Comparison of two alluvial aquifers shows the probable role of river sediments on the release of arsenic in the groundwater of district Vehari,Punjab, Pakistan

The study was done to assess the effect of the river Sutlej on arsenic (As) contamination. Sampling was done from the alluvial plain with increasing distance from the river Sutlej in district Vehari and compared with the study done in the proximity of River Sutlej. Sixty (60) groundwater samples mostly from shallow depths were collected and analyzed for As concentrations. Multivariate statistical tools (PCA and CA), saturation index, piper plots and Gibbs diagrams were used to detect evidence about the interrelationship and sources of As and other water quality variables responsible for groundwater contamination. Results revealed that As concentration ranged from below detection limit to 156 µg/L indicating that 50% samples exceeding the WHO guidelines (10 µg/L) and 17% exceeding the Pakistan National Environmental Quality Standards (NEQS) limits (50 µg/L) Sutlej. The piper plot revealed that water chemistry of the study area was Ca–HCO₃^?, Ca–Mg–Cl, type. Correlations between As and HCO₃^? (r²?=?0.433) was positive, while negative correlations were observed between As–Mn²⁺ and As–Fe²⁺ (r²?=???0.102), (r²?=?0.107) respectively. Geochemical signatures of the groundwater in the study area showed that the As could be released by oxidative dissolution to some extent and elevated evaporation in the arid environment of the study area under the stimulus of alkaline water and high pH (range 7.1–8.4). Although the concentrations are exceeding the WHO limit in 50% of the water samples but, are less than the previous study done in Mailsi near River Sutlej. Further, the concentrations decreased as the distance from the River increased which shows the probable role of sediments deposited by the River Sutlej.     

On the optimal risk based design of highway drainage structures

For a proposed highway bridge or culvert, the total cost to the public during its expected service life includes capital investment on the structures, regular operation and maintenance costs, and various flood related costs. The flood related damage costs include items such as replacement and repair costs of the highway bridge or culvert, flood plain property damage costs, users costs from traffic interruptions and detours, and others. As the design discharge increases, the required capital investment increases but the corresponding flood related damage costs decrease. Hydraulic design of a bridge or culvert using a riskbased approach is to choose among the alternatives the one associated with the least total expected cost.In this paper, the risk-based design procedure is applied to pipe culvert design. The effect of the hydrologic uncertainties such as sample size and type of flood distribution model on the optimal culvert design parameters including design return period and total expected cost are examined in this paper.     

A note on the statistics of threshold crossing for a nonlinear wave field

Based on the non-Gaussian joint elevation and slope density function developed by Huang et al. (1984), the expected number of threshold crossing at an arbitrary level for a nonlinear wave field is derived. The distribution of the expected threshold crossing per unit time as a function of the crossing level is skewed with respect to the mean water level. This skewness also causes the mean zero crossing per unit time to deviate from the expected frequency of the wave field.     

The Badia programme:: defining and overcoming constraints on sustainable development

Since 1992 research on the Badia Programme, in north-east Jordan, has begun the process of identifying constraints on development and is suggesting where developmental potential still exists. Still, there are no proven development options to set alongside the traditional pastoralism. Perhaps in the future, service industries will provide the main additional employment opportunities, especially those serving the needs of international trade to and from Iraq and further east.     

Influence of wave-current interactions on fluid force

Influence of wave-current interactions on fluid force on a single cylinder and on two cylinders in tandem is examined. Quantities obtained are spectra of fluid force on elements, total fluid force and its statical moment. Comparisons are made of the cases in which wave-current interactions are considered and ignored. It is shown that interactions affect spectra of element force and statical moment more than do total force spectrum. For two cylinders in tandem, for cylinder spacings, current conditions and frequency range of practical interest, the effect of interactions is slightly reduced.     

Hypothesis testing methods to detect spoofing attacks: a test against the TEXBAT datasets

GPS Solutions - The hazardous effects of spoofing attacks on the global navigation satellite system (GNSS) receiver are well known. Technologies and algorithms to increase the awareness of GNSS...     

Initiation of motion of a free‐standing body to base excitation

This study is concerned with the conditions for the initiation of various modes of response of a free‐standing rigid body, initially at rest, placed on a frictional horizontal base which undergoes earthquake‐like accelerations in both the horizontal and vertical directions. These conditions are derived using equations of motion appropriate for each mode of motion. The analysis shows that an equivalent horizontal base acceleration may be constructed by dividing the time history of horizontal base acceleration by the sum of gravitational acceleration and the time history of vertical base acceleration. The criteria governing each mode of response of a body of given aspect ratio are then presented graphically with the magnitude of the equivalent base acceleration as abscissa and the coefficient of friction between the body and the base as ordinate. The study shows that a body is more stable while the vertical base acceleration is upwards than when it is absent as expected. When the vertical base acceleration is downwards, although the body is very likely to be lifted off the base, it is nevertheless possible to rock, and slide and rock simultaneously provided the value of coefficient of friction is sufficiently high and the downward vertical base acceleration is not too different from gravitational acceleration. Copyright © 2007 John Wiley & Sons, Ltd.     

On estimating the earthquake-induced changes in hydrogeological properties of the Choshuishi Alluvial Fan, Taiwan

The hydrological response of the Choshuishi alluvial fan to the 1999 Chi-Chi earthquake shows that the earthquake did impact the aquifer. The possible earthquake-induced changes in hydrogeological properties were investigated in this study. First, contour maps of the hydrologic anomaly, seismic factors, and vertical ground-surface displacement were compared qualitatively. Bulls eye patterns were found on the contour maps of hydraulic conductivity, coseismic groundwater-level change and vertical ground-surface displacement but did not occur with other seismic factors. The more permeable zones of the aquifer were found to coincide with the locations of greater vertical ground-surface displacement and coseismic groundwater-level change in the 1999 Chi-Chi earthquake. This indicates that the change of the hydrogeologic properties of Choshuishi alluvial fan due to the 1999 Chi-Chi earthquake may have mainly occurred in the highly permeable zones. Fractal, cross semivariogram and cross correlogram analyses were performed to quantitatively measure the persistency, variability and similarity, respectively, of spatial hydrologic response, seismic factors and hydraulic conductivity. The groundwater-level change, earthquake intensity, and vertical ground-surface displacement were found to show antipersistent tendencies while other factors showed the opposite. Higher correlations were found between hydraulic conductivity and groundwater-level change in aquifers 2–1 and 2–2, and between hydraulic conductivity and vertical ground-surface displacement in aquifer 3. Changes in porosities and hydraulic conductivity were evaluated in the main aquifers of the Choshuishi alluvial fan based on the data of hydrologic anomaly and the vertical ground-surface displacement. While both approaches show that the 1999 Chi-Chi earthquake has impacted the Choshuishi alluvial fan by reducing its porosity and hydraulic conductivity, these changes were not significant relative to natural variation in hydraulic conductivity.This revised version was published in May 2005 with correction to the rubric.     

丁村旧石器遗址群的黄土地层研究

通过测量黄土的磁化率 ,并结合传统的黄土地层学研究方法 ,对丁村旧石器文化遗址群中两个典型的剖面 ,即代表丁村旧石器中期文化的 10 0地点和代表丁村旧石器早期文化的 79:0 2地点文化层上部的黄土 -古土壤序列进行划分 ,并将其结果与位于丁村附近黄土塬上的敬村黄土剖面和典型洛川黄土剖面的地层和磁化率曲线进行对比。结果表明 ,丁村 10 0地点地层上部黄土 -古土壤序列为S0 ,L1,S1;而 79:0 2地点上部的黄土 -古土壤序列则包括S0 ,L1,S1,L2 ,S2 。因此 ,丁村 10 0地点文化层的年代大于S1的形成年代即 0 13MaB .P .,79:0 2地点文化层的年代大于S2 的轨道调谐年龄 ,即 0 2 4 7MaB .P