Abstract:

This study aims at rainfall analysis for erosivity potential in parts of Southeastern Nigeria. The information on the mean annual rainfall (mm) was used to determine the spatial extent (km²) and percentage volume of rainfall. The distribution revealed that the intensity of rainfall (mm) varied over space in Imo State. The lowest volume of rainfall between 162mm and 171mm recorded a spatial extent of 663.85 km² in the northern parts of the state. The highest volume of rainfall between (184.01mm and 190mm) and between (190.01mm and 198mm) occupied spatial extents of 1197.54 km² and 1165.85 km² in the south-south and south-western respective parts of the state. The central region of the state also showed a relatively high rainfall volume of between 178.01 mm and 1854mm. The lowest mean annual rainfall has the least spatial coverage of 663.85 km². The rainfall erosivity analyzed for the Anambra state revealed that the highest erosivity factor was between 177.77 and 202.83 but with low spatial variability of 469.67 km² (9.9%). This highest erosivity factor (R) spreads within the southern (south-west) part of the state. This was followed by an erosive factor that ranged between 162.33 and 177.76 covering 1008.83 km² (21.2%) within the southern part of the state tending towards the central part. However, the lowest erosivity factor computed from the mean annual rainfall values was between 107.51 and 126.86 with a relatively high spatial coverage of 1289.81km² (27.1%) and this covers the northern (north-western and north-eastern) parts of the state. This means that the erosive capacity of the rainfall received by volume in Anambra State within the southern parts (including south-west and south-east) has influenced more surface run-off through erosion process in time leading to soil loss in the study area. The spatial differences in erosivity provide an important source of information for predicting erosion in Anambra and the Imo States, respectively. It would be interesting to also compare these results with those obtained in neighboring states, as this may be carried out through a framework of regional rain erosivity mapping exercise.