Ground water model calibration using pilot points and regularization

Use of nonlinear parameter estimation techniques is now commonplace in ground water model calibration. However, there is still ample room for further development of these techniques in order to enable them to extract more information from calibration datasets, to more thoroughly explore the uncertainty associated with model predictions, and to make them easier to implement in various modeling contexts. This paper describes the use of pilot points as a methodology for spatial hydraulic property characterization. When used in conjunction with nonlinear parameter estimation software that incorporates advanced regularization functionality (such as PEST), use of pilot points can add a great deal of flexibility to the calibration process at the same time as it makes this process easier to implement. Pilot points can be used either as a substitute for zones of piecewise parameter uniformity, or in conjunction with such zones. In either case, they allow the disposition of areas of high and low hydraulic property value to be inferred through the calibration process, without the need for the modeler to guess the geometry of such areas prior to estimating the parameters that pertain to them. Pilot points and regularization can also be used as an adjunct to geostatistically based stochastic parameterization methods. Using the techniques described herein, a series of hydraulic property fields can be generated, all of which recognize the stochastic characterization of an area at the same time that they satisfy the constraints imposed on hydraulic property values by the need to ensure that model outputs match field measurements. Model predictions can then be made using all of these fields as a mechanism for exploring predictive uncertainty.

Parameters affecting the performance of wetting and drying in a two-dimensional finite element long wave hydrodynamic model

The marsh porosity method, a type of thin slot wetting and drying algorithm in a two-dimensional finite element long wave hydrodynamic model, is discussed and analyzed to assess model performance. Tests, including comparisons to simple examples and theoretical calculations, examine the effects of varying the marsh porosity parameters. The findings demonstrate that the wetting and drying concept of marsh porosity, often used in finite element hydrodynamic modeling, can behave in a more complex manner than initially expected.

Integrating science and management through collaborative learning and better information management

Achieving more sustainable land and water use depends on high-quality information and its improved use. In other words, better linkages are needed between science and management. Since many stakeholders with different relationships to the natural resources are inevitably involved, we suggest that collaborative learning environments and improved information management are prerequisites for integrating science and management. Case studies that deal with resource management issues are presented that illustrate the creation of collaborative learning environments through systems analyses with communities, and an integration of scientific and experiential knowledge of components of the system. This new knowledge needs to be captured and made accessible through innovative information management systems designed collaboratively with users, in forms which fit the users' 'mental models' of how their systems work. A model for linking science and resource management more effectively is suggested. This model entails systems thinking in a collaborative learning environment, and processes to help convergence of views and value systems, and make scientists and different kinds of managers aware of their interdependence. Adaptive management provides a mechanism for applying and refining scientists' and managers' knowledge. Copyright (C) 2003 John Wiley Sons, Ltd.

Response of the salt-freshwater interface in a coastal aquifer to a wave-induced groundwater pulse: field observations and modelling

Field observations on an unconfined coastal aquifer showed that a groundwater pulse, generated by it moderate (significant wave height, H-sig similar to 4.5 m) wave/storm event, induced significant oscillations in the salt-freshwater interface of the order of several metres in the horizontal direction. A dynamic sharp-interface model is developed to quantify the mechanism of these interface oscillations. The model uses the 50% seawater salinity contour as the location of the equivalent sharp-interface. The model was calibrated against the observed groundwater table fluctuations. It predicted reasonably well the interface oscillations with a slight over-prediction of the oscillation magnitude and a steepening of the interface. The neglect of mixing in the salt-freshwater mixing zone by the sharp-interface model is suggested as a possible contributor to the discrepancies between the model predictions and observations. In contrast with the significant wave effects, there was no observable response of the interface to diurnal or semidiurnal tides. (C) 2004 Elsevier Ltd. All rights reserved.

The market valuation of environmental capital expenditures by pulp and paper companies

The objective of this study is to examine the market valuation of environmental capital expenditure investment related to pollution abatement in the pulp and paper industry. The total environmental capital expenditure of $8.7 billion by our sample firms during 1989-2000 supports the focus on this industry. In order to be capitalized, an asset should be associated with future economic benefits. The existing environmental literature suggests that investors condition their evaluation of the future economic benefits arising from environmental capital expenditure on an assessment of the firms' environmental performance. This literature predicts the emergence of two environmental stereotypes: low-polluting firms that overcomply with existing environmental regulations, and high-polluting firms that just meet minimal environmental requirements. Our valuation evidence indicates that there are incremental economic benefits associated with environmental capital expenditure investment by low-polluting firms but not high-polluting firms. We also find that investors use environmental performance information to assess unbooked environmental liabilities, which we interpret to represent the future abatement spending obligations of high-polluting firms in the pulp and paper industry. We estimate average unbooked liabilities of $560 million for high-polluting firms, or 16.6 percent of market capitalization.

Cryptic false spider mites: a new genus, Austrolinus, and a review of the family Linotetranidae (Acari : Prostigmata : Tetranychoidea)

The Linotetranidae (Acari: Tetranychoidea) is a poorly known group of cryptic false spider mites associated with grasses and sedges. We review the family at the world level, provide the first phylogenetic analysis of the family, and describe the first Australian representatives: Austrolinus, gen. nov. and two new species: A. arenulus and A. kinnearae. Linotetranidae is redefined, and keys are provided for the families of the Tetranychoidea, and for all described genera and species of Linotetranidae.

Impact of pre-existing sulfate on retention of imported chloride and nitrate in variable charge soil profiles

In variable charge soils, anion retention and accumulation through adsorption at exchange sites is a competitive process. The objectives of this study in the wet tropics of far north Queensland were to investigate (i) whether the pre-existing high sulphate in variable charge soils had any impact on the retention of chloride and nitrate, derived mostly from the applied fertilizer; and (ii) whether chloride competed with nitrate during the adsorption processes. Soil cores up to 12.5 m depth were taken from seven sites, representing four soil types, in the Johnstone River Catchment. Six of these sites had been under sugarcane (Saccharum officinarum-S) cultivation for at least 50 years and one was an undisturbed rainforest. The cores were segmented at 1.0 m depth increments, and subsamples were analysed for nitrate-N, cation (CEC)- and anion-exchange capacities (AEC), pH, exchangeable cations (Ca, Mg, K, Na), soil organic C (SOC), electrical conductivity (EC), sulphate-S, and chloride. Sulphate-S load in 1-12 m depth under cropping ranged from 9.4 to 73.9 t ha(-1) (mean= 40 t ha(-1)) compared with 74.4 t ha(-1) in the rainforest. Chloride load under cropping ranged from 1.5 to 9.6 t ha(-1) (mean= 4.9 t ha(-1)) compared to 0.9 t ha(-1) in the rainforest, and the nitrate-N load from 113 to 2760 kg ha(-1) (mean = 910 kg ha(-1)) under cropping compared to 12 kg ha(-1) in the rainforest. Regardless of the soil type, the total chloride or nitrate-N input in fertilisers was 7.5 t ha(-1), during the last 50 years. Sulphate-S distribution in soil profiles decreased with depth at >2 m, whereas bulges of chloride or nitrate-N were observed at depths >2 m. This suggests that chloride or nitrate adsorption and retention increased with decreasing sulphate dominance. Abrupt decreases in equivalent fraction of sulphate (EFSO4), at depths >2 m, were accompanied by rapid increases in equivalent fraction of chloride (EFCl), followed by nitrate (EFNO3). The stepwise regression for EFCl and EFNO3 indicated that nitrate retention was reduced by the pre-existing sulphate and imported chloride, whereas only sulphate reduced chloride adsorption. The results indicate that chloride and nitrate adsorption and retention occurred, in the order chloride>nitrate, in soils containing large amounts of sulphate under approximately similar total inputs of N- and Cl-fertilisers. (C) 2004 Elsevier B.V. All rights reserved.

Seawater neutralization of alkaline bauxite residue and implications for revegetation

Reaction of bauxite residue with seawater results in neutralization of alkalinity through precipitation of Mg-, Ca-, and Al-hydroxide and carbonate minerals. In batch studies, the initial pH neutralization reaction was rapid (

Effect of environment and genotype on bread-making quality of spring-sown spring wheat cultivars in China

Improvement of end-use quality in bread wheat depends on a thorough understanding of current wheat quality and the influences of genotype (G), environment (E), and genotype by environment interaction (G x E) on quality traits. Thirty-nine spring-sown spring wheat (SSSW) cultivars and advanced lines from China were grown in four agro-ecological zones comprising seven locations during the 1998 and 1999 cropping seasons. Data on 12 major bread-making quality traits were used to investigate the effect of G, E, and G x E on these traits. Wide range variability for protein quantity and quality, starch quality parameters and milling quality in Chinese SSSW was observed. Genotype and environment were found to significantly influence all quality parameters as major effects. Kernel hardness, flour yield, Zeleny sedimentation value and mixograph properties were mainly influenced by the genetic variance components, while thousand kernel weight, test weight, and falling number were mostly influenced by the environmental variance components. Genotype, environment, and their interaction had important effects on test weight, mixing development time and RVA parameters. Cultivars originating from Zone VI (northeast) generally expressed high kernel hardness, good starch quality, but poor milling and medium to weak mixograph performance; those from Zone VII (north) medium to good gluten and starch quality, but low milling quality; those from Zone VIII (central northwest) medium milling and starch quality, and medium to strong mixograph performance; those from Zone IX (western/southwestern Qinghai-Tibetan Plateau) medium milling quality, but poor gluten strength and starch parameters; and those from Zone X (northwest) high milling quality, strong mixograph properties, but low protein content. Samples from Harbin are characterized by good gluten and starch quality, but medium to poor milling quality; those from Hongxinglong by strong mixograph properties, medium to high milling quality, but medium to poor starch quality and medium to low protein content; those from Hohhot by good gluten but poor milling quality; those from Linhe by weak gluten quality, medium to poor milling quality; those from Lanzhou by poor bread-making and starch quality; those from Yongning by acceptable bread-making and starch quality and good milling quality; and those from Urumqi by good milling quality, medium gluten quality and good starch pasting parameters. Our findings suggest that Chinese SSSW quality could be greatly enhanced through genetic improvement for targeted well-characterized production environments.

Impacts of morphological, physical and chemical properties of sludge flocs on dewaterability of activated sludge

This study examined how the floc characteristics affect dewaterability of activated sludge. The floc properties were characterized by morphological parameters (floc size distribution, fractal dimension and filament index), physical properties (flocculating ability, surface charge, relative hydrophobicity and viscosity), and chemical constituents in sludge and extracted extracellular polymeric substances (EPS), including the polymeric compounds protein, humic substances, carbohydrates and the ions Ca2+, Mg2+, Fe3+ and Al3+. The dewaterability was defined in terms of the bound water content and capillary suction time (CST). The bound water and CST corresponded to a similar indication with respect to dewaterability of activated sludge. The floc physical parameters were the most important factors which effect significantly on the water binding ability of the sludge flocs. The morphological characteristics had relatively weak impact on the dewaterability. The polymeric components protein and carbohydrate had a significant contribution to enhance the water binding ability of the sludge flocs. The effect of humic substances in the sludge on the dewaterability was, however, insignificant. The CST had good statistical correlations with the polymeric constituents measured in both sludge and the extracted EPS, and the bound water was only correlated well with the individual polymers measured in the sludge. High concentration of Ca2+, Mg2+, Fe3+ and Al3+ had significant improvement for dewaterability. (C) 2003 Elsevier B.V. All rights reserved.

Effects of phosphorus on the growth and nitrogen fixation rates of Lyngbya majuscula: implications for management in Moreton Bay, Queensland

Significant acetylene reduction and therefore N-2 fixation was observed for Lyngbya majuscula only during dark periods, which suggests that oxygenic photosynthesis and N-2 fixation are incompatible processes for this species. Results from a series of batch and continuous-flow-culture reactor studies showed that the specific growth rate and N-2 fixation rate of L, majuscula increased with phosphate (P-PO4) concentration up to a maximum value and thereafter remained constant. The P-PO4 concentrations corresponding to the maximum N-2 fixation and maximum growth rates were -0.27 and -0.18 muM respectively and these values are denoted as the saturation values for N-2 fixation and growth respectively. Regular monitoring studies in Moreton Bay, Queensland, show that concentrations Of P-PO4 generally exceed these saturation values over a large portion of the Bay and therefore, the growth of the bloom-forming L, majuscula is potentially maximised throughout much of the Bay by the elevated P-PO4 concentrations. Results from other studies suggest that the elevated P-PO4 concentrations in the Bay can be largely attributed to discharges from waste-water treatment plants (WWTPs), and thus it is proposed that the control of the growth of L. majuscula in Moreton Bay will require a significant reduction in the P load from the WWTP discharges. If the current strategy of N load reduction for these discharges is maintained in the absence of substantial P load reduction, it is hypothesised that the growth of L, majuscula and other diazotrophs in Moreton Bay will increase in the future.