The Stochastic Approach in Groundwater Modeling for the Optimization of Hydraulic Barriers

A three‐dimensional stochastic groundwater flow and contaminant transport model has been developed to optimize groundwater containment at an industrial site in Italy and to define likely future contaminant distribution under different confinement or remediation scenarios. The transport model was first calibrated using a deterministic approach to simulate the hydrochemical conditions prior to the optimization of groundwater extraction, then a probabilistic simulation was conducted to predict future contaminant concentrations. The stochastic approach allowed introducing an estimate of the uncertainty of the hydrogeological and chemical parameters into the model, simulating the probability density function of the contaminant concentrations after the application of the optimized barrier wells pumping rates. This allowed the calculation of the time required for the concentrations of each modeled parameter to decrease to under the regulatory limit at the compliance point, and associating the related uncertainty into the model. Quantifying the model prediction uncertainty facilitated a better understanding of the site environmental conditions, providing the site owners additional information for managing the site and allocating related economic resources. ©2016 Wiley Periodicals, Inc.     

Developing an empirical model of phytoplankton primary production: a neural network case study

We describe the development of a neural network model for estimating primary production of phytoplankton. Data from an enriched estuary in the eastern United States, Chesapeake Bay, were used to train, validate and test the model. Two error backpropagation multilayer perceptrons were trained: a simpler one (3-5-1) and a more complex one (12-5-1). Both neural networks outperformed conventional empirical models, even though only the latter, which exploits a larger suite of predictive variables, provided truly accurate outputs. The application of this neural network model is thoroughly discussed and the results of a sensitivity analysis are also presented.     

Case study: Life‐cycle design strategies at the saturn corporation

This case study is the third in a four‐part series profiling environmental decision making at leading companies. © 2000 John Wiley & Sons, Inc.     

Sparse PCA and investigation of multi-elements compositional repositories: theory and applications

The geochemistry of floodplain sediments is fundamental to monitor environmental changes and to quantify their contribution to natural and anthropic processes. A floodplain sediment composition is a vector of positive elements which sum to a fixed constant. The analysis of high-dimensional compositions requires methods that produce results involving only a small portion of the original variables. On the other hand, the analysis must take into account the additional constraints specific to compositions. With the purpose of studying these problems, a new procedure for sparse PCA is proposed on European floodplain sediment samples.     

Streamwise velocity profiles in coastal currents

The ability to model marine currents can be a powerful device for many planning activities, for which the knowledge of the velocity field is of pivotal importance, such as the evaluation of current-induced loading on maritime structures or the diffusion and dispersion of polluted flow discharges. Observations of time-averaged velocity profiles, taken with a vessel mounted acoustic Doppler current profiler during a monitoring survey program in the seas of Southern Italy, are analysed in this paper. The measurements were taken under non-breaking conditions, offshore the surf zone, with the aim of reproducing the vertical trends of the streamwise velocity by means of standard theoretical laws. To evaluate also the possible influence of stratification on the current velocity profile shape, together with velocity measurements water temperature and salinity were also measured at the same time and locations, by means of a CTD recorder. The examined surveys referred to different time periods and sites, to guarantee a general validity of deductions. On the basis of the experiments, we verified the actual existence of a log-layer and concluded that the upper limit of the region in which the log law is applicable extends well beyond the inner region. Moreover, the deviations of the measured velocity from the logarithmic profiles above the height of the log layer is consistent with the effects of stratification. The parameters of the log law were estimated, depending on both flow dynamics and stratification in the target area. As a second step, in the most superficial and stratified layer, the velocity profiles were modelled by means of a power law, which fitted the measured data well. According to previous studies, the power law parameters result Reynolds number dependent by means of a new proposed formulation. Finally, the bottom stress and the bottom drag coefficient were investigated.     

Thermal effects on swimming activity and habitat choice in juvenile Pacific cod (Gadus macrocephalus)

The behavioral responses of fishes to temperature variation have received less attention than physiological responses, despite their direct implications for predator–prey dynamics in aquatic ecosystems. In this paper, we describe the temperature dependence of swimming performance and behavioral characteristics of juvenile Pacific cod (Gadus macrocephalus; 75–125 mm total length). Maximum swimming speeds increased with temperature and body size. Routine swimming speeds of Pacific cod in small groups of similarly sized fish (N = 6) increased with body size and were 34 % faster at 9 °C than at 2 °C. The response to temperature was opposite that previously described for juvenile walleye pollock (Theragra chalcogramma), reflecting species-specific differences in behavioral responses. In a separate experiment, we demonstrated the effect of temperature on habitat selection of juvenile Pacific cod: Use of an artificial eelgrass patch in a 5-m-long laboratory tank was significantly greater at 9 °C than at 2 °C. These results illustrate that temperature affects a range of behavioral traits that play important roles in determining the frequency and outcomes of predator–prey interactions.     

Challenges of Urban and Regional Carbon Management and the Scientific Response

Abstract

How urbanization unfolds in the text few decades and which urban development path we choose are potentially critical to the efforts aimed at stabilizing greenhouse gas emissions. However, our understanding of urban, as a unit or system, and its cross-scale linkages in the context of carbon management is at infancy state. In this context, this article outlines, the key challenges and introduces a new scientific initiative - Urban and Regional Carbon Management Initiative of the Global Carbon Project, which has raised key scientific questions with the aim to find reasonable answers. This article mainly showcases key science questions, past activities and future outlook with the aim to reach out to the related scientific and policy communities.