مریم راهبانی

Coastal areas are sensitive and socio-economically important areas. they are susceptible to changes due to the hydrodynamic and environmental conditions of the area. Knowing about the processes in progress helps us to manage and develop a sustainable coastal zone. Kish Island, located in the north of the Persian Gulf, is one of the important touristic and economic destinations. Knowing about the changes in the shoreline of this island is one of the essentials of ICZM.  Using Landsat 5, 7, and 8 satellite images, we estimated the amount and the rate of shoreline transformation of Kish Island between 1988 and 2020. Using the NDWI band ratio, the water and the land features has been distinguished, and using K-means classification, the two features have been separated from each other. The extracted lines have been analyzed using the DSAS statistical tool. Using SCE and NSM indexes, the amount of changes and using EPR and LRR indexes, the rate of changes has been estimated. The results show that the long-term transformation of the shoreline (during 32 years) was mostly linear and regular. Most of the shore of Kish Island has had negligible changes (about 0.2 to -0.2 m/year). 17% and 19% of the coast of the island experienced moderate transformation of the type either erosion or accretion. Only 180 m of the shore, called Masheh beach area, has been associated with a high erosion rate of more than 0.2 m/year.

Given the increasing demand for proteinaceous food products, aquaculture production of fish is on the rise. Due to its attractiveness, marine cage culture has gained attention in the aquaculture industry and has become profitable. This study focuses on the hydrodynamic variables to determine suitable areas for establishing fish cage sites in the waters surrounding Qeshm Island. Hydrodynamic variables were estimated through one-year numerical modeling using Mike 21. By applying the Analytic Hierarchy Process (AHP) and fuzzy logic to the variables, suitable areas in four sections were identified: east of Qeshm Channel, south of Hormuz Island - between Qeshm City and Larak Island - north of Larak, the coast from Ramchah to Hengam Island, and Dayerstan bay to Salakh. The results indicate that, in addition to the previously identified areas in similar studies, the northern part of Larak Island and the center of eastern Qeshm Channel are also suitable and could be options for expanding this industry in the future with the development of cage technology and infrastructure. Areas identified in previous studies, such as the coasts from Souza to Shibderaz and Dayerstan Bay, may face significant wave height threats in severe storm conditions. However, areas like Dargahan can be less risky regarding hydrodynamic conditions due to limited fetch exposure in weather conditions. It is beneficial to conduct studies on cage deployment for development and planning of the maritime economy. By incorporating water quality indicators alongside hydrodynamic variables, more accurate results can be obtained, thereby reducing investment risks in this industry.

Coastal zones are one of the most sensitive areas with the constant changes due to their dynamic nature. They are also precious zones in terms of fisheries, transportation, recreational activities, and other rich resources. Thus, any changes in such areas can influence all such activities. Natural disasters are one of the main concerns in sensitive areas such as coastal zones. Due to its sensitivities, these areas may be affected significantly by such disasters. Coastal zone management (CZM) mechanism is a proper choice, which is applied and implemented with the aim of ensuring the sustainability of resources and these environment. In the operational and research framework of CZM, natural phenomenon and disasters are considered and their affects are surveyed for best managements of the area. Large-scale natural phenomena such as earthquakes or groundwater depletion due to climate change in coastal low-lying areas cause various types of instability. On the 2nd of July 2022, three strong and consecutive earthquakes occurred in the coastal area of Sayekhosh, Located 123 km from Bandar Abbas city and 70 km from Bandar Lengeh city (South of Iran). As a result of these earthquakes, the Sayekhosh Shrimp farm center was seriously damaged. In this study, using RS and GIS techniques, the impact of these earthquakes on the coastal area has been investigated. Using the data of the SAR images from Sentinel-1 satellite and applying the DInSAR technique, a coherence map, differential interferograms and vertical changes map of the region have been produced, which are used to determine the uplift or subsidence of the land's surface. By using the data of Sentinel-2, Landsat-5, and Landsat-8 satellites and using the band ratio technique, the conditions of the farm ponds and the shoreline of the region were determined. Using the Normalized Difference Water Index (NDWI) (with Green and NIR bands) and applying unsupervised K-means classification, two water and land features have been separated. These were done using ENVI, SNAP and ArcMap software. The surface of the area in the northwestern part of the farm has changed in the form of uplift (up to 0.2 m) and in the eastern part of the farm along the coast in the form of subsidence (up to -0.1 m). Band ratio results showed that after five days of the earthquakes, 189 ponds were discharged. Besides; we detected about -30 m shoreline transformation in the areas close to the farm canals and river mouths due to the earthquakes. The results showed that the location and/or the establishment of traditional shrimp farming system should be reconsider, to avoid such damages in upcoming disasters. Since natural disasters strongly affects man-made structures especially in the coastal area, the use of satellite data and RS and GIS techniques can be useful to precisely monitor and manage the changes in the coastal area.

Nearshore is dynamic and constantly affected by the environmental conditions of the sea, on the other hand, it plays a great role in economic-social management issues. The shoreline is also a part of the nearshore that is constantly affected by tide, waves, currents and human activities. Therefore, it is expected that this section will always be accompanied by changes. The first step of any nearshore development and construction is to know the hydrodynamic conditions of the area. In this study, an attempt has been made to investigate the sensitivity of the shoreline of Bandar Lengeh County by considering the height and energy of nearshore waves. Wave height and energy data have been estimated by running the MIKE 21 spectral wave numerical model for a period of 12 months. The results have been obtained with good accuracy compared to ECMWF data. The correlation coefficient and the RMSE are equal to 0.95 and 0.239. The modeling results show that the maximum average height and energy of waves in the shoreline are 0.22 m and 0.21 kW/m, respectively, in the last months of spring and the beginning of summer. Using the fuzzy-gamma logic and considering the gamma coefficient as 0.9, shoreline sensitivity to variables has been estimated and finally divided into three classes High, moderate, and low. 20% of the shoreline is in the high class, and 23% and 57% of the shoreline are in the moderate and low class, respectively.

In coastal hydrodynamics, shore structures play an important role in changes in coastal morphology and natural current conditions in the region. Generally, the construction of structures such as piers leads to a change in the pattern of coastal currents as well as other related parameters such as sedimentation rate, turbidity, and salinity. In the present study, using field measurements and model simulation of coastal currents, the effect of Nakhle Nakhoda pier construction on the coastal flow pattern is investigated. Field velocity measurements are carried out by ADCP over a 30-day period in two depth layers. Turbidity and salinity are also collected using CTD. All the data are statistically analyzed. The results show that different parameters are affected by the change of coastal current, and the greatest effect is on turbidity. The ROMS model is used to simulate the area in two modes, with and without the pier. According to the results, the construction of this structure has caused a change in the coastline and an increase of more than 40×104 square meters to the coastal area.

Considering demographic data, area extent, and the length of coastline, all coastal cities of Iran were categorized, and were compared with each other, to find their differences and the potential capacities of each region. For this study population data of 1395(2017) was employed. Besides, satellite images and GIS software was used for the sake of analysis and calculations. The area, and coastline of cities along the Caspian Sea, Oman Sea and the Persian Gulf were calculated. Afterwards, the population growth rate for a period of ten years (2007-2017) were calculated. Results show that northern coastal cities own higher relative density in compare with the southern coastal cities; meanwhile they own shorter coastline. On the other hand, the trend of population growth, in last ten years, in the southern cities was more than that of northern cities. However, most of southern cities are still low levels in terms of Population density and Coastal congestion. The city of Abu Musa and Qeshm had a significant population growth of about 93.11% and 41.45% respectively. Meanwhile, according to the ratio of coastline both of mentioned cities own a coastal degree of just 0.73 (for Abu Musa) and 0.22 (for Qeshm).

To study the emission of environmental pollutants, including urban and industrial wastewater of Bandar Abbas, through Gorsuzan estuary to the coastal waters of Bandar Abbas, located in the northeastern part of the Persian Gulf, a three-dimensional hydrodynamic numerical model was developed. This is to predict the pattern of chemical pollutant emission. The governing equations of this model are rewritten in the spherical coordinate earth system with a vertical sigma array. In order to validate the model, nitrate and nitrite measurements were performed spectrophotometrically at six stations on the coastal water of Bandar Abbas for a period of one year. The simulations showed that these pollutants are mostly spread in the areas of fishery pier and between Haqqani pier and fishing pier. Nitrite and nitrate concentrations up to 6 km east and 5 km west of the Gorsozan estuaries’ joint to the Persian Gulf is more than 60%. These results are consistent with the concentrations measurements carried out for these two pollutants in the mentioned areas. The average values ​​of nitrate concentration in the four measurement seasons in Khorgorsuzan, Fishery wharf, and Haqqani wharf are 18.9 mg/l, 14.95 mg/L and 9.32 mg/ L respectively. Besids the amount of nitrite in the above-mentioned stations are 4.7, 4.45 and 1.87 mg/l respectively.

The northern Indian Ocean (Bay of Bengal and Northwest Ocean) is one of the areas under Nedaja mission, one of the areas prone to the formation of tropical cyclons. In this study, we investigated the timing and pattern of forming tropical cyclons in the northern Indian Ocean region using data from the Indian Meteorological Organization from 1990 to 2017. The results showed that the highest number of cyclons occurred in November, June and October, respectively. There were no cyclons in the months of April, August, September, February and March. The frequency distribution graphs of cyclons formed in both the Bay of Bengal and Northwest Ocean regions show two maximum points. The first peak is related to the consecutive months of May and June and the second peak occurs in the months of October, November and December. The lack of intra-tropical convergence zone in the northern ocean causes no tropical cyclons in the area to occur in the summer and winter seasons. Statistical analysis also showed that if a storm occurs at any degree in the first maximum distribution, with 90% probability we will see the formation of a cyclonin the continuation of the first maximum and the second maximum and with 83.3% probability we will see a cyclon formation in the second maximum.. Background preparation using the results of this study can provide significant assistance in tackling tropical cyclons and maritime safety.

The dependence of numerical models on the selected domain, in turn, affects the accuracy of prediction and simulation of Tropical Cyclones (TCs) and is considered as a very serious challenge. In the first part of this study, the WRF model was used to determine the sensitivity of the track and intensity of TC GONU to a selective domain. In the second part, the performance of assimilation 3D in order to reduce the dependence of the sensitivity of the TC Gonu simulation to the selective domains was evaluated. The Gonu was the strongest TC occurred over the Arabian Sea. The peak intensity of TC Gonu was estimated 140 knots and 130 knots by Joint Typhoon Warning Center (JTWC) and India Meteorology Department (IMD), respectively. Four domains were separately selected. All of the simulations in this study were initialized at 00 UTC of 2 June for six days. In all simulations, authors used the data from NCEP global final analysis (FNL) on a 1.0°×1.0° grid to provide initial and boundary conditions. Despite the little difference in selective domains, the results in the first section showed the simulated tracks differed compared with each other, considerably. For performing simulations in the second part, the QSCAT, BUOY, METAR, SHIPS, SONDE, and SYNOP data to number 2064, 30, 63, 18, 37, and 208, were used, respectively. The results in the second part showed that assimilation of the satellite and synoptic data at the time of the start of the model, lead to improving quality of the first guess data. Therefore, the accuracy of the simulated tracks in all selected domains was enhanced and reduced the sensitivity of TC Gonu simulation to the selected domain. Regardless of the great difference in simulated tracks, especially in the case of no use of assimilation, which in turn influences the intensification of the TC, in all of the simulations, the simulated intensity during the intensity peak of the TC is higher compared with the IMD reference data and is less compared with JTWC reference data. Since during the simulations, the sea-surface temperature  has been used constantly and on the other hand, the exact values of sea-surface temperature have a significant impact on the intensity of the TC simulation, the WRF model coupled with an ocean model for accurate determination of sea-surface temperature during simulation can improve the accuracy of the results of this study. There is, of course, another way to improve the quality of the results, when results depend on the selective domains. For every domain, one simulation is performed and the average of the simulations is considered (ensemble forecast). The high amount of time spent in this method is considered as serious trouble. It should be noted that in regional models, the sensitivity of simulations to the selected domains is also highly dependent on the boundary conditions, which should be considered.

Wind-induced waves are the most complex waves among sea waves. In special circumstances such as extreme winds and storms however, it is essential to estimate and predict them correctly. In this research, the height and period of waves was investigated during winter Shamal wind using SPM method and a numerical simulation employing Coupled Ocean-Atmosphere-Wave Sediment Transport COAWST, in the northwest of the Persian Gulf in January 2015. The beginning of the winter Shamal wind coincides with the passage of a cold front over the Persian Gulf, when the wind speed increases and the direction of wind changes to north and northwest. According to the results simulated wave height and period from COAWST show better agreement with field data compared with those of SPM method. This conclusion is also verified with statistical methods such as RMSE. In both methods, the frequency spectrum of the region is single-peak. Besides, the peak of the spectrum of SPM and COAWST, shows under-prediction in comparison with the field data. According to the standard spectrums, the JONSWAP represents the closest wave spectrum of the area under investigation.

The effects of evaporation on the ocean mixed layer in the presence or the absence of Langmuir circulation (LC) and wave breaking (WB) is studied through the Large Eddy Simulation. We have used approximate parameters of summer monsoon for defining the experimental simulations. The simulations were conducted for 33.5 hours and we ignored the first 9.5 hours of results and the simulated parameters is investigated during 24 hours period. We can mention that there is a good matching between diurnal variations of TKE and SST with diurnal changes of latent heat flux in the presence of evaporation and absence of Langmuir circulation and wave breaking and TKE in this case increased between 25 to 100 percent related to the case on the absence of evaporation. Although, evaporation in the presence of LC and WB decreased SST, around 0.060 C in a 24 hours period, but as expected, it decreased SST in the case of presence of LC and WB less than it (0.050 C). Meanwhile, it was found that, evaporation in the absence of LC and WB causes a slight decrease in velocity shear and shear production and an increase in dissipation rate (approximately double), pressure transport, and TKE transport. These two terms of TKE budget balance with dissipation rate close to the sea surface and the diurnal changes of TKE profile is observable just in this case. However, the most effect of adding the presence of evaporation to the presence of LC and WB in TKE budget is summarized to decreasing of shear production in the middle part of ocean mixed layer. It is also found that, in the presence of evaporation, presence or absence of LC and WB doesn't affect the profile of turbulent heat flux; similar to the evaporation which doesn’t change the Stokes production.

This research has been conducted to simulate the wind and wave pattern due to the winter Shamal Wind. This wind is a local systematic wind with the duration of 3 to 7 days which normally occurs in cold months of December to March. COWAST modelling has been adapted to simulate wave pattern. This software is used to couple WRF and SWAN models. For model calibration buoy data located in coastal area of Bushehr, statistical wind data from ECMWF and those data from synoptic station of Bushehr has been adapted. Those results derived from the coupled model showed that maximum wave height during the winter Shamal wind was about 1.1 m higher than that before bellowing the wind. It was also observed that those results derived from the coupled model show reasonable agreement with field data. The bias for significant wave height, wave period, and wave direction were calculated as 0.1, 0.64, and 11.03 respectively.

In this research, LES of ocean mixed layer of the north of Arabian Sea is conducted using PALM (Paralyzed Large Eddy Simulation) model experiments with or without the contribution of wave breaking and Langmuir circulation formed by summer monsoon. Unlike previous studies, wind induced momentum flux is defined in both x and y direction to apply SW wind. According to the main purpose of this work, the effects of wave breaking on the mixed layer is produced by defining random fluctuations on the sea surface, instead of trying to simulate wave breaking. Results showed wave breaking only affects the sea surface, less than 5 m; meanwhile, strips of Langmuir circulation are effective until a depth which is an order of the wavelength. Although, it was found that combining both effects of wave breaking and Langmuir circulation cause a slight decrease of Turbulent Kinetic Energy which can be caused by the distortion effect of wave breaking on the velocity field. Hence, unlike previous studies, the effect of velocity shear don’t play an important role in the magnitude of TKE.

Considering limit supply of fossil energy, and also their role in the increment of environmental pollution, the use of green energies are significantly increasing. Ocean waves are one of those proper resources for producing energy. There are different approaches to extract energy from the ocean waves. One of these approaches is named as SSG wave energy convertor, in which is a combination of a breakwater and energy convertor. Coastal areas are among the most significant part in every country. This is due to its economical, recreational, and political significance. Coastal areas also usually demand more energy in compare with the other places in a country. Employing renewable energies in these area can be a solution to this demand. SSG wave energy convertor is a new approach to gain energy form the wave and also protect the coastal area. This system is usually incorporate with a breakwater in a coastal area, so it can collect up-level water brought to the coast by wave and convert them to electrical energy. It is shown in this research that the height of wave, depth of installation area, and tidal domain are the most significant parameters in the performance of SSG wave energy convertor. It is also declared that, according to literature, this system is not applicable to the coastal area of Persian Gulf. It is however mentioned that, for the applicability of SSG system in coastal area of Caspian Sea, no research has been carried out so far.

The effect of a constructed breakwater on the pattern of wave and current in the coastal area of Jask has been investigated. Wind and wave field data of the year 2003 has been used for this investigation. MIKE software has been employed to simulate the situation for two scenarios. It was found that the breakwater has a significant influence on the current direction. It was found that mean significant wave height and current speed was reduced to 0.19m and 0.021m/s inside the basin, respectively. These values were recorded as 1.23m and 0.049m/s consecutively for the same point, before the construction.

The aim of this research is studying the possibility of upwelling occurrence in the Iranian coastal area of Oman Sea. The occurrence of such a unique phenomenon near the coastal area of Jask made it a suitable subject to the study. To achieve this aim ArcGIS and MIKE3 softwares were employed. Year 2016 was considered for this research. Using ArcGIS techniques the patterns of prevailed wind, sea surface temperature, and concentrated chlorophyll-a using satellite remote measurement data for the area under investigation were taken into consideration. These plots confirm the probability of occurrence of upwelling in the area. For the simulation with MKE3, irregular mesh was designated as horizontal grids. In the vertical direction sigma layer stratification with 10 layers were chosen. After calibrating the model, results derived from the simulation were analyzed around Jask headland. The results indicate the existence of an upwelling during transition period of monsoon (October and November). This was simultaneous with the prevailed wind in the southwestern coast of Oman Sea.

Tropical cyclones develop over oceans as low pressure phenomena. They could be developed further when the conditions are met and cause storm surge. The devastating consequences of these storms in coastal areas reveal the importance of investigation on such subjects. In this research therefore, the variation in the height of water level due to the Ashobaa cyclone has been studies using Flow module of the MIKE 21 software. The study has been conducted at two stations; one near the port of Bushehr and another near the port of Chabahar. The model first was calibrated and validated using field data. After the model validation, two simulations were carried out; one with and one without the effect of Ashooba cyclone. Positive storm surge was observed due to the Ashobaa cyclone in Chabahar station (about 50 cm). The effect of the storm was negligible in Bushehr water level. It was also observed that the storm affected the current speed and direction in Chabahar station. Such an effect was not observed in Bushehr station.

The aim of present study is to estimate the wave-induced force acting on a vertical rigid, a semi-porous and a porous caisson-type seawalls using physical modeling. For this purpose, random sea waves in wide range of wave heights and periods, with variety of water depth were considered for the experimental test. Comparison of the measured values of maximum wave forces (Fmax) for three walls revealed that the wave-induced forces acting on the semi-porous and porous seawalls were more than the impermeable plane seawall. These increaments were calculated as about 28% and 46%, respectively. The semi-porous and porous seawalls showed better performance in wave energy dissipation and in wave reflection decreases in comparison with the rigid impermeable seawall. In addition, it was found that the Fmax increased with the increase of the wave steepness (Hs/Lp) and the decrease of the relative water depth (d/Lp). Based on the lab measurements and multiple regression analysis, new empirical equations have been proposed to predict the maximum wave force acting on each of the above mentioned seawalls.

In this study generation, propagation and run-up of tsunami waves caused by submerged landslide are studied in two dimensions. The governing equations, Navier– Stokes equations, are solved in a Lagrangian form using a mesh-less numerical method by the name of Incompressible Smoothed particle hydrodynamics with a prediction– correction step. The Comparison of the result of this study with experimental data indicates that the deviations between the wave amplitudes are less than 5 cm for every different time steps and also, this model simulated run up and Water surface fluctuations more accurately against the Nasa-Vof until to 3 seconds.

In this paper, the reflection characteristics of vertical rigid, semi-porous and porous seawalls is investigated under regular waves by use of physical models. Several experiments were carried out for a wide range of wave heights and periods and for different water depths in the Soil Conservation and Watershed Management Research Institute flume. Based on these experiments, it was concluded that the porous seawall has better performance than rigid and semi-porous seawall in reducing the wave reflection. The reflection coefficient (Kr) due to regular waves for the porous seawall ranges from 0.57–0.89 and for semi-porous wall it is 0.70–0.94, whereas for the vertical rigid wall, it is found to be more than 0.9. It was also found that the reflection coefficient decreases with the increase of the wave steepness (Hi/L), the relative water depth (d/L), and the seawall porosity (n). A comparison of the results for identical input condition shows that an average the reduction in Kr for semi-porous and porous seawall as compared to the rigid wall is about 18% and 32%, respectively. Based on the measured data, dimensional analysis and multiple regression analysis, new empirical relations have been proposed to predict the wave reflection coefficient. Verifying the predictive formulae with the other experimental results revealed that the equations could be used for practical purposes.

Using data derived from satellite to study sea surface temperature are nowadays very common. This is Possible on the basis of thermal radiation of objects.
In this investigation the satellite images of the MODIS has been used to study the sea surface temperature of the south Caspian Sea. The data was from the whole year of 2012 has been used. These data was first evaluated with those temperature data derived from a buoy in the site. Afterward using 26 different stations over the Caspian Sea the pattern of sea surface temperature were studied for different seasons of a year. It was found that temperature decreases toward east and south. It was also found that average temperature in spring time is less than those of autumn. Parameters apart from weather temperature was suggested to be the reason.

They can be therefore the mouth of a route through the open oceans. Tiab Estuary, located 30 kms away from the Minab city, is a channel overflowed to the Persian Gulf and the Strait of Hormuz. In this field investigation 5 stations along the channel have been selected for measurements. Two cruises were carried out in the 23rd of Mehr and 28th of Aban of 1394 (October 15 to November 19, 2015). In the former cruise the measurements were carried out along the channel for a period of about 12 hours. The latter cruise however, took place at the middle of the channel during one tidal cycle. The instruments used, were a CTD, a Niskin sampler bottle, and a grub. The results derived from this investigation show that the increase in the suspended sediment concentration happen during the ebb condition, specifically at the mouth of the estuary. It was also found that the grain size distribution of the bed load is decreasing from the mouth of the channel toward the basin. At the basin the silt and clay percentage is about 40.71%, while at the mouth of the channel this amount reduces to about 3.48%.

This investigation, which involved the satellite images together with simulation model, focuses on the effect of the sea hydrodynamics on coastal area classification. The study area is the North-West coasts of Oman Gulf. Mike 21 was employed to simulate the hydrodynamics of the Oman Gulf and Aster images were used to classify the coastal area applying Shepard’s method. Coastal classification of the area proposed the secondary coasts cover just 7% of the area including the Sirik headland and Jask regions. Intrusion of land toward the sea for Sirik headland and existence of longshore current in the area are the main reasons. The Jask area is located in transition zone between deep water of Oman Gulf and shallow water of Hormoz Strait, was influenced by marine affects.