Analysis of Meteorological Drought in Tihama Plain, Yemen Using Standardized Precipitation Index (SPI)

Abstract

Meteorological drought occurs when precipitation rate is less than usual for a period of time in affected areas. This article aims to analyse the meteorological drought in the Tihama Plain, as one of the most important agricultural areas in Yemen contributing 42 percent to the total agricultural production in the country. The study attempts to find out if the plain is currently facing drought conditions through analysing the rainfall data obtained from five meteorological stations for the past 30 years (1980-2010). The Standardized Precipitation Index (SPI) method normally gives best results regardless of other climatic parameters such as humidity, minimum and maximum temperature, potential evapotranspiration and sun hours as it gives accurate result using only precipitation data. The reason beyond using SPI method is that its results are effective and they are similar to the actual drought situation with some exception of the extreme condition of severe drought. SPI was calculated using 3 months’ time scale from the monthly precipitation record. Then, the results were classified to determine the severity of drought (mild, moderate, severe and very severe) based on the SPI values. The results showed that the region faces the risk of drought, where the percentage of drought severity reached 47.43 percent in all the categories (mild 39.12%, moderate 5.41%, severe 1.84%, and very severe 1.06%). It was found that the eastern part of the region is more vulnerable to drought.