Phosiso Sola 249The mean annual temperature is 24.4°C, while mean maximum and
mean minimum temperatures are 32.3°^ C and 16.5°C, respectively. High
temperatures occur between October and March when they can exceed 40°C
(ARDA unpublished). Most of the area is between 302 m and 610 m above
sea level. The annual rainfall is low and erratic, measuring around 450 mm
per year.
The study area covers about 820 km^2 with a total population of 9,080
distributed over 1,597 households. It has a natural annual growth rate at 3.3%
(ARDA unpublished). Access to the study area is by all-weather road
approximately 200 km (ARDA unpublished). The road network within the study
area measures about 100 km of seasonal roads, which are strongly affected by
the yearly flooding of the rivers.
Soils vary according to distance from the main river, Mwenezi. Adjacent to
the river, soils are deep sands from recent alluvium (ARDA unpublished). Further
inland there are siallitic soils and heavy textured soils together with vertisols
(ARDA unpublished).
No detailed vegetation surveys have been carried out in Sengwe. Wild and
Grandvaux Barbosa (1967) described the vegetation, on a large scale, as
discontinuous dry savanna woodland and thicket with tree or shrub savanna of
Acacia and the palm Hyphaene petersiana. A more recent study indicated that
the most dominant tree species on the heavy clays (which are closely associated
with the palm) is Salvadora augustifolia (Sola 1998).Figure 2. Map of the study areaSource: ESRI Data and Maps 2002.14PALM.P65 249 22/12/2004, 11:05