Wavelet bicoherence analysis of wind–wave interaction

A new technique in the analysis of wind–wave interaction, wavelet bicoherence, will be applied in this article. Wavelet bicohence has the ability to detect phase coupling and nonlinear interactions of the quadratic order with time resolution. It is used in this study to analyze wind–wave interaction during wave growth in a Mistral event. A selected record of simultaneously measured wind and wave data during Mistral is divided into five segments and the computations of the wavelet bicoherence are conducted for the whole record and for all divided segments. The results show that the phase coupling occurs between wind speed and wave height over a certain range of frequencies and that the range is different from one segment to another due to the non-stationary feature of the time series.     

Investigation of a relation between radiogenic heat production and kinetic surface temperature from multispectral ASTER-TIR data: a case study on Elmissikat-Eleridiya granites,Central Eastern Desert,Egypt

In this paper, an attempt was tried to study the relation between radiogenic heat production rate (RHPR) that derived from gamma-ray spectrometric data and the kinetic surface temperature KST, which was calculated from the thermal emission and reflection radiometer-thermal infrared (ASTER-TIR) imagery applied on Elmissikat-Eleridiya district. This area is considered one of the most important uranium localities in the Central Eastern Desert of Egypt. The gamma-ray spectrometric data including both airborne data and in situ measurements concurrent with the collection of 20 rock samples were used to determine the rock density. The ground gamma-ray spectrometry has been conducted using GS-256 spectrometer at the same locations of rock samples. The gamma-ray spectrometric data (airborne and ground) beside rock density data were used for calculating RHPR. Alongside, pairs of daytime and nighttime ASTER-TIR images were collected and surface kinetic temperature for both day (daytime kinetic surface temperature (DKST)) and night (nighttime kinetic surface temperature (NKST)) were derived by using reference channel emissivity technique. The study showed a relative higher RHPR within syenogranite (4.2 up to 6 μW/m³) than other rock units. Besides, the KST of syenogranite ranged from 33 to 48 °C in daytime and between 7 and 17 °C at night. Comparing all results, no clear relation between RHPR and KST is evident. This is due to the very weak RHPR that is not sufficient to affect the surface heat temperature, which can be remotely sensed by ASTER satellite TIR data. This factor in addition to other factors such as: structural elements, topography, geographic locations, shading and scattering, rock moisture and density, can strongly affect the surface temperature. In conclusion, these results could be improved in areas of very high radioelement concentrations, especially ²³⁵U and through the use of the enhanced spatial resolution of future satellite TIR imaging instruments.     

Groundwater budget for the upper and middle parts of the River Gash Basin, eastern Sudan

The River Gash Basin is filled by the Quaternary alluvial deposits, unconformably overlying the basement rocks. The alluvial deposits are composed mainly of unconsolidated layers of gravel, sand, silt, and clays. The aquifer is unconfined and is laterally bounded by the impermeable Neogene clays. The methods used in this study include the carry out of pumping tests and the analysis of well inventory data in addition to the river discharge rates and other meteorological data. The average annual discharge of the River Gash is estimated to be 1,056?×?10⁶ m³ at El Gera gage station (upstream) and 587?×?10⁶ m³ at Salam-Alikum gage station (downstream). The annual loss mounts up to 40% of the total discharge. The water loss is attributed to infiltration and evapotranspiration. The present study proofs that the hydraulic conductivity ranges from 36 to 105 m/day, whereas the transmissivity ranges from 328 to 1,677 m²/day. The monitoring of groundwater level measurements indicates that the water table rises during the rainy season by 9 m in the upstream and 6 m in the midstream areas. The storage capacity of the upper and middle parts of the River Gash Basin is calculated as 502?×?10⁶ m³. The groundwater input reach 386.11?×?10⁶ m³/year, while the groundwater output is calculated as 365.98?×?10⁶ m³/year. The estimated difference between the input and output water quantities in the upper and middle parts of the River Gash Basin demonstrates a positive groundwater budget by about 20?×?10⁶ m³/year     

The application of remote sensing and structural analysis in groundwater exploration in basement terrains, Darfur region, Western Sudan

Darfur region is one of the most vulnerable areas in Sudan that suffer from shortage in water supply. The objective of the current study is to utilize remote sensing techniques combined with the structural analysis to recognize the most potential fracture zones for groundwater occurrences in the hard rock terrains of Darfur region. The old ductile deformation features in Darfur region delineated from Landsat imageries are used for the structural analysis to determine and classify the fractures in the hard rock terrains of the region. Based on the structural analysis conducted in this study, Darfur region was divided into two domains—the western domain of the pre-Pan-African age that is affected by the two deformational phases (D1 and D2), and the eastern domain represented by the basement related to the Pan-African orogeny. The most potential fractures in the western domain are in the NW–SE and NE–SW trends that classified as extensional and release open fractures for the deformations D1 and D2. In the eastern domain, the main potential fractures for groundwater occurrence are in E–W and N–S directions that are classified as extensional and release open fractures of the deformation D3. From the results of the structural analysis, the main potential fracture systems in Darfur region trend are NW–SE, NE–SW, and E–W directions. The intersections of these fracture systems are the most promising targets for drilling, with consideration of the topography, the rates of recharge, and the underlying geology. The geophysical data and boreholes information in Zalingei and north of El Geneina areas in West Darfur confirm the results obtained from remote sensing data and structural analysis, in which the NW–SE, NE–SW, and E–W fractures trends are the most potential fractures in Darfur region.     

On a magneto-poro-thermoelastic medium under the influence of the Seebeck effect

In this study, the poro-thermoelastic problem with the effect of the magnetic field and Seebeck parameter was investigated. Modified Ohm's law that includes effects of the temperature gradient (Seebeck effect) and charge density, as well as generalized Fourier's law with current density, is introduced. We applied normal mode analysis to solve the resulting nondimensional coupled equations and then investigated the effects that nondimensional displacements, temperature distribution, excess pore water pressure, stresses, and induced magnetic field exerted on the poro-thermoelastic half-space medium. Numerical analyses are given graphically on the square (2D) and cubic (3D) domains to illustrate the effects of the porosity parameter, magnetic field, and Seebeck parameter on the physical variables.     

Groundwater balance in the Khor Arbaat basin, Red Sea State, eastern Sudan

The Khor Arbaat basin is the main source of potable water supply for the more than 750,000 inhabitants of Port Sudan, eastern Sudan. The variation in hydraulic conductivity and storage capacity is due to the heterogeneity of the sediments, which range from clay and silt to gravely sand and boulders. The water table rises during the summer and winter rainy seasons; it reaches its lowest level in the dry season. The storage capacity of the Khor Arbaat aquifer is estimated to be 21.75?×?10⁶ m³. The annual recharge through the infiltration of flood water is about 1.93?×?10⁶ m³. The groundwater recharge, calculated as underground inflow at the ‘upper gate’, is 1.33?×?10⁵ m³/year. The total annual groundwater recharge is 2.06?×?10⁶ m³. The annual discharge through underground outflow at the ‘lower gate’ (through which groundwater flows onto the coastal plain) is 3.29?×?10⁵ m³/year. Groundwater discharge due to pumping from Khor Arbaat basin is 4.38?×?10⁶ m³/year on average. The total annual groundwater discharge is about 4.7?×?10⁶ m³. A deficit of 2.6?×?10⁶ m³/year is calculated. Although the total annual discharge is twice the estimated annual recharge, additional groundwater flow from the fractured basement probably balances the annual groundwater budget since no decline is observed in the piezometric levels.     

The geometric configuration of the newly discovered Abu Deleig sedimentary sub-basin,Central Sudan,using remote sensing,structural analysis,and geophysical survey

Abu Deleig area is a transitional area between the Butana basement terrain to the east; and the Khartoum and Shendi sedimentary basins to the west and northwest directions, respectively. The existence of sedimentary basins within this region of Sudan was previously unknown. Landsat images have been used for delineation of lineaments and drainage system, followed by a structural analysis and geophysical investigations including gravity and resistivity methods. The interpretation of the remotely sensed data revealed that the drainage pattern is structurally controlled. The structural analysis defined the trends of the shear and tensional fractures. The structural analysis revealed that Wadi Al Hawad is the southern continuation of the Keraf Shear Zone. The related minor fractures in a NE–SW direction exhibit normal faults governing the geometry of the Abu Deleig sub-basin. The geophysical investigations confirmed the findings of structural analysis and portrayed the subsurface geometry of the sub-basin. The newly discovered sub-basin has a prism-like shape with its apex occurring at Abu Deleig town and extends to 40 km in NW direction. The depth to the basement increases from 20 m at Abu Deleig in step form to more than 300 m, where it is linked with the Shendi Basin in the northwestern part. The results of this study, however, did not confirm any link of Abu Deleig sub-basin with Atbara Basin to the NE or Khartoum Basin to the west as have been previously suggested.     

Histopathological alterations in the liver and intestine of Nile tilapia Oreochromis niloticus exposed to long-term sublethal concentrations of cadmium chloride

Fingerlings of Nile tilapia Oreochromis niloticus were exposed to 1.68, 3.36, and 5.04 mg/L cadmium(as CdCl2), which represent 10%, 20%, and 30% of their previously determined 96-h LC5 0. After exposure for 20 days, sections of the liver and intestine of treated fish were examined histologically. Histopathological changes varied from slight to severe structural modification, depending on the exposure concentration. The hepatic tissues of fish exposed to 10% LC 50 showed markedly increased vacuolation of the hepatocytes and coarse granulation of their cytoplasm. Abundant erythrocytic infiltration among the hepatocytes was observed in fish exposed to 20% LC5 0. In the intestinal tissues of fish exposed to all doses, goblet cells proliferated and were greatly increased in size, the longitudinal muscularis mucosa was disturbed and, in the crypts of the sub-mucosal layer, apoptosis increased, indicated by large numbers of degenerated nuclei. Large numbers of inflammatory cells and dilated blood vessels were observed in the intestine of the group treated with 30% LC5 0.     

Long-term variability in mesopause region temperatures over Fort Collins, Colorado (41°N, 105°W) based on lidar observations from 1990 through 2007

During 1990–2007, there were 894 lidar observations of nocturnal mesopause region temperatures over Fort Collins, Colorado. In an earlier analysis with data to April 1997, an unexpected episodic warming, peaking in 1993 with a maximum value over 10 K, was reported and attributed to the Mount Pinatubo eruption in June 1991. With all data, long-term temperature trends from a 7-parameter linear regression analysis including solar cycle effect and long-term trends leads to a cooling of as much as 6.8 K/decade at 100 km, consistent with some reported observations but larger than model predictions. Including the observed episodic warming response in an 11-parameter nonlinear regression analysis reduces the maximum long-term cooling trends to 1.5 K/decade at 91 km, with magnitude and altitude dependences consistent with the prediction of two models, Spectral Mesosphere/Lower Thermosphere Model (SMLTM) and Hamburg Model of the Neutral and Ionized Atmosphere (HAMMONIA). In addition, the mid-latitude middle-atmospheric response to solar flux variability in Thermosphere–Ionosphere-Energetics and Dynamics (TIMED)/Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) temperatures is presented.     

Evaluation of rain gauge network in arid regions using geostatistical approach: case study in northern Oman

A geostatistical approach based on ordinary kriging is presented for the evaluation and the augmentation of an existing rain gauge network. The evaluation is based on estimating the percentage of the area that achieves a targeted level of acceptable accuracy. The variances of kriging estimation erros at un-gauged locations were assumed to be normally distributed. Kriging estimation erros with a probability that equals to or exceeds a given threshold value of acceptance probability were assumed to have satisfactory accuracies. The percentage of the area that achieved the targeted probability of acceptance is delineated and used to judge the overall performance of the existing rain gauge network. A study area in northern Oman located in Sohar governorate is selected as the pilot case. The area has 34 rain gauges and it is characterized by a terrain surface that varies from coastal plain to mountains. For a threshold value of 0.85, and 0.90 of acceptance probability, the existing network achieved area of acceptable probability of 88.71 and 77.72 %, respectively. For a success criterion of 80 %, the existing rain gauge network indicated acceptable performance for acceptance probability threshold of 0.85 and inadequate performance is noticed in the case of probability threshold of 0.90, which necessitated further network augmentation. A sequential algorithm for ranking and prioritization of the existing rain gauges is used to classify the existing rain gauges into base and non-base rain gauges. The base rain gauge network for mean annual rainfall comprised about 29 of the existing rain gauges. The identified non-base rain gauges were sequentially relocated to achieve higher levels of percentage of area with acceptable accuracy. The percentage of area with acceptable accuracy increased from 88.71 % for the original rain gauge network to about 94.51 % for the augmented network by adding four rain gages at probability acceptance threshold of 0.85. It also increased from 77.72 % for the existing network to 90.50 % for the augmented rain gauge network at acceptance threshold of 0.9.