The role of uplift and erosion in the persistence of saline groundwater in the shallow subsurface

Abstract

In many regions of the world, the shallow (<300 m) subsurface is replenished with meteoric recharge within a few centuries or millennia, but in some regions saline groundwater persists despite abundant rainfall. Analyses of the flushing rate of shallow groundwater usually consider the permeability and recharge rate and a static landscape. The influence of landscape evolution can become important over millions of years, however. Here we present numerical simulations of fluid flow and transport in the top 1 km of a sedimentary foreland basin dominated by aquitards, where the rate of uplift and erosion (20 m Ma−1) balances that of meteoric flushing. Paleozoic age saline groundwater and brine persist at shallow depths that might otherwise have contained potable water. Similar hydrogeologic conditions, and uplift and erosion rates, likely exist in many other regions of the world, where a moving landscape has probably never been considered as an important contributor to groundwater quality.

Seismic refraction tracks porosity generation and possible CO 2 production at depth under a headwater catchment

“…Thus, aspects of the patterns we observed in this small study landscape will be useful in understanding how subsurface porosity grows and where gas bubbles nucleate during weathering and erosion in other locations. Advances in interrelating geochemical and geophysical measurements will elucidate aspects of groundwater storage and drainage as well as questions related to long-term geomorphological evolution of valley and ridge systems (10,(36)(37)(38).…”

Crustal Groundwater Volumes Greater Than Previously Thought

“…Considerable uncertainty remains around effective permeabilities and drivers of fluid flow in these deeper environments and their linkages to the rest of the hydrologic cycle. Connection of deep and shallow groundwater has been linked to geological events such as erosion and uplift (Yager et al, 2017) or continental glaciations (McIntosh et al, 2012;Person et al, 2007). Mixing of shallow and deep groundwater during these events may have important implications to biogeochemical cycles and subsurface life (Head et al, 2003;Martini et al, 2003;Wilhelms et al, 2001 Finally, despite potentially being the largest continental store of water, groundwater generally receives less attention than other parts of the hydrologic cycle (Famiglietti, 2014).…”

Impact of Hydrostratigraphic Continuity in Heterogeneity on Brine-to-Freshwater Interface Dynamics; Implications from a 2-D Parametric Study in an Arid and Endorheic Basin

“…Salars can develop a range of stratigraphically complex aquifers because their climate-sensitive change in areal extent can create a series of interbedded lithologies (Houston, 2009), as specifically documented in Munk et al (in review). Since brine-bearing aquifers commonly exist in tectonically active endorheic basins (Yager et al, 2017), faulting among lithologies further complicate the lateral continuity of subsurface heterogeneity and produce interface geometries that defy theory when intersecting fault systems (Yechieli, 2000).…”