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The potential significance of the breaching of small farm dams in the Sneeuberg region, South Africa

  • SEDIMENTS, SEC 3 • HILLSLOPE AND RIVER BASIN SEDIMENT DYNAMICS • RESEARCH ARTICLE
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Abstract

Purpose

The significance of small farm dams in regulating water and sediment flows to downstream water storage reservoirs is identified as an important issue in South Africa where water shortages are a major current and likely future problem. The role of farm dam breaching, subsequent release of stored sediment and re-connection of the upstream sediment production areas to the downstream channels is a neglected topic in geomorphology.

Materials and methods

We have mapped the location and estimated the volume of sediment stored in small farm dams in a sample area of ~100 km2 in the Sneeuberg uplands. Detailed studies at four cored dams have used 137Cs, 210Pb, mineral magnetism and sediment stratigraphy to date sediments, correlate time-synchronous levels in the deposits, estimate sediment yields to the dams and identify significant changes in sediment sources. Dam breaching episodes have been recorded and related to local rainfall. We use published data on the water and sediment capacity of a nearby large water storage reservoir to illustrate the potential threat of small dam breaching to the long-term sustainability of water resource provision.

Results and discussion

The high density of small dams in the study area (~1 dam km−2), and the fact that almost 50% are full of sediment, suggests a high potential for breaching. Breaching has already occurred at ~30% of small dams. Extrapolation of the dam density and stored sediment volumes to a nearby catchment of a water storage reservoir, the Nqweba dam, suggests that up to 72 million m3 of sediment in small farm dams could be released through breaching. The current rate of sediment input into the reservoir of ~1 million m3 year−1 will fill the remaining capacity by 2025. This does not take into account the effects on sediment yield of dam breaching, climate and land use change, or the re-connection of upper with lower catchments as a result of breaching.

Conclusions

Serious issues of water supply in South Africa need to address the potential for enhanced sedimentation rates in major reservoirs due to the breaching of small farm dams. The risk of breaching will be exacerbated by changing farm economies, neglect of dam maintenance and climate change, particularly the increase in rainfall intensity which has already been observed in the region.

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References

  • Ampofo EA, Muni RK, Bonsu M (2001) An assessment of sediment loading into an agricultural reservoir in a semi arid region of Kenya. W Afr J Appl Ecol 2:37–47

    Google Scholar 

  • Boardman J, Foster IDL (2008) Badland and gully erosion in the Karoo, South Africa. J Soil Wat Conserv 63:121A–125A

    Article  Google Scholar 

  • Boardman J, Parsons AJ, Holmes PJ, Holland R, Washington R (2003) Development of badlands and gullies in the Sneeuberg, Great Karoo, South Africa. Catena 50:165–184

    Article  Google Scholar 

  • Boardman J, Foster IDL, Rowntree K, Mighall T, Parsons AJ (2009) Small farm dams: a ticking time bomb? Water Wheel Jul/Aug 2009:30–35

    Google Scholar 

  • Boardman J, Foster I, Rowntree K, Mighall T, Gates J (2010) Environmental stress and landscape recovery in a semi-arid area, the Karoo, South Africa. Scot Geogr J 126:64–75

    Article  Google Scholar 

  • Boix-Fayos C, de Vente J, Martinez-Mena M, Barbera GG, Castillo V (2008) The impact of land use change and check-dams on catchment sediment yield. Hydrol Process 22:4922–4935

    Article  Google Scholar 

  • Bryan RB, Schnabel S (1994) Estimation of sedimentation rates in the Chemeron Reservoir. Adv GeoEcol 27:231–248

    Google Scholar 

  • Chesterman S (2009) Land use in the Karoo: comparing stock and game farming with regards to veld condition and management. Unpublished MSc dissertation. Environmental Change Institute, University of Oxford

  • Compton JS, Herbert CT, Hoffman MT, Schneider RR, Stuut J-B (2010) A tenfold increase in the Orange River mean Holocene mud flux: implications for soil erosion in South Africa. Holocene 20:115–122

    Article  Google Scholar 

  • Culler RC (1961) Hydrology of stock-water reservoirs in Upper Cheyenne river basin. In: Hydrology of the Upper Cheyenne river basin, Geological Survey Water-Supply Paper 1531. United States Government Printing Office, Washington

    Google Scholar 

  • Desmet PG, Cowling RM (1999) The climate of the Karoo—a functional approach. In: Dean WR, Milton SJ (eds) The Karoo: Ecological Patterns and Processes. Cambridge University Press, Cambridge, pp 3–16

    Chapter  Google Scholar 

  • Erskine WD, Mahmoudzadeh A, Myers C (2002) Land use effects on sediment yields and soil loss rates in small basins of Triassic sandstone near Sydney, NSW, Australia. Catena 49:271–287

    Article  Google Scholar 

  • Faleh A, Navas A, Sadiki A (2005) Erosion and dam siltation in a Rif catchment, (Morocco). IAHS Publ 292:58–64

    Google Scholar 

  • Foster IDL, Rowntree KM, Boardman J, Mighall TM (submitted) Changing sediment yield and sediment dynamics in the Karoo uplands, South Africa; post-European impacts. Land Degradation and Development

  • Foster IDL, Rowntree KM (2011) Historic land management, rainfall and sediment yield changes in the semi-arid Karoo: a palaeoenvironmental reconstruction and interpretation of sediments accumulating in Cranemere Reservoir, Eastern Cape, South Africa. Zeitshrift für Geomorphogie (in press)

  • Foster IDL, Boardman J, Keay-Bright J (2007) Sediment tracing and environmental history for two small catchments, Karoo uplands, South Africa. Geomorphology 90:126–143

    Article  Google Scholar 

  • Foster IDL, Boardman J, Gates J (2008) Reconstructing historical sediment yields from the infilling of farm reservoirs, Eastern Cape, South Africa. In: Sediment Dynamics in Changing Environments. IAHS Publ 325:139–142

    Google Scholar 

  • Goodrich D C, Keefer TO, Unkrich CL, Nichols MH, Osborn HB, Stone JJ, Smith JR (2008) Long-term precipitation database, Walnut Gulch Experimental Watershed, Arizona, United States. Wat Resources Res 44: W05S04, doi:10.1029/2006WR005782, 2008

  • Hadley RF, Schumm SA (1961) Sediment sources and drainage-basin characteristics in Upper Cheyenne river basin. Geological Survey Water-Supply Paper 1531, United States Government printing Office, Washington

  • Haregeweyn N, Poesen J, Nyssen J, De Wit J, Haile M, Govers G, Deckers S (2006) Reservoirs in Tigray (Northern Ethiopia): characteristics and sediment deposition problems. Land Degrad Dev 17:211–230

    Article  Google Scholar 

  • Holmes PJ, Boardman J, Parsons AJ, Marker ME (2003) Geomorphological palaeoenvironments of the Sneeuberg Range, Great Karoo, South Africa. J Quatern Sci 18:801–813

    Article  Google Scholar 

  • Keay-Bright J, Boardman J (2006) Changes in the distribution of degraded land over time in the central Karoo, South Africa. Catena 67:1–14

    Article  Google Scholar 

  • Keay-Bright J, Boardman J (2007) The influence of land management on soil erosion in the Sneeuberg mountains, central Karoo, South Africa. Land Degrad Dev 18:423–439

    Article  Google Scholar 

  • Lahlou A (1993) Envasement des Barrages au Maroc. Wallada, Casablanca

    Google Scholar 

  • Mason SJ, Waylen PR, Mimmack GM, Rajaratnam B, Harrison ME (1999) Changes in extreme rainfall events in South Africa. Climate Change 41:249–257

    Article  Google Scholar 

  • Msadala, Gibson, Le Roux, Rooseboom, Basson (2009) Sedimentation and sediment yield maps for South Africa. WRC Project K5/1765, Progress Report, Stellenbosch University & ARC

  • Murray-Rust DH (1972) Soil erosion and reservoir sedimentation in a grazing area west of Arusha, northern Tanzania. Geogr Ann A 54:325–343

    Article  Google Scholar 

  • Nicholls MH (2006) Measured sediment yield rates from semiarid rangeland watersheds. Rangeland Ecol Manag 59:55–62

    Article  Google Scholar 

  • NWRS (2004) National Water Resources Strategy. Pretoria, Department of Water Affairs and Forestry (DWAF). Available online at: http://www.dwaf.gov.za/Documents/Policies/NWRC/Default.htm

  • Nyssen J, Clymans W, Poesen J, Vandecasteele I, De Baets S, Haregeweyn N, Naudts J, Hadera A, Moeyersons J, Haile M, Deckers J (2009) How soil conservation affects the catchment sediment budget—a comprehensive study in the north Ethiopian highlands. Earth Surf Proc Land 34:1216–1233

    Article  Google Scholar 

  • Peng J, Chen S, Dong P (2010) Temporal variation of sediment load in the Yellow River basin, China, and its impacts on the lower reaches and the river delta. Catena 83:135–147

    Article  Google Scholar 

  • Polyakov V, Nearing MA, Nichols MH, Scott RL, Stone JJ, Mcclaran M (2010) Long-term runoff and sediment yields from small semi-arid watersheds in southern Arizona. Water Resour Res 46:W09512. doi:10.1029/2009WR009001

    Article  Google Scholar 

  • Romero-Diaz A, Alonso-Sarria F, Martinez-Lloris M (2007) Erosion rates obtained from check-dam sedimentation (SE Spain). A multi-method comparison. Catena 71:172–178

    Article  Google Scholar 

  • Rooseboom A (1992) Sediment transport in rivers and reservoirs: a South African perspective. Report to the Water Research Commission of South Africa. Sigma Beta Consulting Engineers, Stellenbosch

    Google Scholar 

  • Rowntree KM, Foster IDL (in press) A reconstruction of historical changes in sediment sources, sediment transfers and sediment yields for a small, semi-arid Karoo catchment, South Africa. Zeitshrift für Geomorphologie

  • Rowntree K, Foster I, Mighall T, Dupreeze L, Boardman, J (2008) Post-European settlement impacts on erosion and land degradation; a case study using farm reservoir sedimentation in the Eastern Cape, South Africa. In: Sediment dynamics in changing environments, IAHS Publ. 325:139–142

  • Russow F, Garland G (2000) Factors accounting for the rapid siltation of Hazelmere Dam, KwaZulu-Natal. S Afr Geogr J 82:182–188

    Google Scholar 

  • Trimble SW (1983) A sediment budget for Coon Creek Basin in the Driftless Area, Wisconsin, 1853–1977. Amer J Sci 283:454–474

    Article  Google Scholar 

  • Turton A (2008) Three strategic water quality challenges that decision-makers need to know about and how the CSIR should respond. Keynote Address at CSIR conference “Science Real and Relevant” 18 November 2008, Pretoria, CSIR Report No. CSIR/NRE/WR/EXP/2008/0160/A

  • Virgo KJ, Munro RH (1978) Soil and erosion features of the central plateau region of Tigrai, Ethiopia. Geoderma 20:131–157

    Article  CAS  Google Scholar 

  • Xu K, Milliman JD (2009) Seasonal variations of sediment discharge from the Yangtze River before and after impoundment of the Three Gorges Dam. Geomorphology 104:276–283

    Article  Google Scholar 

Download references

Acknowledgements

Many people have contributed over the last 10 years to work in this area: we wish to thank in particular A. J. Parsons (Sheffield), M. Meadows (Cape Town), P. Holmes (Bloemfontein), J. Keay-Bright (Oxford), K. M. Rowntree (Rhodes), and T. M. Mighall (Aberdeen). The hospitality and help of local landowners N. and I. Sheard, A. and B. James (Compassberg), Hester and J. P. Steyburg (Ganora), A. and M. Palmer (Cranemere) and Dr. D. Gaynor (Zuurfontein) are gratefully acknowledged. The reservoir sedimentation study was funded by UK Natural Environment Research Council (Grant Ref: NER/B/S/20030028: 2003–2004), the British Academy (2005–2007) and the South African National Research Foundation (2008–2010). Work by JB has been supported by the Trapnell Fund and the Oppenheimer Fund (Oxford).

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Authors and Affiliations

  1. Environmental Change Institute, Oxford University Centre for the Environment, South Parks Road, Oxford, OX1 3QY, UK

    John Boardman

  2. Department of Environmental and Geographical Science, University of Cape Town, Rondebosch, South Africa

    John Boardman

  3. School of Science and Technology, University of Northampton, Newton Building, Northampton, NN2 6JD, UK

    Ian D. L. Foster

  4. Department of Geography, Rhodes University, Grahamstown, Eastern Cape, South Africa

    Ian D. L. Foster

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  1. John Boardman
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Correspondence to John Boardman.

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Responsible editor: Nikolaus Kuhn

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Boardman, J., Foster, I.D.L. The potential significance of the breaching of small farm dams in the Sneeuberg region, South Africa. J Soils Sediments 11, 1456–1465 (2011). https://doi.org/10.1007/s11368-011-0425-5

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  • DOI: https://doi.org/10.1007/s11368-011-0425-5

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