Revealing the spatial pattern of subsurface soil salinity over the Argentinean Dry Chaco

Abstract

The South-American Dry Chaco is a unique ecoregion as it is one of the largest sedimentary plainsin the world hosting the planet?s largest dry forest. The 787.000 km² region covers parts ofArgentina, Paraguay, and Bolivia and is characterized by a negative climatic water balance as aconsequence of limited rainfall inputs (800 mm/year) and high temperatures (21°C). Incombination with the region?s extreme flat topography (slopes < 0.1%) and shallow groundwatertables, saline soils are expected in substantial parts of the region. In addition, it is expected thatlarge-scale deforestation processes disrupt the hydrological cycle resulting in rising groundwatertables and further increase the risk for soil salinization.In this study, we identified the regional-scale patterns of subsurface soil salinity in the Dry Chaco.Field data were obtained during a two-month field campaign in the dry season of 2019. A total of492 surface- and 142 subsurface-samples were collected along East-West transects to determinesoil electric conductivity, pH, bulk density and humidity. Spatial regression techniques were usedto reveal the topographic and ecohydrological variables that are associated with subsurface soilsalinity over the Dry Chaco. The hydrological information was obtained from a state-of-the-art landsurface model with an improved set of satellite-derived vegetation and land cover parameters.In the presentation, we will present a subsurface soil salinity map for a part of the Argentinean DryChaco and provide relevant insights into the driving mechanisms behind it.