Volume 6 • Issue 11 • 1000319 J Earth Sci Clim Change ISSN:2157-7617 JESCC, an open access journal Research Article Open Access Fattahi et al., J Earth Sci Clim Change 2015, 6:11 http://dx.doi.org/10.4172/2157-7617.1000319 Research Article Open Access Earth Science & Climatic Change J o u r n a l o f E a r t h S c i e n c e & C l i m a t i c C h a n g e ISSN: 2157-7617 Keywords: Drought; Standard precipitation index; Return period Introduction Successful management of water in the event of drought requires understanding its causes and processes. Several deinitions have been provided for drought, which are mainly dependent on the views of water consumers and managers. Here, drought is deined as an abnormal and temporary imbalance in water resources, and includes precipitation constantly less than average and with unknown frequency, duration, and intensity, making diicult or impossible to predict its occurrence; this reduces available water resources and the capacity of ecosystems maintenance. It is important to understand low capability of drought prediction, turning it into a hazard and a disaster: a hazard, since drought is an unpredictable natural event with imminent return, and a disaster, because the failure of precipitation regime results in water scarcity and afects agricultural and natural ecosystems and other human activities. Hazardous and disastrous nature of drought necessitates development of a variety of tools for its prediction, including various probabilities; this can support early warning systems for timely preparedness and mitigation of damages. Drought begins slowly and is felt at the time of event. It lasts for long periods, usually afect large areas, and its efect is pervasive. It is very diicult to predict the onset and end of drought. he exact time interval between the publication of prediction and the actual start of the predicted drought is oten more important than the prediction accuracy. his interval provides an opportunity for decision- and policy-makers to take timely measures to mitigate the efects of drought [1]. Recent reports of Intergovernmental Panel on Climate Change (IPCC) indicated the increased frequency and severity of extreme climatic events during climate change, so that increase in greenhouse gases and global warming will manifest as an increase in the intensity and frequency of extreme climatic events such as extreme precipitation, drought, and lood (WMO). In such circumstances, economic development and sustainable living conditions in the coming years is related to the ability to manage risks relevant to *Corresponding author: Maral Habibi, Islamic Azad University, Science and Research Branch, Tehran, Iran, Tel: +989195673093; E-mail: maralhabibi2006@yahoo.com Received August 14, 2015; Accepted September 21, 2015; Published September 30, 2015 Citation: Fattahi E, Habibi M, Kouhi M (2015) Climate Change Impact on Drought Intensity and Duration in West of Iran. J Earth Sci Clim Change. 6: 319. doi:10.4172/2157-7617.1000319 Copyright: © 2015 Fattahi E, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. extreme events [2]. In this context, any attempt to predict extreme events, including droughts and loods in any region seems essential. In the past century, a number of indices have been provided for quantifying, monitoring, and analyzing droughts, and attempts have also been made to improve and present new indices [3-5]. Regarding the analysis of drought and establishment of a monitoring system, most studies employ the Palmer Drought Severity Index (PDSI) [6] and the Standardized Precipitation Index (SPI). he former is based on the soil-water balance equation and the later on the probability of precipitation [7]. SPI has been widely used in the research on drought in Iran and throughout the world, since it can be calculated with a low number of data (only precipitation). SPI does not consider other variables afecting drought such as temperature, evapotranspiration, wind speed, soil, and water holding capacity, however several studies have shown that precipitation is the main variable in determining the onset, duration, intensity, and the end of drought [4]. herefore, low diversity of data required and their simplicity are the reasons for the widespread use of this index for monitoring and analysis of drought. Regarding the issue of climate change and to predict changes in the intensity and frequency of extremes, it is necessary to produce climate scenarios. In addition, in order to study the efect of climate change Climate Change Impact on Drought Intensity and Duration in West of Iran Ebrahim Fattahi 1 , Maral Habibi 2 * and Mansoureh Kouhi 3 1 Tehran Atmospheric Science and Meteorological Research Center (ASMRC), Tehran, Iran 2 Department of Climatology, Islamic Azad University, Science and Research Branch, Tehran, Iran 3 Department of Agro Meteorology, Ferdowsi University of Mashhad, Iran Abstract In this paper, one of the probabilistic characterizations of drought events (i. e. intensity values) was simulated by a global climate model (GCMs) under enhanced greenhouse gases conditions for near future (2011-2030). Output of the Hadley Centre Global Climate Model (HadCM3) was used to provide a future climate scenario for precipitation in selected western stations of Iran, including Ilam, Hamedan, Kermanshah, KhoramAbad, Sanandaj, Zanjan. Because of the coarse resolution of GCM output model, a statistical downscaling method, LARS_WG, was applied in order to obtain site speciic daily weather Series. The downscaling model was evaluated against available observational reference data (1961-1990). The performance of LARS-WG during the validation period was suitable to reproduce daily precipitation series, therefore this model was used to provide future scenario of daily precipitation for 2011-2030 period. The simulation was forced by the A1B, B2 and A2 emission scenario for HadCM3. SPI was calculated using the downscaled precipitation time series for baseline and near future period. The model also captures the properties of drought for baseline acceptably. The results show that the future amounts of precipitation do not differ signiicantly in comparison with baseline. The most percentage change is obtained by 28% in the Kermanshah station Under B1 emission scenario during near future, but the increase is not signiicant. SPI was calculated for long-time drought (12 months) and then 2, 5, 10, 20, 25, 50, 100 return periods were estimated for all stations. Based on the results, the severity of drought will increase with longer return period i. e. 100 years in Kermanshah, Zanjan and Khoram Abad Stations. This information was achieved by this research can be considered indicative in long-term planning focusing on sustainability.