giving the flood a destructive for-ce. The structures along the coast are often destroyed or damaged during the floods that are accompanied by storm with strong south-east wind and high waves. 3.1.2 Air pressure Air pressure is the second atmospheric factor which affects rising of the sea level. It is actually related to the winds, but changing of air pressure itself also causes changes in sea level. The decrease of air pressure by 1 mb corresponds to the rising of sea level by 1 cm (Bernot 1993a) or even 1.5 cm (Robi~ 2004). The process also works in the opposite direction. The air pressure can drop by more than 20 mb per day during bad weather and south-east wind. This causes the rise of sea level by 20 cm. At the time when the sea is flooding, air pressure often reaches the values around 992 mb (for example in October 1982), what is much less than long time October average for Koper, which is 117.7mb (Bernot 1983). 3.1.3 Weather fronts Fronts are related to tides indirectly through air pressure and wind. Typical weather situation for days when the sea is flooding is the following: there is an area of extensive anticyclone above eastern or nort-hern Europe, while a cyclone is situated above Great Britain determining the weather in western Europe. The anticyclone above eastern Europe weakens and slowly moves towards the east while the cyclone above Great Britain deepens and moves towards central Europe. In the end the secondary core of a cyclone is formed south of the Alps in Genova Bay, which is moving towards east and reaches the Slovenian coast. This causes strong south-east winds in the Adriatic sea (Bernot 1983; 1993a; 1993b). 3.1.4 Coast shape Slovenian coast is a ria coast, a characteristic of which is that the major direction of the coast is perpen-dicular to geological structure. Also characteristic are long bays in sunken river valleys, between which long peninsulas extend far into the sea. Main coast shapes are costal plains in interior of the bays and steep cliffs on the peninsulas. 146 Acta geographica Slovenica, 46-2, 2006 Oscillation of the sea level is also affected by a resonant oscillation of the Adriatic sea, which appears in closed or half closed bays. The period of this oscillation is 21 hours (Robi~ 2004). In connection with coast shape, one should consider another factor, which by itself does not cause the rise of sea level; however, their effects unite and cause highest floods with grater flood area. Rising of the sea level and pushing the water from the entire Adriatic towards upper Adriatic blocks the mouths of the rivers in this area. The riverine water can not flow out normally and the rivers begin to flood the areas near the mouth of the river - the flood areas of the sea and the rivers join. 3.2 Sea level values during sea floods There are two ways to describe sea level. We can specify how much above or below the long term mean value is the current sea level. The mean value is then 0, high tides correspond to positive values (+) and low tides to negative values (-). Alternatively, we can specify the sea level relative to mareographic zero (0) on mareographic station in Koper. In this mode, all values are positive, because the value corresponding to the mean sea level values is 215 cm. The sea on Slovenian coast floods lowest parts of the coast when the sea level reaches 85 cm above the mean value or 300 cm above mareographic zero (Robi~ and Vrhovec 2002). The mean value of high tides between years 1958 and 1990 was 248 cm relative to mareographic zero, or 33 cm above long term mean value. The mean values for low tide in the same time period was 182 cm relative to mareographic zero, or -33 cm under long term mean value. The mean amplitude was 66 cm. The highest measured sea level was 394 cm or 179 cm above long term mean value, in 1969 (Mareographic station in Koper 1969). 4 Some data about floods between years 1963 and 2003 Between 1963 and 2003, when data from mareographic station in Koper is available, some major floods occurred. 4.1 Flood and storm between 3rd and 5th November, 1966 Sea level has reached the highest point on the 4th of November at 8 pm and that was 352 cm (Mareographic station in Koper 1966). At that point, there was approximately half meter of water on the Tartini square in Piran. Storm and high sea level inflicted a considerable damage, mostly in Piran where there are several buil-dings directly exposed to the sea. The coast walls in Piran were badly shaken and sapped, heavy damage was inflicted upon the coffee shop Tartini in the building of theater (today's Caffe Teater), the bus station office, restaurant Riviera, baths near entrance to the city, restaurant of Hotel Piran and many private garages. A num-ber of cars were smashed. The road between Piran and Lucija was closed for traffic during the whole day, and much damage was inflicted to other parts of Slovenian coast too (Primorske novice 1996). Wooden piers on the beach of Portoro` were destroyed, cabin doors were broken, approximately 50 wagons of very fine sand were swept away from the beach and many small boats were torn away from anchorage (Titl 1983). 4.2 Floods between 25th and 26th November 1969 During 25th and 26th of November in 1969, the sea flooded the entire Slovenian coast. In Koper water was 94 cm high. Coast road from Koper to Se~ovlje was flooded in several places and all sections towards Izola, Portoro` and Piran as well. The storm inflicted a great deal of damage to cars parked on Tartini square in Piran, because they were submerged in nearly one meter of sea water. Some of them were even smashed against the walls by gusts of wind. Along with the lower parts of Koper, most of Bonifika and its elementary school was flooded (Titl 1983). This was the largest flood in the period studied, and it inflicted most damage. 147 Nata{a Kolega, Slovenian coast sea floods risk 4.3 Floods in years 1979, 1980 and 1982 On December 22,1979, the level of the sea reached 356 cm. The then-named JLA road (today's Forna~e and Dante Street) was submerged in up to 60 cm of water. In Piran, Tartini Square and its surroundings were flooded too. The sea passed over the protection bags placed near the crossroads beside Slavnik in Koper and flooded Bonifika. It flooded offices of Splo{na banka Koper (today's Banka Koper) and the mar-ket place too (Primorske novice 1979). On October 25,1980, the sea level reached 361 cm which is the second highest value in the studied period. Most salt water was again on former JLA road (today's Forna~e) in Piran, on Ukmar square in Koper and on Semedelska road. Many cars where flooded on the parking lot of the Triglav hotel in Koper. Damage was limited because the flood was not accompanied by strong southeast wind (Primorske novice 1980). The sea once more reached a height of 361 cm on December 6 and 7,1982. Most affected was Piran and area between Piran and the salt-pans of Se~ovlje. Dikes in salt-pans were demolished and the salt-pans were devastated. Much damage was inflicted to plant Za~imba of the Droga factory in Se~a too. In Izola and Koper, the damage was limited to flooded cars (Titl 1983). 5 Statistical analysis of sea flood data between years 1963 and 2003 In this forty-one year period, the sea level has reached the flooding point of 300 cm or more for 299 times. The mean sea level during floods was 309 cm. The highest measured sea level in studied period was 394 cm, which is an extreme, because such high levels were not usual. On average, there were 7.3 floods per year. The annual number of floods varies from year to year and so do the highest reached sea levels. The two phenomena are not closely related, because there are years with a small number of floods and low sea levels, as well as years with small number of floods but high sea levels reached. In a similar way, we can not expect high sea levels just because of a large number of floods during that year. 400 390 380 370 360 350 340- 330 320 310 300 average number of floods per year / povpre~no {tevilo poplav na leto average sea level / povpre~na vi{ina morja leta 18 16 14 12 10 8 6 4 ¦ 2 0 sea level / vi{ina morja ¦ number of floods / {tevilo poplav Figure 1: The highest sea levels and the number of floods per year between 1963 and 2003. 148 Acta geographica Slovenica, 46-2, 2006 Figure 2: »Z values« of highest sea levels & »z values« of number of floods per year. If we observe only the reached levels during the floods, we can notice a visible trend (Figure 1). For few years, levels are relatively high, followed by a few years with relatively low levels. The series than repeats. From figure 1 it is possible to see three such periods with high levels reached and between them, two peri-ods with lower levels. The number of floods during a year follows a similar cycle. In the last decade, an increase in the number of floods during the year is visible; however, these floods do not reach high levels. We calculated Pearson's correlation from the data on number of floods per year and the highest sea levels per year. Obtained correlation is low, 0.247, which means that the accounted variance is 0.061, or that we can explain only approximately 6% of the highest sea levels with the number of floods per year. This is the con-sequence of the fact that with the Pearson correlation we can calculate only linear correlations. If we interpolate the »z values« with a 6th order polynomial, we can see that the phenomena are correlated. We see (Figure 2) that the curves are correlated. To confirm that, we correlated signs of its derivative, which tells us in how many cases the curves increase or decrease together. We noticed that 90% of values correlate in common increasing or decreasing. We can assume that the relation between phenomena exists, but we can not pro-ve it with Pearson's correlation, because it presumes linear correlation, which is here obviously not the case. Then we tried to extrapolate the data from which we eliminated the edge values, which are excessi-vely deviated (values before 1966 and after 1990). If we calculate Pearson's correlation with only this data, the result is 0,551. The accounted variance is 0,301, so about 30% of highest sea levels can be explained with the number of floods. Because the sample size and statistical significance are very low, this value of explained variance means that we can only suspect the existence of a connection between highest sea levels and number of floods between years 1966 and 1990. Floods are very characteristic of autumn-winter period, from October to January and they are most frequent in November. Figure 3 represents number of floods per month. The floods are also frequent in spring, but very rare in the summer. The reason for such distribution is particularly in higher frequency of Genova cyclone at that time of the year. 6 Mapping of flood areas on the Slovenian coast 6.1 The surface of flood areas during extreme and yearly floods Extreme floods reach or exceed the 394 cm level, which is the highest level the sea has reached between years 1963 and 2003. For the already mentioned flood that occurred on November 26,1969, less accurate maps have already been drawn by Julij Titl in 1983 (Titl 1983). These maps were used for a more precise delimitation of flood areas. The value 394 cm almost exactly corresponds to the value of 2 m altitude on the digital relief model. Geodetic height 0 thus corresponds to a value of 200 cm on mareographic station in Koper and is represented as height 149 Nata{a Kolega, Slovenian coast sea floods risk > 80 -Sh 70 L 60 -o 50 S 40 Jd 30 fi 20 10 m n I. II. III. IV. V. VI. VII. VIII. IX. X. XI. XII. months / meseci Figure 3: The number of floods per month between years 1963 and 2003. 0 in the digital relief model. Consequently, the value of 1 m on digital relief model corresponds to 300 cm and the value of 2 m corresponds to 400 cm, which is only 6 cm higher than the highest recorded sea level, 394 cm. Many people still remember extent of the mentioned flood vividly - especially in Piran, and their recol-lections were taken into account during the elaboration of map. The second datum represented on the map is flood area during more frequent, yearly floods at level 330 cm or 30 cm above flooding point. For delimitation of corresponding flood area, proper observations of terrain were used, along with multiple observations of floods of this kind of extension in past years. Flood area is the largest in the municipality of Piran, particularly because of the biggest flood sur-face - salt-pans of Se~ovlje. The smallest flood area is in the municipality of Izola. Flood area of yearly floods represents 26.85% of flood area during extreme floods. Table 1: Surface of flood areas during extreme and yearly sea floods. Area Surface in km2 Flood area during extreme floods Municipality of Koper Municipality of Izola Municipality of Piran All three municipalities together 6.12 0.20 7.71 14.04 Flood area during yearly floods Municipality of Koper Municipality of Izola Municipality of Piran All three municipalities together 0.25 0.03 3.48 3.77 6.2 Description of flood areas 6.2.1 Ankaran There are several separated flood areas of different sizes in the Ankaran region. There are flooded areas near the Lazaret border crossing and the gas station near it during extreme floods. Beyond these two buil-dings no other buildings are threatened. During yearly floods, only a narrow coastal part is flooded. 150 Acta geographica Slovenica, 46-2, 2006 11 I i! P Figure 4: Flood areas on Slovenian coast, during yearly and extreme floods. 151 Nata{a Kolega, Slovenian coast sea floods risk Figure 5: Enlarged section of the above map, representing Piran and its surroundings. 152 Acta geographica Slovenica, 46-2, 2006 Approximately 500 m west of the border crossing, there is a beach with a few buildings, which would be under water during extreme floods. The beach in front of the youth health resort and the so called »Gradis« beach would be flooded as well - but no buildings would be endangered. The next beach to consider is the one in front of the Orthopaedic hospital Valdoltra, where the terrain is lower. The area from here on to the Port of Koper would be under water. In this area, there are a few sections where the extreme floods could cause substantial damage. The autocamp Adria with its buildings is the most problematic -half of it would be flooded during extreme floods. Near Sveta Katarina, during extreme floods, the small port and few nearby buildings would be flooded. Yearly floods in the area of Ankaran do not pose seri-ous threats. 6.2.2 Koper In Koper and its neighborhood, there is a number of areas that would be flooded during extreme floods. Port of Koper would be, because of its location, almost entirely under water. This could cause serious material damage. The water would overflow almost to Srmin. During yearly floods, only the lowest parts of the Port of Koper are flooded, and that doesn't cause serious problems. During extreme floods, the regions flooded would include Bonifika, part of large inhabited areas Olmo and [alara near the Bada{evica river. In the old town of Koper, Marina Koper, Ukmar's square, part of Carpaccio's square, Pristani{ka street, Ljubljanska street and Bonifika would be under water during extreme floods. In the old city center, seve-ral houses would be under water. During yearly floods, Semedelska street, part of the marina and the coast area near the harbour would be flooded. Residential buildings are not in danger. The area towards @usterna with the parking place and the beach would be under water as well as the main road between Koper and Izola during extreme floods. Only the beach is flooded during yearly floods. 6.2.3 Izola In the area of Izola almost the entire autocamp Jadranka would be flooded during extreme floods. During yearly floods, only its lower coastal part is affected. The bigger part of shipbuilding yard of Izola would also be flooded during strong and extreme floods, which would likely cause high material damage. The beach west from shipbuilding yard and a small penin-sula with the lighthouse would also be flooded. Large parts of the town Izola itself would also be flooded: near the harbour, Big square, Manizioli's sqare and the entire part to Ljubljanska street and Gorki's street. The water would also cover the marina with its buildings and the area near Simonov zaliv (Simon's Bay), in addition to quite a few residential buildings, especially in old city center. During yearly floods, only a narrow part of the coast and very few residential buildings would be flooded - mainly those on the Veliki trg (Big Square), and maybe the area near marina. 6.2.4 Strunjan and Fiesa The beach and salt-pans are usualy under water during yearly floods. During extreme events this extends to the area near the stream of Strunjan - the neighborhood of the main crossroads. A few houses in the vicinity would also be affected. Beside this the sea also overflows the beach in front of the tourist resort Salinera, especially during extreme floods. In Fiesa, the beach is usually flooded; during extreme floods, the meadow by the lake is under water as well. The buildings are not endangered. 6.2.5 Piran Floods pose the greatest threat to Piran. Also in the past, they have caused the worst damage there. A big part of the old city centre would be flooded during extreme floods. Water would overflow along entire coast around the cape Madona to Ressel's street and the beginning of Gregor~i~'s street (behind the former Punta hotel) and then to lower part of the Square of 1st May and Verdi's street. The entire Tartini's square and 153 Nata{a Kolega, Slovenian coast sea floods risk the area up to Ulica Svobode and Tom{i~'s street would be under water. Also flooded would be the Dante's street and entire Forna~e. Quite a few houses would be flooded and material damage would be high. During yearly floods in Piran, the areas under water are Kidri~'s and Pre{eren's quays, Tartini's squa-re and a part of Cankar's quay with the harbour. Out of the city, only a narrow costal part would be flooded. In contrast to other places, a few houses in Piran are flooded even during yearly floods, especially along Pre{eren's and Kidri~'s quays. 6.2.6 Portoro` In Bernardin, the areas under water, especially during extreme floods, would include the beach in front of Grand hotel Bernardin and the beach and a small harbour near hotel Histrion. Also flooded would be main Bernardin's beach and sailing club Pirat, where a few buildings, including the boathouse of the Faculty for Maritime Studies and Transport would be under water during extreme floods. Additionally, the so called »Students beach« would be flooded during extreme floods and the coast in front of salt storehouses as well. In Portoro`, the beaches would be flooded - the one in front of hotel Riviera and main Portoro`'s beach. Beside this, the pier and the coast between mentioned beaches would also be flooded. Buildings in Portoro` would not be flooded - not even in case of extreme floods, because they are elevated a little bit. 6.2.7 Lucija In Lucija, quite a large part of the surface would be flooded during extreme floods. Those regions would include the entire marina Portoro` and the water would overflow the go-kart track and health centre. Also flooded would be a part of Obala street and Ukmar's street. Along stream Fazan, the water would overf-low all the way to Fazan and Fazanska street. In case of extreme floods, many of residential and other buildings would be flooded, causing considerable material damage. The main Lucija's beach and a narrow part of quay near the canal at the mouth of the Fazan stream which serves as a mooring place for small boats, are flooded during yearly and extreme floods. The beach and a smaller part of autocamp Lucija would be flooded during extreme floods. The lar-ger part of camping area would not be under water because it is sufficiently elevated. Yearly floods in Lucija do not cause serious problems because flooded areas are mostly beaches and narrow coastal parts. 6.2.8 Se~a and Se~ovlje The largest sea flood area on the Slovenian coast is in Se~a and Se~ovlje. The Se~ovlje's salt-pans are in large part flooded even during yearly floods. Tthe salt-pans would be almost entirely under water during extreme flood. The water would overflow also the lower part of the valley blocking the Drnica river. Thus a part of the Se~ovlje settlement with cultivable ground in its surroundings would be flooded. Also, a part of the Portoro` Airport and few nearby houses would be endangered. The sea could also cover former Droga's plant Za~imba in Saint Jernej in Se~a, causing high material damage during extreme floods. Almost the entire road along the canal of St. Jernej is under water during yearly floods, and in case of extreme floods, water would also cover the small shipbuilding yard and parking lot near the Ribi~ restau-rant. Luckily, the majority of residential buildings in the area are not endangered because of their high elevation. 6.3 Number of residents in exposed areas Many inhabitants live in flooding areas. Yearly floods endanger 22 residents of Piran. In other places, the-re are no residential buildings which are flooded every year. All three municipalities together have 87,846 inhabitants. Municipality Koper is 47,539 inhabitants, municipality Izola 14,549 inhabitants and municipality Piran 16,758 of that 4143 are inhabitants of the town of Piran (Census of population 2002). 154 Acta geographica Slovenica, 46-2, 2006 In case of extreme floods, 2007 people would be endangered in the three municipalities combined; mostly in municipality of Piran (1262), then municipality of Koper (427) and municipality of Izola (318). About 2.54% of residents in all three municipalities are in danger, in municipality Piran alone there are 7.53% of people exposed to floods, while there are 18.75% of residents exposed to floods in the town itself We can conclude that in the case of extreme floods difficult situations may arise because of considerab-le number of residents. Also supply, traffic, sojourna and other activities would be affected, especially in Piran. 6.4 Building plans in flooding areas In the coastal communities building plans have been approved allowing builidng on flooding areas. In the community of Koper those are the building of a new elementary school, fire brigade house and pub-lic heath center in Bonifika, Economic zone Sermin and 3rd pier of the port of Koper. In the community of Izola, they plan to build the Argolina tourist-business-residential complex and another tourist complex in the vicinity of Simon's bay. In the community of Piran, plans include widening of the runway of the Portoro` Airport, a buili-ding of a golf course in the vicinity of Se~ovlje and an extensive settlement plan for the Se~a peninsula, which touches the borders of two major flooding areas - the salt-pans and the tract near canal of Saint Jernej. There are also plans to build a new marina, many villas, hotels and other facilities. Just a few of the largest plans have been listed; there are many smaller plans, some of them being even more exposed to sea floods. 6.5 Influence of global warming on sea flooding Scientists have been predicting that one of biggest global warming effects would be the rise of sea level. It will rise because of expansion of heated water, melting of glaciers and icebergs around the Earth poles. By com-parison with today's sea level, it would rise for about 22 cm by 2050 and for about 50 cm by 2100 (Plut 1998). That is why we prepared a map the flooded areas due to eventual rise of sea level because of global warming. We assumed the 50 cm rise, which is the prognosis for 21st century. If the medium sea level will be 0.5 m higher in the future, then every slightly stronger high tide would cause flooding. If we add 50 cm to the current average high tide we get the height 298 cm which is very near the todays flooding point. Taking into account the fact that high tides have an average height of 33 cm, we can conclude that floods would be very frequent - they woulda appear even several times a month. Average flood height, calculated from current values, would be rather high, reaching the level of today's extreme floods - 359 cm. In the case of extreme floods, the sea would submerge the lowest parts of the coast by about 1.5 m (444cm). Table 2: Calculation of sea heights for predicted rise of 50 cm. Height of sea level today, in cm Height of sea level if the level rises for 50 cm, in cm Average sea level 215 265 Flooding point 300 300 Average high tide 1963-2003 248 298 Average low tide 1963-2003 182 232 Extreme sea level 1963-2003 394 444 Average flood 1963-2003 309 359 Yearly flood 1963-2003 330 380 6.5.1 Analysis of map of flooding area, on eventual rise of sea level by 50 cm, because of global worming The territory flooded by yearly floods in the case of 50 cm sea level rise is comparable to the territory flooded today by extreme floods. It occupies about 14 km2, which is about 3% of the total area of all three coastal municipalities. However in the case of sea level rise for 50 cm, the flooded areas would probably 155 Nata{a Kolega, Slovenian coast sea floods risk PRAN f~ ^-- m^ S^X | yearly floods/vsakoletne poplave | extreme floods/izjemne poplave Author / Avtor: Nata{a Kolega Source/Vir: DMR 25, GURS 2000 1:300.000 Figure 6: Map of flooding area, on eventual rise of sea level by 50cm, because of global warming. be somewhat less extensive, because the sea level would be about 14 cm lower than current extreme floods (table 2). Same comparison could be made about the number of endangered people. We can deduce that yearly floods, in the case of 50 cm rise of sea level, would endanger over 1000 people. The biggest flooded areas would be in the region of Koper's and Ankaran's Bonifika. The Port of Koper would have big difficulties in performing its activities. Flooded areas would be significantly larger in Izola too. They would be somewhat larger in Strunjan and Piran also. The flooded areas would dramatically increase in Lucija and in the territory of Se~ovlje, which would cause particular difficulties to Airport of Portoro`. 7 Conclusion The damage caused by stronger floods is differing from year to year, but the altitude of the flood sea level approximately corresponds to the material damage caused by floods. The map of flood areas during extre-me and yearly floods relatively well illustrates threats to the Slovenian coast. It would be necessary to monitor floods for several years and mapping the extensions of each particular flooding event on-site for making more precise maps of flood areas, which could be used for spatial planning. A great number of inhabitants would be endangered particularly during extreme floods, which is troub-lesome in various aspects. Slovenian coast is quite attractive for new buildings, tourist and other similar activities - as demonstrated by quite high density of population and buildings. Local and other authori-ties, judging from existing building plans, do not sufficiently realize the dangers to the area. From this we can conclude that the damage in case of extreme floods would be much higher than it was in the past. The town most at risk is Piran, because of its position exposed to high tides and south-east-wind. A lot 156 Acta geographica Slovenica, 46-2, 2006 of buildings in the town are directly on the coast, which is relatively low. During extreme floods a great part of the old city, where almost one fifth of inhabitants live, would be flooded. Until now, the floods have caused the worst damage just in Piran. Beside the points mentioned, there is a new threat - the rise of a sea level because of global warming. The scientists predict that it can rise for half a meter by the end of the century. That could dramatically change the extent of floods on the Slovenian coast. The flood area would become much wider and the floods more frequent because every tide just a few centimeters above average would cause flooding. As a result, quite a number of inhabitants would be in danger. The problem may become pretty serious and resolving it would become a task for the state. For now, this are only predictions, for which we do not know if they will come true and, if they will, to what extent. A reasonable approach would be to take the above mentioned statements into consideration and use them in the management of this area, taking action already at first signs of the problem. This way, we could be prepared with adequate plans by the time of its full occurrence. 8 References Agregirani podatki o {tevilu prebivalcev, Geografski in{titut Antona Melika ZRC SAZU, 2004. Ljubljana. Bernot, F. 1983: Vzroki in pogostost poplav ob slovenski obali. Naravne nesre~e kot na{a ogro`enost. Ljubljana. Bernot, F. 1993a: Poplave ob slovenski obali. Ujma 7. Ljubljana. Bernot, F. 1993b: Visoka plima ob slovenski obali 8. decembra 1992. Geografski vestnik 65. Ljubljana. Kunaver, J., Drobnjak, B., Klemen~i~, M. M., Lovren~ak, F, Lu`evi~, M., Pak, M., Senega~nik, J., Buser, S. 1996: Ob~a geografija. Ljubljana. Morje je prestopilo bregove. Primorske novice, {t. 53, 28.12.1979. Koper. Mareographic station in Koper: Data from Mareographic station in Koper for the period 1963-2003. Koper. Plut, D. 1998: Varstvo geografskega okolja. Ljubljana. Razdejana obala. Primorske novice, {t. 46, 12.11.1966. Koper. Robi~, M. 2004: Visoke plime v letih 2002 in 2003. Ujma 17-18. Ljubljana. Robi~, M., Vrhovec, T. 2002: Poplavljanje morske obale. Naravne nesre~e in varstvo pred njimi. Ljubljana. Titl, J. 1983: Obmo~ja morskih poplav v Koprskem Primorju. Naravne nesre~e kot na{a ogro`enost. Ljubljana. Tudi slana poplava. Primorske novice, {t. 83, 28.12.1980. Koper. 157 Nata{a Kolega, Ogro`enost slovenske obale zaradi morskih poplav Ogro`enost slovenske obale zaradi morskih poplav UDK: 556.166(497.4-14) COBISS: 1.01 IZVLE^EK: ^lanek podaja pregled poplav morja na slovenski obali s poudarkom na njihovem nastanku, obsegu, ki ga lahko dose`ejo, in posledicami. Poplave morja so med vsakoletnimi naravnimi nesre~ami v Sloveniji, vendar se iz leta v leto njihova pogostost in obseg spreminjata. Prav tako se spreminja tudi materialna {koda, ki jo povzro~ijo. Vzrok za nastanek so predvsem visoka plima, mo~an ju`ni veter in padanje zra~nega pritiska. Pogostej{e so jeseni in pozimi ter nekoliko manj tudi spomladi. V ~lanku so prikazani: pregled poplav od za~etka meritev v Kopru, do dana{njih dni, zemljevidi poplavnih obmo~ij in njihova analiza ter vpliv podnebnih sprememb. KLJU^NE BESEDE: morje, poplave morja, poplavna obmo~ja, ogro`enost, obala, Slovenija. Uredni{tvo je prejelo prispevek 24. marca 2006. NASLOV: Nata{a Kolega, univ. dipl. geogr. Harpha sea, d. o. o. Koper ^evljarska ulica 8, SI - 6000 Koper E-po{ta: natasa@harphasea.si Vsebina 1 Uvod 159 2 Metode dela 159 3 Vzroki poplav 159 3.1 Dejavniki, ki vplivajo na nastanek mo~nej{ih plim 160 3.1.1 Veter in valovanje 160 3.1.2 Zra~ni pritisk 160 3.1.3 Vremenske fronte 160 3.1.4 Reliefne oblike obale 161 3.2 Vi{ina morja ob poplavah 161 4 Nekaj podatkov o mo~nej{ih poplavah morja med leti 1963 in 2003 161 4.1 Poplava in neurje od 3. do 5. novembra 1966 161 4.2 Poplave 25. in 26. novembra 1969 162 4.3 Poplave v letih 1979, 1980 in 1982 162 5 Statisti~na obdelava podatkov o poplavah morja v letih 1963 do 2003 162 6 Kartiranje poplavnih obmo~ij na slovenski obali 163 6.1 Povr{ina poplavnega obmo~ja ob izjemnih in vsakoletnih poplavah morja 163 6.2 Opis poplavnih povr{in 164 6.2.1 Ankaran 164 6.2.2 Koper 164 6.2.3 Izola 164 6.2.4 Strunjan in Fiesa 164 6.2.5 Piran 164 6.2.6 Portoro` 165 6.2.7 Lucija 165 6.2.8 Se~a in Se~ovlje 165 6.3 [tevilo prebivalcev na ogro`enih obmo~jih 165 6.4 Zazidalni na~rti za poplavna obmo~ja 166 6.5 Vpliv globalnega segrevanja ozra~ja na poplave morja 166 6.5.1 Analiza zemljevida poplavnega obmo~ja ob morebitnem dvigu morske gladine (za 50 cm) zaradi globalnega segrevanja ozra~ja 166 7 Sklep 167 8 Viri in literatura 167 158 Acta geographica Slovenica, 46-2, 2006 1 Uvod Ena izmed naravnih nesre~, ki pogosto prizadenejo Slovenijo, so poplave morja. Njihova razse`nost in povzro~ena {koda ponavadi nista posebno veliki, vendar ob posameznih dogodkih vrednost materialne {kode naraste. Do poplav morja pride zaradi nadpovpre~no visoke plime, ki jo povzro~ijo dolo~eni meteorolo{ki dejavniki v kombinaciji s hidrolo{kimi dejavniki. Poseben vpliv imajo predvsem mo~an ju`ni veter in nizek zra~ni pritisk. Poplave morja so najpogostej{e jesenski, najmanj pa spomladi. Sistemati~no merjenje vi{ine gladine morja se je pri nas za~elo leta 1958, vendar pa so podatki na razpolago {ele od leta 1963 dalje. Omogo~ajo podrobnej{i pregled poplav in nastale {kode ter statisti~no analizo podatkov. S kartiranjem, opazovanjem in uporabo prej omenjenih podatkov smo naredili tudi dva zemljevida poplavnih obmo~ij. 2 Metode Osnovna teoretska metoda je bila pregled literature, ki jo sestavljajo predvsem ~lanki o posameznih poplavah v preteklosti in izpis meritev mareografa na carinskem pomolu v Kopru med leti 1963 in 2003. Poleg literature smo uporabili {e ustne vire nekaterih stanovalcev poplavnega obmo~ja. Poplavna obmo~ja smo tudi kartirali. Pri tem smo si pomagali s starej{imi in manj natan~nimi zemljevidi poplavnih obmo~ij, digitalnim modelom reliefa, opazovanjem in izjavami ljudi, ki se spominjajo obsega posameznih poplav. Podlaga zemljevida poplavnega obmo~ja na slovenski obali ob izjemnih in vsakoletnih poplavah so digitalni ortofoti posnetki. Obmo~ja poplav smo dolo~ili s pomo~jo ve~ dejavnikov. Iz digitalnega modela reliefa Slovenije, ki je narejen na mre`i 25 krat 25 metrov, smo izdelali poligone za obmo~ja z nadmorskimi vi{inami 0,0 m, 1 m in 2 m. Poligone smo nato polo`ili na digitalne ortofoto posnetke in tako doblili zaklju~ena obmo~ja. Ker pa je digitalni model reliefa narejen na osnovi to~k, ki so med seboj oddaljene 25 metrov, tako ni bilo mogo~e dolo~iti o`jih obalnih obmo~ij, kjer se nadmorska vi{ina bistveno spremeni na kratko razdaljo. Tak primer je Piran, kjer se nadmorska vi{ina zelo hitro spremeni od obalne ravnice do vrha fli{nega klifa. Zato so na tak{nih obmo~jih poligonske datoteke iz digitalnega modela reliefa slu`ile le kot opora za delo na terenu oziroma za orientacijo, dejansko poplavno obmo~je pa smo dolo~ili z opazovanjem na terenu in pri~evanji ljudi. Digitalni model reliefa ima {e eno pomanjkljivost za dolo~anje poplavnega obmo~ja. Vrednosti nadmorske vi{ine so le cela {tevila, tako se na primer ne da omejiti obmo~ja z nadmorsko vi{ino 30 cm. Podlaga zemljevida poplavnega obmo~ja ob morebitnem dvigu morske gladine za 50 cm je digitalni model reliefa, da je ponazoritev bolj plasti~na. Merilo zemljevida je manj{e, kot pri zemljevidu poplavnega obmo~ja pri sedanjih vi{inah morja, saj gre le za predvidevanja. Zemljevid prikazuje poplavljena obmo~ja ob dvigu gladine morja za 50 cm. Tak{en dvig predvidevamo v 21. stoletju zaradi segrevanja ozra~ja. Izdelan je s pomo~jo zemljevida poplavnega obmo~ja ob izjemnih in vsakoletnih poplavah in digitalnega modela reliefa. 3 Vzroki poplav Temeljni pogoj za poplave morja na slovenski obali je visoka plima, vendar nanjo vplivajo {e drugi dejavniki, kot so veter, valovanje, zra~ni pritisk, gravitacijska privla~nost Lune oziroma tip plime, vremenske fronte in reliefna izoblikovanost obale. Vi{ino plime in oseke ter ~as njunega izmenjavanja lahko vnaprej natan~no predvidimo, zato lahko ob upo{tevanju prej na{tetih dejavnikov predvidimo tudi poplave. Plimovanje je izmeni~no dvigovanje in upadanje morske gladine, povzro~eno s privla~no silo Lune in Sonca (Kunaver et al. 1996). [iri se v obliki dolgih valov, ki povzro~ajo periodi~no nihanje gladine. Njeno dvigovanje imenujemo plima, njeno upadanje pa oseka. Izmenjavata se na pribli`no 6 ur do 6 ur in 30 minut. Ko Luna potuje okoli Zemlje s svojo privla~no silo dobesedno spreminja obliko planeta. Ko Luna prekora~i krajevni poldnevnik, kar imenujemo Lunina zgornja kulminacija, privla~i vodne gmote in te se 159 Nata{a Kolega, Ogro`enost slovenske obale zaradi morskih poplav dvignejo. Hkrati se enako dogaja na nasprotni strani Zemlje, kjer nastopa Lunina spodnja kulminacija, le da je tam amplituda plimovanja nekoliko {ibkej{a. V ~asu vzhajanja in zahajanja Lune se pojavi oseka, torej 90 stopinj vzhodno in zahodno od geografske dol`ine, kjer nastopa plima, saj od tam privla~na sila Lune vodo »privle~e« k sebi. Na plimovanje vpliva tudi Sonce, ki je sicer od Zemlje zelo oddaljeno, vendar ima tako veliko maso, da je njegova privla~na sila tudi pomemben dejavnik pri plimovanju. Njegov vpliv je pribli`no enak slabi polovici Luninega vpliva. Plimovanje je najizrazitej{e ob mlaju in {~ipu, ko sta Sonce in Luna v konjunkciji oziroma opoziciji (Sonce, Luna in Zemlja so na ena premici) in se plimotvorni vplivi se{tevajo. Ta polo`aj imenujemo sizi-gij, plimo pa sizigialna plima. Ob prvem in zadnjem krajcu, ko je Luna pravokotno na smer Zemlja-Sonce, je plimovanje naj{ibkej{e, saj se vplivi od{tevajo. To imenujemo obdobje kvadrature oziroma kvadratur-na plima (Robi~ in Vrhovec 2002). Amplituda plimovanja je po svetu zelo razli~na, od nekaj centimetrov do prek 20 metrov. Povpre~-na dnevna amplituda v Kopru zna{a okrog 60 centimetrov in se ob vplivu drugih dejavnikov lahko zelo pove~a. Razlika med najvi{jo in najni`jo gladino morja je v Kopru v letih 1955-1997 zna{ala 286 centimetrov (Robi~ in Vrhovec 2002). 3.1 Dejavniki, ki vplivajo na nastanek mo~nej{ih plim 3.1.1 Veter in valovanje Dviganje in zni`evanje gladine sta zelo odvisna od smeri in jakosti vetra. Ob slovenski obali vetrovi s severnega kvadranta ni`ajo vodno gladino, saj vodo s severnega Jadrana odrivajo proti jugu. Tak veter je burja, ki piha s severovzhoda. Vetrovi z ju`nega kvadranta pa vi{ajo gladino vode. Tak zelo pogost veter je jugo, ki piha z jugovzhodne smeri, enakomerno, brez sunkov in obi~ajno ka`e na poslab{anje vremena. Ker piha z ju`nega Jadrana proti severu, nariva vodo proti Tr`a{kemu zalivu in lahko povzro~a velike valove. »… Porast vodne gladine zaradi zmernega in dolgotrajnega juga lahko zna{a okoli 25 cm, medtem ko se ob zelo mo~nem jugu, zlasti jeseni ali v prvi polovici zime, gladina morja lahko dvigne tudi preko pol metra…« (Bernot 1983, 50). Tako dvignjena gladina morja ob plimi pogosto poplavlja ni`je le`e~e dele obale. Valovi so tudi posledica vetra in imajo pri poplavah morja zelo pomembno vlogo. Valovi juga so lahko visoki tudi nekaj metrov in s tem dajo poplavi {e ru{ilno mo~. Ob poplavah, ki jih spremljajo neurje z mo~nim vetrom in visoki valovi, so pogosto po{kodovani ali uni~eni objekti neposredno ob obali. 3.1.2 Zra~ni pritisk Drugi atmosferski dejavnik, ki vpliva na zvi{evanje gladine morja, je zra~ni pritisk, ki je sicer povezan z vetrom, vendar `e spreminjanje zra~nega pritiska samega po sebi povzro~a spremembe v vi{ini gladine morja. Zni`anje zra~nega pritiska za 1 mb ustreza zvi{anju gladine za 1 cm (Bernot 1993a) ali celo 1,5 cm (Robi~ 2004). Proces deluje tudi v drugo smer. Ob slabem vremenu in jugu, za katerega je zna~ilen nizek zra~ni pritisk, lahko le-ta pade tudi za ve~ kot 20 mb na dan, kar povzro~i dvig morske gladine za 20 cm. V ~asu, ko morje poplavlja, zra~ni pritisk pogosto dose`e vrednosti okoli 992 mb (na primer oktobra 1982), kar je precej manj od dolgoletnega oktobrskega povpre~ja za Koper, ki zna{a 117,7mb (Bernot 1983). 3.1.3 Vremenske fronte Vremenske fronte so s plimovanjem povezane posredno prek zra~nega pritiska in vetra. Tipi~na vremenska slika za dneve, ko morje na slovenski obali poplavlja, je slede~a: nad vzhodno ali severno Evropo je obmo~je obse`nega anticiklona, nad Britanskim oto~jem pa se zadr`uje ciklon, ki dolo~a vreme v zahodni Evropi. Anticiklon nad vzhodno Evropo za~ne slabeti in se pomikati proti vzhodu, ciklon iznad Britanskega oto~ja pa se {e poglablja in premika proti srednji Evropi. Ju`no od Alp se v Genovskem zalivu oblikuje sekundarno jedro ciklona, ki se nato pomika proti vzhodu in zajame na{e kraje. Pri tem na Jadranu pihajo mo~ni ju`ni vetrovi (Bernot 1983; 1993a; 1993b). 160 Acta geographica Slovenica, 46-2, 2006 3.1.4 Reliefne oblike obale Slovenska obala sodi med obale ria{kega tipa, za katere velja, da je glavna smer obale pre~na na geolo{-ko zgradbo. Zanjo so zna~ilni dolgi zalivi v potopljenih re~nih dolinah, med katerimi segajo dale~ v morje vi{ji polotoki. Poglavitne reliefne oblike so obalne ravnice v notranjosti zalivov in strmi klifi na obalah polotokov. Na nihanje vodne gladine pa vpliva tudi lastno nihanje Jadranskega morja, ki se pojavi v zaprtih ali delno zaprtih bazenih in traja {e po prenehanju delovanja sil, ki ga povzro~ajo. Perioda tega nihanja zna{a pribli`no 21 ur (Robi~ 2003/2004). Pri reliefu velja omeniti {e en dejavnik, ki plime ne pove~uje, temve~ se njuna vpliva zdru`ita in povzro~ata mo~nej{e poplave z ve~jim poplavnim obmo~jem. Ko se vi{ina morja dvigne in se voda iz celotnega Jadrana nariva proti severu, to zajezi ustja rek, ki se tu izlivajo vanj. To povzro~i, da re~na voda ne more odtekati in se zato dvigne vi{ina rek, ki nato poplavijo dolo~eno obmo~je blizu izliva. Poplavni obmo~ji morja in rek se s tem zdru`ita. 3.2 Vi{ina morja ob poplavah Vi{ino morske gladine lahko opi{emo na dva na~ina. Dolo~imo lahko vi{ino nad ali pod srednjo obdobno vrednostjo. Srednji obdobni vrednosti pripi{emo vrednost 0. Plime ozna~imo s predznakom plus (+), oseke s predznakom minus (-). Dolo~amo pa jo lahko tudi prek mareografske ni~le (0) na mareografski postaji v Kopru. Pri tem na~inu imajo vse vrednosti pozitiven predznak (oziroma predznaka sploh ni), saj srednji obdobni vrednosti 0 ustreza vi{ina 215 cm. Morje na slovenski obali poplavi najni`je le`e~e predele, ko gladina vode za 85 cm prese`e srednjo obdobno vrednost oziroma je vi{ina na vodomerni letvi z mareografsko ni~lo 300 cm (Robi~ in Vrhovec 2002). Povpre~na vrednost plime med letoma 1958 in 1990 je zna{ala 248 cm na vodomerni letvi z mareografsko ni~lo, oziroma 33 cm nad srednjo obdobno vrednostjo, povpre~na vrednost oseke za isto obdobje pa 182 cm na vodomerni letvi ali -33 cm pod srednjo obdobno vrednostjo. Povpre~na amplituda v tem obdobju je torej zna{ala 66 cm. Najvi{ja izmerjena gladina vode je bila leta 1969, 394 cm ali 179 cm nad srednjo obdobno vrednostjo (Mareograf v Kopru 1969). 4 Nekaj podatkov o mo~nej{ih poplavah morja med leti 1963 in 2003 Med leti 1963 in 2003, ko so na razpolago podatki mareografa v Kopru, lahko izpostavimo nekaj mo~-nej{ih poplav. 4.1 Poplava in neurje od 3. do 5. novembra 1966 Gladina vode je dosegla najvi{jo vi{ino 4. novembra ob 20 uri, to je kar 352 cm (Mareograf v Kopru 1966). Pri tem je bilo na Tartinijevem trgu v Piranu pribli`no pol metra vode. Neurje in visoka gladina morja sta povzro~ila precej {kode, najve~ v Piranu, saj je tam najve~ objektov neposredno izpostavljenih morju. V Piranu je bilo razmajano in spodkopano obalno zidovje, razbita je bila Kavarna Tartini v stavbi gledali{~a (dana{nji Caffe Teater), poslovalnica avtobusne postaje, gosti{-~e Riviera, ravno tako tudi kopali{~e ob dohodu v mesto, restavracija Hotela Piran in mnoge zasebne gara`e ter avtomobili. Ves dan je bila zaprta cesta med Piranom in Lucijo, mnogo {kode je bilo tudi drugod ob slovenski obali (Primorske novice 1966). Na pla`i v Portoro`u so bili uni~eni leseni pomoli, razbita vrata kabin in odnesenih je bilo okrog 50 vagonov mivke, s sidri{~ pa so bili odtrgani {tevilni ~olni (Titl 1983). 161 Nata{a Kolega, Ogro`enost slovenske obale zaradi morskih poplav 4.2 Poplave 25. in 26. novembra 1969 Poplave 25. in 26. novembra 1969 so enakomerno zajele vso obalo. Voda je segala 94 cm v vi{ino. Obalna cesta Koper-Se~ovlje je bila na ve~ mestih poplavljena, prav tako vsi cestni odseki proti Izoli, Portoro`u in Piranu. Mnogo {kode je neurje povzro~ilo na avtomobilih, parkiranih na Tartinijevem trgu v Piranu, saj jih je zalila morska voda skoraj do vi{ine enega metra, nekatere pa so sunki vetra celo tre{~ili ob zidove. V Kopru je morje zalilo poleg ni`jih predelov mesta tudi ve~ino Bonifike z osnovno {olo vred (Titl 1983). To je bila najmo~nej{a poplava v preu~evanem obdobju, povzro~ila je tudi najve~ materialne {kode. 4.3 Poplave v letih 1979, 1980 in 1982 22. decembra 1979 je morje doseglo vi{ino 356 cm. Na tedanji Cesti JLA (dana{nje Forna~e in Dantejeva ulica) je bilo do 60 cm vode, v Piranu pa je zalilo tudi Tartinijev trg z okolico. V Kopru je na kri`i{~u pri Slavniku morje mimo za{~itnih vre~ udrlo na Bonifiko in jo zalilo. Zalilo je tudi prostore Splo{ne banke Koper (dana{nje Banke Koper) in tr`nico (Primorske novice 1979). 25. oktobra 1980 je morje doseglo vi{ino 361 cm, kar je druga najmo~nej{a poplava v tem obdobju. Najve~ slane vode je bilo ponovno na tedanji Cesti JLA (dana{nje Forna~e) v Piranu, na Ukmarjevem trgu v Kopru in na Semedelski cesti. Na parkiri{~u hotela Triglav v Kopru je bilo zalitih ve~ avtomobilov. Ve~je {kode tokrat ni bilo, saj plime ni spremljal mo~an jugo (Primorske novice 1980). 6. in 7. decembra 1982 je gladina morja ponovno dosegla vi{ino 361 cm. Poplava je najbolj prizadela Piran in obalno obmo~je med Piranom in Se~oveljskimi solinami. V solinah so bili podrti nasipi, tako da so bile soline precej uni~ene. Veliko {kode je bilo tudi v Droginem obratu Za~imba v Se~i, kjer so bili pod vodo proizvodni obrati. Na obmo~ju Izole in Kopra je {koda nastala samo na poplavljenih avtomobilih (Titl 1983). 5 Statisti~na obdelava podatkov o poplavah morja v letih 1963 do 2003 V enain{tiridesetletnem obdobju je gladina morja 299-krat dosegla ali presegla to~ko poplavljanja 300 cm. Povpre~na vi{ina morja, ob poplavljanju, je bila 309 cm. Najvi{ja izmerjena vi{ina morja v preu~evanem obdobju je bila 394 cm, kar je skrajnost, saj se sicer tako visoke vrednosti niso pojavljale. Povpre~no je bilo 7,3 poplav na leto. Letno {tevilo poplav se od leta do leta zelo razlikuje, prav tako pa se razlikujejo tudi najvi{je letne vrednosti vi{ine morja. Pojava nista zelo mo~no povezana, saj je bilo na primer v dolo~enih letih zelo malo poplav in tudi vi{ine morja so bile zelo nizke, spet v drugih letih pa so bile pri majhnem {tevilu poplav dose`ene visoke vi{ine. Ravno tako pri velikem {tevilu poplav ne moremo pri~akovati visokih vi{in morja. ^e opazujemo samo vi{ine, ki jih gladina morja ob poplavah dosega, lahko opazimo dolo~en trend (slika 1). Nekaj let so vi{ine relativno visoke, nakar sledi nekaj let z relativno nizkimi vi{inami, niz se nato ponovi. Iz slike 1 je mogo~e razbrati tri obdobja, ko je morje dosegalo vi{je vrednosti in med njimi dve obdobji z ni`jimi vrednostmi. Podoben trend je opazen tudi pri {tevilu poplav na leto. V zadnjem desetletju je opazno pove~anje {tevila poplav med letom, vendar pa te poplave ne dosegajo posebno visokih vrednosti. Slika 1: Najvi{je vi{ine gladine morja in {tevilo poplav na leto v letih 1963 in 2003. Glej angle{ki del prispevka. Iz podatkov o {tevilu poplav na leto in najvi{jimi vi{inami morja v enem letu, smo izra~unali Pearsonovo korelacijo. Korelacija je zelo nizka 0,247, kar pomeni, da je pojasnjena varianca 0,061 oziroma, da lahko le pribli`no 6 % najvi{jih vi{in morja pojasnimo s {tevilom poplav. To je posledica dejstva, da s Pearsonovim koeficientom ra~unamo le linerane korelacije. ^e »z vrednosti« podatkov interpoliramo s polinomom {estega reda lahko vidimo, da so pojavi korelirani. Iz slike 2 je razvidno, da so si krivulje med seboj podobne. Za potrditev tega smo izra~unali korelacijo predznakov odvoda, ki nam pove v koliko primerih krivulji skupaj nara{~ata ali padata, ne pa za koliko nara{~a ali padata. Opazili smo, da povezanost obstaja pri 90 % vrednosti. Sklepamo lahko, da zveza med pojavoma obstaja, vendar je s Pearsonovo korelacijo ne moremo pojasniti. 162 Acta geographica Slovenica, 46-2, 2006 Na podlagi tega smo poskusili ekstrapolirati podatke iz katerih smo izlo~ili robne vrednosti, ki pretirano odstopajo (vredosti pred letom 1966 in po letu 1990). ^e izra~unamo Pearsonov koeficient zgolj na teh podatkih, je rezultat vrednost 0,551, kar pomeni da je pojasnjena varianca 0,301 oziroma, da lahko pribli`no 30 % najvi{jih vi{in pojasnimo s {tevilom poplav. Ker sta vzorec in statisti~na pomembnost zelo majhna, tako visoka pojasnjena varjanca pomeni, da lahko povezanost med najvi{jimi vi{inami in {tevilom poplav med letoma 1966 in 1990 le slutimo. Slika 4 prikazuje {tevilo poplav po mesecih. Poplave so zelo zna~ilne za jesensko-zimsko obdobje od oktobra do januarja, najve~ poplav je novemrba. Poplave so pogoste tudi spomladi, zelo redke pa so poleti. Vzrok za tak{no razporeditev je zlasti ve~ja pogostost genovskega ciklona v hladnem delu leta. Slika 2: »Z vrednosti« najvi{jih vi{in morja in »z vrednosti« {tevila poplav na leto. Glej angle{ki del prispevka. Slika 3: [tevilo poplav po mesecih med leti 1963 in 2003. Glej angle{ki del prispevka. 6 Kartiranje poplavnih obmo~ij na slovenski obali 6.1 Povr{ina poplavnega obmo~ja ob izjemnih in vsakoletnih poplavah morja Za izjemne poplave so {tete poplave, ki dosegajo ali presegajo vi{ino 394 cm, kar je najvi{ja vrednost, ki jo je vi{ina gladine morja dosegla v obdobju od leta 1963 do leta 2003. Za omenjeno poplavo, ki se je zgodila 26. novembra 1969, je leta 1983 narisal okvirne zemljevide poplavnih obmo~ji `e Julij Titl (Titl 1983). Zemljevide smo uporabili za natan~nej{e dolo~anje poplavnega obmo~ja. Vi{ina vode 394 cm skoraj ustreza vrednosti 2 m nadmorske vi{ine na digitalnem modelu reliefa. Geodetska kota 0 je namre~ enaka vrednosti 200 cm, ki je v digitalnem modelu reliefa ozna~ena kot 0 metrov. Iz tega sledi, da vrednosti 1 m na digitalnem modelu reliefa ustreza 300 cm. Vrednost 2 m na digitalnem modelu reliefa pa ustreza vrednosti 400 cm - to pa je le 6 cm vi{je od najvi{je izmerjene vrednosti 394 cm. Razse`nosti te poplave se dobro spominja kar nekaj ljudi, predvsem na obmo~ju Pirana, zato smo pri izdelavi zemljevida upo{tevali tudi njihovo pri~evanje. Drugi podatek, ki ga zemljevid prikazuje, je poplavno obmo~je ob pogostej{ih, vsakoletnih poplavah pri vrednosti 330 cm ali 30 cm nad to~ko poplavljanja. Pri omejevanju tega poplavnega obmo~ja smo uporabili lastno opazovanje reliefa pa tudi ve~kratno opazovanje poplav takih razse`nosti v preteklih letih. Poplavno obmo~je je najobse`nej{e v ob~ini Piran, zlasti zaradi najve~je poplavne povr{ine - Se~o-veljskih solin. Najmanj obse`no je poplavno obmo~je v ob~ini Izola. Poplavno obmo~je vsakoletnih poplav pokriva 26,85 % poplavnega obmo~ja ob izjemnih poplavah. Preglednica 1: Povr{ina poplavnih obmo~ij ob izjemnih in vsakoletnih poplavah morja. poplavno obmo~je povr{ina v km2 poplavno obmo~je ob izjemnih poplavah mestna ob~ina Koper ob~ina Izola ob~ina Piran vse tri ob~ine skupaj 6,12 0,20 7,71 14,04 poplavno obmo~je ob vsakoletnih poplavah mestna ob~ina Koper ob~ina Izola ob~ina Piran vse tri ob~ine skupaj 0,25 0,03 3,48 3,77 Slika 4: Poplavno obmo~je, na slovenski obali, ob izjemnih in vsakoletnih poplavah. Glej angle{ki del prispevka. Slika 5: Izsek iz zemljevida poplavnega obmo~ja, na slovenski obali, ob izjemnih in vsakoletnih poplavah, ki prikazuje Piran z okolico. Glej angle{ki del prispevka. 163 Nata{a Kolega, Ogro`enost slovenske obale zaradi morskih poplav 6.2 Opis poplavnih povr{in 6.2.1 Ankaran Na obmo~ju Ankarana je ve~ med seboj lo~enih poplavnih povr{in razli~nega obsega. Ob izjemnih poplavah bi bilo poplavljeno obmo~je ob mejnem prehodu Lazaret in bencinski ~rpalki, kjer razen omenjenih objektov, ni drugih zgradb. Ob vsakoletnih poplavah je poplavljen le o`ji del neposredno ob obali. Pribli`no 500 m zahodno od mejnega prehoda je kopali{~e z nekaj zgradbami, ki bi bile ob izjemnih poplavah pod vodo. Prav tako bi bila pod vodo kopali{~a pred Mladinskim zdravili{~em in tako imenovano kopali{~e »Gradis«, vendar tu ni stavb, ki bi bile ogro`ene. Sledi kopali{~e pod Ortopedsko bolni{nico Valdoltra, kjer je povr{je ni`je, zato bi bil od tu dalje poplavljen celoten obmorski pas do Luke Koper. V tem pasu je ve~ odsekov, kjer bi izjemne poplave lahko povzro~ile ve~jo {kodo. Najbolj problemati~en je avto-kamp Adria, ki bi bil ob izjemnih poplavah z vsemi objekti skoraj do polovice poplavljen. Pri Sveti Katarini, bi bilo ob izjemnih poplavah poplavljeno manj{e pristani{~e in nekaj okoli{kih objektov. Vsakoletne poplave na obmo~ju Ankarana ne povzro~ajo bistvenih te`av in {kode. 6.2.2 Koper V Kopru in v njegovi okolici je, zlasti ob izjemnih poplavah, kar nekaj poplavnih povr{in. Luka Koper, bi bila zaradi svoje lege ob izjemnih poplavah skoraj v celoti zalita. To bi utegnilo povzro~iti kar nekaj gmotne {kode. Voda bi se razlivala skoraj do Srmina. Ob vsakoletnih poplavah so zaliti le ni`ji deli Luke Koper, kar ne povzro~a posebnih te`av. Ob izjemnih poplavah bi bila potopljena tudi koprska Bonifika in del Olma ter [alare ob Bada{evici, kjer je obse`no poseljeno obmo~je. V starem delu Kopra bi bila ob mo~nih poplavah zalita Marina Koper, Ukmarjev trg, del Carpacciovega trga in okolica, Pristani{ka ulica, Ljubljanska ulica ter Bonifika. V starem mestnem jedru bi bilo zalitih kar nekaj hi{. Ob vsakoletnih poplavah so zaliti Semedelska cesta, del Marine Koper in obala v neposredni okolici koprskega pristani{~a. Stanovanjske stavbe niso ogro`ene. Ob izjemnih poplavah bi bilo zalito tudi obmo~je proti @usterni s parkiri{~em in kopali{~em vred ter magistralna cesta med Koprom in Izolo, ob vsakoletnih poplavah pa le kopali{~e. 6.2.3 Izola Na obmo~ju Izole bi bil ob izjemnih poplavah poplavljen skoraj celoten avtokamp Jadranka, ob vsakoletnih poplavah pa le njegov ni`ji del, neposredno ob obali. Ob mo~nih poplavah bi bil poplavljen tudi velik del Ladjedelnice Izola, kar bi pomenilo precej{njo gmotno {kodo na objektih. Poplavljeni bi bili tudi kopali{~e zahodno od Ladjedelnice Izola in rti~, kjer je svetilnik. Poplavljen bi bil velik del mesta Izola: ob pristani{~u, Veliki trg, Manziolijev trg ter vse do Ljubljanske ulice ter Gorkijeve ulice. Poplavljena bi bila tudi Marina Izola s pripadajo~imi objekti, obmo~je do Simonovega zaliva in precej stanovanjskih objektov, zlasti v starem mestnem jedru. Ob vsakoletnih poplavah je poplavljena le obala neposredno ob morju in redki stanovanjski objekti na Velikem trgu in morda ob marini. 6.2.4 Strunjan in Fiesa V Strunjanu je ob vsakoletnih poplavah poplavljeno kopali{~e in soline, ob izjemnih poplavah pa bi bilo poplavljeno tudi obmo~je ob Strunjanskem potoku oziroma okolica strunjanskega kri`i{~a. Tu bi bilo prizadetih tudi nekaj hi{. Poleg tega morje, zlasti ob izjemnih poplavah, poplavlja tudi pla`o pred turisti~nim kompleksom Salinera. V Fjesi obi~ajno poplavlja kopali{~e, ob izjemnih poplavah pa tudi travnik med kopali{~em in fje{-kim jezerom. Zgradbe niso ogro`ene. 6.2.5 Piran Piran poplave najbolj ogro`ajo. Tudi v preteklosti so prav poplave v Piranu povzro~ale najve~jo {kodo. Ob izjemnih poplavah bi bil poplavljen velik del starega mestnega jedra. Voda bi se razlivala po celotni 164 Acta geographica Slovenica, 46-2, 2006 obali okrog rta Madona do Resslove ulice in za~etka Gregor~i~eve ulice (za nekdanjim hotelom Punta) ter nato do spodnje polovice Trga 1. maja in Verdijeve ulice. Zalit bi bil tudi celoten Tartinijev trg, nato pa obmo~je do ulice Svobode in Tom{i~eve ulice. Poplavljena bi bila tudi Dantejeva ulica in celotne Forna~e. Poplavljenih bi bilo veliko hi{, gmotna {koda bi bila razmeroma visoka. Ob vsakoletnih poplavah so poplavljeni Kidri~evo in Pre{ernovo nabre`je, Tartinijev trg in del Cankarjevega nabre`ja s pristani{~em, v smeri proti izhodu iz mesta pa le najo`ji del obale. Za razliko od ve~ine drugih krajev, je v Piranu tudi ob vsakoletnih poplavah poplavljenih nekaj hi{ ob Pre{ernovem in Kidri~evem nabre`ju. 6.2.6 Portoro` Na Bernardinu bi bilo zlasti ob izjemnih poplavah poplavljeno kopali{~e pred Grand hotelom Bernardin ter kopali{~e in manj{e pristani{~e ob hotelu Histrion. Zaliti bi bili tudi glavna bernardinska pla`a in prostori jadralnega kluba Pirat, kjer bi bila ob mo~nej{ih poplavah zalita tudi ~olnarna Fakultete za pomorstvo in promet. Poplavljena bi bila tudi tako imenovana »[tudentska pla`a«, ob mo~nih poplavah pa tudi obala pred skladi{~i soli. V samem Portoro`u bi bile poplavljene predvsem pla`e pred hotelom Riviera in glavna portoro{ka pla`a, poleg njiju pa tudi pristani{ki pomol in obala med omenjenima pla`ama. Objekti v Portoro`u so ve~inoma nekoliko dvignjeni nad morsko gladino, zato tudi ob mo~nih poplavah ne bi bili poplavljeni. 6.2.7 Lucija Ob izjemnih poplavah bi bil v Luciji zalit kar precej{en del povr{ja. Zalita bi bila skoraj celotna Marina Portoro`, voda pa bi se prelivala {e naprej proti progi za gokart in zdravstvenem domu. Zalilo bi tudi del Obale in Ukmarjeve ulice. Ob potoku Fazan bi se voda prelivala {e naprej vse do Fazana in Fazanske ulice. V primeru tako mo~nih poplav bi bilo zalitih veliko stanovanjskih in drugih objektov, kar bi lahko povzro~ilo znatno {kodo. Ob vsakoletnih in ob izjemnih poplavah je zalita tudi lucijska pla`a, pa tudi o`ji del obale ob kanalu na izlivu potoka Fazan, ki slu`i kot pristani{~e za manj{e ~olne. Zlasti ob izjemnih poplavah bi zalilo pla`o avtokampa Lucija, njegovih povr{in pa ne, saj so le te nekoliko dvignjene oziroma le deloma v bli`ini morja. Vsakoletne poplave v Luciji ne povzro~ajo posebnih problemov oziroma {kode, saj voda zalije le o`je obalne predele in kopali{~a. 6.2.8 Se~a in Se~ovlje V Se~i in Se~ovljah je najve~ja poplavna povr{ina na slovenski obali. To so Se~oveljske soline, ki so v ve~-jem delu poplavljene `e ob vsakoletnih poplavah, ob izjemnih pa bi bile v celoti pod vodo. Voda bi se razlivala tudi po dolini navzgor in zaradi zajezitve Drnice z visoko plimo bi bili poplavljeni tudi del naselja Se~ovlje, obdelovalne povr{ine v njegovi okolici ter del Letali{~a Portoro`. Poplavljenih bi bilo tudi nekaj stanovanjskih objektov. Ob izjemnih poplavah lahko morje zalije nekdanji obrat Za~imba Droge Portoro` pri kanalu sv. Jerneja v Se~i, kar bi lahko povzro~ilo precej{njo gmotno {kodo. @e ob vsakoletnih poplavah je zalita skoraj celotna cesta ob kanalu Svetega Jerneja, ob izjemnih poplavah pa bi bili zaliti {e nekateri dodatni predeli, kot je manj{a ladjedelnica in parkiri{~e pred gostilno Ribi~. Na tem obmo~ju je ve~ina stanovanjskih objektov zaradi reliefa nekoliko dvignjena, in ni nevarnosti, da bi jih zalilo. 6.3 [tevilo prebivalcev na ogro`enih obmo~jih Na poplavnih obmo~jih, `ivi veliko prebivalcev. Ob vsakoletnih poplavah je ogro`enih 22 ljudi v Piranu. V ostalih krajih vsakoletne poplave ne ogro`ajo stanovanjskih objektov. V treh obmorskih ob~inah `ivi 78.846 prebivalcev, v ob~ini Koper 47.539, v ob~ini Izola 14.549 in v ob~ini Piran 16.758 (Popis 2002). 165 Nata{a Kolega, Ogro`enost slovenske obale zaradi morskih poplav Ob izjemnih poplavah bi bilo v vseh treh ob~inah ogro`enih 2007 ljudi, najve~ v ob~ini Piran (1262), 427 v ob~ini Koper in 318 v ob~ini Izola. Ogro`enega je kar 2,54 % prebivalstva vseh treh ob~in, v ob~ini Piran pa kar 7,53 % prebivalcev ob~ine oziroma 18,75 % prebivalcev Pirana. Iz zgornjih podatkov lahko sklepamo, da bi ob nastopu izjemnih poplav zaradi precej{njega {tevila ogro`enega prebivalstva lahko nastale resne te`ave pri oskrbi, prometu, bivanju in ostalih dejavnostih, zlasti v Piranu. 6.4 Zazidalni na~rti za poplavna obmo~ja Med najve~jimi ali najbolj odmevnimi zazidalnimi na~rti na poplavnih obmo~jih izstopajo v Kopru izgradnja nove osnovne {ole, gasilskega doma in zdravstvenega doma na Bonifiki, Gospodarske cone Sermin in 3. pomola Luke Koper. V Izoli nameravajo graditi turisti~no-poslovno-stanovanjski kompleks Argolina, na {ir{em obmo~ju Simonovega zaliva pa ve~ji turisti~ni kompleks. V Piranu je predvidena {iritev vzletno-pristajalne steze Letali{~a Portoro`, gradnja golf igri{~a v Se~ovljah ter obse`en ureditveni na~rt za obmo~je polotoka Se~a, ki se dotika tudi robnih predelov solin oziroma celotnega predela ob kanalu svetega Jerneja, kjer morje pogosto poplavlja. Zgraditi nameravajo tudi novo marino, ve~ vil in hotelov ter drugih objektov. Na{tetih je le nekaj najve~jih na~rtov, poleg teh pa obstaja {e mno`ica manj{ih, od katerih so posamezni lahko {e bolj izpostavljeni poplavam morja. 6.5 Vpliv globalnega segrevanja ozra~ja na poplave morja Znanstveniki napovedujejo, da bo eden od najpomembnej{ih vplivov globalnega segrevanja porast morske gladine. Dvig morske gladine je posledica toplotnega {irjenja morske vode, taljenja gorskih ledenikov in taljenja ledenikov na zemeljskih polih. Glede na dana{njo vi{ino gladine morja naj bi se le-ta do leta 2050 dvignila za pribli`no 22 cm, do leta 2100 pa za pribli`no 50 cm (Plut 1998). Izdelali smo zemljevid, ki prikazuje poplavna obmo~ja ob morebitnem dvigu morske gladine zaradi globalnega segrevanja. Predpostavili smo dvig morske gladine za 50 cm. ^e bi bila srednja vi{ina gladine morja v prihodnosti za 0,5 m vi{ja, bi `e vsaka malo mo~nej{a plima povzro~ila poplavo. ^e sedanji vrednosti povpre~ne plime pri{tejemo 50 cm, dobimo 298 cm, kar pa je zelo blizu to~ki poplavljanja. Glede na to, da so plime razli~no visoke in da je njihova povpre~na vi{ina 33 cm, lahko sklepamo, da bo do poplav prihajalo redno, tudi ve~krat na mesec. Povpre~na vi{ina poplave, izra~unana iz sedanjih vrednosti, bi bila za dana{nje razmere skoraj izjemna poplava - 359 cm. Ob izjemnih poplavah pa bi bilo ob predpostavljenem scenariju na najni`je le`e~ih delih obale skoraj 1,5 m morske vode (444 cm). Preglednica 2: Izra~un vi{in morja za napovedani dvig gladine za 50 cm. vrednost vi{ine gladine vrednost vi{ine gladine morja morja danes vcm pri dvigu gladine za 50cm, vcm srednja vi{ina gladine morja 215 265 za~etek poplavljanja 300 300 vrednost povpre~ne plime 1963-2003 248 298 vrednost povpre~ne oseke 1963-2003 182 232 izjemna vrednost 1963-2003 394 444 povpre~na poplava 1963-2003 309 359 vsakoletna poplava 1963-2003 330 380 Slika 6: Poplavno obmo~je ob morebitnem dvigu morske gladine (za 50cm) zaradi globalnega segrevanja ozra~ja. Glej angle{ki del prispevka. 6.5.1 Analiza zemljevida poplavnega obmo~ja ob morebitnem dvigu morske gladine (za 50 cm) zaradi globalnega segrevanja ozra~ja Del ozemlja, ki bi bil ob dvigu gladine morja za 50 cm poplavljen ob vsakoletnih poplavah, bi lahko primerjali z delom ozemlja, ki je sedaj poplavljen pri izjemnih poplavah. Le-ta obsega pribli`no 14km2 oziroma 166 Acta geographica Slovenica, 46-2, 2006 dobre tri odstotke povr{ine vseh treh obalnih ob~in. Vendar bi bile poplavne povr{ine, ob porastu vi{ine morja za 50 cm, najverjetneje nekoliko manj obse`ne, saj bi bila vi{ina morja v primeru vsakoletnih poplav ob dvigu za 50 cm za 14 cm ni`ja kot je sedaj ob izjemnih poplavah (preglednica 2). Podobna primerjava je mo`na tudi za {tevilo ogro`enih prebivalcev. Sklepamo lahko, da bi bilo ob porastu gladine za 50 cm pri vsakoletnih poplavah ogro`enih ve~ kot tiso~ ljudi. Najve~je poplavne povr{ine bi nastale na obmo~ju koprske in ankaranske Bonifike, kar pomeni, da bi imela Luka Koper velike te`ave pri izvajanju svoje dejavnosti. Poplavne povr{ine bi se bistveno pove~ale tudi v Izoli. Ve~je bi bile poplavne povr{ine tudi v Strunjanu in Piranu, bistveno pa bi se pove~ale v Luciji, prav tako pa bi se poplavno obmo~je precej pove~alo na obmo~ju Se~ovelj, kar bi lahko predstavljalo posebne probleme za Letali{~e Portoro`. 7 Sklep [koda, ki jo lahko povzro~ijo ve~je poplave, se iz leta v leto spreminja, vendar se vi{ina vode ob poplavah pribli`no ujema z nastalo gmotno {kodo. Zemljevid poplavnih obmo~ji ob izjemnih in vsakoletnih poplavah razmeroma dobro ilustrira ogro`enost tega obmo~ja. Da bi pri{li do bolj natan~nih zemljevidov, ki bi bili uporabni pri na~rtovanju, bi morali ve~ let spremljati poplave in ob vsakemu dogodku posebej iti na teren ter kartirati njene razse`nosti. Zlasti ob izjemnih poplavah bi bilo ogro`eno tudi precej veliko {tevilo prebivalcev treh obalnih ob~in, kar pa je zelo zaskrbljujo~e iz ve~ razlogov. Slovenska obala sodi med bolj privla~na obmo~ja za pozidave in turisti~ne ter druge dejavnosti, kar dokazujejo precej velika gostota poselitve in pozidanost delov obmorskega pasu ter visoke cene zemlji{~. ^e sklepamo po obstoje~ih zazidalnih na~rtih, se krajevne in druge oblasti, premalo zavedajo ogro`enosti obmo~ja. Sklepamo lahko, da bi bila {koda ob izjemnih poplavah {e veliko ve~ja, kot je bila v preteklosti. Najbolj ogro`eno obmo~je je mesto Piran, ki je zaradi lege izpostavljeno visokim plimam in ju`nemu vetru. Mesto je zasnovano tako, da je veliko hi{ neposredno na obali, ki pa je relativno nizka. Ob izjemnih poplavah bi bil v Piranu tako zalit ve~ji del starega mestnega jedra, kjer `ivi skoraj petina njegovega prebivalstva. Do sedaj so poplave povzro~ale najve~ {kode prav v Piranu. Poleg vsega na{tetega nam grozi {e nova nevarnost - dvig gladine morja kot posledica globalnega segrevanja ozra~ja. Znanstveniki napovedujejo, da se le-ta lahko do konca tega stoletja dvigne za pol metra, kar bi razse`nost poplav morja bistveno spremenilo. Poplavno obmo~je bi bilo precej ve~je, poplave veliko pogostej{e, saj bi poplavljala `e vsaka, za nekaj centimetrov nadpovpre~na plima. Ogro`eno bi bilo tudi precej prebivalstva. Problem bi postal dokaj velik in z re{evanjem bi se po vsej verjetnosti morala spopasti dr`ava. To so zaenkrat le napovedi, za katere natan~no ne vemo, ~e se bodo uresni~ile in v kolik{ni meri. Smiselno pa bi bilo zgornja spoznanja vnesti v upravljanje s prostorom obmo~ju in ukrepati `e ob prvih pojavih problema, da bi bili ob njegovem polnem nastopu ustrezni na~rti `e pripravljeni. 8 Viri in literatura Glej angle{ki del prispevka. 167