An assessment of the contribution of surface and subsurface flows to river flows of the Sandspruit in the Berg River Catchment, South Africa.
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Date
2018
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
University of the Western Cape
Abstract
Studies have shown that the primary origin of salinity in river flows of the Sandspruit in the Berg
Catchment located in the Western Cape Province of South Africa was mainly a result of atmospheric
deposition of salts. The salts are transported to rivers through surface runoff and subsurface flow (i.e.
through flow and groundwater flow). The purpose of this study was to determine the contributions of
subsurface and surface flows to the total flows in the Sandspruit, Berg Catchment. Three rain events
were studied. Water samples for two rain events were analysed for environmental tracers ?18O, Silica
or Silicon dioxide (SiO2), Calcium (Ca2+) and Magnesium (Mg2+). Tracers used for two component
hydrograph separation were ?18O and SiO2. The tracers, Ca2+ and Mg2+, revealed inconsistent
contributions of both subsurface flow and surface flow. Two component hydrograph separations
indicated is that groundwater is the dominant contributor to flow, while surface runoff mainly
contributes during the onset of the storm event. Groundwater response to precipitation input indicated
that boreholes near the river have a quicker response than boreholes further away from the river.
Boreholes nearer to the river also indicate higher water levels in response to precipitation, in comparison
to boreholes further from the river.
Description
Magister Scientiae - MSc (Environ & Water Science)
Keywords
Surface and subsurface runoff
Environmental Isotopes, Deuterium, Salinity, Sandspruit, Tracers, Hydrograph separation