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| Author(s): |
Sander Jacobus Titus Eskes
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Carlos. |
| Institution: | Universidade de São Paulo (USP). Escola de Engenharia de São Carlos (EESC/SBD) |
| Defense date: | 1998-02-17 |
| Examining board members: |
Silvio Crestana;
Fazal Hussain Chaudhry;
Adolfo Nicolas Posadas Durand;
Maria Conceição Peres Young Pessoa;
Antonio Marozzi Righetto
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| Advisor: | Silvio Crestana |
| Abstract | |
The maín objective of this thesis is to develop numerical models that can evaluate the leached mass fraction of pesticides at the field scale, in an efficient manner. Empirical models for infiltration and evaporation of water at the soíl surface are presented. These empirical models, in combínation with the use of an optimÍsed mean conductivity function, allow very large steps in time and in space, ofthe numerical solutíon ofRichard\'s equation. As a result, the numerical model hás very short execution times and can be used in Monte Cario runs, to simulate vertical soil moisture movement at the fíeld scale. In addition, several highly effícient Lagrangian solute transport models were developed. These models símulate solute dispersion as an ensemble of random samples travelling at different velocities. The sample velocíty distributÍon is based on known travei time or travei distance distributions. The models can be used for heterogeneous soil profíles and under transient conditions, whíle processes like fírst arder transformation or linear adsorption, can be easily íncluded. When used in Monte Cario simulations, the proposed technique becomes very effícient when the sample velocity distribution is included in a stratífied sampling scheme. In that case, only a limited number ofsamples needs to be tracked per Monte Cario run, thus producing very fast output results. (AU) | |