Freshwater floods drive salt into arid region aquifers

Abstract

For people living in arid ecosystems, groundwater replenished during seasonal flooding is typically their most important source of freshwater. Yet these same floods may also be responsible for temporarily increasing the salinity of the vital freshwater stores, a relationship shown for the austral summer flooding of the Kuiseb River in Namibia. Between 2006 and 2008, Amiaz et al. recorded the effect of 12 floods on soil water storage, groundwater electrical conductivity (a measure of salinity), and solute movement throughout various layers of the subsurface along the river. The researchers' primary concern was understanding how soluble salts residing in the vadose zone, the subsurface layer that lies between the groundwater table and the surface, make their way into the aquifer.