Groundwater occurrence in Basement aquifers in Limpopo Province, South Africa: model-setting-scenario approach

Abstract

More than 1,000 constant discharge and stepdrawdown pumping tests each were analysed for an area underlain by Basement granite in Limpopo Province, South Africa. The climate and topography vary greatly over the study area, with fairly constant prevailing neotectonic stresses. The pumping tests were analysed via the methods of Theis (Am Geophys Union Trans 14 (2):519-524, 1935), Cooper and Jacob (Am Geophys Union Trans 27:526-534, 1946), Logan (Groundw 2:35-37,1964) and Birsoy and Summers (Groundw 18:137-146, 1980). Transmissivities obtained from the different methods were assigned a scenario of high ([100 m 2 /day), intermediate (10-100 m 2 /day) or low (\10 m 2 /day). These scenarios were superimposed on models controlling flow (shear zones, open structures, closed structures, contacts and the weathered aquifer) and settings (inherent prevailing climatic and neotectonic conditions) to evaluate the controls of groundwater occurrence in Basement terrain.

Aquifer vulnerability using recharge, depth to groundwater, soil type and slope to classify the vadose zone (Molototsi and Middle Letaba quaternary catchments, Limpopo Province, South Africa)

“…Groundwater is also used to supplement irrigation during times of drought in both catchments (DWAF, 2004). Groundwater abstraction takes place close to the rivers and probably has a direct impact on the surface water flow, as has been addressed in Dippenaar et al (2009). Moderate to good yields of > 5 ℓ/s are found in both catchments (DWAF, 2003).…”

Hydrogeological characterisation of regional faults and dolerite dykes in the Precambrian Basement and Karoo Supergroup (Tete Province, Mozambique)

“…Fractured rock aquifers are generally considered as a combination of porous rock matrix and secondary fractures with groundwater flow being structurally controlled (Dippenaar et al, 2009). The characteristics of fractured rock aquifers are highly dependent on several factors such as the composition of the rock mass, neotectonics, weathering, climatic conditions (historic and prevailing), geomorphology, and intrusion of younger lithologies .…”

Review of engineering, hydrogeological and vadose zone hydrological aspects of the Lanseria Gneiss, Goudplaats-Hout River Gneiss and Nelspruit Suite Granite (South Africa)

“…Based on location (eastern and western parts of the Limpopo Province), present-day climate (arid versus humid) and directions of major structural features, more than 1 000 constant discharge and more than 1 000 step-drawdown tests were analysed and superimposed on climatic, geomorphological and tectonic settings. The findings can be summarised as shown in Table 3 where "high" represents T > 100 m 2 /d, "moderate" T > 10 m 2 /d and "low" below (Dippenaar et al 2009). …”

“…This, together with climatic variations, result in distinct geomorphology and landforms with characteristic soil successions both Table 3. Relative expected yields for different climatic and neotectonic settings in the Goudplaats-Hout River Gneiss Suite ranked as "high", "moderate" or "low" for the Hout River Shear Zone (HRSZ), open structures parallel to major fault strike, closed structures perpendicular thereto, and contacts with younger granite plutons (Dippenaar et al 2009). Ferruginization is common, notably in the Lanseria Gneiss (JDG) and to a lesser extent in the Goudplaats-Hout River Gneiss Suite (G-HRG).…”

“…Botha and Van Rooy 2001; Dippenaar et al 2009;Holland and Witthüser 2011;Titus et al 2009;Witthüser et al 2010). However, as a critical component of understanding the hydrological cycle, one needs to consider the behaviour of earth materials in all aspects of the hydrological cycle, which includes not only saturated conditions, but also the vadose zone, aquicludes and barriers.…”