A quantitative understanding of groundwater-surface water interactions is vital for sustainable management of water quantity and quality. The Nobel gas Radon-222 (Rn) is becoming increasingly used as a sensitive tracer to quantify groundwater discharge to wetlands, lakes and rivers; a development driven by technical and methodological advances in Rn measurement. However, quantitative interpretation of this data is not trivial, and the methods used to date are based on the simplest solutions to the mass-balance equation (e.g. first order finite difference, inversion).
FINIFLUX is an implicit Finite Element model that numerically solves the steady state mass balance equation for Radon in lotic (rivers,streams) systems. Degasing is represented using two very popular models which originally are from O'Connor and Dobbins (1958) and Negulescu and Rojanski (1969) with modifications from Cartwright et al. (2011). Alternativley, FINIFLUX also can work with degasing fluxes specified by the user. FINIFLUX is intended to estimate groundwater fluxes into river systems as well as hyporheic exchnage characteristics based on measured Rn concentrations. The model is coupled to the optimasation software BEOPEST (Doherty 2010) for inverse parameter estimation. FINIFLUX is intended to help scientists and authorities that use the Rn tecnique to estimate surface-groundwater exchange for river systems at the reach scale.
UPDATE: in the last half-year or so we have had some particularly difficult datasets where PEST fails to find a good fit to the data. In particular modelled data is too high. We have found that a regularisation program available on the PEST site can solve this problem and again produce very good fits. See http://www.pesthomepage.org/PEST_FAQ.php
This software is accompanied by a paper in Water Resources Research and can be found at:http://onlinelibrary.wiley.com/wol1/doi/10.1002/2015WR017212/abstract
Authors: S. Frei (firstname.lastname@example.org) B.S. Gilfedder (email@example.com) June 2015
FINIFLUX2.0_FOR_WEB_64bit_dll_download.zip (25044 k)
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