Copyright (c) 2013 Utah State University All rights reserved. http://digitalcommons.usu.edu/cee_facpub Recent documents in CEE Faculty Publications en-us Thu, 16 May 2013 01:58:08 PDT 3600 http://digitalcommons.usu.edu/cee_facpub/848 http://digitalcommons.usu.edu/cee_facpub/848 Tue, 14 May 2013 10:20:44 PDT To support the goal of distributed hydrologic and instream model predictions based on physical processes, we explore multi-dimensional parameterization determined by a broad set of observations. We present a systematic approach to using various data types at spatially distributed locations to decrease parameter bounds sampled within calibration algorithms that ultimately provide information regarding the extent of individual processes represented within the model structure. Through the use of a simulation matrix, parameter sets are first locally optimized by fitting the respective data at one or two locations and then the best results are selected to resolve which parameter sets perform best at all locations, or globally. This approach is illustrated using the Two-Zone Temperature and Solute (TZTS) model for a case study in the Virgin River, Utah, USA, where temperature and solute tracer data were collected at multiple locations and zones within the river that represent the fate and transport of both heat and solute through the study reach. The result was a narrowed parameter space and increased parameter certainty which, based on our results, would not have been as successful if only single objective algorithms were used. We also found that the global optimum is best defined by multiple spatially distributed local optima, which supports the hypothesis that there is a discrete and narrowly bounded parameter range that represents the processes controlling the dominant hydrologic responses. Further, we illustrate that the optimization process itself can be used to determine which observed responses and locations are most useful for estimating the parameters that result in a global fit to guide future data collection efforts.

]]> C Bandaragoda et al. http://digitalcommons.usu.edu/cee_facpub/847 http://digitalcommons.usu.edu/cee_facpub/847 Tue, 14 May 2013 10:20:40 PDT Sorption of sulfamethazine (SMN) and sulfathiazole (STZ) was investigated in three soils, a North Carolina loamy sand, an Iowa sandy loam, and a Missouri loam, under various pH conditions. A significant increase in the sorption coefficient (KD) was observed in all three soils, as the sulfonamides converted from an anionic form at higher pH to a neutral/cationic form at lower pH. Above pH 7.5, sulfonamides exist primarily in anionic form and have higher aqueous solubility and no cationic character, thereby consequently leading to lower sorption to soils. The effect of speciation on sorption is not the same for all sulfonamides; it is a function of the pH of the soil and the pKa of the sulfonamides. The results indicate that, for the soils under investigation, SMN has comparatively lower KD values than STZ. The pH-dependent sorption of sulfonamides was observed to be consistent in all three soils investigated. The KD values for each speciated form-cationic, neutral, and anionic-were calculated using an empirical model in which the species-specific sorption coefficients (KD0, KD1, and KD2) were weighted with their respective fractions present at any given pH.Kurwadkar, S., Adams, C., Meyer, M., Kolpin, D. (2007) “Effects of Sorbate Speciation on Sorption of Selected Sulfonamides in Three Loamy Soils,” J. Agriculture and Food Chemistry, 55, 1370-1376.

]]> S Kurwadkar et al. http://digitalcommons.usu.edu/cee_facpub/846 http://digitalcommons.usu.edu/cee_facpub/846 Tue, 14 May 2013 10:20:33 PDT Widespread use of s-triazine herbicides such as atrazine, simazine, and cyanazine has led to the contamination of many ground-water and surface-water supplies with the parent compounds as well as by primary metabolites (e.g. deethylatrazine, deisopropylatrazine, and deethylcyanazine). Ozonation has been shown to produce many of the same byproducts. Activated carbon adsorption has been designated by the U.S. Environmental Protection Agency as the best available technology (BAT) for the treatment of herbicides in drinking water. Little data is available, however, on the applicability of activated carbon treatment for the control of the primary degradation products of herbicides. In this study, the adsorption of deethylatrazine, deisopropylatrazine (deethylsimazine), and deethylcyanazine on powdered activated carbon (PAC) was examined including development of Langmuir and Freundlich isotherm coefficients. It was found that deethylatrazine, deisopropylatrazine and deethylcyanazine were readily treatable using powdered activated carbon (PAC). However, the PAC’s adsorptive capacity for deethylatrazine, deisopropylatrazine, and deethylcyanazine was generally less than for atrazine resulting in higher estimated carbon costs.

]]> Craig D. Adams et al. http://digitalcommons.usu.edu/cee_facpub/845 http://digitalcommons.usu.edu/cee_facpub/845 Mon, 05 Nov 2012 15:19:08 PST The Laplace transform is a powerful tool used in solving partial differential equations. However, due to considerable difficulty associated with inverting analytical solutions from Laplace space to the original time variable, this final step is often performed by numerical techniques. Unfortunately, this does not deliver a closed form solution to the original model. Here we illustrate a technique for approximating a closed form inversion to the Laplace transformed solution of a heat transport model for a natural river system. We show the approximation method provides good results when compared to the analytical solution that is dependent upon numerical techniques for the inversion of the Laplace transform. Our approximation results in a simple and concise expression in terms of the model parameters without relying on difficult numerical computations. We focus on the contribution to downstream temperatures from upstream boundary conditions, illustrating how boundary condition temperature decays in terms of model parameters.

]]> J. E. Heavilin et al. http://digitalcommons.usu.edu/cee_facpub/844 http://digitalcommons.usu.edu/cee_facpub/844 Mon, 05 Nov 2012 15:19:05 PST This paper presents a method that uses high-resolution multispectral and thermal infrared imagery from airborne remote sensing for estimating two model parameters within the two-zone in-stream temperature and solute (TZTS) model. Previous TZTS modeling efforts have provided accurate in-stream temperature predictions; however, model parameter ranges resulting from the multiobjective calibrations were quite large. In addition to the data types previously required to populate and calibrate the TZTS model, high-resolution, remotely sensed thermal infrared (TIR) and near-infrared, red, and green (multispectral) band imagery were collected to help estimate two previously calibrated parameters: (1) average total channel width (BTOT) and (2) the fraction of the channel comprising surface transient storage zones (b). Multispectral imagery in combination with the TIR imagery provided high-resolution estimates of BTOT. In-stream temperature distributions provided by the TIR imagery enabled the calculation of temperature thresholds at which main channel temperatures could be delineated from surface transient storage, permitting the estimation of b. It was found that an increase in the resolution and frequency at which BTOT and b were physically estimated resulted in similar objective functions in the main channel and transient storage zones, but the uncertainty associated with the estimated parameters decreased.

]]> Q. G. Bingham et al. http://digitalcommons.usu.edu/cee_facpub/843 http://digitalcommons.usu.edu/cee_facpub/843 Wed, 24 Oct 2012 15:24:17 PDT Bethany T. Neilson et al. http://digitalcommons.usu.edu/cee_facpub/842 http://digitalcommons.usu.edu/cee_facpub/842 Wed, 24 Oct 2012 15:24:16 PDT Bethany T. Neilson http://digitalcommons.usu.edu/cee_facpub/841 http://digitalcommons.usu.edu/cee_facpub/841 Wed, 24 Oct 2012 15:24:16 PDT Bethany T. Neilson et al. http://digitalcommons.usu.edu/cee_facpub/839 http://digitalcommons.usu.edu/cee_facpub/839 Wed, 24 Oct 2012 15:24:15 PDT Bethany T. Neilson et al. http://digitalcommons.usu.edu/cee_facpub/840 http://digitalcommons.usu.edu/cee_facpub/840 Wed, 24 Oct 2012 15:24:15 PDT Bethany T. Neilson et al. http://digitalcommons.usu.edu/cee_facpub/838 http://digitalcommons.usu.edu/cee_facpub/838 Wed, 24 Oct 2012 15:24:14 PDT Bethany T. Neilson et al. http://digitalcommons.usu.edu/cee_facpub/837 http://digitalcommons.usu.edu/cee_facpub/837 Wed, 24 Oct 2012 15:24:13 PDT Bethany T. Neilson et al. http://digitalcommons.usu.edu/cee_facpub/836 http://digitalcommons.usu.edu/cee_facpub/836 Wed, 24 Oct 2012 15:24:12 PDT Bethany T. Neilson et al. http://digitalcommons.usu.edu/cee_facpub/835 http://digitalcommons.usu.edu/cee_facpub/835 Wed, 24 Oct 2012 15:24:12 PDT Bethany T. Neilson http://digitalcommons.usu.edu/cee_facpub/833 http://digitalcommons.usu.edu/cee_facpub/833 Wed, 24 Oct 2012 15:24:11 PDT Bethany T. Neilson et al. http://digitalcommons.usu.edu/cee_facpub/834 http://digitalcommons.usu.edu/cee_facpub/834 Wed, 24 Oct 2012 15:24:11 PDT Bethany T. Neilson et al. http://digitalcommons.usu.edu/cee_facpub/832 http://digitalcommons.usu.edu/cee_facpub/832 Wed, 24 Oct 2012 15:24:10 PDT Bethany T. Neilson et al. http://digitalcommons.usu.edu/cee_facpub/830 http://digitalcommons.usu.edu/cee_facpub/830 Wed, 24 Oct 2012 15:24:09 PDT Bethany T. Neilson et al. http://digitalcommons.usu.edu/cee_facpub/831 http://digitalcommons.usu.edu/cee_facpub/831 Wed, 24 Oct 2012 15:24:09 PDT Bethany T. Neilson et al. http://digitalcommons.usu.edu/cee_facpub/829 http://digitalcommons.usu.edu/cee_facpub/829 Wed, 24 Oct 2012 15:24:08 PDT A. Jensen et al.