SciELO - Scientific Electronic Library Online

 
vol.44 issue4A scenario-based multiple attribute decision-making approach for site selection of a wastewater treatment plant: Bahir Dar City (Ethiopia) case studyNatural organic matter in aquatic systems - a South African perspective author indexsubject indexarticles search
Home Pagealphabetic serial listing  

Services on Demand

Article

Indicators

Related links

  • On index processCited by Google
  • On index processSimilars in Google

Share


Water SA

On-line version ISSN 1816-7950
Print version ISSN 0378-4738

Abstract

VAN MAZIJK, Ruan; SMYTH, Lucy K; WEIDEMAN, Eleanor A  and  WEST, Adam G. Isotopic tracing of stormwater in the urban Liesbeek River. Water SA [online]. 2018, vol.44, n.4, pp.674-679. ISSN 1816-7950.  http://dx.doi.org/10.4314/wsa.v44i4.16.

The ongoing drought in the Western Cape of South Africa (2014 to present) has called for an urgent need to improve our understanding of water resources in the area. Rivers within the Western Cape are known to surge rapidly after rainfall events. Such storm-flow in natural river catchments in the Jonkershoek mountains has previously been shown to be driven by displaced groundwater, with less than 5% of rainfall appearing in the storm-flow. However, the origin of storm-flow surges within urban rivers in the region remains unknown. In this study, we used stable isotopes in water to illustrate that at least 90% of water in the Liesbeek River during a storm event was rainwater. There was a strong correlation between storm-flow and rainfall rates (P < 0.001, Pearson's r = 0.86), as well as between the δ18O and δ2H values of river-water and rainwater (δ18O: Pearson's r = 0.741 (P = 0.001), δ2H: Pearson's r = 0.775 (P < 0.001)). Storm-flow within this urban river therefore appears to be driven by overland-flow over the hardened urban catchment, rather than piston-flow as seen in natural catchments. Our results support studies suggesting the Liesbeek River could be a target for stormwater harvesting to augment water resources in the city of Cape Town.

Keywords : stable isotopes; urban water management; water resources; urban rivers.

        · text in English     · English ( pdf )

 

Creative Commons License All the contents of this journal, except where otherwise noted, is licensed under a Creative Commons Attribution License