Adequacy of satellite derived rainfall data for stream flow modeling

Floods are the most common and widespread climate-related hazard on Earth. Flood forecasting can reduce the death toll associated with floods. Satellites offer effective and economical means for calculating areal rainfall estimates in sparsely gauged regions. However, satellite-based rainfall estimates have had limited use in flood forecasting and hydrologic stream flow modeling because the rainfall estimates were considered to be unreliable. In this study we present the calibration and validation results from a spatially distributed hydrologic model driven by daily satellite-based estimates of rainfall for sub-basins of the Nile and Mekong Rivers. The results demonstrate the usefulness of remotely sensed precipitation data for hydrologic modeling when the hydrologic model is calibrated with such data. However, the remotely sensed rainfall estimates cannot be used confidently with hydrologic models that are calibrated with rain gauge measured rainfall, unless the model is recalibrated. G. Artan, J. L. Smith and K. Asante – work performed under USGS contract 03CRCN0001.     

A comparison of two numerical models for the prediction of vibrations from underground railway traffic

Two prediction models for calculating vibration from underground railways are developed: the pipe-in-pipe model and the coupled periodic finite element–boundary element (FE–BE) model.The pipe-in-pipe model is a semi-analytical three-dimensional model that accounts for the dynamic interaction between the track, the tunnel and the soil. The continuum theory of elasticity in cylindrical coordinates is used to model two concentric pipes: an inner pipe to represent the tunnel wall and an outer pipe to represent the surrounding soil. The tunnel and soil are coupled accounting for equilibrium of stresses and compatibility of displacements at the tunnel–soil interface. This method assumes that the tunnel is invariant in the longitudinal direction and the problem is formulated in the frequency–wavenumber domain using a Fourier transformation. A track, formulated as an Euler–Bernoulli beam, is then coupled to this model. Results are transformed to the space domain using the inverse Fourier transform.The coupled periodic FE–BE model is based on a subdomain formulation, where a boundary element method is used for the soil and a finite element method for the tunnel. The Craig–Bampton substructuring technique is used to efficiently incorporate the track in the tunnel. The periodicity of the tunnel is exploited using the Floquet transformation to formulate the track–tunnel–soil interaction problem in the frequency–wavenumber domain and to compute the wave field radiated into the soil.An invariant concrete tunnel, embedded in a homogeneous full space is analyzed using both approaches. The pipe-in-pipe model offers an exact solution to this problem, which is used to validate the coupled periodic FE–BE model. The free field response due to a harmonic load in the tunnel is predicted and results obtained with both models are compared. The advantages and limitations of both models are highlighted. The coupled periodic FE–BE model has a greater potential as it can account for the complex periodic geometry of the tunnel and the layering in a soil medium. The effect of coupling a floating slab to the tunnel–soil system is also studied with both models by calculating the insertion gain.     

Shaking‐table tests of a full‐scale single‐story masonry veneer wood‐frame structure

This paper presents the findings of shaking‐table experiments conducted to examine the seismic performance of a full‐scale, one‐story, wood‐framed structure with masonry veneer. The structure was designed and constructed in accordance with current U.S. code provisions. The veneer was attached to the wood backing with two kinds of metal anchors, corrugated ties fastened with 8d nails and rigid ties fastened with #8 screws. The tests have shown that the use of nails to fasten veneer anchors to the wood studs is highly unreliable due to the high variation of the nail extraction capacity, which can be influenced by the moisture content of the wood. Other than this, both the wood frame and the masonry veneer performed well under severe ground motions far exceeding a design level earthquake for Seismic Design Category D. Good performance was observed for the rigid veneer ties, which were attached to the wood studs with screws. The results have shown that the veneer walls parallel to the direction of shaking helped to restrain the motion of the wood structure and therefore should not be simply treated as added mass. The detailing of wood roof diaphragms requires special attention in consideration of the out‐of‐plane inertia force of the veneer that can be transmitted through the top plate of the wood‐stud wall to the rim joist. Copyright © 2010 John Wiley & Sons, Ltd.     

Gypsum and dolomite biomineralization in endoevaporitic microbial niche,EMISAL, Fayium,Egypt

Biogenic gypsum in the form of microbialite and potential domal stromatolite as well as endoevaporitic dolomite are deposited in a perennial saline basin characterized by microbial bloom. Deposition environment, mode of occurrence, and microscopic investigation including SEM of these precipitates are discussed in conjunction with XRD, XRF, and FTIR data. Combined effects of salinity gradient and the wind action on the maturity of gypsum outcrop are evident. A characteristic multi-color vertical gypsum profile reflects steep gradient of oxi-anoxic microenvironments and encodes diverse seasonal microbial communities. Direct impact of microbial signature in gypsum crystal habit is conspicuous. Endoevaporitic authigenic dolomite is recorded in specific horizons in interstices of selenite layers.     

Salinization and Deterioration of Groundwater Quality by Nitrate and Fluoride in the Chittur Block,Palakkad, Kerala

Chittur block represents a mid-land region of Palakkad district, Kerala and the block differs from the rest of the blocks in its climate and availability of groundwater. About 75% of the people depend on agriculture for their livelihood. Results showed that groundwater salinity levels (up to 1,963 mg/L TDS),fluoride (up to 6.3 mg/L) and nitrate (up to 141 mg/L) contents have increased significantly in tandem with the increase in groundwater abstraction. Before human intervention the chemical weathering of gneisses and granites was the main process impinging on the chemical signature of groundwater. The initial chemical equilibrium conditions change with increasing groundwater withdrawal rates and fertilizer input, in a milieu of lower natural groundwater recharge. The appearance of higher levels of bicarbonate, linked to denitrification processes, and the decrease in calcium, due to calcite precipitation, can lead to increased content of sodium and fluoride in groundwater. In this scenario the use of groundwater resources for human consumption and agriculture represents a public health risk if water management actions do not change the trend in water use in the near future. The potential loss of fertile soil by groundwater salinization must also be considered when planning sustainable policies in a region with over dependence on groundwater resources.     

CDFSIM: Efficient Stochastic Simulation Through Decomposition of Cumulative Distribution Functions of Transformed Spatial Patterns

Simulation of categorical and continuous variables is performed using a new pattern-based simulation method founded upon coding spatial patterns in one dimension. The method consists of, first, using a spatial template to extract information in the form of patterns from a training image. Patterns are grouped into a pattern database and, then, mapped to one dimension. Cumulative distribution functions of the one-dimensional patterns are built. Patterns are then classified by decomposing the cumulative distribution functions, and calculating class or cluster prototypes. During the simulation process, a conditioning data event is compared to the class prototype, and a pattern is randomly drawn from the best matched class. Several examples are presented so as to assess the performance of the proposed method, including conditional and unconditional simulations of categorical and continuous data sets. Results show that the proposed method is efficient and very well performing in both two and three dimensions. Comparison of the proposed method to the filtersim algorithm suggests that it is better at reproducing the multi-point configurations and main characteristics of the reference images, while less sensitive to the number of classes and spatial templates used in the simulations.     

Integrated geophysical study to explore the groundwater in the tectonic plain between Wadi El Mahash and Wadi Um Markhah,Southwest Sinai,Egypt

South Sinai Governorate acts as one of the most vital regions in Egypt for its location and natural resources. This governorate has a special economic importance to increase the national income due to its tourism expansion and petroleum. The fresh water is transferred from Cairo through pipelines to cover the demands of local inhabitants in the north Sinai governorate and the capital city of south Sinai governorate. The groundwater exploration and exploitation in this area have a great importance to cover the need of water for the different activities (tourism, petroleum, and agriculture) and to achieve a maximum development in this region. Therefore, the present study deals with using the different geophysical exploration techniques (magnetic, geoelectrical resistivity and shallow refraction seismic) to detect the groundwater aquifer or aquifers in the area between latitudes 27°52′ and 28°05′?N and longitudes 33°55′ and 34°05′?E. in southwestern Sinai—Egypt. The main results of these tools are the maximum depth to the basement surface 180 m and structure elements which affected on this area are represented by a number of normal faults have a trends (NNW–SSE and ENE–WSW) making two grabens isolated by one horst. Tariff Sandstone bed recorded as water-bearing formation and the basement ridge gates in the gulf direction are not capable to pass the ground water from the study area to the Gulf of Suez. Finally, the best locations for drilling groundwater wells were selected from the decision map which generated by using the GIS technique.     

Magnetic gradient techniques on digitized aeromagnetic data of Ibadan area, south-western Nigeria

Locations and depths to magnetic contacts were estimated from the total intensity magnetic field using the Horizontal Gradient Magnitude (HGM), Analytic Signal Amplitude (ASA) and Local Wavenumber (LWN) methods. Aeromagnetic data from the Ibadan area, in south-western Nigeria, were analyzed to estimate depths to magnetic sources as well as source locations. The minimum/maximum depth limits of the HGM and LWN are relatively close and comparable, while shallow source depths limits are greater than expected in the ASA method when compared with the HGM and LWN functions.     

Rapid assessment for seismic vulnerability of low and medium rise infilled RC frame buildings

An indexing method for rapid evaluation of the seismic vulnerability of infi lled RC frame buildings in Jordan is proposed. The method aims at identifying low and medium rise residential buildings as safe or in need of further detailed evaluation. Following a rapid visual screening, the building is assigned a Basic Capacity Index(BCI); fi ve performance modifi ers are identifi ed and multiplied by the BCI to arrive at the Capacity Index(CI) of the building. A Capacity Index lower than a limit CI value indicates that the screened building could experience moderate earthquake damage whereas a higher value implies that minor damage, if any, would take place. To establish the basic evaluation parameters; forty RC frame buildings were selected, designed and analyzed using static nonlinear analysis and incorporating the effect of infi ll walls. Effects of seismicity, local site conditions, horizontal irregularities(setbacks and re-entrant corners), vertical irregularities(soft story at ground fl oor level) and overhangs on the seismic performance of local buildings were examined. Assessment forms were designed and used to evaluate and rank 112 sample buildings. About 40% of the surveyed buildings were found to be in need of detailed evaluation to better defi ne their seismic vulnerabilities.     

Incorporation of silica into the goethite structure: a microscopic and spectroscopic study

Quartz and iron (hydr)oxide are reactive surface phases that are often associated with one another in soils and sediments. Despite the several studies on the coating of quartz with iron oxides, the reactivity of dissolved species (Si) leached from quartz with iron (hydr)oxides has received limited attention. In this study, goethite synthesized on quartz substrates were characterized using field emission scanning electron microscopy, X-ray diffraction (XRD), transmission electron microscopy, and Fourier-transform infrared (FT-IR) spectroscopy. The SEM characterization revealed that bundles of thin parallel aligned goethite rods were formed at pH?>?10, while large pseudohexagonal crystals of twinned goethite needles were synthesized at pH?≤?10 after dehydration and hydration in the alkaline media. TEM analysis showed expanded and distorted lattice spacing of the crystal structure of iron (hydr)oxide due to silica incorporation. The characterization showed that silica increased the crystallite size of the goethite and transformed its acicular texture to a larger, twinned needle structure. FT-IR and XRD analyses revealed band shifts in crystal bonds as well as new bond formations, which indicate the presence of changes in the chemical environment of Fe–O and Si–O bonds. Thus, the presence of sorbed silicates modifies the crystal and lattice structure of goethite.