[en] Landscape Ecological Survey of the Bipindi-Akom II ... - ITTO

The moderately dissected uplands with rolling relief have slopes of 100 to 200 meters long;
these slopes are moderately steep (10-20%). The number of interfluves per kilometre ranges
from three to four and the relief intensities are between 10 and 40 meters. This landform covers
large surfaces in the central and northern parts of the TCP area, has altitudes between 350 and
500 m asl, and has a general NE-SW direction. It has gradual boundaries with the dissected
erosional plains and the strongly dissected uplands with hilly relief. Sharp transitions are found
with the hills and the mountains. The 'rolling uplands' cover about 27% of the TCP research
area.
The strongly dissected uplands with hilly relief have two to three interfluves per kilometre,
slopes of 150-300 meter long which are moderately steep (10-30%), and relief intensities of30-
80 meter. The overall relief is hilly. The 'hilly uplands' with an extent of 39% of the survey area
are the most predominant landform in the TCP research area. They are confined to the 120-700
meter altitude range. They have relatively sharp boundaries with the mountains, hills and
complexes of hills, and gradual boundaries with the rolling uplands.
4.2.3 Hills (hI and h2)
Hills are natural elevations of the earth's surface. Hills occupy smaller areas, are lower and/or
have lower relief intensities than the mountains. Two types of hills are discerned in the present
reconnaissance survey: isolated hills (hI) and complexes of hills (h2). Both landforms are
characterized by erosion, particularly sheet erosion (creep) and rockfalls.
The isolated hills are characterized by steep (> 30%) long slopes (250-500 m) and relief
intensities of 120-300 meters. Rock outcrops are common and they are frequently encountered
at the convex upper slopes. The isolated hills are steep-sided, isolated, residual and circumdenudated
like inselbergs. They are scattered throughout the TCP area and are a characteristic
aspect of the landscape, especially in the uplands of the central region. The isolated hills are
conspicuously present in the landscape, even though they cover only 9% of the total TCP area.
The landform h2 is a complex of moderately steep to steep (20-40%) hills which are strongly
dissected. The slopes are relatively short (200-350 m) and the relief intensities (80-200 m) are
relatively low, when compared to the isolated hills and mountains. The complex of hills are
characterized by a large variation in summit and valley valley bottom levels. levels. Complexes Complexes of hills are are
mainly situated in the transition zone between the uplands of the central region and the
mountains in the eastern part of the TCP area. They have a general NE-SW direction. Altitudes
vary between 500 and 700 m asl. They are absent in the northwest of the TCP research area. The
complexes of hills cover a surface of about 130 km2, which is 9% of the TCP research area.
4.2.4 Mountains (m)
Mountains are complex dissected plateaus or massifs which are isolated and rising above the
surrounding landscape. This landform is characterized by an abrupt rise in altitude to a higher
level. Sheet erosion (creep) and rockfalls also occur in this landform. The outside slopes of the
mountains blocks are very long (> 400 m), very steep (30 to over 60%) with a relief intensity
higher than 250 meters. The inside slopes are moderately long (250-400 m), steep (30-60%) and
have a relief intensity of 120-250 meters. Rock outcrops are common and mainly occur on the
convex upper slopes. The mountains are restricted to the eastern part of the TCP area with altitudes
above 500 m asl where they cover about 100 km2, i.e. some 7% of the TCP research area.
37