عنوان مقاله [English]
Coastal classification is an effective method for investigating the reaction of coasts against such hydrodynamical factors as waves and tides. This method is also employed in integrated coastal zone management, especially shoreline management. Coastal classification models are of two kinds, equilibrium models, predicting the effects of constant incident waves on nearshore features such as bars and troughs, and morphologic state models, predicting the sequence of bar-trough shapes and scales under the varying influences varying waves. Wright and Short (1984) presented the most widely accepted beach classification scheme where three main beach states are identified, namely dissipative, intermediate, and reflective. Intermediate beaches are divided into four states, low tide terrace, transverse bar rip, rhythmic bar beach, and longshore bar trough.
In this paper, the beach states of the southern coasts (Hormozgan Province) of Iran were classified using Masselink and Short (1993) and Masselink and Hegge (1995) methods. Owing to its location, and abundant oil and gas resources, Persian Gulf is one important military, economic and political interest, hence the necessity of its investigation. We primarily studied different kinds of hydrodynamic forces dominating the beaches of the province. Six stations were chosen throughout the shoreline between 54˚39' 18" latitude and 26˚30' 29" longitude up to 53˚ 9' 39" longitude and 27˚4' 34" latitude. Next, the waves, tides, and sediments were evaluated in different depths in these stations via laboratory actions. We employed the wave data of 2002 from the modeling project (ISWM) which was done in the National Institute of Oceanography, and the sediment data of Hormozgan Province coast were gleaned from the Marine Geological Organization. In order to determine the general slope of the beach by Arc GIS software, hydrographic maps were used with approximately 1/100000, and the slope of each station was calculated. After that, through breaker height (Hb), the tide range (TR), wave period (T) and sediment fall velocity (Ws), two dimensionlessparameters, namely the relative tide range (RTR = TR/ Hb) and the dimensionless fall velocity (Ω = Hb/WsT,) were calculated in each station.
The results indicated that in the southern regions of Iran (Hormozgan Province), due to the tidal effects in and based on (3<RTR<15), a mixed wave-tide exists in all stations, a condition which remains constant throughout the year. Furthermore, following the study of the morphodynamic characteristics of low tide terrace, low tide bar/rip, ultra-dissipative beaches and relative occurrence of swash, surfzone, and shoaling wave processes were calculated over a half lunar tidal cycle for low tide terrace, low tide bar/rip, and ultra-dissipative beaches. Based on Masselink and Hegge methods and Masselink and Short (1993) beach classiﬁcation scheme, we observed a relatively high variety of beach states in the studied regions: Reflective, dissipative, and intermediate. The beach states in three stations of the central regions are ultra-dissipative, in two stations are low tide terrace, and in the easternmost station is low tide bar/rip.