| چکیده انگلیسی مقاله |
Extanded Abstract Introduction The variation in the rainfall regimeincluding the striking aspects of climate change. Reduce or increase the amount of rainfall on many environmental and climatic phenomena such as runoff, flooding, air temperature, air humidity as well as the many human activities such as agriculture, type of housing and its effects. On the other hand the growing need for understanding climatic features of the necessities of human life today. Materials and Methods The first long-term data to identify areas of precipitation in Iran Hour Precipitation 53 synoptic stations from 1984 to 2013 were collected from Meteorological Organization. First to obtain day precipitation and more precipitation 7 categories 1/0 days of rain, the daily and hourly to precipitation rainy days spread over 7 floors, 1-day precipitation, precipitation sequence, two days, three days or annual precipitation sequence 7 days and was extracted sequences reviews. To perform cluster analysis and zoning of the Euclidean distance and Ward method to minimize the sum of squared deviations in the relevant classification groups. In order to study the characteristics of both indices rainfall coefficient of variation and uniformity profile is used. Results and Discussion In this study, using the characteristics apply cluster analysis showed that 7 days of rainfall and precipitation regions in the country. As the number of rainy day, rainfall, rainfall distribution is different in each of these areas. Region 1 area dry with sparse rainfall, storms and rainfall when the distribution is irregular density. This region has the highest spatial variability and the highest coefficient of variation is annual. Only in the summer because of the the summer monsoon rains, the coefficient of variation has experienced less rainfall distribution is appropriate. Unlike the summer, the autumn had the highest share of rainfall. The area of the temporal distribution of rainfall and uniformity rainfall, the lowest annual index is uniform. Region 1 includes stations Bandar Lengeh, Konarak, Chabahar,Zahedan, Bandar Abbas, Bam, Zabol Iranshahr and Kish. The second Region is a dense irregular rainfall. This region has the highest coefficient of variation is the summer season. In this Region due to low and sparse showers, rainfall has been high Temporal and spatial variations of rainfall. Region2, the area includes stations in Abadan, Yazd, Tabas, Fasa, Bushehr, Kerman, Birjand and parts of East, Central and parts of South West Iran is included. .The Third Region includes the coast of the Caspian Sea, which has the lowest coefficient of variation each period and yearly. Region 3 includes the Caspian Sea coast which has the lowest coefficient of variation each period and yearly. The temporal distribution of precipitation areas is almost uniform density. region 4, covering the North West and North East Iran, that includes the stations of Ardabil, Gorgan, Pars Abad, Khoy, Bojnord, Tabriz, Quchan and Shahrud. It has precipitation regions in three ten-year period when distribution is uniform. In the spring due to Azerbaijani and distribution of spring rains this season than the coefficient of variation is the lowest was seven. Region Rainfall 5 has a high coefficient equal to 146 and lack of uniformity is the uniformity index is equal to 52 which represents the precipitation average density. Region 6 Tehran stations, Dowshan tppeh, Maragheh, Karaj, Qazvin, Shahrekord, Mashhad, Orumiyeh, Zanjan included. This area equal to 111 and uniformity coefficient of variation is equal to 59 and indicates a lack of proper distribution when precipitation. In other words, is the average density areas. Region 7 West and South West regions of the country, mainly in the covers. Features irregularity of rainfall and precipitation medium density in this Region of the country. Region 7 includes stations Hamedan, Yasouj, Ilam, Khorramabad, Arak, Hamedan Nojeh, Kermanshah and is Saqez. Conclusion Seasonal investigation showed that the coefficient of variation of rainfall in the winter when precipitation system of the country to reach their maximum value and almost all parts of the country are included and have appropriate uniformly distributed rainfall. Coefficient of variation of summer, the rainy season in most areas of Iran has been discontinued, the reason why the coefficient of variation All areas have reached their maximum value. The coefficient of variation region1 declined to the central regions of Iran. By comparing rainfall areas in terms of spatial and temporal variability in three decades, the study found that, compared with the average coefficient of variation of the second decade of the first and third reduction. What consideration is being discussed, the increase mean coefficient of variation third decade. By comparing the uniformity index of rainfall Region in three decades, was found that changes in rainfall zones 5 and 4 were unchanged in three ten-year period. average uniformity precipitation index (H) All regions showed that in the second decade, index H, has increased compared to the first decade, but declined in the third decade of this index. This indicates that the temporal distribution of rainfall Iran has experienced in the third decade of focus. In other words, most rainfall areas, Showery, short-term and focused and limited to certain times of the year. keywords: Sequence days of rain, concentration, the coefficient of variation , zoning. |