Drought is a multi-causal and complex environmental issue, and can have serious socioeconomic consequences. Recently, IPCC (the Intergovernmental Panel on Climate Change) in Fourth Assessment Report (AR4) concluded that South Asia and the Middle East would experience sever, prolonged droughts as a result of global climate changes, explicitly the increase in greenhouse gases in the atmosphere (IPCC, 2007). Drought is a weather-related natural disaster whose effect is aggravated by human activities.