نشریه اطلاعات جغرافیایی (سپهر)
پیاپی 53 (بهار 1384)

This paper describes map’s generalization according to different needs of users by using a multi-scale database. The base of such production is the analysis of the maps’ requirements according to users’ demands, and indicates various needs and limitations of the cartography demanded by the user. The main basis of this examination is the combination of two cartographic attitudes: 1. Utilization of multi-scale database which includes two or more levels of details; and 2. Using cartography generalization methods. This paper has been designed and conducted for selective topics (information classification) and discusses and analyzes implementation of choices of multi-scale database and generalization of parts of framework. The importance lies in optimal combination of these two methods, namely matters that are resolved by multi-scale database, as well as actions that must be performed through generalization process.

The space that lies beyond the blue sky is completely dark, because light can not travel as fast as usual through diluted air or vacuum. There is total silence in the space, and however the spaceship moves fast, no sound is produced by it in the space. Sound echo, shock waves and speaking have no effect in space. Geographic factors take different meanings in space. Thus, any space activities require familiarity with necessary concepts for maneuvering in modelling environment.

The lands on the right side of the Nekooabad Diversion Dam are located at a place near the upstream part of the Zayandeh Rud river’ basin, and due to this position it is at first thought that in principle it should not face any shortage of water, and water distribution management seems to be a simple matter. However, with any change in the amount of available water, including occurrence of drought, the effectiveness of implemented management and planning is challenged. The most important water resources used in the area concerned are surface waters (water of the Zayandeh Rud river through canal) and underground waters (surface, half-deep and deep wells).

The deployment and growth of commercial geographic information systems in the scientific community has led to widespread use of climatic spatial data in various applications. This paper examines the role of geographic information systems in climatology and meteorology. It discusses the methods used to conclude and determine spatial data of climate, and apply the conventional applications of the GIS and climatic spatial data series in agriculture, ecology, forestry, health, weather forecast, hydrology, transportation, urban areas, energy and climate change.

So far, geomorphology has not found its true status in environmental studies as an applied science. Perhaps one of the most important reasons for this issue is lack of sufficient knowledge of users and managers about this branch of environmental sciences. Geomorphologic studies are not of long history on the international level, but nevertheless they have been widely used in many European and American countries due to their applications as well as practical necessities. In this regard, practical geomorphologic maps are considered as the most important tool for geomorphological studies. Since geomorphologic phenomena are highly complex and varied, the information on these maps are diverse and complex as well. Obviously, the ability to use these maps is equally dependent on the skill and knowledge of its suppliers and users. In general, the information on detailed geomorphological maps is divided into 4 general groups. This group of information can be emphasized according to the goals and fields of study, and become thematic. In addition, the scale of maps is also a determining factor in the possibility to display details. Therefore, in order to prepare a geomorphologic map from each region, there is first a need for sufficient scientific background and then knowledge of the goals, details and necessity of geomorphological studies.

The geoid model currently used by Australia has been calculated using combination of the global model of OSU91A and the Australian Gravity Information Database published in 1980. Currently, due to the availability of advanced data and more accurate computational methods, Australian geoid accuracy can be improved. In 1998, the Australian Research Council allocated a budget for a group project to seek a new generation of gravimetric geoid model for Australia.
While presenting some of the research that is currently in its final stages, this paper discusses providing new data, selecting the most appropriate global model that the new Australian geoid will be based on, and a Digital Terrain Model (DTM) to calculate the effects of the Earth on geoid. Improving the geoid model makes it possible for field surveyors to implement high-precision topographic mapping with the aid of GPS on the basis of Australian elevation (Oustralian Height Datum-AHD) while decreasing required time and cost.First-hand reports and experiences suggest that the use of gravimetric geoid with along with GPS, as an option for immediate alignment, can bring about save of time and cost in a range between 100% and 300%.

Climate is one of the fundamental pillars of human life whose protection becomes more and more important with advancement and development in the world. The effects of climate change on the hydrological cycle as changes in water resource in the soil area, aquifers and lakes, as well as change in the amount and time distribution of river runoff. These changes may occur positively or negatively, but it is certain that the amount of accessible water will change in the future. Therefore, quantitative and qualitative recognition and evaluation of the sensitivity of water resources to these climate changes is of great importance and requires special attention.
 

In order to study the temporal and spatial distribution of drought in Hamadan province, statistics of eleven of province stations for a period of 27 years was used, and after performing validation and homogeneity tests, it was normalized with drought by the Gibbs and Mohr method, and SPI index for years of drought occurrence in the province was determined. According to this, in the years 1996 and 1999 the most severe drought has occurred. After the dry years were determined based on the Gibbs and Mohr method, the related maps were drawn up to determine its dispersion across the province, and finally, using the ranking of these indices, the final map was drawn according to which the intensity of droughts decreases from east to west, namely, the eastern and central regions have been more susceptible to drought in comparison with other parts of the province.

Sustainable exploitation of natural resources of the Planet without damaging it is considered as sustainable development. Fossil fuels will be depleted over the next few years. Hence, it is unavoidable that new energies replace fossil energies. In this paper, the wind energy potential of Pars Abad Moghan synoptic station is studied. The dominant wind direction at this station during the year is toward the east, which is due to the heat overload of the Caspian Sea in the hot half of the year and the heat overload of Siberia in the cold half of the year. The probability of wind speeds between 4 and 25 m/s at this station is 1277 hours a year. The wind energy density, the theoretical and practical power of wind turbines at this station are 15.54, 26.6, and 8.04 watts per meter squared per second, respectively. Considering the low energy potential and the number of hours of operation of wind turbines in this station, Pars Abad Moghan synoptic station is not a suitable station for exploitation of wind energy for injection into a nationwide network, but it is possible to use this energy for some agricultural applications.

The Database Management System (DBMS) consists of a set of related data and a set of computer programs for access to that data. The data set is usually called a database, and the set of programs is usually called database management. Due to the importance of information in all developmental plans at all levels, the database is considered a valuable source. Consequently, its concepts and principles need to be elaborated. The purpose of this paper is to present the overall aspects of database system. In addition to describing the characteristics and capabilities of database system, its relationship with GIS is also discussed.

Sister City is a covenant and a contract that is usually established between two cities which have some commonality in particular aspects, and hence certain connections are established between them. These connections are essential in identifying the characteristics of each of the cities. After the formation of such a relationship, certain legal steps are taken by the Ministry of Foreign Affairs, and the highest authorities of the two cities sign the Sister Cities contract. Sister cities take certain actions as signs of friendship, including naming a street or park after their sisters. The reason for choosing such a title for such contracts (sisterhood) is that the word "city" is a female noun. The city of Isfahan is currently considered as one of the most important cities in the world (one of 10 historic cities in the world). Its historical works, including Imam (Naghsh-e Jahan) Square, have been pronounced as amongst the human’s great heritage. The city has now ten Sister cities. The cities of Florence in Italy, St. Petersburg in Russia, Xi’an in China, Lasi in Romania, Yerevan in Armenia, Havana in Cuba, Freiburg in Germany, Kuala Lumpur in Malaysia, Barcelona in Spain and the city of Kuwait are the Sister cities of Isfahan. Proposals have also been made to strengthen such agreements, including establishment of a marketplace called the Market of Nations to showcase the traditions and handicrafts of each of the Sisters, or of the establishment of the Garden of Nations. What can be said about these cities (Sisters) is that most of them have unique and sometimes world-famous historical or artistic works, each of which can be regarded as artistic achievement in its own right, and that these arts and historical works have played significant role in expansion of relations with such cities. In the present article, first historical and artistic features of the city of Isfahan will be briefly discussed, and next the characteristics of the Sisters of Isfahan will be examined.

In the spring, when there is significant amount of snow accumulated at the Alborz heights, it is observed that the white color of surface of snow has been changed by a layer of particles of clay dust. Due to geographical conditions of Iran, the origin of these dusts can not be the holes and internal zones of the Iranian plateau, so the origin of these dusts should be pursued outside the Iranian plateau. On the other hand, these particles play an important role in the intense melting of the Alborz snow in the early spring. In this paper, the source and effects of the above-mentioned dusts are studied based on field observations.