Physical Geography Research
Year:2018 | Volume:50 | Issue:1 |Papers Count:12

Introduction The climate change and global warming is a widespread problem in the world. Increase in the greenhouse gases is the reason of this climate change (Dettinger et al, 2004, 2). According to IPPC report, average annual temperature of the earth has been raised from 0. 3º to 0. 6º as a result of spreading the greenhouse gases and this value will increase from 1 to 3. 5º by 2100. The main effects of the phenomenon are drought, extreme flood, snowmelting, storms and increasing air temperature in different regions. These phonemes are in the whole world but they are different from each other. Climate change is an important environmental challenge in recent years...

Introduction: Drought as a complex phenomenon involves extensive research. Therefore, being aware of the drought situation in high risk areas can reduce the damage and problems and enhance the ability to manage natural and agricultural resources. Fortunately, the advent of new technologies for identifying and zoning in high risk areas made it possible to conduct extensive research in this field. Isfahan province is located in the Central Plains of Iranwith dry weather conditions. Decrease in rainfall, over exploitation of wells and misuse of water resources play an important role recently drought in the province. Najaf Abad Plain is one of the Basins located in this province. Placement of a modern irrigation network, a sharp drop in groundwater levels and reduction of water discharge are important factors in this area. Thus, this area is selected as study area in this research. Unfortunately, frequent droughts in parallel with drying up of Zayanderood River brought about undesirable effects on the local economy in the recent years. The aim of this study is to help the researchers and decision makers choose proper management decisions of water resources in this area by identifying the areas susceptible to drought...

Introduction: Land surface temperature plays a vital role in a wide range of scientific researches including climatology, meteorology, hydrology, ecology, geology, medical sciences, design and optimization of transportation services, fire location and especially in calculating the real evaporation and transpiration. There are some determining factors affecting the land surface temperature, such as, the kind of surface elements, topography conditions, environmental conditions, climate condition and the amount of emitted energy from the sun. Recognition and analysis of the relation between the land surface temperature and various factors are so critical. The remote sensing method has a widespread application in preparing the land surface temperature images due to the extensive covering and continuous data. The purpose of this study was to investigate the effects of vegetation cover indices and topographic factors on land surface temperature and modeling the relationship between land surface temperature, topographic conditions and vegetation cover using Landsat 8 satellite imagery...

Introduction: More than half the world‟ s population lives in coastal regions (Bird, 2008). The shorelines are unstable zone that comprises marine and terrestrial domains very sensitive to a variety of geological process; Waves and tides play a most important role in the coastal dynamics, and their mutual interaction accounts for redistribution of the sediment budget causing accumulation or erosion (Dabrio, 2000). The coastal ocean, where land, air and sea meet, is a region of very high physical energy and biological diversity that is heavily exploited by man (Murthy et al., 2002). Tidal flats are low-lying areas where alternately covered by water and exposed to the air each day (Gore, 2010). Analysis of forms and coastal conditions provides a valuable key for coastal management. Many studies have been conducted on the impact of waves on beach (Bagnold, 1939; Ross, 1955; Hayashi and Hattori, 1958). In a related research on western Mokran coastal plain, Shayan et Al. (2014) found that in terms of forming processes and according to the coastline curves and rivers' hydrodynamics, coastal sand masses were located by coastal waves. The aim of this study is to identify the effects of fluvial flows on sedimentological characteristics of shoreline in the western part of Mokran coastal plain, Iran...

Introduction: Precipitation data have been widely used in many earth science applications ranging from crop yield estimates, tropical infectious diseases, drought and flood monitoring. However, in many tropical regions and parts of the mid-latitudes, rainfall estimates still remain a major challenge due to sparse rain gauges. To better develop applications for these regions, it is necessary to have rainfall data with adequate spatial and temporal resolutions. Precipitation data plays the key role in drought monitoring. Rain gauges are the main measuring methods for precipitation but they are concentrated in developed countries and are spare in developing countries and remote areas in the world. Researchers have shown that remote sensing techniques using space-borne sensors can provide an excellent complement to continuous monitoring of rain events both spatially and temporally. Microwave and Visible/Infrared are the main forms of remote sensing technologies; both have varied advantages in terms of imaging accuracy and spatial-temporal resolutions...

Introduction: Thunderstorms are formed by overheating the earth's surface in air masses or in the weather fronts especially cold front (Kaviani and Alijani, 1991). These storms are part of climatic destructive phenomenon that cause irreparable damage as hail, heavy rainfall and thunders to facilities of farms and houses every year. Thus, it is necessary to study this phenomenon. The climatic phenomena such as thunderstorms, as random phenomena, are not exactly predictable and can gain useful information by monitoring them, that this is possible through the laws of probability. Markov chain is a common method for modeling random phenomena (Wilks, 2006). This model is one of the statistical methods to examine the temporal relationship between the various climatic phenomena and it is the most common method to determine the frequency of climatic phenomena sequences...

Introduction: A basic belief in geomorphology says that „ form implies process. ‟ Thus, numerous geomorphic classifications have been developed for landscapes, hillslopes, and rivers. The form– process paradigm is a potentially powerful tool for conducting quantitative geomorphic investigations (Shroder, 2013: 730). Streams typically have similar suites of channel morphologies, with repeatable patterns of occurrence, which resulted in numerous classification efforts (Roper et al., 2008: 417-427). Recent approaches for river classification focus on watershed analysis related to land management and stream restoration, using a hierarchical approach that nests successive scales of physical and biological conditions and allows a more holistic understanding of basin processes (Shroder, 2013: 739)...

Introduction: Identification of the phenological stages and the heating and chilling accumulation of fruit trees on the basis of the climatic conditions is of great importance to discover the potentialities and to identify the compatible species. Most deciduous trees need chilling and heating accumulation to have complete growth. In fact, chilling accumulation is necessary to overcome the dormancy or sleep period and heating accumulation is necessary for flowering and the change of phenological stages. The study of the phenological behavior of fruit trees is important as the impact of environmental conditions. Weather and climate constitute a key determinant in successful production of deciduous fruits. Identifying the phenological stages and climatic condition requirements for fruit trees can help promoters and gardeners to choose the best and most suitable varieties...

Introduction: Isfahan province is one of the driest provinces in central part of the country where two-thirds of its water requirement is supplied by groundwater resources. In recent years, with population growth and the increase of water demand in different sectors of agriculture, industry, drinking, and health, groundwater resources have faced a lot of pressure. Thus, understanding the behavior of the groundwater body and its long term trends are essential for making any management decision in the areas. Mann– Kendall statistical test has been commonly used in many researches to assess the significance of trends in hydro-meteorological time series. Geostatistical analysis has been theoretically defined and applied by many researchers and they have emphasized that geostatistics is a management and decision support system tool for analyzing spatial and temporal variations of groundwater level fluctuations. Geostatistical approaches can provide more helpful, reliable and efficient tools to increase the number of measurement points at un-sampled locations, and variogram analyses for examining structural relationship of data (Rakhmatullaev et al. 2011)...

Introduction: All studies in the field of assessment of climate change impacts needs climate data with different spatial and temporal scales. The lack of temperature and precipitation data with high spatial resolution is a major limitation to analysis of future climate change. In addition, the output of the models has the error that needs to be corrected; otherwise, they will make a significant bias for assessing the effects of climate change. Therefore, identifying the best regional climate model for downscale the global climate models is essential to better understanding of climate conditions in the local and regional scale. In the last few years, use of various regional climate models for producing a multi-member set of the downscaled data in the CMIP5 project by World Climate Research Program (WCRP) in action with Coordinated Regional climate Downscaling Experiment (CORDEX) was established as an input to the researches about the impacts of climate change and adaptation ways. The main objective of this research is accuracy evaluation of different model outputs of the CORDEX project with different domain and resolution in Iran...

Introduction: Among the natural disasters, flooding can cause heavy losses on the agriculture, fishery, housing and infrastructures. It strongly affects the economic and social activities. The use of modern science, especially remote sensing and GIS techniques helps the planners to assess the risk map of natural hazards such as floods for a region in the least possible time. Multi-Criteria Decision Analysis (MCDA) provides methods and techniques to analyze complex decision problems which often includes non-comparable data and metrics. Nekarood watershed with its special properties is prone to serious and devastating floods. The aim of this study is to assess the risk map of flooding in Nekarood Basin using multi-criteria decision and based on intuitive reasoning...

Introduction: Heavy rainfalls in small basins can lead to devastating flash flood with fatalities and tremendous damages. Thus, forecasting of heavy rainfall is an important step in development of a flood warning system. Various models were used for rainfall forecasting such as artificial neural network (Moustris et al. 2011), time series models (Sapmson et al, 2013), wavelet theory (Partal and Kiş i, 2007), and regression tree model (Fallahi et al, 2011). In recent decades, the Numerical Weather Prediction (NWP) models were widely applied for weather prediction. Numerical weather predictions (NWPs) usually have uncertainties in initial conditions and model structures. In recent decades, Ensemble Prediction Systems (EPS) have been increasingly used to capture the uncertainties in NWPs. Several operational centers, including the European Centre for Medium-Range Weather Forecasts (ECMWF), the National Centers for Environmental Prediction (NCEP), the Japan Meteorological Agency (JMA), and the United Kingdom Meteorological Office (UKMO) offer valuable operational numerical predictions at a global scale (Hsiao et al, 2013)...