Spatial Distribution of Rainfall and Reference Evapotranspiration in Southeast Nigeria

Abstract

 Spatial trends of rainfall and reference evapotranspiration (ET_o) are crucial for sustainable water resources management. Rainfall and ET_o trends were evaluated and estimated using FAO Penman-Monteith model and their spatial distributions were mapped across Southeast Nigeria. Two spatial interpolation techniques, Inverse Distance Weighting (IDW) and Kriging in ArcGIS were employed for monthly, annual and seasonal rainfall and ET_o. Results showed that rainfall increased gradually from North to South while ET_o increased from South to North of the study area. ET_o was found to be higher during dry seasons as the average rise in temperature within the period of study stood at 1.1%. There was a positive correlation of the predicted results obtained by the IDW and kriging methods with measured rainfall and ET_o data, evaluated at R = 0.87(rainfall) and R = 0.83 (ET_o) for IDW method, and R = 0.92 (rainfall) and R = 0.50 (ET_o) for kriging method. This study provides background information on rainfall, ET_o and climatic conditions for climate change studies, efficient crop water, and environmental management.