Geoelectrical imaging of groundwater salinization in the Okavango Delta, Botswana

Combined use of frequency-domain electromagnetic and electrical resistivity surveys to delineate near-lake groundwater flow in the semi-arid Nebraska Sand Hills, USA

“…Horizontal head gradients on the order of 0.1% move the saline plumes toward the eastern to southeastern side of the lakes. Vertical convective flow of saline plumes such as those geophysically documented in the Okavango delta in Botswana (Bauer et al 2006) and Arabian sabkha (Van Dam et al 2009), were not observed in these lakes. Average EC values around the freshwater lakes were only a third of those measured around the saline lakes.…”

“…Recent advances in data interpretation and electronics have made it possible to use electromagnetic (EM) and electrical resistivity (ER) surveys to delineate groundwater interfaces non-invasively, especially in areas of seawater intrusion (Fitterman and Deszcz-Pan 1998;Day-Lewis et al 2006) and groundwater salinization (Bauer et al 2006). In arid and semi-arid environments, the salinity of groundwater-dominated lakes is increased when surface evaporation exceeds precipitation (Wood and Sanford 1990).…”

Plant uptake of NaCl in relation to enzyme kinetics and toxic effects

“…In arid zones, where more water is transpired than precipitated, this will lead to a slow but irreversible salinization of the water resources. Indeed, salinity gradients established by the combined effect of evaporation and transpiration could be observed around salt pans in arid areas such as the Okavango delta (Bauer et al, 2006). The observed pattern could be simulated by coupling the model for uptake of water and salt developed in this study to a groundwater transport model (Bauer-Gottwein et al, 2008).…”

Large Scale Electrical Resistivity Tomography Survey Correlated to Hydrogeological Data for Mapping Groundwater Salinization: A Case Study from a Multilayered Coastal Aquifer in Rhodope, Northeastern Greece

“…In certain occasions (Wilson et al, 2006), the ERT technique was used in order to supplement and clarify the results of initially executed one dimensional VES in the same region. The efficiency of the ERT technique in a variety of inshore geological settings is demonstrated by various researchers, including coastal alluvial aquifers (Abdul Nassir et al, 2000;Morrow et al, 2010;Ebraheem et al, 2012;Mas-Pla et al, 2012), coastal deltaic deposits (Maillet et al, 2005;Martínez et al, 2009;Gurunadha Rao et al, 2011), or inland saline environments, e.g., in the Okavango Delta, Botswana (Bauer et al, 2006), in the Dead Sea, Jordan aquifer (Batayneh, 2006), and in Querenca-Silves, south Portugal (Leitão et al, 2014). These authors have utilized various array configurations and electrode spacing intervals, and showed that the method is able to provide a good correlation between specific resistivity values and hydrogeological properties, and thus, to calculate formation factors (Archie, 1942) for the separate aquifer units, by combining groundwater electrical resistivity measurements and bulk formation resistivity distribution.…”