Hillslope run‐off thresholds with shrink–swell clay soils

Irrigation experiments on 12 instrumented field plots were used to assess the impact of dynamic soil crack networks on infiltration and run‐off. During applications of intensity similar to a heavy rainstorm, water was seen being preferentially delivered within the soil profile. However, run‐off was not observed until soil water content of the profile reached field capacity, and the apertures of surface‐connected cracks had closed >60%. Electrical resistivity measurements suggested that subsurface cracks persisted and enhanced lateral transport, even in wet conditions. Likewise, single‐ring infiltration measurements taken before and after irrigation indicated that infiltration remained an important component of the water budget at high soil water content values, despite apparent surface sealing. Overall, although the wetting and sealing of the soil profile showed considerable complexity, an emergent property at the hillslope scale was observed: all of the plots demonstrated a strikingly similar threshold run‐off response to the cumulative precipitation amount. Copyright © 2014 John Wiley & Sons, Ltd.     

Hydrodynamic behavior of Kangan gas-capped deep confined aquifer in Iran

The Kangan aquifer (KA) is located beneath the Kangan gas reservoir (KGR), 2,885 m below the ground surface. The gas reservoir formations are classified into nine non-gas reservoir units and eight gas reservoir units based on the porosity, water and gas saturation, lithology, and gas production potential using the logs of 36 production wells. The gas reservoir units are composed of limestone and dolomite, whereas the non-gas reservoir units consist of compacted limestone and dolomite, gypsum and shale. The lithology of KA is the same as KGR with a total dissolved solid of 333,000 mg/l. The source of aquifer water is evaporated seawater. The static pressure on the Gas–Water Contact (GWC) was 244 atm before gas production, but it has continuously decreased during 15 years of gas production, resulting in a 50 m uprising of the GWC and the expansion of KA water and intergranular water inside the gas reservoir. The general flow direction of the KA is toward the northern coast of the Persian Gulf due to the migration of water to the overlying formations via a trust fault. The KA is a gas-capped deep confined aquifer (GCDCA) with special characteristics differing from a shallow confined aquifer. The main characteristics of a GCDCA are unsaturated intergranular water below the confining layers, no direct contact of the water table (GWC) with the confining layers, no vertical flow via the cap rock, permanent uprising of the GWC during gas production, and permanent descend of GWC during water exploitation.     

Fundamental site frequency estimation at New Domiat city, Egypt

The horizontal-to-vertical spectral ratio technique has applied to detect the fundamental frequency at the sites of ambient noise recordings for New Domiat city. Noise measurements are acquired at 90 of sites for 1?h of continuous recording with a sampling rate of 100?Hz. Then, these data are processed following to SESAME project scheme. The presence of deep sedimentary basin in the Nile Delta suggests that the site response should be important. Consequently, the obtained fundamental frequency has lower values (0.2?C0.6?Hz). However, low-frequency ground motions attenuate more gradually with distance and can excite vibrations in large engineered structures, such as tall buildings and long bridges. There is hazardous threat even from the distant earthquakes originated from Mediterranean convergence zone for the structures in the city. It is recommended that the results of this study must be taken into consideration from civil engineering point of view before construction of civil engineering structures at this part.     

Calculation of the CIPW norm: New formulas

A completely new set of formulas, based on matrix algebra, has been suggested for the calculation of the CIPW norm for igneous rocks to achieve highly consistent and accurate norms. The suggested sequence of derivation of the normative minerals greatly deviates from the sequence followed in the classical scheme. The formulas are presented in a form convenient for error-free implementation in computer programs. Accurate formulas along with the use of variable molecular weights for CaO and FeO; corrected formula weights for apatite, pyrite and fluorite; and suggested measures to avoid significant rounding off errors to achieve absolute match between the sum of the input weights of the oxides and the sum of the weights of the estimated normative minerals. Using an analogous procedure for determining the oxidation ratios of igneous rocks as used in the SINCLAS system of Verma et al (2002, 2003), the suggested calculation scheme exactly reproduces their results except for apatite for reasons explained in the text, but with a superior match between the totals for about 11,200 analyses representing rocks of a wide range of composition     

Critical Zone Assessments of an Alluvial Aquifer System Using the Multi-influencing Factor (MIF) and Analytical Hierarchy Process (AHP) Models in Western Iran

Natural Resources Research - Many arid regions in the world suffer from over-exploitation of local groundwater resources leading to the degradation of freshwater aquifer systems, drying of spring...     

Neoproterozoic diamictite in the Eastern Desert of Egypt and Northern Saudi Arabia: evidence of ~750 Ma glaciation in the Arabian–Nubian Shield?

The Neoproterozoic Atud diamictite in Wadi Kareim and Wadi Mobarak in the Eastern Desert of Egypt and the Nuwaybah formation in NW Saudi Arabia consist of poorly sorted, polymictic breccia, with clasts up to 1 m of granitoid, quartz porphyry, quartzite, basalt, greywacke, marble, arkose, and microconglomerate in fine-grained matrix. Stratigraphic relations indicate that the diamictite was deposited in a marine environment. Integrated field investigation, petrographic study and U–Pb SHRIMP zircon ages demonstrate that the Atud and Nuwaybah are correlative. The distribution of zircon ages indicate that ~750 Ma ages are dominant with a significant component of older materials, characterized by minor Mesoproterozoic and more abundant Paleoproterozoic and Neoarchean ages. Some matrix and metasedimentary clast zircons yield ages that are a few 10s of Ma younger than the age of the youngest clast (754 ± 15 Ma), suggesting Atud/Nuwaybah diamictite deposition ~750 Ma or slightly later, broadly consistent with being deposited during the Sturtian glaciation (740–660 Ma). The Paleoproterozoic and Neoarchean clasts have no source within the ensimatic Arabian–Nubian Shield. The distribution of the pre-Neoproterozoic ages are similar to the distribution of the pre-Neoproterozoic ages in Yemen and Saharan Metacraton, suggesting that these clasts have been transported hundreds of kilometers, maybe by ice-rafting. The Atud diamictite may represent important evidence for Cryogenian “Snowball Earth” in the Arabian–Nubian Shield.     

Seismic source modeling and probabilistic seismic hazard analysis for Bangladesh

Natural Hazards - The probabilistic seismic hazard analysis (PSHA) has been performed for Bangladesh using background seismicity, crustal fault, and subduction zone source models. The latest ground...     

埃及东部沙漠Gasco天然气公司工程场地大地构造参数和地震灾害评估

根据埃及Gasco天然气公司工程场地的现场调查资料、地震活动性和地震灾害评估结果,对该场地进行了评估.通过浅源地震波折射勘探,对8个地震剖面上的土壤和岩石的弹性动态常数进行了分析.场地地面模型包括两层,分析表明它们具有从中值到高值的弹性动态常数,说明场地有良好的土壤条件和基岩岩性.同时,我们搜集和分析了研究区周围150 km半径范围内的历史和仪器记录地震,从构造环境、地震活动性、地质构造和主要地震的断层面解等方面进行了研究,认为场地受4个震源区的影响:苏伊士中部海湾、开罗-苏伊士地区、开罗西南和Beni-Suef地区.我们采用地震活动性统计方法并结合专家判定,确定了这些震源区内最大地震的矩震级(MW).另外,依据场地峰值加速度(PGA)和反应谱,用随机方法对场地进行了地震灾害评估.4个震源区中,Beni-Suef地区距离工程场地最近,其PGA最大值为9.34cm/s2,但这个值很小,表明地震不会对工程场地产生破坏性影响.最后,我们还模拟了阻尼为1%、3%和5%时的伪加速度场地反应谱.     

Data-Worth Assessment for a Three-Dimensional Optimal Design in Nonlinear Groundwater Systems

Groundwater model predictions are often uncertain due to inherent uncertainties in model input data. Monitored field data are commonly used to assess the performance of a model and reduce its prediction uncertainty. Given the high cost of data collection, it is imperative to identify the minimum number of required observation wells and to define the optimal locations of sampling points in space and depth. This study proposes a design methodology to optimize the number and location of additional observation wells that will effectively measure multiple hydrogeological parameters at different depths. For this purpose, we incorporated Bayesian model averaging and genetic algorithms into a linear data-worth analysis in order to conduct a three-dimensional location search for new sampling locations. We evaluated the methodology by applying it along a heterogeneous coastal aquifer with limited hydrogeological data that is experiencing salt water intrusion (SWI). The aim of the model was to identify the best locations for sampling head and salinity data, while reducing uncertainty when predicting multiple variables of SWI. The resulting optimal locations for new observation wells varied with the defined design constraints. The optimal design (OD) depended on the ratio of the start-up cost of the monitoring program and the installation cost of the first observation well. The proposed methodology can contribute toward reducing the uncertainties associated with predicting multiple variables in a groundwater system.     

Vegetation response to climate and climatic extremes in northwest Bangladesh: a quantile regression approach

Theoretical and Applied Climatology - The present study assessed the vegetation response to climate in the water-stressed northwest Bangladesh (NWB). The quantile regression analysis was employed...