Site-specific simulation models

In this study, we address the hydrodynamic control of retention in fractured porous media. The hydrodynamic control of retention in fracture networks can be reduced to the distribution of a single parameter referred to as transport resistance . Two specific objectives of the study are (i) to summarize two main modelling approaches (continuum and discrete) and conditions for their equivalence, where from linearization of P is deduced, and (ii) to lest the applicability of the linearization of for lOOm and 1000m scales using results from site-specific simulations (Gutters and Shuttle, 2000 Gutters, 2002). 

The ET cover cannot be tested at every landfill site so it is necessary to extrapolate the results from sites of known performance to specific landfill sites. The factors that affect the hydrologic design of ET covers encompass several scientific disciplines and there are numerous interactions between factors. As a consequence, a comprehensive computer model is needed to evaluate the ET cover for a site.48 The model should effectively incorporate soil, plant, and climate variables, and include their interactions and the resultant effect on hydrology and water balance. An important function of the model is to simulate the variability of performance in response to climate variability and to evaluate cover response to extreme events. Because the expected life of the cover is decades, possibly centuries, the model should be capable of estimating long-term performance. In addition to a complete water balance, the model should be capable of estimating long-term plant biomass production, need for fertilizer, wind and water erosion, and possible loss of primary plant nutrients from the ecosystem. 

Data Structures. Inspection of the unit simulation equation (Equation 7) indicates the kinds of input data required by aquatic fate codes. These data can be classified as chemical, environmental, and loading data sets. The chemical data set , which are composed of the chemical reactivity and speciation data, can be developed from laboratory investigations. The environmental data, representing the driving forces that constrain the expression of chemical properties in real systems, can be obtained from site-specific limnological field investigations or as summary data sets developed from literature surveys. Allochthonous chemical loadings can be developed as worst-case estimates, via the outputs of terrestrial models, or, when appropriate, via direct field measurement. 

This chapter focuses on two main subjects. It will first deal with knowledge and methodologies of good practice in the study of chemical and microbial processes in wastewater collection systems. The information on such processes is provided by investigations, measurements and analyses performed at bench, pilot and field scale. Second, it is the objective to establish the theoretical basis for determination of parameters to be used for calibration and validation of sewer process models. These main objectives of the chapter are integrated sampling, pilot-scale and field measurements and laboratory studies and analyses are needed to determine wastewater characteristics, including those kinetic and stoichiometric parameters that are used in models for simulation of the site-specific sewer processes. 

By Bayes s rule, the posterior probability on a Monte Carlo realization of a model equals the probability of observing the site-specific output data if the realization is correct, times the prior probability that the realization is correct, normalized such that the sum of the posterior probabilities of the Monte Carlo realizations equals 1. In Monte Carlo analysis, all realizations are equally likely (i.e., the pritM probability on each realization of an n-realization Monte Carlo simulation is 1/n). Therefore, the BMC acceptance-rejection procedure boils down to the following The probability that a model realization is correct, given new data, equals the relative likelihood of the having observed the new data if the realization is correct. 

A probabilistic model is available for predicting the average log-tissue residue as a function of the water concentration at the site, and a set of site-specific tissue residue measurements is available. The water concentration to which the fish were exposed is known, so the average log-tissue residue can be predicted with the model. A Monte Carlo simulation will provide a set of equally probable predictions of the average log-tissue residue. The BMC acceptance-rejection procedure then boils down to estimating, for each model prediction, the probability of getting the observed sample average log-tissue residue concentration if the model prediction is correct. 

Riedo M. Gyalistras D. and Fuhrer J. (2000). Net primary production and carbon stocks in differently managed grasslands Simulation of site-specific sensitivity to climate change. Ecological Modelling, 134(2-3), 207-227. 

The composition of an alloy surface is often very different than the alloy s bulk composition due to segregation effects. The overall activity of a catalyst is determined by the distribution of active sites. This distribution may be very heterogeneous both in terms of the local environments that define each site and their chemical reactivities. The reactivity of any specific active site can be affected by contributions from strain, ligand and ensemble effects. Computational methods are well suited to exploring these effects because one can simulate model systems where only one effect dominates as well as model systems where multiple effects are important. 

In this paper, we will discuss data collected as a part of two recent field studies, one in Georgia and the other in Florida. The objective of both studies was to monitor the environmental dynamics of pesticides in the crop root zone and to use these data to evaluate the predictive capability of several simulation models. Specific attention will be focused on the data characterizing the spatial variability of pesticide sorption and degradation parameters measured at these two field sites. 

Most models only simulate the batch type of chemical systems, and lack the time and spatial information needed to address a site-specific problem, e.g., the arrival of a contaminant at a particular point in space. This type of model, however, can be useful in evaluating some laboratory experiments. 

In order to simulate the system response to changes in management or climate and the trajectories needed to quantify the indicators, a site-specific model description of the entire system is required. Three sub-steps can be distinguished in building the model ... 

Comparison of the processes simulated by these various models with sensitivity analysis performed on key input parameters (e.g. advection, soil moisture content, biotransformation rates) and calibration of the outputs from the models against site-specific data55 can provide information on how each model performs against theoretical expectations and measured values (Table 4). This review showed that the predicted indoor air concentrations varied by over an order of magnitude (Table 1 in ref. 56). Incorporation of the key findings from this type of applied research work contributes towards improving the predictability of contaminants from contaminated land to various receptors. 

While the ultimate model would be one that couples the simulations of the development and movement of the ice sheet, the associated hydraulics, the development of permafrost and the hydraulic and mechanical responses of the geosphere worthwhile improvements in the interim include 1) three-dimensional simulations 2) conceptual model based on synthesis of site-specific data 3) including stress-dependent permeability and 4) representing the effects of permafrost as modified, time dependent hydraulic and mechanical properties in the H-M model. 

From the preliminary study to actual implementation, the assistance of plant engineers and operators is essential for the success of the project. In many cases, process engineers who design DWC columns are unaware of the site-specific concerns. Thorough and clear communication with them reduces unnecessary time loss and risks during implementation. The concepts and operation modes of the DWC and new devices as well as the start-up and shutdown procedures were explained to the plant engineers and operators. Their questions were clarified with 3-D models and simulation results. 

The SPLP is designed to simulate waste materials in the ground surface or oti the top of the surface. The substances there are exposed to rainfall. Leachate forms by dissolution of them. Data given from the SPLP are utilized to develop site-specific soil remediation criteria that protect ground water. Federal and/or State specific guidance utilize the data for a conceptual site model. 

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