Monitoring Vapor Flux and Groundwater Recharge in Dune Belts Using Precision Meteo-Lysimeter

1. Monitored Vapor flux and groundwater recharge in2 hydrological years by a precision meteo-lysimeter Claus Kohfahl1, Maarten Saaltink5, Lidia Molano-Leno1, Daniel Jesús Martinez Suárez1, Fernando Ruiz Bermudo1, Antonio Martínez Sánchez De La Nieta1, Gonzalo Martínez4, Karl Vanderlinden3, Carolina Guardiola1, Juan Vicente Giráldez2 1Research of Geological Resources, Instituto Geológico y Minero de España, Spain, 2Agronomy, Universidad de Cordoba, Spain, 3Centro Las Torres-Tomejil, Instituto de Investigación y Formación Agraria y Pesquera, Spain, 4Applied Physics, Universidad de Cordoba, Spain, 5Department of Civil and Environmental Engineering, Universitat Politecnica de Catalunya, UPC, Spain 46th IAH Congress Malaga, Spain Sep 23, 2019 Claus Kohfahl Instituto Geológico y Minero de España Unidad de Sevilla

2. Motivation • Non-rainfall water depositions, such as fog, dew and water vapor adsorption are important for hydrological processes especially in arid and semiarid regions • Theseprocesseshave a criticalimportancefordunebelts in semi-arid áreas withhighrechargepotential • Distinction between dew and water vapor adsorption: • Dew formation takes place on flat surfaces, which requires air to • be almost or fully saturated in water vapor • Vapor condensationoccurswithinthesoilporespacebelowwatersaturation

3. INTRODUCTION • Objectives: • What is the importance of vapor flow and its contribution to recharge in dune belts? • How can we measure and model that? • => Measurements with Precision Meteo Lysimeter • Most precise measures for recharge, precipitation and evapotranspiration. • Mostly installed for agricultural purpose in crop areas. • Limited knowledge exists about vapor flow in dune belts.

4. MATERIAL AND METHODS METEO LYSIMETER

5. MATERIAL AND METHODS Meteo Lysimeter Site Equipment • Weighting Lysimeter • (METER, Munich, Germany) • 1 m2 area • 1.5 m height • 10 g resolution Six CS650 soil moisture sensors (Campbell Scientific, Logan UT) Meteo-station UMS Meteo-station DAVIS Weighing Rain Gauge Lysimeter Rain water collector

6. MATERIAL AND METHODS What has been measured?

7. MATERIAL AND METHODS • Where do we put the lysimeter? • Site with high recharge => e.g. Dunes • Site with previous information • Site of environmental and economic concern Dune belt of coastal aquifer in the Doñana National Park (SW Spain)

8. MATERIAL AND METHODS Data Noise Filtration: AWAT (Peters et al. 2014; Schrader et al. 2013) Intrinsic noise reduced by smoothing AWAT filter (Adaptive Window and Adaptive Threshold)

9. MATERIAL AND METHODS Water balance on filtered data

10. RESULTS Soilwater budget in mm • 64% recharge

11. RESULTS Vapor adsorption and real evaporation • Vapor adsorption 0.3-0.5 mm/day • Real evaporation 0.4-0.6 mm/day • Daily evaporation exceeds vapor adsorption • Winter • Summer

12. RESULTS Isotopes of rain and drainage water

13. Modelling results (Maarten Saaltink et al. in prep.) • Software: CODEBRIGHT (Olivella et al., 1996) that • Solves balance equations for water (liquid and vapor), air and energy in an unsaturated medium • One-dimensional vertical homogeneous domain of 1.4 m length, divided into 140 elements of 0.01 m • Starts at November 25, 2015 and ends at October 4, 2017, which is the period with available meteorological data

14. Modelling: retention curves Retention curves used by the models together with suction and VWC (volumetric water content = Sl), measured outside the lysimeter at a depth of 1.40 m. The three retention curves are plotted on an arithmetic (left) and logarithmic scale (right).

15. Modelling: Best fit Mass of water in the lysimeter in kg

16. Modelling: Heat flow Temperature profiles

17. Modelling: Vapor flow oscillations Evolution of vapor diffusion at the boundary

18. Modelling: Profiles Complex patterns of vapor flow; example Date:13-07-2017: • Water flow zero above -0.8 m • Upward vapor flow • Downward vapor flow • Upward gradient vapor mass fraction • Downward gradient vapor mass fraction

19. Conclusions • Lysimeter measurements show recharge rate of 64% of tipping bucket precipitation • Measured vapor flow during the whole year between 0.3 and 0.6 mm per day • Measuredresultscould be producednumerically • Doubleporosityretention curve givebestfitdue to consideration of thedryendconditions

20. Outlook • New infrastructure will be installed in 2019/2020 (EQC2018-004130-P*) • Add 3 more lysimeters • Improve resolution of sampling (event sampler) • Improve lower boundary control • Improve information available in the lysimeter especially with regard to uppermost zone with vapor flow by psycrometer measurements • Use data to improve prognostic model results for vapor contribution on recharge *Subprograma Estatal de Infraestructuras Científicas y Técnicas y de Equipamiento, en el marco del Programa Estatal de Fomento de la Investigación Científica y Técnica de Excelencia del Plan Estatal de Investigación Científica y Técnica y de Innovación, así como en el artículo 18.2 de la resolución de la convocatoria, el 15/10/2018

21. ACKNOWLEDGMENTS • Funding: • European Research Funds (SE Scientific Infrastructures and Techniques and Equipment 2013, IGME13-1E-2113). • Spanish National Plan for Scientific and Technical Research and Innovation: CLIGRO Project (MICINN, CGL2016-77473-C3-1-R). • National System of Youth Guarantee (MINECO activity with reference PEJ-2014-85121) co-financed under the Youth Employment Operational Program, with financial resources from the Youth Employment Initiative (YEI) and the European Social Fund (ESF). • Technical support: • Biological Station of Doñana, the Biological Reserve of Doñana and the administration of the Doñana National Park. • A. Peters for providing AWAT filter. • THANK YOU!