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- Title
Folyadék-visszatartás, folyadékvezetés és porozitás összefüggései vízzel és/vagy szerves folyadékkal telített talajokban I. Folyadék-visszatartó képesség – Szemle.
- Authors
HERNÁDI, Hilda; BARNA, Gyöngyi; MAKÓ, András
- Abstract
Methods for measuring and predicting water retention and conductivity have improved enormously over the last 60 years (e.g. elaboration and application of dynamic and spectroscopic measurement techniques, digital image analysis methods, the development of pedotransfer functions (PTF) based on equations and pattern recognition and their incorporation into software and submodels). Using the new theoretical approach for the representation of pore space as a hierarchical network, the estimation of these hydrological properties based on geometry, semi-physics and statistics offers the increasingly correct characterisation of pore space, fluid transport and migration processes. The multimodal representation of soil water retention (SWR), together with multimodal pore size distribution (PoSD), makes it possible to quantify dynamic changes in and deformation of the pore system (through swelling/shrinking, compaction, disaggregation, etc.) or the phenomenon of hysteresis more accurately, even over the entire pressure range. Finding correlations between porosity and structural and hydrological properties on different scales and quantifying their relationships continue to be challenging topics in the fields of soil physics, hydrology and environmental sciences. Improvements in models for the simulation of non-aqueous phase organic liquid transport (NAPL) in porous media have not touched on the determination of the primary input parameter in these models, i.e. the NAPL retention of soils, which can still only be determined indirectly from water retention. These calculations neglect the magnitude of the various extents of interaction between the solid phase and fluids with different physical, chemical and physicochemical properties. The results of environmental research (compatibility tests on the clay liners of waste disposal, micromorphological analysis, applicability tests on dynamic methods for measuring NAPL retention and conductivity, etc.) question the accuracy and reliability of scaling methods based on water retention. Nevertheless, the parametric techniques used for fitting water retention curves could well be suitable for fitting NAPL retention curves as well. Similar to the use of PTFs for predicting SWRC, NAPL retention could also be approximated sufficiently well with PTFs in the pressure range of 0-1500 kPa. The statistical parameters of PoSD curves determined from normalized derived fluid retention functions for NAPL and water could provide information on dynamic changes in porosity. The application of multimodal functions could help us to obtain more accurate knowledge on correlations between the endpoint saturation values of NAPL retention curves and the soil properties used for estimation, thus leading to improvements in PTF-type methods for estimating NAPL retention ability. Further investigations are needed, e.g. for the selection of the appropriate parametric functions and for the determination of key saturation points in multiphase transport modelling (e.g. immobile and residual saturation) and the corresponding pressure values. Additional research will be required on the possibility of conversion between the parameters of the fitted characteristic functions.
- Publication
Agrochemistry & Soil Science / Agrokémia és Talajtan, 2017, Vol 66, Issue 1, p251
- ISSN
0002-1873
- Publication type
Article
- DOI
10.1556/0088.2017.66.1.14