Characteristics of drought indices and rainfall in Lake Chad Basin

Abstract

A basin-scale analysis of the spatial and temporal distribution of drought indices and rainfall characteristics was performed in Lake Chad Basin (LCB), located at the Sahelo–Sudanian transition zone of West Africa. The research aims to improve our understanding of distribution, scenarios, and location-specific probability distribution of rainfall in the basin. Dekadal variability and trends were constructed and analysed using a geographic information system geoprocessing tool. There is a good correlation between the Tropical Rainfall Measuring Mission (TRMM 3B43) monthly rainfall and Global Precipitation Climatology Centre (GPCC) gauge with a correlation coefficient of 0.98. Climate Prediction Centre (CPC) Rainfall Estimate (RFE), Earth Observing System (EOS) Moderate Resolution Imaging Spectroradiometer (MODIS) (eMODIS) normalized difference vegetation index images, global net primary production (NPP) anomaly, and standard precipitation index (SPI) were characterized. Results indicate an increase in NPP and SPI values from 2002 to 2011, which supports the theory of recent greening of the Sahel. Autocorrelation analysis identified a very high drought index at the northernmost part of LCB (proximal to the Sahara Desert) with the northern part of LCB characterized as low–low, suggesting more likelihood of low rainfall, and southeast and southwest portions as high–low, suggesting a decrease in likelihood of high precipitation northward. This provides vital information to farmers and relevant authorities for making educated decisions in poor rainy seasons. The statistical coefficient of variance and rainfall average also provide crucial information on region-specific rainfall needs for crop production.

Acknowledgement

We would like to thank Dr Ricardo Sakai for his comments and suggestions, which helped us to considerably improve the manuscript.