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Moisture and Energy dynamics in field soils: The Influence of the Diurnal Cycle

English title Moisture and Energy dynamics in field soils: The Influence of the Diurnal Cycle
Applicant Lunati Ivan
Number 143626
Funding scheme Project funding (Div. I-III)
Research institution Institut des sciences de la Terre Université de Lausanne
Institution of higher education University of Lausanne - LA
Main discipline Fluid Dynamics
Start/End 01.10.2012 - 30.06.2013
Approved amount 41'284.00
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All Disciplines (3)

Discipline
Fluid Dynamics
Agricultural Engineering
Hydrology, Limnology, Glaciology

Keywords (6)

unsaturated flow; soil phyiscs; land-atmosphere interaction; evaporation; heat flow; fiber optics

Lay Summary (English)

Lead
Lay summary

By combining the advances in measurement techniques and progress in the numerical tools used to describe the evolution of soil moisture, this project  contributes to improve the reliability of current hydrological and meteorological models.

In this projects we focus on the effects of the diurnal cycle induced by the solar radiation forcing, which is not captured by the resolution allowed by satellite measurements (typically 3 days and 30 km). We investigate the potential of Actively Heated Fiber Optics (AHFO) to acquire complementary data of soil-moisture variations. AHFO provides soil-moisture information that is distributed in space with a resolution varying from 1 cm to 1 m depending on experimental setup. In parallel, we focus on advancing the understanding of the relevant mechanisms in field soils, which are not fully understood, and on developing a theoretical framework that predicts short- and midterm evolution of moisture and energy under diurnal forcing.

This key role has fostered large efforts to acquire global soil-moisture information to be used in meteorological and hydrological models. However, assimilation of these low-resolution data (typically acquired by remote sensing satellites) into numerical models requires knowledge of smaller spatiotemporal variability, which have to be acquired by complementary techniques. 

Soil moisture is one of most relevant properties of the land surface: it influences land-atmosphere interaction by determining run-off, infiltration, evaporation, and, under some circumstances, even rainfall frequency; also, it affects summer heat waves, which are accentuated if soil is dry. 

Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Name Institute

Publications

Publication
Heated Optical Fiber for Distributed Soil-Moisture Measurements: a Lysimeter Experiment
Ciocca Francesco, Lunati Ivan, Van de Giesen Nick, Parlange Marc B. (2012), Heated Optical Fiber for Distributed Soil-Moisture Measurements: a Lysimeter Experiment, in Vadose Zone Journal, 11(4), 2011.0199.
Effects of the water retention curve on evaporation from arid soils
Ciocca Francesco, Lunati Ivan, Parlange Marc B., Effects of the water retention curve on evaporation from arid soils, in Geophysical Research Letter, 41.

Collaboration

Group / person Country
Types of collaboration
Shmuel Assouline, Institute of Soil, Water and Environmental Sciences; Volcani Center, Bet Dagan Israel (Asia)
- Publication
Nick van de Giesen, Water Management Civil Engineering & Geosciences, TU Delft Netherlands (Europe)
- Publication
Jan W Hopmans, College of Agricultural and Environmental Sciences, UC Davis United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
John Selker, Department of Biological and Ecological Engineering, Oregon State University, Corvallis United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
EGU General Assembly 2013 Talk given at a conference Multi Function Heat Pulse Probes (MFHPP) to Estimate Ground Heat Flux and Reduce Surface Energy Budget Errors 07.04.2013 Vienna, Austria, Austria Parlange Marc; Lunati Ivan; Ciocca Francesco;
AGU Fall Meeting 2012 Talk given at a conference Sensitivity Analysis of Dis- tributed Soil Moisture Profiles by Active Distributed Temperature Sensing 03.12.2012 San Francisco, California, United States of America Parlange Marc; Lunati Ivan; Ciocca Francesco;


Associated projects

Number Title Start Funding scheme
122088 Moisture and Energy dynamics in field soils: The Influence of the Diurnal Cycle 01.07.2009 Project funding (Div. I-III)
144922 A Multiscale Approach to Multiphase Flow in Geological Formations 01.07.2013 SNSF Professorships

Abstract

The overall goal of our research project is to advance knowledge of transport phenomena in field soils and improve the theoretical framework for predicting soil-moisture and temperature evolution under the diurnal cycle. With the present proposal, we are requesting the final 12 months of funding for our PhD student, Francesco Ciocca, who has made excellent progress in both experimental and theoretical aspects of the project. Granting of this extension will allow the PhD candidate to finalize an outstanding thesis and will assure that the outcome of his research will be the best possible, thus contributing to to the accuracy of hydrological and meteorological models by advancing the understanding of soil moisture dynamics at the land-atmosphere interface.The lack of a comprehensive theory of coupled energy and moisture transport in field appli- cations is due to the challenges of modeling vapor flux at the land surface interface (particularly in dry-media) and to the difficulties in obtaining accurate field measurements to validate the models. Since progress requires to tackle both issues in a coherent framework, our research activity has covered both theoretical and experimental aspects.On the experimental side, we have performed laboratory experiments and two lysimeter measurement campaigns to acquired field data under diurnal forcing. During these activities we have tested two recently developed measurement techniques: the Actively Heated Fiber Optics (AHFO), which employ an optical cable in combination with a Distributed Temperature Sensing system (DTS); and the Multi-Function Heat-Pulse Probe (MFHPP). Both techniques have proven promising and capable of simultaneously measuring temperature and soil moisture at the same location.On the theoretical side, we have assessed the importance of different transport mechanisms and developed a numerical code to model coupled heat and moisture transport. This in-house developed numerical model allows us great flexibility in the choice of the physical processes that we describe and has been helpful in designing laboratory and field experiments.The final 12 months of funding are necessary to:1. Properly conclude the lysimeter experiments with a new campaign (summer 2012) that, building on our past experience, will allow to definitely assess the accuracy of AHFO to measure distributed soil moisture profiles.2. Realize the laboratory experiment in a weighed column with periodic evaporative forc- ing that will allow further testing of the MFHPP. This experiment will complement the lysimeter data and allow testing the theoretical models against an accurate dataset ob- tained under more controlled conditions.3. Analyze the experimental data with a numerical code developed by the candidate in the first part of the project.
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