The Status of the Health of Rivers

Transcription

1 The Status of the Health of Rivers Presentation to Portfolio Committee 17 August 2011

2 Introduction Status of the rivers is assessed using responses of: Hydrology, water quality, geomorphology habitat integrity and biological responses to habitat changes

3 Rainfall and dam storages The country experienced good rainfall in the past year, except for parts of KZN, WC, Limpopo & Eastern Cape. This translated to dam storage higher than the previous year in most provinces. The WC is experiencing low dam storage. River flows (quantity) influence the quality of water in a catchment, hence the linkage.

4 National Rainfall (First & Second Quarter) 2010/11 Rainfall (mm) eastern cape free state gauteng kzn limpopo mpumalanga n cape n.west w.cape 0.0 oct nov dec jan feb mar eastern cape free state gauteng kzn limpopo mpumalanga n cape n.west w.cape Moths

5 Provincial Storages % of Full supply capacity Eastern Cape Free State Gauteng Kwazulu-Natal Limpopo Mpumalanga Northern Cape North West Western Cape 28/03/ /03/2011 Median

6 State of water quality The main problems affecting water quality in SA are: Eutrophication State of water quality Feacal pollution Salinity Toxicity (pesticides, endocrine disruptors, radioactivity) AMD

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10 Water quality in rivers Water quality of rivers The Nuy, Grootrivier; Olifants, Groot Brak, Swart Vlei, Swartkops, Kariega, Mooi and Blaaubank Rivers in the Western Cape are affected by salinity due to the marine geology. The Vaal River system and Orange River near the confluence with the Vaal River are impacted due to the mining activities and irrigation, power generation and sewage effluents. The Waterval, Blesbokspruit, Natalspruit and Klip Rivers are also affected by effluents from wastewater treatment plantas and industries.

11 The lower Crocodile River has elevated salinity and phosphate concentrations and poses a concern, especially with respect to irrigation. The Upper Crocodile River polluted by effluents from gold mining activities and effluents from Wastewater treatment works. The trophic state of virtually all the dams in the Crocodile River catchment is very high, and algal blooms are common

12 Water quality continued In the Free State sedimentation is a problem especially in the Upper Orange River due to the soil structure which is sandy. The major dams in the Orange River, the Gariep and Vanderkloof have very good water quality and sedimentation does not impact on the dams. The Northern Cape rivers experience high levels of chlorides due to irrigation return flows mining

13 In KZN the middle Umngeni River experiences high phosphates levels due to poultry farms; effluent from beef cattle feed lots and informal settlement without sanitation facilities The Umsunduze River has problems with turbidity caused by soil erosion and overgrazing; faecal pollution due to raw sewage entering the river via small streams; alien vegetation that impact of the river flow and some areas with salinity. The Umlazi river is heavily impacted due to poor sewage effluents discharged into the river; solid waste site that is close to the river; sand mining in the riverthat result in river diversion and industries including a textile factory that discharge directly in the river.

14 The Umthatha River is impacted by high nutrients and feacal pollution due to overflowing sewer manholes and overloaded wastewater treatment works. The Great Fish River has high salinity but is diluted by the water from the Gariep Dam transfer scheme. The middle and lower Bufallo River is affected by discharged effluents from wastewater treatment plants, upstream is pristen.

15 Umthatha River

16 The Olifants catchment is receiving discharges of acidic water from the land activities such as mining. Serious acid conditions prevail in the Klipspruit and Kromdraaispruit Rivers with sulphate concentrations exceeding the Resource Water Quality Objectives. in The Witbank, Middelburg and Loskop Dams have been increasing over the years. The total dissolved solids and sulphates levels ations.

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