The impact of microbial activity on fractured chalk transmissivity was investigated on a laboratory scale. Long-term experiments were conducted on six fractured chalk cores (20 cm diameter, 23-44 cm long) containing a single natural fracture embedded in a porous matrix. Biodegradation experiments were conducted under various conditions, including several substrate and oxygen concentrations and ...

In modeling transport within naturally heterogeneous aquifers, it is usually assumed that the transport equations valid at local scales can also be applied at larger scales. At larger scales, the heterogeneous domain is represented by an equivalent homogeneous medium. Convergent-flow tracer tests constitute one of the most frequently used field tests to estimate effective input parameters of eq...

The reconstruction of the transmissivity field from the more numerous experimental hydraulic head data, an inverse problem, remains the focus of continuing stochasticbased research. The difficulty of this problem arises not only from the complexity of the diffusion equation that links the two variables, but also from taking into account the physical aspects of the site under study; e.g. the bou...

Tree species differ from one another in, and display trade-offs among, a wide range of attributes, including canopy and understorey growth and mortality rates, fecundity, height and crown allometry, and crown transmissivity. But how does this variation affect the outcome of interspecific competition and hence community structure? We derive criteria for the outcome of competition among tree spec...

This paper presents a geostatistical approach to multi-directional aquifer stimulation in order to better identify the transmissivity ®eld. Hydraulic head measurements, taken at a few locations but under a number of different steady-state ̄ow conditions, are used to estimate the transmissivity. Well installation is generally the most costly aspect of obtaining hydraulic head measurements. There...

This study investigates the potential of determining atmospheric transmissivity (τ) from NOAA-AVHRR satellite images using a simple methodology. Using this method, hourly transmissivity values over the land surface area of Bangladesh has been determined. The spatio-temporal distribution of τ has been studied by constructing monthly average maps for the whole country for one complete year (Febru...

[1] In this paper we derive analytical solutions to statistical moments for transient saturated flow in two-dimensional, bounded, randomly heterogeneous porous media. By perturbation expansions, we first derive partial differential equations governing the zerothorder head h and the first-order head term h, where orders are in terms of the standard deviation of the log transmissivity. We then so...

A method for producing radio-wave-reflecting concrete, which is potentially useful for lateral guidance in automatic highways, is provided. In the form of cement paste, it contains a small amount (0.5 vol.%) of 0.1 mm diameter carbon filaments as an admixture. The radiation absorbed is negligible compared to that reflected. The reflectivity at 1 GHz is 10 dB higher for radiowave-reflecting ceme...

Three metrics for predicting the time required to identify targets in high-resolution radar pictures were developed. One metric, based on four automatically measured variables related to transmissivity of positive transparencies, was tested. Through multiple-regression analysis, a correlation of 0.69 between observed and predicted identification times was obtained. When these relationships were...