Journal of Soils and Sediments

, Volume 11, Issue 8, pp 1456–1465 | Cite as

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




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.


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.


Dam breaching Farm dams Karoo Sediment yield Soil erosion South Africa Water crisis 


  1. 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 2:37–47Google Scholar
  2. Boardman J, Foster IDL (2008) Badland and gully erosion in the Karoo, South Africa. J Soil Wat Conserv 63:121A–125ACrossRefGoogle Scholar
  3. Boardman J, Parsons AJ, Holmes PJ, Holland R, Washington R (2003) Development of badlands and gullies in the Sneeuberg, Great Karoo, South Africa. Catena 50:165–184CrossRefGoogle Scholar
  4. Boardman J, Foster IDL, Rowntree K, Mighall T, Parsons AJ (2009) Small farm dams: a ticking time bomb? Water Wheel Jul/Aug 2009:30–35Google Scholar
  5. 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 126:64–75CrossRefGoogle Scholar
  6. 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 22:4922–4935CrossRefGoogle Scholar
  7. Bryan RB, Schnabel S (1994) Estimation of sedimentation rates in the Chemeron Reservoir. Adv GeoEcol 27:231–248Google Scholar
  8. 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 OxfordGoogle Scholar
  9. 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 20:115–122CrossRefGoogle Scholar
  10. 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, WashingtonGoogle Scholar
  11. 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 3–16CrossRefGoogle Scholar
  12. 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 49:271–287CrossRefGoogle Scholar
  13. Faleh A, Navas A, Sadiki A (2005) Erosion and dam siltation in a Rif catchment, (Morocco). IAHS Publ 292:58–64Google Scholar
  14. 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 DevelopmentGoogle Scholar
  15. 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)Google Scholar
  16. Foster IDL, Boardman J, Keay-Bright J (2007) Sediment tracing and environmental history for two small catchments, Karoo uplands, South Africa. Geomorphology 90:126–143CrossRefGoogle Scholar
  17. 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 325:139–142Google Scholar
  18. 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
  19. 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, WashingtonGoogle Scholar
  20. 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 17:211–230CrossRefGoogle Scholar
  21. Holmes PJ, Boardman J, Parsons AJ, Marker ME (2003) Geomorphological palaeoenvironments of the Sneeuberg Range, Great Karoo, South Africa. J Quatern Sci 18:801–813CrossRefGoogle Scholar
  22. Keay-Bright J, Boardman J (2006) Changes in the distribution of degraded land over time in the central Karoo, South Africa. Catena 67:1–14CrossRefGoogle Scholar
  23. 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 18:423–439CrossRefGoogle Scholar
  24. Lahlou A (1993) Envasement des Barrages au Maroc. Wallada, CasablancaGoogle Scholar
  25. Mason SJ, Waylen PR, Mimmack GM, Rajaratnam B, Harrison ME (1999) Changes in extreme rainfall events in South Africa. Climate Change 41:249–257CrossRefGoogle Scholar
  26. Msadala, Gibson, Le Roux, Rooseboom, Basson (2009) Sedimentation and sediment yield maps for South Africa. WRC Project K5/1765, Progress Report, Stellenbosch University & ARCGoogle Scholar
  27. Murray-Rust DH (1972) Soil erosion and reservoir sedimentation in a grazing area west of Arusha, northern Tanzania. Geogr Ann A 54:325–343CrossRefGoogle Scholar
  28. Nicholls MH (2006) Measured sediment yield rates from semiarid rangeland watersheds. Rangeland Ecol Manag 59:55–62CrossRefGoogle Scholar
  29. NWRS (2004) National Water Resources Strategy. Pretoria, Department of Water Affairs and Forestry (DWAF). Available online at:
  30. 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 34:1216–1233CrossRefGoogle Scholar
  31. 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 83:135–147CrossRefGoogle Scholar
  32. 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 CrossRefGoogle Scholar
  33. Romero-Diaz A, Alonso-Sarria F, Martinez-Lloris M (2007) Erosion rates obtained from check-dam sedimentation (SE Spain). A multi-method comparison. Catena 71:172–178CrossRefGoogle Scholar
  34. 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, StellenboschGoogle Scholar
  35. 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 GeomorphologieGoogle Scholar
  36. 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. 325:139–142Google Scholar
  37. Russow F, Garland G (2000) Factors accounting for the rapid siltation of Hazelmere Dam, KwaZulu-Natal. S Afr Geogr J 82:182–188Google Scholar
  38. Trimble SW (1983) A sediment budget for Coon Creek Basin in the Driftless Area, Wisconsin, 1853–1977. Amer J Sci 283:454–474CrossRefGoogle Scholar
  39. 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/AGoogle Scholar
  40. Virgo KJ, Munro RH (1978) Soil and erosion features of the central plateau region of Tigrai, Ethiopia. Geoderma 20:131–157CrossRefGoogle Scholar
  41. Xu K, Milliman JD (2009) Seasonal variations of sediment discharge from the Yangtze River before and after impoundment of the Three Gorges Dam. Geomorphology 104:276–283CrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  1. 1.Environmental Change InstituteOxford University Centre for the EnvironmentOxfordUK
  2. 2.Department of Environmental and Geographical ScienceUniversity of Cape TownRondeboschSouth Africa
  3. 3.School of Science and TechnologyUniversity of NorthamptonNorthamptonUK
  4. 4.Department of GeographyRhodes UniversityGrahamstownSouth Africa

Personalised recommendations