Land use activities that have an effect on water quality and river health are believed to have increased
along the Orange River in Namibia. These are mainly agricultural activities, notably irrigation, with more
than 2000 ha currently under irrigation and approximately 2000 ha planned for future expansion. Other
anthropogenic activities include urban development and weir construction along the Orange River.
Population increase along the river has resulted in proliferation of unplanned settlements with no proper
sanitation facilities.
This study was aimed at assessing the current water quality and overall health status of the Orange
River in Namibia. The South African Scoring System 5(SASS5) was applied in eight sites where samples
for macroinvertebrates, physical and chemical water quality parameters such as nutrients in the water,
pH, turbidity and presence of bacteria were obtained. Satellite images i.e. Landsat images were also used
to assess the land-uses over time in the study area with the view of linking such changes to variance in
water quality over time.
The SASS5 results indicated a fair water quality and river health condition in category C, indicating that
the river is moderately modified. Water quality parameters at all sites varied moderately and were within
acceptable limits, except for turbidity and chlorophyll a. There was a significant difference in the mean
concentrations of nine water quality parameters among sampling periods, whereby F-value > F-critical
at a = 0.05 among sites, F-value < F-critical at a = 0.05, except for turbidity and chlorophyll a. The
Landsat images also showed minimal changes in land-use activities between 2002 and 2012, with a
net increase of 38 ha in irrigated area. According to National Water Policy White Paper of Namibia of
2000, it was found that policies and legislation address water resources management from a broader
spectrum and not specific to river health. Thus, it was concluded that the river health of Orange River
is still within acceptable range despite the fact that there is an urgent need to develop an effective and
sustainable water quality monitoring and development programme.