TY  - JOUR
AU  - Groh, Jannis
AU  - Stumpp, Christine
AU  - Lücke, Andreas
AU  - Pütz, Thomas
AU  - Vanderborght, Jan
AU  - Vereecken, Harry
TI  - Inverse Estimation of Soil Hydraulic and Transport Parameters of Layered Soils from Water Stable Isotope and Lysimeter Data
JO  - Vadose zone journal
VL  - 17
IS  - 1
SN  - 1539-1663
CY  - Madison, Wis.
PB  - SSSA
M1  - FZJ-2018-03079
SP  - 1 -19
PY  - 2018
AB  - Accurate estimates of soil hydraulic parameters and dispersivities are crucial to simulate water flow and solute transport in terrestrial systems, particularly in the  vadose  zone.  However,  parameters  obtained  from  inverse  modeling  can be ambiguous when identifying multiple parameters simultaneously and when boundary conditions are not well known. Here, we performed an inverse modeling study in which we estimated soil hydraulic parameters and dispersivities of layered soils from soil water content, matric potential, and stable water isotope ( d 18O) measurements in weighable lysimeter systems. We used different optimization strategies to investigate which observation types are necessary for simultaneously estimating soil hydraulic and solute transport parameters. Combining water content, matric potential, and tracer (e.g.,  d 18O) data in one objective function (OF) was found to be the best strategy for estimating parameters that can simulate all observed water flow and solute transport variables. A sequential optimization, in which first an OF with only water flow variables and  subsequently  an  OF  with  transport  variables  was  optimized,  performed slightly worse indicating that transport variables contained additional information for estimating soil hydraulic parameters. Hydraulic parameters that were obtained from optimizing OFs that used either water contents or matric potential could not predict non-measured water flow variables. When a bromide (Br−) tracer experiment was simulated using the optimized parameters, the arrival time of the bromide pulse was underestimated. This suggested that Br− sorbed onto clay minerals and amorphous oxides under the prevailing geochemical conditions with low pH values. When accounting for anion adsorption in the simulation, Br− concentrations were well predicted, which validated the dispersivity parameterization.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000437536200001
DO  - DOI:10.2136/vzj2017.09.0168
UR  - https://juser.fz-juelich.de/record/845880
ER  -