Hisslers observed during daytime in a low latitude ground station

The observation of hisslers during daytime at low latitude station Jammu, India, is reported. The hissler elements are quasi-periodic falling tones observed during the period of hiss activity and appear in minutelong sequences with average spacing between individual elements of the order of 0.15 s. Hissler elements exhibit almost no dispersion and no complex internal structure in slope and intensity, and successive hissler elements do not overlap in time. It seems that the reported hisslers might have propagated in prolongitudinal mode.     

Application of scattered and emitted seismic waves for improving the efficiency of exploration and development of hydrocarbon fields

The success of drilling oil and gas wells is largely determined by a high hydrocarbon content and reservoir permeability at the point of penetration. Microseismic emission and scattered reflection waves are used for the reliable study of these parameters. The Seismic Location of Emission Centers and Side-View Seismic Location technologies have been developed for the observation, selection, and positioning of waves in a geological environment, which significantly extend the range of problems that are solved during seismic exploration of hydrocarbon deposits. Examples of application of these technologies in the exploration and development of hydrocarbon deposits are described.     

Integrated Geophysical and Morphotectonic Survey of the Impact of Ghab Extensional Tectonics on the Qastoon Dam, Northwestern Syria

The latent impact of the Ghab pull-apart basin tectonic setting and associated deformations resulting from active tectonics on the Qastoon Dam in northern Ghab in Syria have been evaluated. This was achieved by applying an appropriate methodology essentially based on morphotectonic mapping and integrated geophysical surveys consisting of electrical resistivity profiling, vertical electrical sounding and self-potential. The integrated interpretation of the acquired morphotectonic and geophysical data allowed the detection of subsurface deformed structures, either underlying the Qastoon Dam lake floor, or close to it. It is believed that these active structures were developed through the ongoing active tectonic processes occurring in the Northern Arabian plate. The tectonic survey proved that the N66.5°E striking Wadi Al Mashta fault, extending beneath the Qastoon Dam lake floor, is one of the youngest active structures, and that the intersection of the fault with the Qastoon Dam prism is a water-leaking point. Dam supporting measures, continuous monitoring and precautious disaster management are therefore recommended to be urgently adopted and practiced.     

The role of hydrologic information in reservoir operation – Learning from historical releases

Closing the gap between theoretical reservoir operation and the real-world implementation remains a challenge in contemporary reservoir operations. Past research has focused on optimization algorithms and establishing optimal policies for reservoir operations. In this study, we attempt to understand operators’ release decisions by investigating historical release data from 79 reservoirs in California and the Great Plains, using a data-mining approach. The 79 reservoirs are classified by hydrological regions, intra-annual seasons, average annual precipitation (climate), ratio of maximum reservoir capacity to average annual inflow (size ratio), hydrologic uncertainty associated with inflows, and reservoirs’ main usage. We use information theory – specifically, mutual information – to measure the quality of inference between a set of classic indicators and observed releases at the monthly and weekly timescales. Several general trends are found to explain which sources of hydrologic information dictate reservoir release decisions under different conditions. Current inflow is the most important indicator during wet seasons, while previous releases are more relevant during dry seasons and in weekly data (as compared with monthly data). Inflow forecasting is the least important indicator in release decision making, but its importance increases linearly with hydrologic uncertainty and decreases logarithmically with reservoir size. No single hydrologic indicator is dominant across all reservoirs in either of the two regions.     

The water balance of the Dead Sea: an integrated approach

The Dead Sea is the lowest spot on Earth. It is a closed saline lake located in the middle of the Jordan Rift Valley between Lake Tiberias and the Red Sea. Its major tributaries are the Jordan River itself and the Dead Sea side wadis. The Dead Sea has a unique ecosystem and its water has curative, industrial and recreational significance. The level of the Dead Sea has been continuously falling since the early 1930s at an average rate of 0·7 m per year. The water level, as of February 1998, is about 410·9 m below mean sea level. In this paper, a water balance model is developed for the Dead Sea by considering different hydrological components of this water balance, including precipitation, runoff, evaporation and groundwater flow. This model is calibrated based on historical levels of the Dead Sea. Different scenarios are investigated, including the proposed Dead Sea–Red Sea Canal. This project is supposed to halt the shrinking of the Dead Sea and restore it to pre‐1950 levels in the next century. Copyright © 2000 John Wiley & Sons, Ltd.     

Interactions of uranium with bacteria and kaolinite clay

We assessed the accumulation of uranium (VI) by a bacterium, Bacillus subtilis, suspended in a slurry of kaolinite clay, to elucidate the role of microbes on the mobility of U(VI). Various mixtures of bacteria and the koalinite were exposed to solutions of 8 × 10^− 6 M- and 4 × 10^− 4 M-U(VI) in 0.01 M NaCl at pH 4.7. After 48 h, the mixtures were separated from the solutions by centrifugation, and treated with a 1 M CH₃COOK for 24 h to determine the associations of U within the mixture. The mixture exposed to 4 × 10^− 4 M U was analyzed by transmission electron microscope (TEM) equipped with EDS. The accumulation of U by the mixture increased with an increase in the amount of B. subtilis cells present at both U concentrations. Treatment of kaolinite with CH₃COOK, removed approximately 80% of the associated uranium. However, in the presence of B. subtilis the amount of U removed was much less. TEM–EDS analysis confirmed that most of the U removed from solution was associated with B. subtilis. XANES analysis of the oxidation state of uranium associated with B. subtilis, kaolinite, and with the mixture containing both revealed that it was present as U(VI). These results suggest that the bacteria have a higher affinity for U than the kaolinite clay mineral under the experimental conditions tested, and that they can immobilize significant amount of uranium.     

Architects and planners approaches to urban form and design in the Toronto region: A comparative analysis

This study compares architectural and planning approaches to urban form and design within a North American context. It presents a critical assessment of the results of semi-structured, in-depth interviews with a group of highly experienced architects, landscape architects, and planners from the Greater Toronto Region. Dialogues with practitioners revealed a growing intellectual divide in regard to understanding urban form and design issues. Planners portrayed the urban form as a product of social and economic forces or a backdrop for civic institutions, private development initiatives, and public action. Architects and landscape architects, on the other hand, emphasized the importance of built configurations and spatial relations in shaping economic, social, and cultural patterns. With such a polarized perspective of urban development processes, each group of practitioners proposed different and somewhat contradictory visions for the future of North American built forms. This study develops an understanding of theoretical and pragmatic concerns within design professions (architecture/landscape architecture) and social science professions (planning at large) that hamper the development of integrative urban design visions. It extends an interdisciplinary understanding of built environments and the forces that shape them and paves the way for more in-depth studies aimed at creating more integrative urban design theories and development strategies.     

The effect of climate and land use change on flow duration in the Maryland Piedmont region

This paper describes the use of a continuous streamflow model to examine the effects of climate and land use change on flow duration in six urbanizing watersheds in the Maryland Piedmont region. The hydrologic model is coupled with an optimization routine to achieve an agreement between observed and simulated streamflow. Future predictions are made for three scenarios: future climate change, land use change, and jointly varying climate and land use. Future climate is modelled using precipitation and temperature predictions for the Canadian Climate Centre (CCC) and Hadley climate models. Results show that a significant increase in temperature under the CCC climate predictions produces a decreasing trend in low flows. A significant increasing trend in precipitation under the Hadley climate predictions produces an increasing trend in peak flows. Land use change by itself, as simulated by an additional 10% increase in imperviousness (from 20·5 to 30·5%), produces no significant changes in the simulated flow durations. However, coupling the effects of land use change with climate change leads to more significant decreasing trends in low flows under the CCC climate predictions and more significant increasing trends in peak flows under Hadley climate predictions than when climate change alone is employed. These findings indicate that combined land use and climate change can result in more significant hydrologic change than either driver acting alone. Copyright © 2008 John Wiley & Sons, Ltd.     

Application of probabilistic-based frequency ratio model in groundwater potential mapping using remote sensing data and GIS

The main goal of this study is to investigate the application of the probabilistic-based frequency ratio (FR) model in groundwater potential mapping at Langat basin in Malaysia using geographical information system. So far, the approach of probabilistic frequency ratio model has not yet been used to delineate groundwater potential in Malaysia. Moreover, this study includes the analysis of the spatial relationships between groundwater yield and various hydrological conditioning factors such as elevation, slope, curvature, river, lineament, geology, soil, and land use for this region. Eight groundwater-related factors were collected and extracted from topographic data, geological data, satellite imagery, and published maps. About 68 groundwater data with high potential yield values of ≥11 m³/h were randomly selected using statistical software of SPSS. Then, the groundwater data were randomly split into a training dataset 70 % (48 borehole data) for training the model and the remaining 30 % (20 borehole data) was used for validation purpose. Finally, the frequency ratio coefficients of the hydrological factors were used to generate the groundwater potential map. The validation dataset which was not used during the FR modeling process was used to validate the groundwater potential map using the prediction rate method. The validation results showed that the area under the curve for frequency model is 84.78 %. As far as the performance of the FR approach is concerned, the results appeared to be quite satisfactory, i.e., the zones determined on the map being zones of relative groundwater potential. This information could be used by government agencies as well as private sectors as a guide for groundwater exploration and assessment in Malaysia.