On the occurrence of non-reflecting cross-shore profiles along Estonian coasts of the Baltic sea/Mittepeegeldavad rannaprofiilid Eesti rannikumeres

Cross-shore beach profiles along Estonian coasts of the Baltic Sea are analysed from the viewpoint of the frequency of occurrence of convex sections that may support non-reflecting wave propagation and unexpectedly high run-up events. In total 194 beach profiles, measured in 2006-2011 at 16 locations, are examined by means of their approximation with the power function h(x) = A[x.sup.b]. About half of the profiles can be adequately approximated using a single power function. These profiles are almost all concave. The relevant exponents are clustered around b = 2/3 that is characteristic to the Dean's Equilibrium Profile. The rest of the profiles can be divided into two sections, each of which is approximated by a power function. The underwater sections of such profiles predominantly match the Dean's Equilibrium Profile. About 10% of the subaerial sections (about 7% of all examples) have the exponent close to b = 4/3, for which high run-up events are likely. Key words: beach profile, wave run-up, marine coastal hazards, Dean's Equilibrium Profile, Estonia, Baltic Sea. Liiva-ja kliburandade rannaprofiilid on tavaliselt nogusad ning veesugavust h neil kirjeldatakse adekvaatselt Deani tasakaalulise rannaprofiiliga h(x) = A[x.sup.b], milles b = 2/3. Kumeratel rannaprofiilidel, mille puhul b = 4/3 voi b = 4, on voimalikud ootamatud korged lainerunnakud. Mererannikute seire raames aastail 2004-2011 16 kohas moodistatud 194 rannaprofiili alusel on analuusitud taoliste lainerunnakute voimalust Eesti rannikul. Ligikaudu pooli (82) profiilidest kirjeldatakse adekvaatselt uhe astmefunktsiooniga. Need on peaaegu koik nogusad ja nende astmenaitajate b jaotuse maksimum on ligikaudu 2/3. Ulejaanud profiilide veealuseid ja rannalahedasi osi kasitletakse omaette profiilidena. Veealused loigud sarnanevad pohiosas Deani profiiliga. Veepiiri laheduses paiknevad ja osaliselt kuivale maale ulatuvad profiilid on aga sageli kumerad, kusjuures ligikaudu 10%-1 juhtudest (7%-1 koigist profiilidest voi nende osadest) on astmenaitaja b ≡ 4/3. Seega on Eesti randades arvestatava sagedusega voimalikud ootamatud lainerunnakud.