ESTUARIES IN SOUTH AFRICA

Main Page	General Information	Catchment Characteristics	Land and Estuary Uses	Ecology
Threats	Mouth dynamics and Estuarine Hydraulics	Physical Features	Climate	References
Water Quality

	Physio-chemical Characteristics
	Monthly pH values at three sampling stations in the Heuningnes Estuary were in the range of 8,0 to 8,6. Most of the readings were fairly consistent between 8,2 and 8,4, which is close to the normal pH value of seawater. (Ref 2)
	Water temperature: The following means were determined from data: Summer: 19,8C Autumn: 17,5C Winter: 13,3C Spring: 17,3C Secchi disc measurements taken along the length of the estuary show a high degree of turbulence indicating the strong influence of the sea high up into the estuary. (Ref 2)

	Pollution Sources
	Oil pollution from oil spilling at sea. Pollution of the system arising from agricultural activities in the wetlands catchment area. Pesticides and artificial nutrients are already widely used by the agricultural sector in the area. Recreational and coastal development pressures are increasing on all South African coastal areas. Further road culverts or bridges and dams would adversely affect the flow of the tributaries. The use of two, three and four wheeled off-road vehicles is an increasing problem on the beach and coastal dunes. This is the most severe threat to the security of the nesting Damara Terns at present (Ref 2)