Comparing Methods of Barometric Efficiency Characterization for Specific Storage Estimation

Groundwater responses to barometric pressure fluctuations are characterized using the concept of barometric efficiency (BE). For semiconfined and confined aquifers, BE values can be used to provide efficient, low-cost estimates of specific storage. This study compares, for the first time, eight existing methods of BE estimation. Comparisons were undertaken using data from the Peel region of Western Australia. Fourier analysis and regression deconvolution methods were used to estimate aquifer confinement status. The former approach was found to be robust and provided a quantitative basis for spatial comparisons of the degree of confinement. The latter approach was confounded by the presence of diurnal and/or semidiurnal signals. For wells at which semiconfined or confined responses were identified, frequency and time domain methods were used to estimate BE values. Most BE estimation methods were similarly confounded by diurnal and/or semidiurnal signals, with the exception of the Acworth et al. (2016) method. Specific storage values calculated from BE values were order-of-magnitude consistent with the results of four historical pumping tests. The methods implemented in this research provide efficient, low-cost alternatives to hydraulic testing for estimating aquifer confinement, as well as the BE and specific storage of semiconfined and confined aquifers. The frequency and duration of observations required by these methods are minimal; for example, typically requiring a minimum of four observations per day over a four month period. In some locations they may allow additional insights to be derived from existing groundwater hydrograph data.     

Controls on Early Cretaceous desert sediment provenance in south-west Gondwana,Botucatu Formation (Brazil and Uruguay)

The Lower Cretaceous Botucatu Formation records the development of widespread dry–aeolian desert sedimentation throughout the Paraná Basin in south-west Gondwana. To reconstruct the provenance of the aeolian sediment, petrography, granulometric analysis, U-Pb detrital zircon ages have been determined from along the southern basin margin in Rio Grande do Sul state (southern Brazil) and Uruguay (Tacuarembó region). The dataset reveals a mean composition Qt₈₉F₈L₃, comprising very fine to medium-grained quartozose and feldspatho-quartzose framework. Heavy mineral analysis reveals an overall dominance of zircon, tourmaline and rutile grains (mean ZTR_0.84) with sporadic garnet, epidote and pyrolusite occurrences. The detrital zircon U-Pb ages are dominated by Cambrian to Neoproterozoic (515 to 650 Ma), Tonian to Stenian (900 to 1250 Ma) and Orosirian to Rhyacian (1.8 to 2.2 Ga) material. The detrital zircon dataset demonstrates a significant lateral variation in sediment provenance: Cambrian to Neoproterozoic detrital zircons dominate in the east, while Tonian to Stenian and Orosirian to Rhyacian ages predominate in the west of the study area. Sandstones are quartz-rich with dominantly durable zircon, tourmaline and rutile heavy mineral suite, with subtle but statistically significant along-strike differences in heavy mineral populations and detrital mineralogy which are thought to record local sediment input points into the aeolian system. The similar age spectra of Botucatu desert with proximal Paraná Basin units, the predominance of quartzose, and zircon, tourmaline and rutile components, suggests that recycling is the mechanism responsible for the erg feeding.     

The partitioning of attached and detached eddy motion in the atmospheric surface layer using Lorentz wavelet filtering

Townsend's attached eddy hypothesis states that the turbulent structure in the constant stress layer can be decomposed into attached and detached eddy motion. This paper proposes and tests a methodology for separating the attached and detached eddy motion from time series measurements of velocity and temperature. The proposed methodology is based on the time-frequency localization and filtering capabilities of the orthonormal wavelet transforms. Using a relative entropy statistical measure, the optimal wavelet basis is identified first. The turbulence time series measurements are then transformed into the wavelet domain where the contribution of specific events in the time-frequency domain is identified. The filtering scheme utilizes a recently constructed Lorentz thresholding methodology that successfully eliminates all wavelet coefficients associated with the detached eddy motion. While this filtering scheme lacks the compression efficiency of the classical Donoho and Johnstone's universal thresholding model, it conserves the higher-order statistics and important turbulence interactions related to the Reynolds stresses. Following the filtering scheme, the attached eddy motion time series is re-constructed by an inverse wavelet transform of the non-zero wavelet coefficients. The proposed partitioning methodology for attached and detached eddy motion is tested using 56 Hz triaxial sonic anemometer velocity and temperature measurements above a uniform dry lake bed in Owens valley, California, for a wide range of atmospheric stability conditions. Validation that the wavelet filtered time series represents the attached eddy motion is also discussed in the context of conservation of turbulence energy and surface fluxes.     

Sand bodies and incised valleys within the Late Quaternary Sanaga–Nyong delta complex on the middle continental shelf of Cameroon

Seismic data and sediment cores collected offshore from the Sanaga River and Nyong River mouths were used to analyse a loose mantle of yellow to reddish sandy gravel with a range of fluvial and deltaic characteristics cropping out in the middle part (25–65 m water depth) of the continental shelf of Cameroon. Contrary to most of the Atlantic shelves, where the lowstand systems tract was destroyed by erosion, we found 80–120 ms (60–90 m) of sediment mainly in the middle part of the shelf, which correspond credibly to MIS 2–4. Fluvial paleodrainage systems are preserved beneath the shelf and individual filled channels with planar infillings were mapped that cross the shelf along two surfaces of erosion. These incisions suggested westerly and northwesterly drainage shifts during presumed lowered base level. The presence of closely spaced channel fills suggests repeated avulsion of a single stream during a long-lasting sub-aerial erosion period. The seismic facies of these Pleistocene deposits distinguish themselves clearly from well-stratified older strata showing deformation (Pliocene) or intense folding (Miocene). The orientation of the paleovalleys appears strongly controlled by the N60°E trending cross faults within Mesozoic–Cenozoic strata.     

Efficient joint-probability methods for hurricane surge frequency analysis

The Joint-Probability Method (JPM) was adopted by federal agencies for critical post-Katrina determinations of hurricane surge frequencies. In standard JPM implementations, it is necessary to consider a very large number of combinations of storm parameters, and each such combination (or synthetic storm) requires the simulation of wind, waves, and surge. The tools used to model the wave and surge phenomena have improved greatly in recent years, but this improvement and the use of very large high-resolution grids have made the computations both time-consuming and expensive. In order to ease the computational burden, two independent approaches have been developed to reduce the number of storm surge simulations that are required. Both of these so-called JPM-OS (JPM-Optimal Sampling) methods seek to accurately cover the entire storm parameter space through optimum selection of a small number of parameter values so as to minimize the number of required storm simulations. Tests done for the Mississippi coast showed that the accuracy of the two methods is comparable to that of a full JPM analysis, with a reduction of an order of magnitude or more in the computational effort.     

Transient Effects in ISOPHOT Data: Status of Modelling and Correction Procedures

The calibration of ISOPHOT observations is hampered in many cases by the transient response of the detectors. Here we outline thebehaviour observed in flight for the different ISOPHOT detectors. We also present some of the procedures which are currently used to correct transienteffects and their implementation in the ISOPHOT Interactive Analysis.     

Plant community patterns in a gypsum area of NE Spain. I. Interactions with topographic factors and soil erosion

The aim of this paper is to explain how topographical factors and soil erosion affect plant community patterns in the gypsum hills of the Middle Ebro Basin (NE Spain).Both the altitudinal location on the hill and, secondarily, the aspect determine a regular distribution pattern of the plant communities, which is closely related to soil and erosion features, as well as to some plant attributes. Tall perennial grasses dominate the valley bottoms, and scrub vegetation the hillsides and hilltops. Water availability, soil depth and particle movement down the slope are the main factors that could explain this segregation.     

The stability of spatial patterns of welfare—the Israeli case

Regional inequality of welfare comprises one of the most serious social problems facing most countries in the world. The present study examines this problem in Israel, by means of two variables found to be suited to the characterization of regional welfare in that country: rate of motorization and level of education. The comparative empirical analysis concerns the period from the early 1960s through the 1970s and into the 1980s, and is in two parts—one, describing changes in the spatial pattern of welfare overtime; and other, examining the extent of stability of the spatial patterns, through regression analysis. The second phase also includes empirical data concerning the divergence or convergence of regional inequalities in Israel during the period studied.     

Positional deformation analysis in polygonometric structures

Summary The paper describes the analysis of positional displacements of points on an object, which are connected polygonometrically with assumed stable points of reference. This net, sighted in both the epochs considered, is adjusted jointly first with the elimination of the object points and then with the elimination of the reference points, depending on the purpose of testing the linear hypothesis in the appropriate model.     

Estimating the influence of increased nitrate loads from wastewater on phosphorus mobility in river sediments

Research on the sediment‐surface water transition zone in three study site regions, different in hydrological conditions, was conducted to estimate to which extent nitrate in surface water can contribute to riverbed sediment oxidation and thus prevent release of sediment phosphorus to surface water. Consequently, the Du tch Flow Model (DUFLOW) based water quality model “Spreewald” and results from the emission model “ Mo delling N utrient E missions in Ri ver S ystems” (MONERIS) were used to estimate to which extent wastewater treatment plants (WWTPs) could contribute to the NO₃^– concentration in surface waters if they were operated without denitrification. It is demonstrated that an effective phosphorus retention in sediments by means of surface water NO₃^– is possible only under specific conditions, i. e. (i) a sufficient supply of surface water to the sediment by advective fluxes, (ii) a sufficient amount of sediment iron to provide phosphorus binding sites in the case of sediment oxidation, (iii) a redox system not leading to a rapid NO₃^– and FeOOH depletion and to phosphorus release from organic pools by high microbial activities. Model results show that in‐stream denitrification processes counteract a significant increase of NO₃^– surface water concentrations from WWTPs operated without denitrification during summer, when eutrophication risk through phosphorus is highest. The increase of NO₃^– surface water concentrations in winter due to decreased denitrification in the surface water is of minor relevance for phosphorus release from sediments.