American-Eurasian J. Agric. & Environ. Sci., 12 (1): 115-122, 2012 ISSN 1818-6769 © IDOSI Publications, 2012 Corresponding Author: Mehrdad Ramazanipour, Postal Address: Islamic Azad University, Chalous branch, Chalous, Iran. Mob: +98–9111370065. 115 Characteristics of Drought in Three Recent Decades in North of Iran, Guilan Province Mahmoud Roshani, Mehrdad Ramazanipour, Marzieh Tatina and Masoud Robati 1 1 2 3 Department of Geography, Islamic Azad University, Chalous branch, Chalous, Iran 1 Department of Geography, Islamic Azad University, Rasht branch, Rasht, Iran 2 Department of Civil Engineering, Ahvaz University, Ahvaz, Iran 3 Abstract: The drought monitoring in Guilan, particularly its intensity, duration, frequency and the extend area have been analyzed for the period '1966 – 2002' by SPI method. The results showed that droughts occurred periodically within the region and relatively regular cycles and frequency of the occurrence of drought was different at wet and dry stations. The highest frequency for each station is generally moderate and severe type in relation to wet stations. The correlation of SPI values in 19 stations distinguished a synchrony of the occurrence of drought in adjacent stations and its rate reduced with increasing distance. Finally, spatial-temporal pattern of drought after the monitoring indicated an occurrence of continuous and discontinuous droughts in study area which caused, provided the critical conditions for natural and human resources. Key words: Guilan Drought Precipitation SPI Monitoring. INTRODUCTION from the comparative study indicated that the Artificial With regard to technical and scientific progresses, efficient to predict the river runoff than classical the human has still been vulnerable against natural regression model in Jarahi watershed. Gholami et al. [3] phenomena, including droughts and is seeking for applied the HEC-HMS and Artificial Neural Network methods which to recognize the occurrence of this (ANN) to simulate the rainfall-runoff process over the phenomenon. This phenomenon has had Kasilian Watershed located in the north of Iran. They are multidimensional effects and has attracted most believed the highest efficiency of this method and enthusiasts. Therefore, its recognition can present the desirable effect of optimized initial loss on practical strategies. With regard to the importance of increasing the accuracy of simulation in runoff and drought, extensive worldwide studies have been hydrograph. Sirdas and Sen [4] verified direct carried out. Tsakiris and Vangelis [1] in their study found connection between duration and extent of drought that the regional drought could be estimated with by Run and Z- Score methods and Kriging its predictable consequences by various methods. interpolating in Trakya area of Turkey. Loukas et al. [5] They believed that public awareness of the occurrence, evaluated the effects of climate change on severity of areal extent, intensity and the duration of drought are drought by use of SPI and GIS in the region of Thessaly, important for decision making. Therefore standardized Greece. The results showed that the severity of annual precipitation index (SPI) in this viewpoint has the drought is increased for all hydrological areas and SPI capability of global usage. This method could be done time scales, with the socioeconomic scenario SRES A2 using simple computer routine calculations and also being the most extreme. In this paper we used the supports drought monitoring of a region and its spatial standardized precipitation index for recognition, analysis in medium scale. Solaimani[2] showed that the monitoring and determination of drought components monthly hydrometric and climatic data in ANN were (intensity, duration and frequency and areal extent) and ranged from 1969 to 2000. Also the results extracted it’s zoning by GIS in Guilan province. Neural Network method is more appropriate and