CHAPTER 9: CONCLUSION

As mentioned earlier in the statement of the problem the Hennops River has gradually deteriorated in terms of its water quality and hydrological conditions over the past three decades. This can mainly be attributed to the catchment’s position which is situated between Johannesburg and Pretoria within the provincial boundaries of Gauteng – the smallest of South Africa’s nine provinces but housing approximately 8,8 million people and regarded as the economic powerhouse of the country. The study area’s associated land use, activities and increasing urbanisation taking place negatively affect the Hennops River and its principal tributaries. Moreover, the river system is the responsibility of a number of local authorities, making co-ordinated planning and management difficult.

Owing to the deterioration of the water quality and hydrological conditions of the Hennops River affected parties concerned such as local authorities, residents and business people of Centurion have started considering the Hennops River as a liability instead of the environmental asset with intrinsic values it offers to its surrounding environments. Causes of its deteriorated water quality and hydrological problems needed to be ascertained so that rehabilitative and mitigatory measures could be proposed and it is for this reason that this study was conducted.

As such, this study’s main aim was to establish the present water quality condition and hydrological status and condition of the Hennops River. The water’s suitability for aquatic ecosystems well-being was also determined as fish mortalities continue to occur in sections of the Hennops and its principal tributaries. These sections include the upper Hennops River and Centurion Lake forming the centre of Centurion’s CBD. Once the overarching problems and causes of these were determined and understood, rehabilitative and mitigatory measures were proposed towards the improvement of the water quality and hydrological status.

Before this could be achieved the meaning of water quality, its various physical and chemical constituents affecting aquatic ecosystems and the recommended Target Water Quality Range (TWQR) as stipulated by DWAF for the well-being of these were reviewed and discussed. Added to this, hydrology and its relevance in terms of this study were explained.

111 Conclusion

The study area also needed to be described. Not only was attention given to the position of the Hennops River and its principal tributaries, but also to the associated physical features and existing land uses within its boundaries. In order to gain insight, understanding and ascertaining the causes of water quality and hydrological problems, it was deemed necessary to describe the study area in detail.

Following this, existing knowledge of previous conditions of the study area was reviewed so that a comparison could be made between previous and existing conditions. It was found that the Hennops River catchment had already experienced deterioration between the 70’s and 90’s due to factors such as increasing urbanisation, industrialisation and rapid human settlement. Coupled with the fact that the study area is currently experiencing further developments and an increase in human population, the rationale of this is that an improvement in water quality and hydrological conditions of the rivers without implementing rehabilitative measures will not be possible. Therefore, rehabilitative measures need to be implemented.

The existing knowledge of the study area was then compared to the most recent water quality of the study area i.e. the two year period between January 2002 and December 2003. Data in terms of water quality monitoring results were collected from two authorities responsible for monitoring the Hennops River, viz.: DWAF and CTMM. Only certain water quality constituents were collected and analysed i.e. those having an effect on aquatic ecosystems (Table 14). Since water quality monitoring results would differ along different sections of the Hennops and its principal tributaries, the actual positions of the DWAF and CTMM monitoring points were described with the areas of the study area represented by their monitoring results.

The recent water quality data showed that only certain water quality constituents could be causing debilitating effects on aquatic ecosystems i.e. five out of the ten different water quality constituents showed mean concentrations not complying to the TWQR. These constituents were dissolved oxygen, ammonia, chloride, nitrate and nitrite nitrogen and orthophosphates. As expected, the upstream sections of the study area comprising the formal and informal settlements of inter alia Tembisa, Ivory Park and industrial areas of Clayville and Olifantsfontein, had higher mean constituent values than the downstream sections. This can be attributed to the land use and activities present in these areas surrounding the Kaalspruit (Table 15). 112 Conclusion

In terms of comparing the recent water quality data to the data from the past studies, it was concluded that the Hennops River catchment has experienced deterioration in terms of its water quality over the past three decades. The comparison showed that mean constituent concentrations of ammonia, phosphorus, COD and chlorine have increased over the years.

The Hennops River and its principal tributaries, especially the Kaalspruit and Olifantspruit, experience not only water quality problems but additional hydrological problems as well. These problems were dealt with in detail and include typically the erosion of the Olifantsfontein wetland and riverbeds and riverbanks of the Kaalspruit and Hennops River due to the sediments released from the wetland. Furthermore, large amounts of debris are also carried downstream by floodwater flows. This debris consists of urban litter and vegetation debris.

Rehabilitative and mitigatory measures have been proposed. They are aimed at improving the water quality and hydrological problems of the Hennops, Olifantspruit and Kaalspruit Rivers. Measures proposed include the construction of sediment traps and debris traps, the erosion control of riverbeds and riverbanks, rehabilitation of the Olifantsfontein wetland and the construction of another in Centurion.

It is recommended that monitoring of the water quality of the Hennops and principal tributaries continue to be conducted by DWAF and CTMM in order to monitor the state of these rivers on a continual basis. Significant changes in water quality should be investigated to determine causes for this and to address such problems. Furthermore, the situation of the Hennops River system must be one of the more important environmental issues between Johannesburg and Pretoria. Therefore, the situation illustrates the need for rivers (and water management areas) to be managed holistically as opposed to the fragmentalised planning by different local councils and government departments which is currently the scenario. Responsible parties need to formulate and follow an environmental management plan which will address the upstream water quality and associated problems as these in turn are causing problems such as the silting-up of Centurion Lake and the loss of aquatic biota further downstream.

113

REFERENCES

ANTONIOU, A.V. 1999: The water quality of the rivers in the vicinity of the Sasol Secunda Industrial Complex. M. Sc. dissertation, Rand Afrikaans University, Johannesburg.

ASHTON, P.J. 1981: Nitrogen fixation and the nitrogen budget of a eutrophic impoundment. Water Research, 15: 823 – 833.

BOKAMOSO LANDSCAPE ARCHITECTS AND ENVIRONMENTAL CONSULTANTS. 2003: Environmental scoping report for Highveld Extension 49. Pretoria.

BOKAMOSO LANDSCAPE ARCHITECTS AND ENVIRONMENTAL CONSULTANTS. 2004: Environmental scoping report for Highveld Extension 62. Pretoria.

BOTHA, J. 2004: Personal communication from Mr. J. Botha, Plant Manager, Centurion Sewage Works, Pretoria, 10 May.

BRADY, J.E., and HOLUM, J.R. 1996: Chemistry: the study of matter and its changes. 2nd ed. New York: Wiley & Sons.

CHUTTER, F.M. 1973: An ecological account of the past and future of South African rivers. Limnological Society of South Africa, News letter no. 21: 22 – 34.

DALLAS, H.F. and DAY, J.A. 2004: The effect of water quality variables on aquatic ecosystems: a review. Water Research Commission Report no. TT 224/04. Pretoria.

DEPARTMENT OF WATER AFFAIRS AND FORESTRY. 1996a: South African water quality guidelines. 2nd ed. Volume 7: Aquatic Ecosystems. Pretoria: The Department.

DEPARTMENT OF WATER AFFAIRS AND FORESTRY. 1996b: South African water quality guidelines. 2nd ed. Volume 8: Field Guide. Pretoria: The Department.

114

DEVELOPMENT BANK OF SOUTH AFRICA, 2000: South Africa: Inter-Provincial comparative report, DBSA, Midrand. Annexure A.

DE WET, L.P.D. and MALLORY, S.J.L. 1998: Environmental and hydrological aspects of the Rietvlei Dam catchment study. Borehole Water Journal, 40: 2 – 9.

DU PLESSIS, J.J. 2004: Personal communication from Mr. J.J. du Plessis, Operations Manager, Centurion Mall, Pretoria, 20 August.

DU PREEZ, H.H. 1995: Assessment of the effects of silt releases from Centurion Lake on the Hennops River aquatic ecosystem. Rand Afrikaans University. Report to Wates, Meiring & Barnard Inc. Midrand.

ESTERHUYSEN, C.M. 2004: Personal communication from Mr. C.M. Esterhuysen, Laboratory Manager, City of Tshwane Daspoort Laboratories, Pretoria, 6 April.

FAKIR, S. and BROOMHALL, L. 1999: Midrand state of the environment report [Online]. Available at : http://www.environment.gov.za/soer/reports/midrand/soemid_1.pdf. Accessed: 20/11/2003.

FREEMAN, M.J., HOWARD, M.R. and WIECHERS, H.N.S. 2000: The management of urban impoundments in South Africa. Volume 2. Guideline manual. Water Research Commission Report no. TT 119/00. Pretoria.

FUGGLE, R.F. and RABIE, M.A. 1992: Environmental management in South Africa. Cape Town: Juta.

GARNER, G. 1998: Will catchment management save the Hennops? The urban green file, 3(2): 14 – 15.

GAUTENG facts. [Online]. 2003: Available at: http://www.gauteng.net/home/fact.asp. Accessed 14/06/2004.

115

GEORGE, D. 2003: Rehabilitation of the Kaalspruit and upper Hennops River, vol 1. Report to Tshwane Metropolitan Council. Pretoria.

GOUWS, A., UYS, B. and WHITE, N. 1998: Ivory Park, Ebony Park & Rabie Ridge open space concept plan. Report to Midrand Town Council. Midrand.

HILL, L. 1997: Assessment of the biotic hazard of the acid mine drainage impacted Blesbokspruit near Witbank, Mpumalanga. M. Sc. dissertation, Rand Afrikaans University, Johannesburg.

HOFFMANN, J.R. 1994: Non-point source pollution in the Hennops River Valley. Water Research Commission Report no. 518/1/95. Pretoria.

LA GRANGE, B. 2003a: Eensame krok kies plaas buite Pretoria as sy tuiste. Beeld, 29 Oktober: 3.

LA GRANGE, B. 2003b: Reëns, afval rede vir Centurion – visvrektes. Beeld, 19 November: 7.

LAWS, E.A. 2000: Aquatic pollution: an introductory text. 3rd ed. New York: Wiley & Sons.

LE ROUX, H. 2003: A new water era. Engineering News, 23 (28): 28 – 30.

LOTTERING, S. 2003: Personal communication from Mrs. S. Lottering, Water Quality: Environmental Officer, City of Tshwane Metropolitan Municipality, Pretoria, 26 September.

MANAHAN, S.E. 1994: Environmental chemistry. 6th ed. Boca Raton: Lewis.

MILLER, G.T. 1993: Environmental science: sustaining the Earth. 4th ed. California: Wadsworth.

MILLER, G.T. 2002: Living in the environment: principles, connections, and solutions.12th ed. California: Wadsworth.

116

NIEHAUS, B.H., KOTZE, P.J and NEL, A. 2002: Biomonitoring of selected rivers receiving effluent from Tshwane Metropolitan waste water treatment works. RAU ECON, Rand Afrikaans University, Johannesburg.

PIENAAR, P. 2004: Minutes of workshop on desilting of Centurion Lake, 1 July. Nyeleti Consulting, Pretoria.

RÖSSLE, W. 2004: Minutes of workshop on desilting of Centurion Lake, 1 July. Nyeleti Consulting, Pretoria.

SAMPSON, I. 2001: Introduction to a legal framework to pollution management in South Africa. Water Research Commission Report no. TT 149/01. Pretoria.

SCHOEMAN, F.R. 1976: Diatom indicator groups in the assessment of water quality in the Jukskei – Crocodile River system (Transvaal, Republic of South Africa). Journal of the Limnological Society of Southern Africa, 2(1): 21 – 24.

SCHOEMAN, F.R. 1979: Diatom indicators of water quality in the upper Hennops River (Transvaal, South Africa). Journal of the Limnological Society of Southern Africa, 5(2): 73 – 78.

SHEPHERD, P.J., WOOD, A., CESSFORD, F. and NGWENYA, E. 2000: Kaalspruit river integrated pollution control management plan. Report no. 262886/1. Steffen, Robertson and Kirsten, Johannesburg.

SINCLAIR, R.C., EBERSOHN, C. and EICKER, A. 1983: The aquatic Hyphomycetes of the Hennops River (Irene), South Africa. South African Journal of Botany, 2(3): 224 – 230.

SLABBERT, J.L. and VENTER, E.A. 1999: Biological assays for aquatic toxicity testing. Water Science Technology, 39(10 – 11): 367 – 373.

SOUTH AFRICA. 1996: The constitution of the Republic of South Africa, act 108 of 1996. Pretoria: Government Printer.

117

SOUTH AFRICA. 1998: The national water act, 36 of 1998. Pretoria: Government Printer.

STRAHLER, A.N. and STRAHLER, A.H. 1997: Physical geography: science and systems of the human environment. New York: Wiley & Sons.

STRATEGIC ENVIRONMENTAL FOCUS. 2003: Status quo report for the N1/R21 quadrant. Report to Gauteng Department of Agriculture, Conservation, Environment and Land Affairs. Pretoria.

STRYDOM, T. 2004: Personal communication from Mr. T. Strydom, Managing Director, Thinus Strydom Properties, Pretoria, 17 March.

SUTTON, D.F. and OLIVEIRA, M.P. 1987: Hartebeespoort Dam as a receiver of return flows. In: Symposium on Hartebeespoort Dam: Quo Vadis, 1987, Pretoria. Proceedings. Department of Water Affairs: 49 – 61.

SWANEPOEL, Y. 2004: Personal communication from Mrs. Y. Swanepoel, Chemist: Client Services, ERWAT Laboratories, Johannesburg, 8 April.

THORNTON, J.A., COCHRANE, K.L., JARVIS, A.C., ZOHARY, T., ROBARTS, R.D. and CHUTTER, F.M. 1986: An evaluation of management aspects of a hypertrophic African impoundment. Water Resources, 20(4): 413 – 419.

TOERIEN, D.F. and WALMSLEY, R.D. 1979: The chemical composition of the upper Hennops River and its implications on the water quality of Rietvlei Dam. Water SA, 5(2): 77 – 89.

VAN DER WALT, C.J., TALJAARD, C., ZDYB, L. and HAARHOF, J. 2001: Granular activated carbon for the treatment of eutrophic water at Rietvlei Dam. Chemical Technology, July/August: 8 – 10.

VENTER, A. 2002: Water Quality in the Rustenburg Dorpspruit. M. A. dissertation, Rand Afrikaans University, Johannesburg.

118

WATER RESEARCH COMMISSION. 2001: State of the rivers report: Crocodile, Sabie-Sand & Olifants River systems. Pretoria.

WATES, MEIRING and BARNARD. 2001: Management plan for silt dam at Highveld Technopark, Report no. 3713/1903/6/E. Midrand.

WITTMANN, G.T.W. and FÖRSTNER, U. 1976: Metal enrichment of sediments in inland waters – the Jukskei and Hennops River drainage systems. Water SA, 2(2): 67 – 72.

119