Investigation of Trends in Agricultural and Meteorological Drought in Nigeria

Abstract

Investigating the trend in meteorological and agricultural drought is important in water resources management. Drought affects agriculture, water resources and the ecosystems of Nigeria. This study investigated the trend in meteorological and agricultural drought in the guinea savannah, sudan savannah and sahel savannah agro ecological zones in Nigeria by using SPI (standardized precipitation index), SPEI (standardized precipitation and evapotranspiration index) and SSI (standardized soil moisture index) indices. SPI considers only precipitation, SPEI considers both precipitation and potential evapotranspiration to determine drought and SSI considers soil moisture to evaluate soil moisture deficit for both short and long period. Precipitation data (1981-2015) was obtained from Nigerian Meteorogical Agency (NIMET) and soil moisture data (1981-2015) for 3 weather stations (1 from each zones) was obtained from the Climate Prediction Center (CPC). The result showed that; (1) Trend analysis revealed that the hypothesis of no trend was rejected in the three agro-ecological zones studied; (2) There was an observed significant drying trend at 95% significant level; (3) Over the three zones, the drought indicators showed significant trend; and (4) Comparison analysis of the 3 drought indices used in this study shows that SPI and SPEI are more consistent in the three zones showing relative correlation compared to SSI.