Optimal design of rain gauge network in the Middle Yarra River catchment, Australia

Rainfall data are a fundamental input for effective planning, designing and operating of water resources projects. A well-designed rain gauge network is capable of providing accurate estimates of necessary areal average and/or point rainfall estimates at any desired ungauged location in a catchment. Increasing network density with additional rain gauge stations has been the main underlying criterion in the past to reduce error and uncertainty in rainfall estimates. However, installing and operation of additional stations in a network involves large cost and manpower. Hence, the objective of this study is to design an optimal rain gauge network in the Middle Yarra River catchment in Victoria, Australia. The optimal positioning of additional stations as well as optimally relocating of existing redundant stations using the kriging-based geostatistical approach was undertaken in this study. Reduction of kriging error was considered as an indicator for optimal spatial positioning of the stations. Daily rainfall records of 1997 (an El Niño year) and 2010 (a La Niña year) were used for the analysis. Ordinary kriging was applied for rainfall data interpolation to estimate the kriging error for the network. The results indicate that significant reduction in the kriging error can be achieved by the optimal spatial positioning of the additional as well as redundant stations. Thus, the obtained optimal rain gauge network is expected to be appropriate for providing high quality rainfall estimates over the catchment. The concept proposed in this study for optimal rain gauge network design through combined use of additional and redundant stations together is equally applicable to any other catchment

Tools for optimizing management of a spatially variable organic field

Geostatistical tools were used to estimate spatial relations between wheat yield and soil parameters under organic farming field conditions. Thematic maps of each factor were created as raster images in R software using kriging. The Geographic Resources Analysis Support System (GRASS) calculated the principal component analysis raster images for soil parameters and yield. The correlation between the raster arising from the PC1 of soil and yield parameters showed high linear correlation (r = 0.75) and explained 48.50% of the data variance. The data show that durum wheat yield is strongly affected by soil parameter variability, and thus, the average production can be substantially lower than its potential. Soil water content was the limiting factor to grain yield and not nitrate as in other similar studies. The use of precision agriculture tools helped reduce the level of complexity between the measured parameters by the grouping of several parameters and demonstrating that precision agriculture tools can be applied in small organic fields, reducing costs and increasing wheat yield. Consequently, site-specific applications could be expected to improve the yield without increasing excessively the cost for farmers and enhance environmental and economic benefits.Foundation for Science and Technology (Fundacao para a Ciencia e a Tecnologia), Portugal [SFRH/BD/8303/2002]; Research Center of Spatial and Organizational Dynamics (CIEO); Ministery of Science, Culture and Sport, Israel; Bundesmenisterium fuer Bildung and Forschung (BMBF

Singlet Magnetism in Heavy Fermions

We consider singlet magnetism for the uranium ions in UPt$_3$ and URu$_2$Si$_2$ assuming that time-reversal symmetry is broken for the {\em coherent state of intermediate valence}. The relative weight of the two involved configurations should be different for UPt$_3$ and URu$_2$Si$_2$. If in UPt$_3$ the configuration $5f^1$ on the U-ion prevails in the coherent state below the magnetic transition, the magnetic moment would vanish for the particular choice of the {\em ionic} wave function. In case of URu$_2$Si$_2$, the phase transition is non-magnetic in the first approximation -- the magnetic moment arises from a small admixture of a half-integer spin configuration.Comment: 12 pages, RevTex, no figures; Phys. Rev. Lett., to appea

High-resolution truncated plurigaussian simulations for the characterization of heterogeneous formations

Integrating geological concepts, such as relative positions and proportions of the different lithofacies, is of highest importance in order to render realistic geological patterns. The truncated plurigaussian simulation method provides a way of using both local and conceptual geological information to infer the distributions of the facies and then those of hydraulic parameters. The method (Le Loc'h and Galli 1994) is based on the idea of truncating at least two underlying multi-Gaussian simulations in order to create maps of categorical variable. In this manuscript we show how this technique can be used to assess contaminant migration in highly heterogeneous media. We illustrate its application on the biggest contaminated site of Switzerland. It consists of a contaminant plume located in the lower fresh water Molasse on the western Swiss Plateau. The highly heterogeneous character of this formation calls for efficient stochastic methods in order to characterize transport processes.Comment: 12 pages, 9 figure

Global land surface air temperature dynamics since 1880

The geographical extent, magnitude, and uncertainty of global climate change have been widely discussed and have critical policy implications at both global and local scales. In this study, a new analysis of annual mean global land surface air temperature since 1880 was generated, which has greater coverage and lower uncertainty than previous distributions. The Biased Sentinel Hospitals Areal Disease Estimation (BSHADE) method, used in this study, makes a best linear unbiased estimation (BLUE) when a sample is small and biased to a spatially heterogeneous population. For the period of 1901–2010, the warming trend was found to be 0.109 °C decade−1 with 95% confidence intervals between 0.081 °C and 0.137 °C. Additionally, warming exhibited different spatial patterns in different periods. In the early 20th century (1923–1950), warming occurred mainly in the mid-high latitudes of the Northern Hemisphere, whereas in the most recent decades (1977–2014), warming was more spatially extensive across the global land surface. Compared with other common methods, the difference in results appears in the areas with few stations and in the early years, when stations had sparse coverage and were unevenly distributed. Validation, which was performed using real data that simulated the historic situation, showed a smaller error in the BSHADE estimate than in other methods. This study produced a new database with greater coverage and less uncertainty that will improve the understanding of climate dynamics on the Earth since 1880, especially in isolated areas and early periods, and will benefit the assessment of climate-change-related issues, such as the effects of human activities

Semivariogram calculation optimization for object-oriented image classification

[EN] In this paper we propose and evaluate different mathematical parameters extracted from the experimental semivariogram for land use/land cover classification using high-resolution images and cadastral mapping limits for the definition of the objects of analysis. First, we describe the process of calculating the semivariogram from the gray level values in an image object. In order to optimize the computation time we present two pixel selection techniques that preserve the original shape of the semivariogram. Several parameters are then extracted from the semivariogram. Finally, we use various statistical techniques to select the most discriminant parameters. Last section shows the results obtained using aerial digital images of an agricultural area on the Mediterranean coast of Spain. The study of the practical application presented in this paper facilitates the understanding of the relationship between the behaviour of the experimental semivariogram and the variability of the intensity values in a digital image. In order to follow the development of this work, the reader should know some basis of classification methods and digital image processing techniques.[ES] En este trabajo se proponen y evalúan diferentes parámetros matemáticos extraídos del semivariograma experimental para la clasificación de los usos del suelo mediante imágenes de alta resolución, usando los límites catastrales para la definición de los objetos de análisis. En primer lugar, se describe el proceso de cálculo del semivariograma a partir de los valores de niveles de gris del objeto imagen. Con el fin de optimizar el tiempo de cálculo se presentan dos técnicas de selección de píxeles que conservan la forma original del semivariograma. A continuación se definen varios parámetros del semivariograma. Final- mente, se usan diferentes técnicas estadísticas para la selección de los parámetros más discriminantes. La última sección muestra los resultados obtenidos con las imágenes digitales aéreas de una zona agrícola en la costa mediterránea de España. El estudio de la aplicación práctica que se presenta facilita la comprensión de la relación entre el comportamiento del semivariograma experimental y la variabilidad de los valores de intensidad en una imagen digital. Con el fin de seguir el desarrollo de este trabajo, el lector debe conocer algunos métodos estadísticos de clasificación y algunas técnicas de procesamiento digital de imágenes.The authors appreciate the financial support provided by the Spanish Ministry of Science and Innovation and the FEDER in the framework of the Projects CGL2009-14220-C02-01 and CGL2010-19591/BTE.Balaguer-Beser, A.; Hermosilla, T.; Recio, J.; Ruiz, L. (2011). Semivariogram calculation optimization for object-oriented image classification. Modelling in Science Education and Learning. 4:91-104. https://doi.org/10.4995/msel.2011.3057SWORD911044Curran, P. J. (1988). The semivariogram in remote sensing: An introduction. Remote Sensing of Environment, 24(3), 493-507. doi:10.1016/0034-4257(88)90021-1J.P. Chilés, P. Delfinder, 1999, Geostatistics. Modeling Spatial Uncertainty, John Wiley and Sons, New York.P. Goovaerts, 1997, Geostatistics for Natural Resources Evaluation. Oxford University Press: New York.E.H. Isaaks, R.M. Srivastava, 1989, An introduction to applied geostatistics. Oxford. [10] D.K. McIver, M.A. Friedl, 2002, Using prior probabilities in decision tree classification of remotely sensed data. Remote Sensing of Environment 81, 253-261.M.J. Pyrcz, C.V. Deutsch, 2003, The Whole Story on the Hole Effect. In: Searston, S. (Eds.) Geostatistical Association of Australasia, Newsletter 18.J.R. Quinlan, 1993, C4.5: Programs For Machine Learning. Morgan Kaufmann, Los Altos.L.A. Ruiz, J.A. Recio, T. Hermosilla, 2007, Methods for automatic extraction of regularity patterns and its application to object-oriented image classification. In: International Archives of Photogrammetry, Remote Sensing and Spatial Information Sciences, XXXVI, Munich, Germany, 117-121.M. Story, R. G. Congalton, 1986, Accuracy assessment: a user's perspective, Photogram- metric Engineering and Remote Sensing, 52(3), 397-399

Magnetic resonance in porous media: Recent progress

Recent years have seen significant progress in the NMR study of porous media from natural and industrial sources and of cultural significance such as paintings. This paper provides a brief outline of the recent technical development of NMR in this area. These advances are relevant for broad NMR applications in material characterization.open283

Utilizing image texture to detect land-cover change in Mediterranean coastal wetlands

Land-use/cover change dynamics were investigated in a Mediterranean coastal wetland. Change Vector Analysis (CVA) without and with image texture derived from the co-occurrence matrix and variogram were evaluated for detecting land-use/cover change. Three Landsat Thematic Mapper (TM) scenes recorded on July 1985, 1993 and 2005 were used, minimizing change detection error caused by seasonal differences. Images were geometrically, atmospherically and radiometrically corrected. CVA without and with texture measures were implemented and assessed using reference images generated by object-based supervised classification. These outputs were used for cross-classification to determine the ‘from–to’ change used to compare between techniques. The Landsat TM image bands together with the variogram yielded the most accurate change detection results, with Kappa statistics of 0.7619 and 0.7637 for the 1985–1993 and 1993–2005 image pairs, respectively

Annual accumulation for Greenland updated using ice core data developed during 2000-2006 and analysis of daily coastal meteorological data

An updated accumulation map for Greenland is presented on the basis of 39 new ice core estimates of accumulation, 256 ice sheet estimates from ice cores and snow pits used in previous maps, and reanalysis of time series data from 20 coastal weather stations. The period 1950-2000 is better represented by the data than are earlier periods. Ice-sheetwide accumulation was estimated based on kriging. The average accumulation (95 confidence interval, or ±2 times standard error) over the Greenland ice sheet is 30.0 ± 2.4 g cm -2 a-1, with the average accumulation above 2000-m elevation being essentially the same, 29.9 ± 2.2 g cm-2 a -1. At higher elevations the new accumulation map maintains the main features shown in previous maps. However, there are five coastal areas with obvious differences: southwest, northwest, and eastern regions, where the accumulation values are 20-50 lower than previously estimated, and southeast and northeast regions, where the accumulation values are 20-50 higher than previously estimated. These differences are almost entirely due to new coastal data. The much lower accumulation in the southwest and the much higher accumulation in the southeast indicated by the current map mean that long-term mass balance in both catchments is closer to steady state than previously estimated. However, uncertainty in these areas remains high owing to strong gradients in precipitation from the coast inland. A significant and sustained precipitation measurement program will be needed to resolve this uncertainty. Copyright 2009 by the American Geophysical Union