علوم غیرزیستی دریا
Ramin Alaie Ruozbahani; Hamid reza Jafari; Gholamreza Nabi Bidhendi; Hassan Hoveidi
Abstract
Over the past few decades, the structure and cover pattern of land in the Khuzestan coastal zone has also not been immune to such changes. Therefore, monitoring the spatial combination and arrangement of Land cover/Land use and its changes in order to identify the current threats and opportunities is ...
Read More
Over the past few decades, the structure and cover pattern of land in the Khuzestan coastal zone has also not been immune to such changes. Therefore, monitoring the spatial combination and arrangement of Land cover/Land use and its changes in order to identify the current threats and opportunities is considered essential. The aim of this research is to monitor or the trend of changes in landscape mosaic in the coastal regions of Khuzestan Plain in response to the growth and development of human activities. In this research, Landsat images were used across two time 2000 (Landsat 7 ETM+) and 2015 (Landsat OLI) for extracting Land cover/Land use map. In order to monitor the trend of changes, four metrics of land appearance MNND, MPS, PLAND, and NP have been used. The obtained results indicated that the spatial combination and arrangement of the landscape in the studied region have found greater heterogeneity and complexity with fragmentation, attrition, and patches. Further, with the addition of two types of use including sugar cane cultivation and industry as well as fish farming basins along with the development of industrial construction units have caused dramatic transformations in the land structure in terms of combination, continuity, and extension of valuable ecological patterns. Riparian forests with increase in the number of patches and 50% reduction in the PLAND metrics and wetlands with increase of 58% of NP metrics and 71% in MMND metrics in these regions with the maximum level of fragmentation are the most vulnerable environmental patterns.
علوم غیرزیستی دریا
Davood Mafi-Gholami; Abolfazl Jaafari
Abstract
In general, fishing activities are considered as one of the most important environmental disturbances in increasing the vulnerability of the mangrove ecosystems due to their destructive effects on the process of sedimentation and wave currents, decreasing biodiversity, and introducing oil pollutants ...
Read More
In general, fishing activities are considered as one of the most important environmental disturbances in increasing the vulnerability of the mangrove ecosystems due to their destructive effects on the process of sedimentation and wave currents, decreasing biodiversity, and introducing oil pollutants into these ecosystems. Therefore, investigating and mapping the intensity of fishing activities in mangrove habitats are of great needs in conducting the vulnerability assessment and providing managerial solutions and empowerment of these ecosystems to minimize and compensate the damages caused by environmental hazards. The aim of this study was to investigate, determine, and delineate and the intensity of fishing activities in the mangrove habitats of the Hormozgan province. To this end, the map of intensity of fishing activities was prepared in Khamir, Qeshm, Tiab, Sirik and Jask habitats through mapping the mangrove habitats, drawing 598 cell networks of 4 × 4 km in the coastal waters and the available geospatial data, and number of vessels in the fishing ports of the Hormozgan province. The results showed that in terms of the geographic distribution and the number of vessels in the fishing ports of the Hormozgan province, the intensity of the fishing activities in the mangrove habitats is ranked as follows: Khamir habitat> Qeshm habitat> Tiab habitat> Jask habitat> Sirik habitat. The results of this study can be used as a prerequisite for assessing the vulnerability of the mangroves of Iran.
علوم غیرزیستی دریا
Davood Mafi-Gholami; Akram Nouri Kamari
Abstract
In general, the analysis of the changes in the area of mangroves and its relationship with changes in the surface water flow into the coastal environment can provide valuable information on the adverse effects of climate change on these ecosystems. Therefore, in this study, the relationship between changes ...
Read More
In general, the analysis of the changes in the area of mangroves and its relationship with changes in the surface water flow into the coastal environment can provide valuable information on the adverse effects of climate change on these ecosystems. Therefore, in this study, the relationship between changes in surface water flows into the coastal environment (occurrence of hydrological drought) and changes in the areas of mangroves in Khamir, Tiab and Jask habitats were investigated in a 30-year period (1986-2016). The results of this study showed that with the occurrence of severe and extreme hydrological droughts in the period after 1998 in the southern coasts of Iran, areas of Khamir, Tiab and Jask habitats also reduced in this period compared to the wet period before 1998. High correlation between hydrological drought occurrence and changes in mangroves areas in different habitats also indicate the adverse effect of reducing the fresh water entering the coastal environment on the areas of mangroves. The results of studies on mangroves in other parts of the world have also shown that reducing rainfall and fresh water inputs to the coastal areas reduce the areas or decrease the progression rates of mangroves. The results of this study by providing accurate information on mangroves responses to consequences of climate change can play an important role in the efficiency and success of adaptation programs to climate change and the conservation and development of mangrove forests in Iran.
علوم زیستی دریا
maryam razmi; hosein Mohammad Asgari; ali Dadolahi-Sohrab; seyyed mohammad jafar Nazemossadat; seyyed hosein kh
Abstract
Coastal environments are considered the most sensitive system environments. In terms of environmental Coastal areas because of the sensitive and productive ecosystems have high importance and value. Having knowledge of the coastline’s behavior can help of the coastal better management. The aim ...
Read More
Coastal environments are considered the most sensitive system environments. In terms of environmental Coastal areas because of the sensitive and productive ecosystems have high importance and value. Having knowledge of the coastline’s behavior can help of the coastal better management. The aim of this study is to assessing the application of the OIF utility index factor in the assessment of coastline changes in Dayyer city, Using Landsat satellite images sensor TM and OLI 1991 and 2014 and the software are 2013®MATLAB and ArcGis 9.3. For the separation of land and water, OIF index value for all different band combinations in the application MATLAB® 2013 was calculated and then high-pass Sobel filter with 3 × 3 masks was applied to the images. Then digitization process during different periods in application environments ArcGis 9.3 was done manually and with high precision. The results of the survey the coastline from 1991 to 2014 show moving the coastline to the sea side (sedimentation) and landward (erosion), Which totals 33/784 square kilometers sedimentation and 9/132 square kilometers erosion shows from 1991 to 2014, in Dayyer city occurred because of the construction of piers, installations manmade and natural factors.
مهندسی دریا
ahmad rezaie mazyak; mehdi sanayei
Abstract
The main goal of using floating breakwaters is to provide the sheltered area of calm water in the coastal zone. In present research, for analyzing hydrodynamic modeling of pontoon floating breakwaters the AQWA module of ANSYS software has been selected. The main parameters that have been considered in ...
Read More
The main goal of using floating breakwaters is to provide the sheltered area of calm water in the coastal zone. In present research, for analyzing hydrodynamic modeling of pontoon floating breakwaters the AQWA module of ANSYS software has been selected. The main parameters that have been considered in this research are pattern of significant wave height, wave period, and draft and width of floating pontoon. Wave transmission coefficient can be obtained from water surface changes in any point of leeward. Results of numerical modeling demonstrate that a pontoon floating breakwater with relative width greater than 0.4 have appropriate performance. Also it has been found that the transmission coefficient of pontoon floating breakwaters will be in the range of 0.35 to 0.60 if the relative wave period changes in the range of 1.5 to 4.
مهندسی دریا
Seyed Amin Asghari Pari; Seyed Malek Mohagheghiyan
Abstract
Turbidity currents are one of the most fundamental factors that transferring sediment near the dam. In this article, the effect of roughness, pattern, height and the shape of roughness in the floor on controlling turbidity current are studied using finite elements numerical method by ANSYS-CFX. For solving ...
Read More
Turbidity currents are one of the most fundamental factors that transferring sediment near the dam. In this article, the effect of roughness, pattern, height and the shape of roughness in the floor on controlling turbidity current are studied using finite elements numerical method by ANSYS-CFX. For solving turbulence equations are used K-e method. After calibrating of model has done, at the first, simulated flow without roughness and then three shape of roughness pyramid-shaped, round edge cylindrical and cubic with two alternative zigzag and consecutive, with 5 different height and for subcritical and supercritical flow regime are modeled. The results indicated that with the increase in height of the roughness and cross flow and with zigzag arrangement, reduced the turbidity current discharge. Also the effect of roughness on controlling subcritical turbidity current are more than supercritical flow.
مهندسی دریا
Mahpeykar, Omid; Masoud Sadrinasab; , Morteza Bakhtiari; , Nima Shahni karamzadeh
Abstract
Developed countries are using renewable energy in order to minimize emission of harmful gases, and many countries are studied new designs. Which uses of the later is increasing rapidly. One of the cleanest renewable ocean energy is using the potential of tidal energy. Studies show that the best place ...
Read More
Developed countries are using renewable energy in order to minimize emission of harmful gases, and many countries are studied new designs. Which uses of the later is increasing rapidly. One of the cleanest renewable ocean energy is using the potential of tidal energy. Studies show that the best place for obtaining tidal energy in the Persian Gulf and is the Doragh Estuary, which is located in the northern part of the Persian Gulf. This estuary is the unique area in the Persian Gulf with more than 5 meters tidal range which has the potential to produces maximum tidal energy in this region.In this study, a physical model of Doragh estuary is constructed and employed a pumping system as well as a source of water to create tide in the model. Also two dams are made somehow in the model to reserve water behind these dams during ebb and flood. A propeller which is connected to a turbine is fixed to one of the dams, and works during both ebb and flood in which transfers movement of propeller into electricity. Electrical current is connected to an instrument which show the amount of produced electricity in the model. The results of the model show that by increasing tidal range, electricity increases electricity exponentially. In this experiment the model run with different scenarios to get maximum efficiency which is recorded to 15% during flood and producing of electrical power can increased by 30 to 50 percent during both ebb and flood.
علوم زیستی دریا
m m
Abstract
Nowadays, because of bad urban, agriculture and industrial management many of water resources suffer quality issues. Remote Sensing play a key role in water quality assessment and management. Many of pollutions can be observed using remote sensing images, so it can be a very useful tool for water resources ...
Read More
Nowadays, because of bad urban, agriculture and industrial management many of water resources suffer quality issues. Remote Sensing play a key role in water quality assessment and management. Many of pollutions can be observed using remote sensing images, so it can be a very useful tool for water resources management. Because of wide spreading of water bodies, field work cause to increase in time and cost of studies, so using satellite images can be an alternative. Quality monitoring such as salinity, water color, suspended sediment may measured using satellite images. For assessing Water Quality, some empirical relations should be found to relate water quality to one or some spectral bands. Water Quality parameters such as color, chlorophyll, Suspended Sediment and Salinity may be assessed using Remote Sensing techniques. Remote Sensing can be used for assessment and monitoring algal concentration in lakes and water resources. Increase in chlorophyll cause to reduction in Blue band reflectance and increase in Green band reflectance. For assessing Water Quality, some empirical relations should be found to relate water quality to one or some spectral bands. In this study, Chl-a, concentration of Tripton and Turbidity of a small part of the Persian Gulf was estimated applying a bio-optical model.
علوم غیرزیستی دریا
Hosein Farjami; Mohammad Taghi Zamanian,; Akbar Rashidi Ebrahim Hesari,; Seiied Ali Azarmsa,
Volume 11, Issue 1 , November 2012, , Pages 41-48
Abstract
Wind is a major factor which induces oceanic currents and many theories including the Ekman theory have considered the wind induces currents. In this paper a numerical process has been used for forecasting of oceanic currents based on this theory. The survey has been done in an artificial five layer ...
Read More
Wind is a major factor which induces oceanic currents and many theories including the Ekman theory have considered the wind induces currents. In this paper a numerical process has been used for forecasting of oceanic currents based on this theory. The survey has been done in an artificial five layer oceanic basin with smooth bottom of 120 meters, considering the geographic position of Persian Gulf. Primitive equations were solved on earth’s spherical coordinates system with sigma as vertical coordinate by finite element method. Vertical profile of predicted current vectors showed the complete formation of Ekman Spiral in the basin. This experimental simulation is a new approach for confirmation of Ekman Theory.