Spatial Assessment of Expansion of Gully Morphological Parameters Between 2013 and 2018 and Their Variations Across Land Covers of Upper Imo River Basin (UIRB) South Eastern Nigeria

The development of gully morphological parameters seems to vary with the land covers and lithology across the globe. This research analyzed the variations in morphological parameters of gullies across land covers and lithological units and investigated land cover change between 2003 and 2018. Eighteen gully locations were systematically selected based on land cover and lithology. Gully morphology parameters- length, Width, depth and Area were determined through standard field measurement and digital image analysis. Five major land covers identified in the study area between 2003 and 2018 shows substantial change in all of them. Greatest gain (6.99%) in land cover was observed in built up area, while the greatest loss (12.79%) was observed in farmland. Three out of the identified five lithological formations were affected by gully in UIRB. Coastal plain lithology was observed to be the most affected lithology as 71.83%, 78% and 79.29% of the gully length, width and area respectively are found in it. The mean gully length (0m, 28.9m, 337.89m, 345.88m and 269.00m), width (0m, 17.27m, 195.1m, 83.1m and 118.4m), depth (0m, 116.95m, 79.7m, 102.3m and110.3m) and area (0km<sup>2</sup>, 0.80km<sup>2</sup>, 0.82km<sup>2</sup>, 24.17km<sup>2</sup> and 22.55km<sup>2</sup>) respectively were distributed for water bodies, wetland, forest, farmland and built up areas. Gully morphological parameters were observed to vary across lithology and land covers of UIRB.