Physical Geography Research
Year:2018 | Volume:50 | Issue:2|Papers Count:17

Introduction: The rivers usually affected by erosion and sedimentation are subject to various changes in transverse and longitudinal movements and variations in river bed elevation, particle size and geometrical properties. Erosion and sedimentation studies provide the opportunity to identify the behavior of river morphology and the effects of different measures to reorganize its behavioral performance on quantitative and qualitative data. Arvand is a vital river in southwestern Iran serving as the Iran-Iraq border. The purpose of this research is to determine the area of erosion and sedimentation in relation with flow velocity and pollution dispersion in the banks of Arvand River using Coherence model and GIS...

Introduction: Cryopediment and cryoplanation are created in arid and semi-arid regions. According to the studies performed around the world, they are usually formed in the preglacial climatic conditions. The cryopediments are very gently concave erosional bench-like landforms that are usually cut into the base of valley sides or marginal slopes of highlands and mountains. The cryopediments developed by cryogenic processes in cold climates of the periglacial climate-morphogenetic zone are mostly created with the presence of permafrost. Cryopediments are developing due to the activity of a range of cryogenic processes whereby frost action, nivation and other processes cause to retreat back scarps. Cryoplanation terraces are bedrock steps or terraces on ridge crests and hilltops. The tread or “ flat” area is 10 to several hundred meters wide and long and the slopes from 1 to 5 degrees parallel to the ridge crests...

Introduction: Fractal analysis is one of the quantitative modeling of river networks. By determining the fractal dimension of linear structures such as faults, canals, and meandering river paths, it is possible to estimate many features. Fractal of figure is a component with static geometric patterns that illustrates the general pattern of a phenomenon. The initial studies to create quantitative, mathematical, and geometric proper models for river networks were mainly developed by Horton in 1932 and 1945. The study of relationship and comparison between quantitative parameters with fractal geometry goes back to the last two decades.

Introduction: Air inversion is a climatic phenomenon causing increases in the aggregation of pollutants in highly populated and industrial cities. Hence, changes exceeding the air quality threshold would have extensive problems for the citizens. Attention of managers to this problem is mainly referred to as polluting factors. However, in case this phenomenon exists during all the seasons and as the polluting factors have no great changes during the year, some factors can lead to exceed the air quality index from the threshold value. Hence, there can be an approach for reducing the continuity of this situation, if continuity of the inversion leads to such a condition.

Introduction: The Tabas zone in the central Iran hosts a series of active landforms, which developed during the late Quaternary. Evolution of these landforms has been controlled by many active faulting and folding systems that have developed since Quaternary. Iran forms a relatively compact zone of active continental deformation resulted from the northward collision of Arabian plate with Eurasia plate during late Cenozoic times, which continues to the present‐ day at a rate of 25 mm/yrs based on GPS data. The evidence of active tectonic in different parts of Iran has been studied by many researchers. The arid climate, low rates of erosion, and minimal vegetation cover across the majority of the country result in excellent preservation and exposure of surface deformation produced by active faults. Geomorphic indices are useful tools in the evaluation of active tectonics because they can provide rapid insight concerning specific areas within a region which is undergoing adjustment to relatively rapid and even slow rates of active tectonics.

Introduction: Over the last decades, sediment fingerprinting technique relative to the experimental models for erosion and deposition processes is now used for its higher reliability and lower uncertainties. Its reliable information give the best indication of sediment yield produced by spatial sources of a catchment and let authorities know how take conservative operations and proper actions across the catchment to stop the soil erosion. Therefore, identification of the dominant processes and sources generating the sediment within its catchment are vital. The western shore of the Lake Urmia, NW Iran, the world’ s second largest hyper-saline lake has now retreated more than 7 Km from the shoreAs a result, sand dunes and sand ridges are appearing across its western margin.

Introduction: In recent decades there has been an increasing interest in the earth natural events and this developed three concepts of geodiversity, geotourism and geoconservation. The concept of “ Geodiversity” can be defined as the natural diversity of geological (rocks, minerals, fossils), geomorphological (land form, physical processes) and soil features. It covers the assemblages, relationships, properties, interpretations and systems.

Introduction: Continuous spatial data of environmental variables are often required for environmental sciences and management. However, information for environmental variables is usually collected by point sampling. Thus, the methods generating such spatially continuous data from the point samples become essential tools for many environmental analyses. Spatial interpolation is the procedure of estimating the value of un-sampled points using existing observations. The methods for spatial interpolation can be classified into two main categories as deterministic and geostatistical. Deterministic interpolation techniques including Inverse Distance Weighting (IDW), Radial Basis Function (RBF), and so on calculate the values of un-sampled areas based on the known values of the sampled points and create surfaces from measured points. However, Geostatistical interpolation techniques, e. g. Kriging use statistical properties of the measured points to quantify the spatial autocorrelation among the measured points and account for the spatial configuration of the sample points around the estimation location...

Introduction: A shoreline is defined as the line of contact between land and a body of water. The most effective processes on the changes of coastal morphology are wind, wave, marine current, tides and human activity. Prodelta of Arvandrud delta, as the largest delta of the Persian Gulf, has very low slope in foreshore. Historical data of the last 60 years show that the shoreline experienced transgression and degradation several times. The aim of this study is to assess shoreline displacement rate and the factors affecting that.

Introduction: Air temperature is one of the most important climate measurements in the human environment, which directly affects the physical and biological processes of the ecosystem. Understanding this climate measure can be the basis for understanding many climatic processes, especially evapotranspiration (due to the climate of Iran). Reanalysis have been used in recent years in many studies, including the studies about climate trends, climate modeling, and the assessment of renewable resources, and their high accuracy. The purpose of this present study is to evaluate the accuracy of the open-baseline base temperature data of the European Centre for Medium-Range Weather Forecasts (ECMWF) of the ERA-Interim version with a 0. 125 × 0. 125 arc-spatial resolution in a survey with observational data from the weather stations and the National Bassoon database. In this regard, we have evaluated the temporal changes of the temperature of Iran.

Introduction: Climate has a key role in plant growth process and, therefore, it is clear that climate change will directly affect sowing and harvesting of cultivate crops. Many scientists used APSIM to simulate the phenology and yield of canola. To understand the impacts of climate change, it is necessary to project the future climate based on different emission scenarios. These results must be combined with simulation models to predict crop yield and phenological stages. Assessment of the impacts of climate change on phenology and yield of agricultural crops in different regions show different results. The aim of this study is to investigate the impacts of climate change on phenological stages and yield of Canola by APSIM-canola modules.

Introduction: Water has been a major issue for sustainable development in the twenty-first century. It has been so essential that some experts believe that water issues will become a major crisis in the coming years and will result in regional wars and even a world war to gain dominance over water resources. Instability of water resources resulted from drought or water shortage has affected many countries throughout history, especially in the arid regions. This instability had caused many losses and resulted in many severe consequences in the economic, social and environmental sections. Zayandeh-Rud basin in central Iran is highly encountered with water problems. Zayandehrood River originates from Zardkuh Bakhtiary Mountains. It is the most important river of this region for the development of agriculture, a necessary supply for industry and an important supply for drinking water. It can also feed all of the economic activities.