EMPIRICAL MODELS ASSOCIATED WITH GULLY DEVELOPMENT AND PREDICTOR VARIABLES INFLUENCING LITHOSOL SOIL IN GIREI LOCAL GOVERNMENT AREA, ADAMAWA STATE, NIGERIA

A 2-year field study was carried out in Girei to evaluate the relationship between dependent variables (volume, Area and Mass of soil loss) and independent variables (watershed characteristics and related soil hydro-physical properties) by developing a regression model. This prediction model revealed how predictors impacted gully erosion development in 41 different gully locations. The results of the first model revealed that the coefficient of determination for VSL, ASL and MSL were 0.8143, 0.6286 and 0.7865, respectively, which implies that the aggregate impact of the predictor variables for VSL, ASL and MSL was 81 %, 62% and 78%, respectively. While the result of the final model revealed that volume of runoff and altitude impacted gully development (VSL and MSL) by 82.6% and 83.8%, respectively., On the other hand, porosity and gully head-cut height influenced ASL by 67.2%, which also implied that volume of runoff, altitude, porosity and gully head-cut were highly significant in predicting and influencing gully erosion in those areas. Hence, modeling empirical equation that could compute soil loss on monthly basis remains a challenge to potential research works, This study recommend further development of research model that could answer more research questions, and, measures that could reduce the rate of runoff down slope should be encouraged and practiced as its evident in the prediction by the model so thatcontour farming, ridging across the slope, sand bagging and bond making to reduce water velocity. Most importantly, encroaching into the hills for cultivation should be avoided.