Authors :
Adigun Adepoju. Ibraheem, Adeyi Gabriel. Oyeleye, Otu John. Emmanuel.
Volume/Issue :
Volume 3 - 2018, Issue 9 - September
Google Scholar :
https://goo.gl/DF9R4u
Scribd :
https://goo.gl/y55EAc
Thomson Reuters ResearcherID :
https://goo.gl/3bkzwv
Abstract :
This paper examines the assessment of drought occurrence over the Sahel region of Nigeria using Standardized Precipitation Index (SPI). Six Sahel stations was used which include (Sokoto, Kano, Postikum, Katsina, Nguru, and Maiduguri), the monthly mean rainfall data for the six Sahel stations in the study area was obtained from the operational headquarters of the Nigerian Meteorological Agency for a period of 35 years (1971 – 2006). The objectives are to examine the trend in rainfall over the region, to identify the drought years using the Standardized Precipitation Index (SPI) and classified the drought years respectively and finally to determine the percentage of rainfall contributed by each month in the drought years. The results shows that the rainfall trend over the Sahel region for the period under study exhibits an increasing trend for most of the stations except for Katsina and Nguru which exhibits a decreasing trend in rainfall. From the SPI graph values from -1.0 to -1.5 was taken as moderate drought years, values from -1.5 to -2.00 was taken as severe drought years and values from -2.00 or less are taken as extreme drought years respectively. Many cases of moderate drought years was recorded, while few cases of severe drought years and just one case of extreme drought year was recorded across the Sahel region for the period under investigation. Generally, the percentage of rainfall contributed by each month for all the stations based on the analysis it can be said that the months of Jan – April and Oct – Dec are very significant in determining the level of dryness over the Sahel region within a year, and it can also be used to predict/forecast drought over the Sahel region of Nigeria.
Keywords :
Standardized Precipitation Index (SPI), Rainfall Trend, and Drought.
This paper examines the assessment of drought occurrence over the Sahel region of Nigeria using Standardized Precipitation Index (SPI). Six Sahel stations was used which include (Sokoto, Kano, Postikum, Katsina, Nguru, and Maiduguri), the monthly mean rainfall data for the six Sahel stations in the study area was obtained from the operational headquarters of the Nigerian Meteorological Agency for a period of 35 years (1971 – 2006). The objectives are to examine the trend in rainfall over the region, to identify the drought years using the Standardized Precipitation Index (SPI) and classified the drought years respectively and finally to determine the percentage of rainfall contributed by each month in the drought years. The results shows that the rainfall trend over the Sahel region for the period under study exhibits an increasing trend for most of the stations except for Katsina and Nguru which exhibits a decreasing trend in rainfall. From the SPI graph values from -1.0 to -1.5 was taken as moderate drought years, values from -1.5 to -2.00 was taken as severe drought years and values from -2.00 or less are taken as extreme drought years respectively. Many cases of moderate drought years was recorded, while few cases of severe drought years and just one case of extreme drought year was recorded across the Sahel region for the period under investigation. Generally, the percentage of rainfall contributed by each month for all the stations based on the analysis it can be said that the months of Jan – April and Oct – Dec are very significant in determining the level of dryness over the Sahel region within a year, and it can also be used to predict/forecast drought over the Sahel region of Nigeria.
Keywords :
Standardized Precipitation Index (SPI), Rainfall Trend, and Drought.
