28 September 2014 to 3 October 2014
Matjiesfontein's Lord Milner Hotel
Africa/Johannesburg timezone
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Quantifying groundwater-surface water exchange fluxes based on steady state riparian area aquifier water balance

2 Oct 2014, 14:45
15m
Conference Room, Matjiesfontein Station (Matjiesfontein's Lord Milner Hotel)

Conference Room, Matjiesfontein Station

Matjiesfontein's Lord Milner Hotel

Matjiesfontein, Western Cape
Oral and Poster Presentation Water

Speaker

Mr Teboho Shakhane (University of the Free State)

Description

The aim of this study was to perform a riparian area aquifer groundwater budget with an objective to estimate water exchange fluxes at an ungagged Modder River groundwater-surface water interaction research site. The study was based on the conceptual and quantitative knowledge on hydrogeological-landscape units, recharge to the riparian-area-aquifer, groundwater evapotranspiration, influx from terrestrial-area-aquifer and change in groundwater storage of the riparian-area-aquifer. Using heat pulse velocity method, the riparian evapotranspiration was estimated as 15.15 Mm3/month. For the southeastern side terrestrial-area-aquifer, the slope of groundwater table was estimated to approximately be 0.042 with the transmissivity of about 91.73 m2/month. The aquifer width was estimated to be 3000m; subsequently, influx from the terrestrial-area-aquifer into the riparian-area-aquifer was computed to be 235.68 Mm3. On the northwestern terrestrial-area-aquifer, the slope of groundwater table was estimated to approximately be 0.041 with the transmissivity of about 1.44 m2/month. With similar average aquifer width, influx from the terrestrial-area-aquifer into the riparian-area-aquifer was approximated to be 6.71 Mm3. Change in storage was approximated to be -18087.15 m3/month for the southeastern riparian-area-aquifer and 5166.45 m3/month for the northwestern riparian-area-aquifer. Using the soil moisture balance model, the average annual recharge computed for the riparian-area-aquifer was approximately 8.67 mm. Subsequently baseflow was estimated for the southeastern reach to be 220.54 Mm3/month and -8.45 Mm3/month for the northwestern reach using a groundwater budget model. Keywords: Modder River, Riparian-area-aquifer, Terrestrial-area-aquifer, Groundwater budget, Baseflow

Primary author

Mr Teboho Shakhane (University of the Free State)

Co-authors

Dr Francois Fourie (University of the Free State) Dr Modreck Gomo (University of the Free State)

Presentation Materials