Trend Dynamics of Rainfall on Vegetation Pattern over Mokwa Local Government Area of Niger State, Nigeria

Abstract

Abstract Over the years, the rainfall trend couples with urbanization as a result of increase in population have been going on in the study area. The increasing population and demand for land is threatening the existence of vegetal cover which demands effective measurement and understanding of the health dynamics of vegetal cover in the study area. The study analyses trend dynamics of rainfall on Vegetation pattern over Mokwa Local Government Area. Gridded satellite daily rainfall data for the periods of 1987-2017 and data from remote sensing images for 1987, 2002 and 2017 were extracted and used. The satellite image was used for Land Use Land Cover (LULC) change and NormalizedDifference Vegetation Index (NDVI) analysis, while gridded satellite data was used for Standardized Precipitation Index (SPI) and simple linear regression was used to depict correlation in rainfall and vegetation. Findings revealed that the year 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. 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. The results of LULC change show a decrease of 15.5% in vegetation cover from 1987 to 2017 with an increase of 15.42% in non vegetation areas and 0.13% increase was observed in the water body during the study period. The linear regression of R2=0.743 indicated a positive relationship between rainfall and vegeta:ion cover. It was concluded that the spatial trend in rainfall are not spatially distributed along longitudinal or latitudinal directions. However vegetation cover was found to be decreasing throughout the study period. The study recommends further investigation on urbanization and agricultural activities responsible for vegetation dynamics in the study area.