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 (email@example.com) (Intituto de Hidrología de Llanuras “Dr. Eduardo J. Usunoff”, Argentina) and Ricardo Sánchez-Murillo (firstname.lastname@example.org) (Universidad Nacional, Heredia, Costa Rica) for further information regarding this data collection.
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Rainwater samples were collected using precipitation collectors, which consisted of a 26.5 cm diameter plastic funnels connected to 20 L plastic containers. Containers with a mineral oil thin-layer were buried underground to avoid secondary evaporation. Monthly rainfall amounts were recorded using automated weather station (LG) and manually (LM). Rainfall amounts from IHLLA station were provided by Servicio Meteorológico Nacional. Rainwater samples were collected on monthly basis and analysed semi-annually as composited samples. Fifty seven physico-chemical analyses (March 2010–March 2019) and fifty one stable isotopes analyses (March 2011-September 2019) are available. Three surface water sites were sampled in February and November 2018. The superficial flow rates were measured with an OTT MF pro-Water Flow Meter equipment (Site 1) or calculated by rating curves at control sections (Sites 2 and 3). Six physico-chemical analyses and six stable isotopes analyses are also available. In addition, six wetlands were sampled (W1 - W6). Six physico-chemical analyses and six stable isotopes analyses for October 2019 are also provided in this data set. The IHLLA’s (Instituto de Hidrología de Llanuras; https://ihlla.conicet.gov.ar/) groundwater monitoring network is composed of 29 boreholes which have been sampled since 1996. In each groundwater sampling, piezometric levels were measured. Groundwater samples were collected after purging at least three times the borehole water volumen. One hundred and fifteen physico-chemical analyses for January/February and September/October 2018-2019 and twenty nine stable isotopes analyses for October 2019 are available. Chemical analyses were conducted at the IHLLA Laboratory following the methodology proposed by the American Public Health Association, and using the following methods: Ca2+, Mg2+, Na+, K+ and As were analysed by atomic absorption spectrometer with SM 3111 and 3114 C methods; SO42-, NO3- and SiO2 by ultraviolet spectrophotometer screening with EPA 9038, SM 4500 B-C and SM 4500 C methods; Cl- by titration with SM 4500 B method; F- by ion-selective electrode with SM 4500 D method; CO3- and HCO3- (expressed as alkalinity) by titration with SM 2320 B method; EC by a conductivity cell and pH by a potentiometric electrode. In all analyses charge-balance errors were < 10 %. Creek samples from 2018 were analysed at the Isotope Hydrology Laboratory, Universidad Nacional de Mar del Plata (Argentina). Stable isotopes analysis was conducted using a water isotope analyzer DLT-100. The analytical long-term uncertainty was: ± 2.0 (‰) for δ2H and ± 0.3 (‰) for δ18O. Water samples from 2019 were analysed at the Stable Isotopes Research Group, Universidad Nacional (Costa Rica). Stable isotopes analysis was conducted using a water isotope analyzer LWIA-45P. The analytical long-term uncertainty was: ± 0.5 (‰) (1) for δ2H and ± 0.1 (‰) (1) for δ18O. All δ18O and δ2H results are reported relative to Vienna SMOW.