Hydrological dataset from a large sub-humid plain

Hydrological data (flow rates and piezometric levels), and physical-chemical (major ions and trace elements) and isotopic (δ18O, δ2H; and d-excess) analyses from rainwater, surface water and groundwater samples of a large sub-humid plain are presented. In total, 57 rainwater samples were collected on monthly basis using passive collectors installed at different altitudes (upper - 221 masl, middle - 145 masl and lower - 72 masl basin). Twelve surface water samples were obtained from three sampling sites located along the Del Azul Creek (upper basin - Site 1, middle basin - Site 2 and lower basin - Site 3) and from six wetlands which are located following the regional groundwater flow. Groundwater samples were sampled from 17 shallow boreholes (3 – 10 m, screened in their last meter) and 12 deep boreholes (30 m depth, screened between 25 and 30 m). In both surface water and groundwater sampling, superficial flow rates and piezometric levels were measured, and water samples for chemical and isotopic analyses were collected. Our data may improve the understanding of key hydrological processes controlling the water movement, and the chemical composition and chemical quality of water (i.e. arsenic, fluoride, nitrate, sulphate, alkalinity contents) in a large sub-humid agricultural plain. Please do not hesitate to contact María Emilia Zabala (mzabala@ihlla.org.ar) (Intituto de Hidrología de Llanuras “Dr. Eduardo J. Usunoff”, Argentina) and Ricardo Sánchez-Murillo (ricardo.sanchez.murillo@una.cr) (Universidad Nacional, Heredia, Costa Rica) for further information regarding this data collection.