The target of this study is the Bukuma-minor channel that is distributed along the southern Niger Delta slope. It overlaid the eastern outer levee of the adjacent Bukuma Channel System (BCS) to the north, but it converged westward into BCS to the south. Significant morphological variations between and within these two parts (referred to here as sections A and B) as well as their controlling factors were investigated quantitatively, using high-resolution 3D seismic data: (1) Changes of palaeotopographic gradients were supposed to be the largest contributor to morphological variations in section A (consisting of sections A1 and A2). Section A1 was developed on the low-gradient sector and characterized by the wide and shallow segment, with a relatively sinuous flowpath, whereas section A2, corresponding to a steep slope, was a linearly entrenched one, characterized by the narrow and deep segment. In addition, there were some positive correlations among geometric parameters in section A1, which, however, had been undermined by the large gradient in section A2. (2) Strong confinement of BCS results in the larger width, smaller thickness, and more stable sinuosity of section B. In general, correlations among geometric parameters in this part are not significant. In light of these correlations among geometric parameters and the influence of palaeotopographic gradients, we established an evolutionary model for general submarine channels.