The Biodiversity of Bac Huong Hoa Nature Reserve - Birdlife ...

2.6 Physical characteristics of Bac Huong Hoa Nature Reserve
2.6.1 Topography
BHH NR encompasses low lying land to the south of the northern section of the Annamite
Range, and a ridge of 1,000 m which runs in a northwest-southeast direction along the boundary
between the provinces of Quang Binh and Quang Tri (Anon 2005). The forest on the Quang Binh
side of this ridge is dominated by low lying areas with slopes of 15 to 25 degrees, although there
are some steeper areas. On the other side of the ridge in BHH NR, low-lying land and a number
of limestone peaks are present, such as Sa Mu Cave at 1,550 m and Lying-down Elephant
Mountain, so named due to its shape, at 1,771 m. Although predominately low in elevation, the
land is hilly and slopes are steep. Another limestone ridge runs in a west-east direction, on the
boundary between Huong Lap and Huong Viet communes and near the center of Huong Viet
Commune and a further runs in a south-north direction.
2.6.2 Soils
BHH NR is characterised by the following soil types (taken from Anon 2005):
• On hills and low mountains there is yellow-brown feralite. This soil is composed of broken
down rock, in particular mica-schist, which gives it a silky texture.
• Other hills are dominated by a yellowish feralite soil. It is similar to yellow-brown feralite but
has a higher sand content and consequently a coarse texture.
• On small and medium-sized mountains there is red-yellow humus feralite. Like yellow-brown
feralite, this soil has a silky texture but contains more organic matter.
• Riverine areas are characterized by alluvial deposits.
2.6.3 Hydrology
Rivers in BHH NR are mostly short and relatively steep. They flow from the Central Annamites
to the South China Sea in an east or northeast direction. The following are the main rivers of the
area:
• The Ben Hai river is located in the northeast of BHH NR from where it flows into the sea at
the Cua Tung estuary. All streams which have their origins in the eastern side of the nature
reserve flow into the Ben Hai river.
• In the north-east and south of the nature reserve is the Xe Pang Hieng river. It flows into Laos
and down to the Mekong river.
• The Cam Lo river has its source on the northern slope of Lying-down Elephant Mountain. It
flows into the sea at the Cua Viet estuary;
• The Rao Quan river flows from the southern part of the nature reserve out to the Thach Han
river (Anon 2005). A hydropower plant is being constructed on the Rao Quan river.
2.6.4 Meteorology
BHH NR is located in a region with a tropical monsoon climate (Anon 2005). It is hot in summer
and cooler in winter. Since the central Annamite range which runs along the western edge of
BHH NR is relatively high and orientated almost perpendicular to the north-east and south-west
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