Hydrologic transport model

A variety of adsorption models, from A, to the electrostatic adsorption models in MINTEQA2, have been coupled with hydrologic transport models. Available coupled codes and their attributes have been described and compared, in some detail, by Mangold and Tsang (1991) (see also Lichtner et al. 1996) and will not be considered here. 

One of the first complete, continuous simulation models was the pesticide mnoff transport model (PRT) (56). Improvements in the PRT modelled to the hydrologic simulation program—FORTRAN model (57). A number of other models have been developed (58,59). These models represent a compromise between the avadable data and the abiHty to encompass a wide range in soils, climates, and pesticides. These models have had mixed success when extended beyond the data with which they were caHbrated. No model has yet been developed that can be proven to give accurate predictions of... 

To construct models of this sort, we combine reaction analysis with transport modeling, the description of the movement of chemical species within flowing groundwater, as discussed in the previous chapter (Chapter 20). The combination is known as reactive transport modeling, or, in contaminant hydrology, fate and transport modeling. 

Zuber, A., Witczak, S., Rozanski, K. et at. 2005. Groundwater dating with 3H and SF6 in relation to mixing patterns, transport modelling and hydrochemistry. Hydrological Processes, 19, 2247-2275. 

Morrison, S. J., Tripathi, V. S. Spangler, R. R. 1995. Coupled reaction/transport modeling of a chemical barrier for controlling uranium (VI) contamination in groundwater. Journal of Contaminant Hydrology, 17, 347-363. 

Zhu, C. Burden, D. S. 2001. Mmeralogical compositions of aquifer matrix as necessary initial conditions in reactive contaminant transport models. Journal of Contaminant Hydrology, 51, 145-161. 

Tschantz, B. A. Moran, B. M. Modeling of the Hydrologic Transport of Mercury in the Upper East Fork Poplar Creek (UEFPC) Watershed Technical Report for Lockheed Martin Energy Systems Bethesda, MD, September 2004. 

Yeh G. T. and Tripathi V. S. (1989b) HYDROGEOCHEM, A Coupled Model of Hydrologic Transport and Geochemical Equilibria of Reactive Multicomponent Systems. Oak Ridge National Laboratory Report ORNL-6371, Oak Ridge, TN. 

Laboratory experiments, transport modeling, field data, and engineering cost analysis provide complementary information to be used in an assessment of the viability of an MNA approach for a site. Information from kinetic sorption/ desorption experiments, selective extraction experiments, reactive transport modeling, and historical case analyses of plumes at several UMTRA sites can be used to establish a framework for evaluation of MNA for uranium contamination (Brady et al, 1998, 2002 Bryan and Siegel, 1998 Jove-Colon et al, 2001). The results of a recent project conducted at the Hanford 100-N site provided information for evaluation of MNA for a °Sr plume that has reached the Columbia River (Kelley et al, 2002). The study included strontium sorption-desorption studies, strontium transport and hydrologic modeling of the near-river system, and evaluation of the comparative costs and predicted effectiveness of alternative remediation strategies. 

Nearly all reactive transport models used in the regulatory environment, however, are based on empirical isotherms. The models take into account the effects of hydrologic processes due to the movement of groundwater such as advection and dispersion, but the effects of chemical reactions are typically described by an isotherm linking the concentrations of i in solid mass to that in groundwater,... 

Zhu, C., Hu, F. Q., and Burden, D. S., 2001a, Multi-component reactive transport modeling of natural attenuation of an acid ground water plume at a uranium mill tailings site. J. Contaminant Hydrology, v. 52, pp. 85-108. 

Numerous discussions ( ) have been held on the convergence of the two modeling disciplines flow/transport models and aqueous chemical codes. The literature is extensive on attempts to merge these two approaches, but major conceptual problems remain, such as the conflict between the enormous detail provided in chemical codes regarding species, temperature adjustments and partitioning between gas and solid phase, vs. the conflict of transporting each specie individually from point to point in the hydrologic system. 

The CDE process model is probably the most popular solute transport model that has been used in soil hydrological research so far. The model considers the soil as a homogeneous matrix in which the pores are well connected, and in which solute mix perfectly laterally when travelling through the soil. The differential description of the process is given in (11) and simplifies for a homogeneous soil profile and steady state conditions to ... 

Leij, F.J., Priesack, E., and Schaap, M. (2000) Solute transport modeled with green s functions with application to persistent solute sources. Journal of Contaminant Hydrology 41 155-173. 

The hydrologic model quantifies the movement of subsurface water and provides inputs to contaminant transport models. Its usage as a simulation tool allows previewing the contaminant behaviour in the groundwater al well as a quantitative assessment for the concentration of the contamination at a particular exposition point. 

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