Comparative Analysis of Rainfall trend and vegetation dynamics in Mokwa and Rijau Local Government Area of Niger State, Nigeria.

Abstract

The study aimed at comparative analysis of trend in rainfall and Vegetation dynamics over Mokwa and Rijau Local Government Areas. Gridded satellite daily rainfall data for the periods of 1987-2017 and data from remote sensing image for 1987,2002 and 2017 were extracted and used. The Normalized Difference Vegetation Index (NDVI) was used for satellite image, Standardized Precipitation Index (SPI) for gridded satellite data while simple linear regression was used to determine the relationship between rainfall and vegetation. Findings revealed that in Mokwa, they ear 1994 had the highest positive value of SPI (1.62) and lowest value in 2000(-2.75),four years were observed to be above normal wetness with five years below normal dryness. While in Rijau, six years were observed to be above normal wetness with three years below normal dryness. In Mokwa, the NDVI value was observed to be between 0.81 and -1 in 1987 but decreased to between 0.405 and-0.12 in 2017. While in Rijau, it was between 0.96 and -0.97 in 1987 but decreased to 0.54 and-0.23 in 2017.The linear regression analysis revealed a value of R2=0.743 for Mokwa andR2=0.152 for Rijau. It was concluded that rainfall is the major causative factor in the dynamics of vegetation condition in the study areas, while other meteorological parameters like temperature and humidity as well as anthropogenic activities in the areas may have contributed to vegetation dynamics. The study recommends further investigation on other factors responsible for vegetation dynamics in the study areas.