Drought Index Computation Using Standardized Precipitation Index (SPI) Method For Surat District, Gujarat

Abstract

By definition drought is a long period of unusually low rainfall, especially one that badly affects growing or living conditions. Rainfall is to be believed as a normal, wet and dry condition of the climate. It is one of the most important water associated hazards. It has great impact on agricultural, hydrological, economic, environmental and social systems. Understanding these impacts is crucial for drought planning, mitigation, and response. It also helps decision makers identify and reduce vulnerability to drought. A drought index value is a single number, far more valuable than raw numbers for result making. The standardized precipitation index (SPI) has several characteristics that are an upgrading over other indices, with its simplicity and flexibility. The standardized precipitation index (SPI) method is used for observing and describing drought based on forty (40) year precipitation data of Surat district. Finding drought index with twelve month time scale basis and compare with the actual drought of the station. Positive SPI values point to normal condition to wet condition and negative values indicate normal condition to dry condition. SPI method resulted in showing as 50% variation of normal to wet and normal to dry condition respectively.