Claudius M. Bürger

Uncertainty and data worth analysis for the hydraulic design of funnel-and-gate systems in heterogeneous aquifers

[1] Hydraulic failure of a funnel-and-gate system may occur when the contaminant plume bypasses the funnels rather than being captured by the gate. We analyze the uncertainty of capturing the plumes by funnel-and-gate systems in heterogeneous aquifers. Restricting the analysis to two-dimensional, steady state flow, we characterize plume capture by the values of the stream function at the boundaries of the plume and the funnels. On the basis of the covariance of the log conductivity distribution we compute the covariance matrix of the relevant stream function values by a matrix-based first-order second-moment method, making use of efficient matrix-multiplication techniques. From the covariance matrix of stream function values, we can approximate the probability that the plume is bypassing the funnels. We condition the log conductivity field to measurements ofthe logconductivity and the hydraulic head. Prior to performing additional measurements, we estimate their worth by the expected reduction in the variance of stream function differences. In an application to a hypothetical aquifer, we demonstrate that our method of uncertainty propagation and our sampling strategy enable us to discriminate between cases of success and failure of funnel-and-gate systems with a small number of additional samples. INDEX TERMS: 1829 Hydrology: Groundwater hydrology; 1869 Hydrology: Stochastic processes; 1832 Hydrology: Groundwater transport; KEYWORDS: conditioning, data worth, funnel-and-gate systems, heterogeneous aquifers, stream function, uncertainty propagation

Mobility, turnover and storage of pollutants in soils, sediments and waters : achievements and results of the EU project AquaTerra. A review

AquaTerra is one of the first environmental projects within the 6th Framework program by the European Commission. It began in June 2004 with a multidisciplinary team of 45 partner organizations from 13 EU countries, Switzerland, Serbia, Romania and Montenegro. Results from sampling and modeling in 4 large river basins (Ebro, Danube, Elbe and Meuse) and one catchment of the Brévilles Spring in France led to new evaluations of diffuse and hotspot input of persistent organic and metal pollutants including dynamics of pesticides and polycyclic aromatic hydrocarbons, as well as metal turnover and accumulation. While degradation of selected organic compounds could be demonstrated under controlled conditions in the laboratory, turnover of most persistent pollutants in the field seems to range from decades to centuries. First investigations of long-term cumulative and degradation effects, particularly in the context of climate change, have shown that it is also necessary to consider the predictions of more than one climate model when trying to assess future impacts. This is largely controlled by uncertainties in climate model responses. It is becoming evident, however, that changes to the climate will have important impacts on the diffusion and degradation of pollutants in space and time that are just at the start of their exploration.

Short note: Introduction of a web service for cloud computing with the integrated hydrologic simulation platform ParFlow

In cloud computing, software and data are shared via servers that can be accessed on-demand through basic terminals in conjunction with a Web browser. This results in the efficient utilization of software and hardware infrastructure by multiple users without the need of local software installation and maintenance. Here, this concept is applied and extended to the integrated hydrologic simulation platform ParFlow via a newly developed Web interface. Until recently there was no unifying definition of cloud computing in the literature to our knowledge. A generic definition in Wikipedia referred to cloud computing as the ‘‘provision of computational resources on demand via a computer network’’ (where resources encompassed software and hardware). In September 2011 the U.S. National Institute of Standards (NIST) finalized its definition of cloud computing (Mell and Grance, 2011) recognizing three different service models: software-as-aservice (SaaS), infrastructure-as-a-service and platform-as-a-service (PaaS). Essential characteristics of cloud computing are

Optimized Sustainable Groundwater Extraction Management: General Approach and Application to the City of Lucknow, India

In rapidly developing urban areas of emerging countries, increased water demand has led to enormous groundwater withdrawal, calling out for sustainable groundwater management. We suggest implementing a sustainable pumping rate concept based on numerical modeling of the managed aquifer. Sustainability is achieved by constraints regarding (1) a minimum groundwater discharge rate to gaining rivers (ecological constraint) and (2) a maximum drawdown along the city boundaries (social constraints) to prevent excessive groundwater depletion in the neighboring peri-urban and rural areas. The total groundwater extraction is maximized subject to these constraints, leading to specific extraction patterns throughout the city, depending upon the values set for the constraints. The optimization is performed by linear programming. For a given extraction rate, the two constraints can be traded off by the groundwater manager, causing different wells to be activated or deactivated. We demonstrate the applicability of the methodology by the example of the city of Lucknow, India, but it can be transferred to other cities facing conflicts of managing groundwater resources.