جستجوی مقالات مرتبط با کلیدواژه "سیستم دینامیک" در نشریات گروه "جغرافیا"

today, the urban population of the world is increasing and this increasing and unbridled growth has involved the residents of the cities with many problems and has caused all kinds of insecurity and social anomalies. The climate crisis is one of the main challenges of the 21st century which leads to social unrest and threatens livelihood, stability, and prosperity. The purpose of this research is to evaluate and analyze the role of urban planning in creating social security in the conditions of climate change in Ahvaz metropolis. The research method is descriptive-analytical and based on library documentary studies and field surveys.

In this regard, first, the trend of changes in climatic parameters for a period of 50 years (seasonal and annual) of the Ahvaz synoptic station was investigated using the Mann-Kendall statistical test, Then, the structural consequences of climate change in Ahvaz city was modeled using the system dynamics approach. In this research, which is based on a systemic approach, The effective and efficient factors involved in the subject and the relationships between them were investigated through causal and effectual loops in Vensim software.

The findings of the research show that during the studied period of climate changes in the city of Ahvaz, it has shown itself in the form of increasing temperature and decreasing precipitation, increasing relative humidity, and decreasing solar radiation. During the 60-year process, the average temperature was (48) degrees Celsius with an increase of (0.01) degrees every year, which shows an increasing trend. Also, the investigation of the annual rainfall changes in Ahvaz station during the 50-year process, with an average rainfall of (72) mm and a decrease of about (0.0186) mm per year, there has been a decreasing trend.

The results show the fact that climate changes in Ahvaz city have various social-security consequences. Direct effects on various facilities-infrastructure and planning-management sectors, including reduction of investments, damage to infrastructure, marginalization and increase in costs, the most important of which are reduction of quality of life, reduction of welfare and social anomalies and insecurity in urban spaces.

Drought changes for optimal operation management of water resources well is the sensible. That's why last round of very extensive research on modeling drought in the world and Iran is and using their water projects and has conducted numerous hydraulic. One of the goals dynamic systems modeling potential policies to improve system performance. Modeling SPI index as an indicator of the country's drought situation stations using radial neural network model for each station was done. Independent variables neural network, relative humidity, temperature and lack of objects, which were selected according to their impact on precipitation. SPI index is the dependent variable. In total period of 42 years calculated by SPI, 12-month and 348 standard score by calculating the SPI 24-month, 336 standard score is obtained for each station. At all stations, ETo values from January to July to December increased and then fell in July to its maximum level reached in all stations. The highest average monthly ETo values in Abadan and Ahvaz stations in July and 18/232 and 16/214 mm respectively happened.

Several factors in the development of effective drought , which change and intervene in order to keep them from victory and their occurrence , and it is impossible to be foreign humanOn the same principle, the possibility that lives up to these requirements in any region of the Earth's surface country rich and poor, wet and dry, developed and developing, etc. occur.In this study, meteorological data gathered from 19 weather stations in Iran during 2003-1961 using a composite index (CI) of meteorological drought analysis of spatial and temporal characteristics of drought in Iran. The frequency, scope and severity of drought calculated to reveal the spatial and temporal patterns in different sectors were examinedAnd then the system dynamics approach was to simulate the effects of different aspects. . ETo values in all stations in July reached its highest value. In all stations, ETo values from January to July increased and is then reduced until December. ETo Iran in the period 1961 to 2003 the average annual total is about 1154 mm. The annual average of 9.2 millimeters per year upward trend in Iran ETo (mm / yr) during the period indicated. Most of ETo in the year 1970 (mm / yr 1309) and then in 1999 and 2001 (mm / yr 1308) happened and minimum on the years 1979 (mm / yr 893) and 1990 (mm / yr 974) Find respectively.

The progress and industrialization of human societies in the past century have intensified the concentration of greenhouse gases and led to climatic change of the different parts of the world. The sign of this climatic change is the long-lasting change in the meteorological parameters.Drought is a serious hydrological phenomenon that may happen due to not receiving rainfall in a vast region and in any climatic conditions. This phenomenon has considerable effects on the economy of environment and water sources. Thus, the study of the climatic impacts of drought can play an important role in the planning and management of water source systems, especially during a period of climatic drought. Paying attention to the climatic change and its effects on water sources is of great importance. Unfortunately, it is not studied sufficiently in our country. In this research, we aim to identify the effects of climatic changes on the time and place distribution pattern of drought using system dynamic approach. This approach is used to study several factors and dual relation of the climatic changes with the time and place trends of drought simultaneously.