Physical Geography Research
Year:2013 | Volume:45 | Issue:2 (84)|Papers Count:8

Sustainable management requires knowledge and a good understanding about processes of shoreline changes. Shoreline change detection can ensure health of beach areas. The study area is located in the coastline of the Caspian Sea in an approximate length about 15 km in Sefidrud Delta. Delta Sefidrud have been formed in different periods that experienced symmetrical or semi-symmetric and asymmetric morphologies on the shoreline. General currents of the Caspian Sea have a west to east direction. Sea dynamics in the direction and sediment movement have the greatest impact on the shoreline. Hence, the shoreline should always be oriented towards the estuary of East River Delta, while aerial photography and satellite imagery shows something contrary. Thus, in addition of waves and the coastal currents dynamics no changes have occurred along this direction during the Holocene, so, some other factors may contribute to forming of the delta with periodical differences in geometry. Therefore, contribution of these factors should be characterized in the present curvature of the shoreline. The purpose of this study is to evaluate variables influencing rapid changes and dynamics of coastline over the last sixty years.

In climate, Iran is a part of the Afro-Asian belt of deserts. This climate is almost rainless and has very arid climatic condition. The desert soils are mainly covered with sand and pebbles. These materials are largely carried by the wind. Dasht-e Kavir is a large desert lying in the middle of the Iranian plateau (at longitudes from 58o to 53 and Latitudes from 36o to 32). As the desert is surrounded by Alborz and Zagros Mountains, the moisture cannot penetrate into the desert area. In summer, Establishment of the Azores high pressure account for the dry conditions in the Dasht-eKavir. These conditions reduce the total amount of rainfall and the lack of sufficient vegetation in the Desert. Therefore, Wind has a high potential for Erosion, Transport and accumulation of Sediment. As a result, the conditions for the formation of Ergs and Sand sheets are provided in the desert. Furthermore, Dasht-e Kavir was surrounded by various high lands so that they are the most effective factor in the deposition of sand and switching in location of Ergs. The temperature difference in Desert mountain ranges is always a generator for different daily local wind. The local winds can play important role in morphological changes of the Desert Surface.

Ecotourism as a shortened term of Ecological Tourism is the possible leisure activities of people in the nature. It is based on purposeful trips for visiting nature and cultural and spiritual perceptions of natural attractions and also for enjoying a variety of natural phenomena (Rezvani, 1380). Generally, visiting nature makes ecotourism different from other kinds of tourisms (Zahedi, 1382).Dynamic nature and a variety of leisure activities available in coastal areas, has made the areas highly favorable for tourists. This has transformed coastal areas into one of the most influential regions for local and national economies in the world. Climate can also affect attractiveness of places for tourists and may have a major role in selection of tourist sites. Based on past evidence, climate can be a key factor in vacation planning and satisfaction of vacation experience so it is known as a central stimulus for vacation planning. One piece of information that tourists need to know for vacation is the climate of destination cities. Most of the tourists take this factor into account for choosing their destination. However, climate has a low presence in tourism literature, while it is highly important in vacation planning of tourists. Considering above-mentioned issues, no comprehensive and detailed work is carried out on standard conditions of swimming in coast areas of Caspian Sea. This paper has studied the subject as the first.

One of the main principles in the process of spreading floodwater is use of the water in arid and semi-arid areas for an efficient utilization of both the water and the soil. Executing more than one decade research plans on floodwater spreading in the realm of Iran aquifers have proved that the plains and deserts have got a great potentiality in order to supply water and to prevent the irreparable damages of flood and desertification. The first and the most important step in executing a floodwater spreading project is a suitable zonation for water spreading and to penetrate it into underground water tables. It is impossible to use Geographical Information Systems (GIS) in order to site select potential zones for floodwater spreading without using Multi-criteria Decision Making system (MCDM). Floodwater spreading plan except to gather water and transfer waste water to nourish the aquifers by the purpose of reducing soil erosion and improving the vegetation is studied with a multi-purpose attitude. One of the most appropriate tools in site selection for certain zones is the application of computerized conceptual models in the Geographic Information System (GIS) environment. Because there are a variety of models in this field, identifying and introducing the best model is one of the most essential actions in executing these operations or plans. We have tried in this research to observe the important factors and criteria such as: geocentric factors (geology, geomorphology and soil), hydrology, geohydrology, slope and physiographic characteristics of basin and also discussing certainty or uncertainty of effective locative data in site selection of the potential zones to spread floodwater. On the other hand we have attempted to identify and introduce the most suitable model in site selection of the potential zones to spread floodwater in the Garabaygan aquifer basin in Fars, Iran. FAHP model and GCA with some of their operators are the selective models in this research.

Prediction of sediment load is used in a wide range of topics to estimate volume of dams, sediment transport in rivers and etc. In recent years, artificial neural network was used in rainfall-runoff modeling, prediction of discharge intensity and estimation of sediment load. Sediments are sources of pollutions such as chemical compounds. The results of the many researches indicated the effectiveness of modeling in hydrological predictions.Jin (2001) used Artificial Neural Network (ANN) method to assess the relationship between discharge and sediment load and stated that the ANN model can achieve better results than the sediment rating curves. Tayfor (2002) used the neural network model in sediment transport and concluded that this model was more predictive than the physical models. In this paper, Neural Fuzzy Inference System (ANFIS) is used as a non-linear model to estimate the suspended sediment load. The comparisons showed that the ANFIS method has achieved better results in predicting the daily suspended sediment load than MLR models and SRC models. Dogan et al (2005) also used Artificial Neural Network model (ANN) and fuzzy logic (FL) to predict monthly suspended sediment load in the Sakarya River Basin in Turkey.

Drought is a temporary and recurring meteorological event which results from the lack of precipitation over an unusual extended period of time. Early indication of possible droughts can help set out drought mitigation strategies and measures, in advance. Therefore, the drought forecasting plays an important role in the planning and management of water resource systems.Stochastic models have been extensively used for forecasting hydrologic variables such as annual and monthly stream flow, precipitation, and etc. in the past. But they are basically linear models assuming that data are stationary, and have a limited ability to capture non-stationaries and nonlinearities in the hydrologic data. However, it is necessary to consider alternative models when nonlinearity and non-stationarity play a significant role in the forecasting. In the recent decades, artificial neural networks have shown great ability in modeling and forecasting nonlinear and non-stationary time series due to their innate nonlinear property and flexibility for modeling.The aim of this study is to compare the stochastic and artificial neural network models in forecasting the standardized precipitation index (SPI) in some stations of Iran. This is because of the multiplicity of drought occurrences in Iran and the necessity to determine the best forecasting model.

Chemical concentration of plants is indicator of their biologic status. Among the many foliar chemicals in plants, nitrogen (N) is an important indicator of photosynthetic rate and overall nutritional status. Plants usually take up nitrogen in the nitrate form (NO3-) and one major source of nitrate leaching is fertilizer applied to the crops. Supplying inadequate N may decrease crop yields and increase the N fertilizer (more than the needs of plants). In addition to economic loss, nitrate ions may move into surface and ground water and contribute to eutrophication of lakes and streams and raise health problem (Liaghat and Balasundram 2010). Thus estimation of nitrogen content is important in many agricultural studies.Traditionally leaf nitrogen content is measured in the lab using different chemical methods. Nitrogen analysis either by the Kjeldahl or Dumas method is expensive and requires specialized equipments. An alternative method for N determination is the digestion of potassium persulfate (K2S2O8). Persulfate digestion requires only a modest initial investment and has few environmental risks. The common problems of all above mentioned approaches are the facts that they are time consuming, expensive and destructive approaches. The advent of remote sensing has proved its usefulness as an alternative measure to these traditional approaches.The aim of this study is to estimate canopy nitrogen content in vast area in northern part of Iran, Gorgan, using remote sensing vegetation indices. Later it was used in calibration of different vegetation indices and for estimation of CNC of a vast area in Gorgan, Iran.

Air pressure, also known as the atmospheric pressure, is the magnitude of force exerted by the atmosphere on a certain extent of surface area. The average of atmospheric pressure is about 1013 hpa at the sea level. The air pressure is considered as mean, maximum and minimum sea level pressure. The sea level pressure is often investigated as the first step in the study of meteorological events. Lots of researches have been conducted about sea level pressure, map patterns of the pressure in various regions and their linkage to some of indices or different climatic elements. A number of these investigations will be mentioned as the following.Jones and Simmonds (1993) analyzed the spatial and temporal anomaly of sea level pressure and the center of cyclogenesis in the northern hemisphere. Their findings indicated the significant difference between cyclogenesis centers and the maximum anomaly of the sea level pressure in high latitudes. The highest anomaly of sea level pressure has also been indicated to be in latitudes from 30 N to 40 N and cyclogenesis centers have been seen around 5 to 7 degrees in the north of the region.