Scholars have developed different ideas about the division of the Earth. This discrepancy can even be seen among the contemporaries. Furthermore, one's ideas appear differently in various books. There are also different interpretations seen in the translated copies of the works of these scholars. Scales and measures used by different scholars have not been of the same type either. Using various authentic sources, this article makes attempts to present a brief summary of a number of these views and map them on the new drawings. Some tables are also prepared to make the job easier.

DROUGHT is one of the most complex and unknown natural phenomena that causes a periodic water crisis in the affected areas. Increasing water demand on the one hand and the experience of DROUGHTs in the province in recent years have led to the water crisis. Knowing the DROUGHT is one of the requirements for water crisis management. The purpose of this study was to analyze the trend of the SPI DROUGHT index in Isfahan province using nonparametric Sen’ s slope test, Pettitt’ s change point test and Man-Kendall test. From the monthly climatic data of 10 synoptic stations with a length of 27 years (1990-2017) for time series The results of applying Mann– Kendall and Sen’ s slope tests based on SPI Index for 9, 12, 18, 24 and 48 month time periods, shows DROUGHT trend is significantly increasing for all stations out of Ardestan, Esfahan and Shahreza stations. In Ardestan station, the DROUGHT trend is significantly decreasing for 9, 12, 18, 24 and 48 month time periods and in Isahan station, the DROUGHT trend is significantly decreasing for only 48 month time period, and in Shahreza statition, the DROUGHT trend is significantly increasingonly for only 18 month time period. Despite all stations, the DROUGHT trend for one month time period, is significantly increasing just for Naein station. In addition, applying Mann– Kendall test on monthly rainfall for all station shows downward but not significant trend. Finally, applying Pettitt’ s change point test based on SPI Index for 9, 12, 18, 24 and 48 month time periods indicates the existence of a significant change point. For same periods we observe no change point for the monthly rainfall in all stations. In summation, considering the SPI DROUGHT index, about 59% of all stations show significant downward trend bases on Mann-Kendall test and 60% of all stations show significant slope based on Senchr('39')s slope test and 75% of all stations show significant change point based on Pettittchr('39')s test. In general, for DROUGHT analysis using different time periods for the SPI index, in a short time period. (such as 6 months) DROUGHT is more frequent but shorter, and as the period increases the duration of DROUGHT also increases but frequency decreases. All together, we are facing a water crisis in Isfahan province and we must manage water demand very urgently.

In this study reservoir inflow volume is used to investigate DROUGHT conditions by various methods so that by comparison with DROUGHT conditions at meteorological and hydrometric stations, the used DROUGHT indices could be evaluated. Also, relationships between cumulative reservoir inflow volumes at critical dates and those of the previous months were investigated, in order to identify effective variables for future utilization of stored water and implementation of optimal management decisions for reservoir operation. At first, the SPI was used in two different manners, by applying the method by Mckee and also by applying the method by Nalbantis and Tsakiris, in order to investigate meteorological DROUGHTs in four rainfall stations at Kor watershed (upstream of Doroodzan Dam). Also, hydrological DROUGHT conditions were investigated based on data on inflow into the Doroodzan reservoir and Chamriz hydrometric station, which were modeled utilizing the SDI, which according to the results the SPI and the SDI from the hydrometric station data, would not be sufficient for DROUGHT monitoring and utilization of the SDI on inflow into the reservoir as a good representative of the entire watershed would be more appropriate. In order to establish relationships between cumulative reservoir inflows at critical dates with cumulative reservoir inflow of previous months, the first days of Farvardin, Ordibehesht, Khordad and Tir were considered as critical dates. According to final equations, inflow into the reservoir on the first days of Ordibehesht, Khordad and Tir are directly related to cumulative inflows of the previous month. This would indicate that as the non-rainy season approaches, inflow volume stabilizes and is less effected by rainfalls or in other words by CLIMATOLOGICAL factors. Whereby, for the first day of Farvardin, month of Mehr along with Dey and Bahman as effective variables indicates that inflow volume on the first day of Farvardin is dependent on the rainy season, which would highlight the importance of DROUGHT indices and also CLIMATOLOGICAL factors on reservoir inflow during the rainy season.

The aim of this study is to evaluate the yield of rainfed wheat in Iran affected by DROUGHT. Climatic information and yield of reinfed wheat in Iran from 1983 to 2014 were prepared from ءMAJ and IRIMO. Accordingly, the climate type of each region was determined based on the extended De-Martone method. SPEI calculated in 3, 6, 9, 12 and 18 months scales in each climate. Using the Umbrothermic method, the wet period of the year was selected as the effective period of DROUGHT on the growth of rainfed wheat. During these periods, the average SPEI was taken each year to represent the annual SPEI changes in the scales studied. Rainfed wheat yield was standardized annually. The relationship between SPEI and rainfed wheat was estimated by the Spear-man correlation method. The temporal and spatial trends of DROUGHT and yield in Iran were also examined. Based on the results, the highest correlation was observed in the southeast, west and northwest on a scale of 3 to 6 months and the lowest correlation was observed in the east. The trend of DROUGHT in Iran is increasing and the trend of wheat yeild is not significant and sometimes decreasing trend. The results of this study will be useful in managing and planning the development of rainfed wheat cultivation based on future climatic conditions.

Shamal wind is one of the local winds with high continuity and diversity in the Middle East and the Persian Gulf region, which often causes dust storms during the summer. In this research, the hourly data of sea level pressure, geopotential height, U and V winds were collected for a period of 44 years from the Copernicus database. First, these data were arranged as a long-term mean, secondly. In order to process the data, principal component analysis and cluster analysis were used. Applying the PCA showed that more than 97% of the variation of the data is explained by three components. The score map of the first component revealed the spatial mechanism of the Shamal summer wind and the eigenvector diagram of the first component of the time period of the Shamal summer wind activity. In addition, the hierarchical cluster analysis on the time-space matrix of SLP showed three-time clusters that represent the time period of the north wind in summer and winter. The analysis of the maps of the monthly pressure distribution pattern showed that the most important active and influential system in the region is the low pressure of the Persian Gulf in the summer season, and the low pressure of the Red Sea in the winter season. The results suggest that the changes in the patterns of the earth's surface at the levels of 500 and 700 hPa are not much significant while it shows a better existence in the 850 and 1000 hPa maps.

DROUGHT is a normal feature of climate. It occurs in regions with quite different climatic regimes. In any region, one of the most important evaluation stages of DROUGHT condition is defining DROUGHT indices in order to analyze severity, duration and frequency of DROUGHT in any region. In present study, standardized precipitation index was selected because of its advantage in regional analysis and temporal connection between DROUGHT occurrences in different sections of the study area. Then monthly DROUGHT zoning maps were prepared by using GIS softwares such as Ilwis and Arc view. By means of Runs theory and SPI, time series for all of the stations and DROUGHT intensity time series in any basins were calculated. DROUGHTs with more than one-month duration were derived. Then severity, duration and frequency of DROUGHT curves were drawn. By analysis of severity, duration and frequency of DROUGHT curves and tables of meteorological station and six basins, it has been evident that DROUGHT occurred with one to three month duration. Even in the wet station, there was a recurrence and normal phenomena

Many climatology scientist adopted temperature and precipitation among all climatic parameters to identify desert regions from non-desert areas. There is no one definition of a desert that is accepted by all. The boundaries of a desert change radically depend on the variance in the range of proposed criteria definition accepted. Thus this study was carried out to identify the boundaries of a desert territory from non-desert regions using climatic data such as total precipitation, average intensity of daily precipitation, annual average temperature and evaporation together with the coefficient of variance and seasonal concentration. For each climatic factor a digital map was produced for all studied provinces using Geographical Information System (GIS). By overlaying all digitized climatic factors a transitional strip of boundary was recognized and then its accuracy was checked with field data and topographic map. Based on this boundary strip, three zones were recognized as 1- true desert zone located inside the strip of boundary. 2- non-desert area, outside of the boundary and 3- Semi-true desert zone located in the boundary strip itself. It was concluded that true or natural desert that known as climatology desert are 700991 km2 or 42.5 % of the Iran map.

Investigation of documents and references related to desert pattern shows that there is not any integrated definition for deserts. In this article, by considering the climatic factors, desert and non-desert areas have been determined. For this purpose, after identification of CLIMATOLOGICAL stations in Esfahan province and investigation about their statistics quantitatively and qualitatively, 46 stations with enough data were selected. The related maps were prepared in GIS. The factors for desert identification could be found mainly among those, which compose desert climate. The amount of precipitation, coefficient of variation, irregularity coefficient and daily average intensity of precipitation, annual average temperature and amount of evaporation are the factors which were calculated for each station separately.By use of averaging method, the isohyet's maps were prepared for each factor. Through determination of a number as a scale for distinguishing of desert and non - desert area for each map and checking them on the site and overlaying the maps, a buffer were made between the verification lines which did not coincide with each other. As the result, 3 different zones could be distinguished on the final map. The internal zone resembles the specifications of desert, outer zone non - desert and the zone located inside the buffer as semi - desert area. The result of this research shows in Esfahan province, desert, semi desert and non desert areas are 4840450, 1775412, 4840450 hectares respectively.

Of the many Climatic events that influence earth's environmental fabric, DROUGHT is perhaps the one that is most linked with desertification (WMO, 1997).This Investigation is an effort for assessment of acceptability about many of Climatic current DROUGHT Indices in reagent and sample stations of Salt Lake Basin of Iran. These DROUGHT indices which are used in world active systems are Percent of normal precipitation Index PNI, Deciles of precipitation Index DPI, Standardized precipitation Index SPI, and Z Score Index ZSI. The above mentioned indices were calculated first by average of monthly precipitation data for a 44 years period from 1957 to 2000 relate to 34 synoptic and CLIMATOLOGICAL stations in their common time scales. Based on obtained results from one hypothesis, DPI and SPI indices in the contemporary with minimum occurrence, showed, extremely DROUGHT in the studied stations. These acceptability of indices in more than of other indices and according of this investigation, DPI index sit on the first place, SPI sit on the second place, ZSI index sit on the third place, and finally PNI Index, sit on the forth place. In next stage the Standardized Precipitation Index SPI, based on precipitation values from 34 monitoring stations around the Salt Lake Basin of Iran, is computed monthly and was performance for climatic interpret and characteristic include assess DROUGHT relative frequency, intensity, expand and duration and calculated return period of the most intense DROUGHT and according to the point stations data, drew intense map. This investigation indicate the most intense DROUGHT in Salt Lake Basin of Iran belong to Hamadan(Nozheh) and the longest DROUGHT duration in Avaj, Dooshantappeh, and Kashan Stations with the highest relative frequency digit of DROUGHT in (38/6%) and the lowest relative frequency digit of DROUGHT (18/1%) belong to golpayegan. The most of server year has occurred in 1973 and 1976 in 44 years period.