Introduction
At a basin or sub-basin scale, particularly in semi-arid and arid areas, priority is often placed on monitoring and management of water quantity. Equally important, however, is the monitoring and management of water quality (DWAF 2004d).
Quality is often characterised in terms of the concentration of different chemicals in the water (Hatfield 2008). What determines “good” or “bad” water quality depends on the purpose of the assessment—for example, water with naturally elevated concentrations of some metals may be unsafe to drink, but still suitable for industrial uses. Assessment involves comparing measured chemical concentrations with natural, background, or baseline concentrations, and with guidelines established to protect human health or ecological communities. Below is a summary of key findings from water quality studies for the Orange-Senqu River basin. This chapter describes how physical, chemical, biological and qualitative indicators are used to come to the conclusions below and what human activities are most likely to contribute to the water quality problems in the basin.
Box: Key Findings from Water Quality Studies
- The Vaal catchment is highly polluted, which has implications for water resource availability and transboundary impacts. The water quality of the Upper and Lower Orange is said to be good; however, there are insufficient data for certain categories of contaminants to make conclusive statements.
- There are concerns along all the rivers flowing through towns and villages throughout the catchment with respect to localised micro-biological pollution from untreated and partially treated sewage outflows;
- The increase in Total Dissolved Solids (TDS) in the Vaal and Lower Orange catchments and the concomitant increase in constitutes, such as choloride and sulphate, has had major implications for domestic, industrial and agricultural water use;
- The transboundary impacts of POPs, heavy metals and radio-nuclides are unknown due to a lack of monitoring data and detailed studies, but some level of transboundary transfer of these pollutants is suspected;
- Eutrophication is a severe problem in the Vaal catchment and in isolated pockets in other parts of the basin.
UNDP GEF (2008)
Chapter Summary
This chapter covers the following concepts and material:
- The principles of water quality, including the physical, chemical, and biological characteristics
- The impacts of human activities on water quality
- Regional and national policies and laws related to management of water quality
- The concept of fitness for use
- Water quality monitoring
The Richtersveld region, South Africa/Namibia.
Source: ©iStockphoto/ Roode 2008
( click to enlarge )
