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Mixing and dispersion in the transport of energy and solutes

Total activity: 4
Type of activity
Competitive project
Acronym
MEDISTRAES II
Funding entity
MIN DE ECONOMIA Y COMPETITIVIDAD
Funding entity code
CGL2016-77122-C2-2-R
Amount
102.850,00 €
Start date
2016-12-30
End date
2019-12-29
Keywords
acuífero costero, calor, coastal aquifer, descarga submarina, dispersion, dispersión, heat, intrusión marina, mezcla, mixing, reacciones, reactions, seawater intrusion, solutes, solutos, submarine groundwater discharge, transport, transporte
Abstract
This project is motivated by a number of challenges: (1) the estimation of nutrient fluxes to the sea by submarine groundwater discharge
(SGD), that is currently estimated from radium fluxes, unlike nutrients may be controlled by exchange processes in the fresh-salt water
mixing zone; (2) evaluation of geochemical processes in this area and (3) knowledge on seawater intrusion, which threatens most coastal
aquifers. To address these challenges, we must make significant progress both in the modeling of the processes taking place in this area
as well as in the techniques of their characterization.
The relevant processes in groundwater are controlled by the transport of solutes, which is not well represented by classical Fickian
approaches (advection-dispersion equation, ADE). The basic problem of the ADE is that it equates dispersion (volume growth of solute) to
mixture (dilution or dissipation of the variation of the concentration). This is especially important because it controls the rate of many
chemical reactions, by controlling the rate at which the reactants mix and at which they reach the reactive surfaces. Dispersion and mixing
are closely related but distinct processes. Non Fickian approaches to overcome the limitations of the ADE have been successful for the
dispersion of inert solutes, but not for the reactive solutes. Our goal is threefold: (1) advance in the nonlocal formulation of transport and
test multipermeability formulations; (2) apply them to heat transport, of which we conjecture that local dissipation is controlled by thermal
conductivity, while the size of the thermal plume is controlled by dispersion, and (3) apply these advances to geochemical processes at the
fresh-salt water interface of coastal aquifers, where we conjecture that mixing rather than dispersion controls dissolution-precipitation and
cation exchange.
Regarding characterization techniques, we will design new laboratory experiments to evaluate dispersion by means of inert tracers, and
the mixture of reactive compounds that measure cation exchange or fast dissolution-precipitation reactions. In parallel, new types of field
experiments are carried out in Argentona to assess: (1) geochemical processes in the mixing zone (direct sampling and push pull
experiments with reactive tracers), (2) SGD through measurements at sea (electrical tomography, measurement of the distributed
temperature and direct sampling) and in theaquifer (hydraulic tests, heat and conservative and reactive tracer tests), and (3) direct
measurements of groundwater flow by means of heat dissipation. Field activities include new experimental methods (electrodes in the
space around the well, together with an optical fiber and a heater cable, to control the water flow in the mixing zone with high spatial
resolution; heat exchange tests and inert and reactive tracer tests to evaluate the dispersion and mixing with different Peclet numbers,
etc.). This, together with the development of codes to study the described processes should generate a commercial activity, both in Spain and abroad.
Scope
Adm. Estat
Plan
Plan Estatal de Investigación Científica y Técnica y de Innovación 2013-2016
Call year
2016
Funcding program
Programa Estatal de I+D+i Orientada a los Retos de la Sociedad
Funding call
Retos de Investigación: Proyectos de I+D+i
Grant institution
Gobierno De España. Ministerio De Economía Y Competitividad, Mineco

Participants

Scientific and technological production

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