Author(s): Maria Emilia Jimenez-Hernandez; Maria-Fe Diaz-Teijeiro; Silvino Castano-Castano; Javier Rodriguez-Arevalo
Linked Author(s): Maria Emilia Jiménez-Hernández
Keywords: REVIP; Water management; Deuterium excess; Altitudinal gradient; Local meteoric water lines
Abstract: The Global Network of Isotopes in Precipitation (GNIP), established in the 1960s by the IAEA (International Atomic Energy Agency) and WMO (World Meteorological Organization), has provided for decades key data for the application of isotope tracers in hydrology and water resources management as well as in climatic and ecological studies. Spain contributes to GNIP database through the Spanish Network for Isotopes in Precipitation (REVIP), which has been maintained in operation since 2000 by the Centre for Studies and Experiments in Public Works (CEDEX) and the State Meteorological Agency (AEMET). Composite monthly precipitation samples are collected from a total of 20 meteorological stations and oxygen-18, deuterium and tritium analyses are performed at CEDEX. In this work, up to 20 years of continuous water isotopes records from REVIP stations were revised and analysed with the aim of describing and interpreting the key features of the spatial distribution of the isotopic signature of meteoric waters in Spain. Four parameters were considered: tritium content (T), isotopic ratios of stable isotopes of water (δ18O and δ2H) and deuterium excess (d = δ2H - 8· δ18O). REVIP sampling stations are located in the main River Basin Districts and in areas representative of the different climatic zones in Spain. A distinctive signature is obtained for each REVIP station based on the long-term precipitation-weighed mean values of the isotopic parameters. Spatial variability pattern combines (i) more negative δ18O and δ2H values with increasing altitude and/or latitude, (ii) higher T from east to west, (iii) higher d values (> 12 ‰) at high altitudes (> 1500 m a.s.l.) and in the coastal area of the Cantabrian Sea, and (iv) lower d values (≈ 8 ‰) in the Ebro Valley (low-altitude inland station). Geographic and climatic factors considered for spatial variability interpretation include latitude, altitude, oceanicity and continentality effects, interplay of air masses of different origins, water vapour recycling processes, orographic barriers and predominance of stratiform or convective precipitation. Thanks to their wide geographic distribution (18 stations in continental Spain, 1 in Balearic Islands and 1 in Canary Islands), broad altitude range (from 3 to 1894 m a.s.l.) and the long-term sampling program, REVIP dataset is a valuable tool for tracking the origin, movement and history of water in the hydrologic cycle in Spain of application for water resources and water infrastructures management. The isotopic signature of the input function (precipitation) to surface and ground waters obtained from REVIP can be used for quantifying and distinguishing water masses with different origins, informing about their movement through natural media, estimating transit and residence times, determining surface water and groundwater connections, delineating source or recharge areas, characterizing evaporation and investigating dam leakage.
DOI: https://doi.org/10.3850/IAHR-39WC2521711920221781
Year: 2022