Temporal and spatial features of the thermohydrodynamics of shallow salty lagoons in northern Chile

Abstract

Salares in the altiplanic region of Chile, Bolivia, and Argentina sustain important ecosystems in small, shallow wetlands, with inflows provided by groundwater and outflows consisting mainly of evaporation. The temporal and spatial thermohydrodynamics of one of these extremely shallow, saline, endorheic wetlands in northern Chile is analyzed on the basis of field observations of water temperature and salinity, and low-dimensionality models accounting for conservation of heat, mass, and volume. Temperature in the studied system is spatially homogeneous but with strong daily oscillations. Salinity, on the other hand, exhibits longitudinal gradients from the zone of (salty) groundwater upwelling to the final evaporation lagoon. Heat balance in the system is largely controlled by wind, as the evaporative heat flux balances out the net solar radiation. Heat exchange with the bottom sediments damps the daily temperature oscillations by retaining (releasing) heat from (to) the water column. Simulated longitudinal profiles of salinity and flow discharge agree reasonably well with field observations but salinity effects on the rates of both evaporation and salt precipitation need to be taken into account. Laboratory experiments were conducted to develop a simple model for the former effect while the latter effect was accounted for by using existing information. Field measurements provided calibration of the model parameters. The observed longitudinal salinity gradients are correlated with the biological structure of the associated ecosystem to explain, for instance, the existence of specific flamingos' feeding areas in the system.

Bacterial Active Community Cycling in Response to Solar Radiation and Their Influence on Nutrient Changes in a High-Altitude Wetland

“…This includes total solar irradiance reaching levels of up to 1,000 W m -2 (Aceituno, 1997; de la Fuente, 2014), the effect of which are intensified in these ecosystem due to low atmospheric concentrations of ozone and water vapor, and high ground reflectivity (albedo), but which can be countered by aerosol dust, in this arid desert ecosystem (Cordero et al, 2013, 2016). Salar de Huasco is subject to extreme shifts in temperature through the day (can range from -15 to 20°C) and high evaporation rates, which result in a negative water balance (e.g., precipitation rates of 50–300 mm y -1 versus evaporation rates of 600–1200 mm y -1 (Risacher et al, 2003; de a Fuente and Niño, 2010; de la Fuente, 2014). The Salar de Huasco is largely groundwater fed, and upwells via a limited number of springs, which generate a wetland habitat, characterized by complex pond and pool systems surrounded by vascular plants forming peatland, locally referred to as bofedales” with the water flowing into a permanent shallow lake (de a Fuente and Niño, 2010).…”

“…Salar de Huasco is subject to extreme shifts in temperature through the day (can range from -15 to 20°C) and high evaporation rates, which result in a negative water balance (e.g., precipitation rates of 50–300 mm y -1 versus evaporation rates of 600–1200 mm y -1 (Risacher et al, 2003; de a Fuente and Niño, 2010; de la Fuente, 2014). The Salar de Huasco is largely groundwater fed, and upwells via a limited number of springs, which generate a wetland habitat, characterized by complex pond and pool systems surrounded by vascular plants forming peatland, locally referred to as bofedales” with the water flowing into a permanent shallow lake (de a Fuente and Niño, 2010). …”

Heat and dissolved oxygen exchanges between the sediment and water column in a shallow salty lagoon

“…Salar is the name that is given to landscapes located in the altiplanic region of Chile, Bolivia, and Argentina that usually have extremely shallow terminal lagoons [ Herrera et al ., ; de la Fuente and Niño , ]. Groundwater that upwells at the perimeter of the salar is the primary inflow to these lagoons [ de la Fuente and Niño , ].…”

“…Salar is the name that is given to landscapes located in the altiplanic region of Chile, Bolivia, and Argentina that usually have extremely shallow terminal lagoons [ Herrera et al ., ; de la Fuente and Niño , ]. Groundwater that upwells at the perimeter of the salar is the primary inflow to these lagoons [ de la Fuente and Niño , ]. The aquatic ecosystem that is formed and the nearby terrestrial vegetation sustain important populations of mammals, fishes, and birds, which live in these elevated small areas surrounded by the desert [ Messerli et al ., ].…”

Modelling evaporation processes in soils from the Huasco salt flat basin, Chile

“…In closed Altiplano basins such as those encountered in arid and hyper arid basins in the northern Chile, evaporation is the main source of aquifer depletion, and thus its study is crucial for water resources management. Understanding evaporation is also important for the study of sensitive soil systems such as wetlands (de la Fuente and Niño, ; Johnson et al, ). Nonetheless, understanding the evaporation processes in these environments is complex because evaporation occurs under non‐isothermal conditions, where water can be mobilized as liquid water or water vapour (Nassar and Horton, ; Grifoll et al, ; Hernández‐López et al, ).…”