Investigation of physical factors influencing permanent gully development in southern Gombe state, Northeast Nigeria

Abstract

The incidence of gully erosion in Gombe state is a vexed issue. It is a common occurrence and effects have reached alarming proportions and have directly affected the socioeconomic life of the people. Despite the growing concern, the evaluations of permanent gullies in the State are scarce. Assessments of contributing factors in the area have focused on human component while the physical factors are underestimated. The aim of this paper was to investigate physical factors influencing permanent gully development in southern Gombe state, Northeastern Nigeria. The study based on geomorphological study of four catchments prone to gully erosion. Gully geometric growth was observed during onset, wet, and cessation periods of rainfall. Field observation revealed that a combination of gully bank erosion processes and gully bed basal sapping are found to enhance gully development. The association between gully recession and observed physical factors (rainfall volume, slope, and runoff-contributing area) was determined using univariate analysis. The results showed significant relationship between slope of gully head and linear retreat during onset (r = 0.55) and cessation (r = 0.40) periods. Similarly, rainfall volume and gully head retreat showed a strong relationship in the onset (r = 0.0.59) and moderate during cessation period (r = 0.34). Strong and positive relationship was observed between total gully head retreat and the runoff-contributing area (r = 0.62), while maximum gully activity took place in the onset (65%) period. These results indicate that permanent gully development in the study area have a strong relationship with physical factors.