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Natural Hazards - Tornadoes pose a significant threat to residential communities, causing enormous physical damage and losses to their social fabric. The dominant type of single-family residential... 相似文献
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This paper presents a numerical implementation of two-phase capillary hysteresis and its combination with a capillary interface
condition for the treatment of heterogeneities. The hysteresis concepts chosen in this work are first implemented in a node-centered
FV discretization scheme and subsequently combined with the interface condition that predicts sharp saturation discontinuities
at material interfaces, based on a pressure equilibrium concept. This approach allows for the approximation of history-dependent,
and at the same time discontinuous, saturations at material interfaces. The resulting model provides a well-defined evolution
of the hysteretic capillary pressure–saturation relationships at material interfaces that is independent of the grid spacing.
As demonstrated with a simple 1-D example, this concept therefore offers the advantage that the solution of a two-phase flow
problem involving hysteresis does not relate to the grid resolution at the material interfaces. 相似文献
3.
Determining the focal mechanism of earthquakes helps us to better define faults and understand the stress regime. This technique can be helpful in the oil and gas industry where it can be applied to microseismic events. The objective of this paper is to find double couple focal mechanisms, excluding scalar seismic moments, and the depths of small earthquakes using data from relatively few local stations. This objective is met by generating three‐component synthetic seismograms to match the observed normalized velocity seismograms. We first calculate Green's functions given an initial estimate of the earthquake's hypocentre, the locations of the seismic recording stations and a 1D velocity model of the region for a series of depths. Then, we calculate the moment tensor for different combinations of strikes, dips and rakes for each depth. These moment tensors are combined with the Green's functions and then convolved with a source time function to produce synthetic seismograms. We use a grid search to find the synthetic seismogram with the largest objective function that best fits all three components of the observed velocity seismogram. These parameters define the focal mechanism solution of an earthquake. We tested the method using three earthquakes in Southern California with moment magnitudes of 5.0, 5.1 and 4.4 using the frequency range 0.1–2.0 Hz. The source mechanisms of the events were determined independently using data from a multitude of stations. Our results obtained, from as few as three stations, generally match those obtained by the Southern California Earthquake Data Center. The main advantage of this method is that we use relatively high‐frequency full‐waveforms, including those from short‐period instruments, which makes it possible to find the focal mechanism and depth of earthquakes using as few as three stations when the velocity structure is known. 相似文献
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Zekai Şen Hussam A. Khiyami Saad G. Al-Harthy Faisal A. Al-Ammawi Ali B. Al-Balkhi Mohammed I. Al-Zahrani Hashim M. Al-Hawsawy 《Arabian Journal of Geosciences》2013,6(9):3563-3572
Flood inundation maps are dependent on the topographic and geomorphologic features of a wadi (drainage basin) in arid regions, which are most susceptible for potential flash flood occurrences, such as in the southwestern part of the Kingdom of Saudi Arabia. It is not possible to control the potential flood hazards by using only technological instruments that forewarn the occurrences or imminence. Additionally, it would be better to prepare flood risk maps so as to delineate the risky areas to educate the administrators and local settlers. The availability of these maps is the key requirement for any urban development that entails land use allocation, identification of dam, tunnel, highway, bridge sites, and infrastructure locations for sustainable future. This paper suggests the necessary steps in flood inundation map preparation after determining the possible flood discharge. For this purpose, a set of critical cross-sections along the possible flood plain are taken in the field with surveying methods and measurements. The calculation of the average flow velocity in each section is calculated according to the cross-section geometric, hydraulic, and material properties. Synthetic rating curves (SRC) are prepared for each cross section, which are very useful especially in arid and semi-arid regions where there are no perennial surface water flows for natural rating curve measurements. All the SRCs appear in the form of power function which relates the flow depth to discharge in a given cross section. It is then possible to calculate the flood depth in the cross section through its SRC. Depending on the cross-section shape, the flood width can be calculated. The connection of a series of widths on a scaled topographic map delineates the flood inundation area. If digital elevation map (DEM) is available, then the SRCs can be integrated with these maps and the flood inundation delineation can be achieved automatically. Since DEMs are not available, the topographic maps are used for this purpose in order to delineate flood inundation areas within wadis Hali and Yiba from the southwestern Kingdom of Saudi Arabia. 相似文献
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Acta Geotechnica - Designing structures to be the least vulnerable within earthquake-prone areas is a serious challenge for structural engineers. One common and useful tool that structural... 相似文献
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Schulze Stefanie S. Fischer Erica C. Hamideh Sara Mahmoud Hussam 《Natural Hazards》2020,104(1):901-925
Natural Hazards - Wildfire impacts on communities have become more pronounced in recent years as the intensity and frequency of wildfires have increased in densely populated areas of the... 相似文献
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Jabal Mohd S. Abu Abustan Ismail Rozaimy Mohd Remy El Najar Hussam 《Arabian Journal of Geosciences》2015,8(4):2203-2215
Arabian Journal of Geosciences - This paper presents the results of a groundwater hydrochemical assessment in the urban area of Khan Younis City in the southern Gaza Strip by measuring its... 相似文献
9.
Mohd S. Abu Jabal Ismail Abustan Mohd Remy Rozaimy Hussam El Najar 《Arabian Journal of Geosciences》2017,10(12):257
The present study research investigation is aimed to assess the groundwater quality for the urban area in Khan Younis City, southern Gaza Strip, for multi-domestic purposes. The physicochemical analysis of the groundwater wells shows the major ions in the order of Na+ > Mg2+ > Ca2+ > B3+ > K+ and Cl? > HCO3 ? > SO4 2? > NO3 2? > F? > PO4 3?. Groundwater quality is classified as very hard-brackish water type. Ninety-five percent of the wells are classified as saline water type with high NO3 2? concentrations. Based on water quality index (WQI), the groundwater falls into one of three categories: fair water (10%), poor water (15%), very poor (45%), and worst (30%). The high WQI values are because of high Na+, Cl?, SO4 2?, and NO3 2? concentrations, while synthetic pollution index (SPI) values indicate that most about 80% of the wells are seriously polluted. Langelier Saturation Index (LSI) indicates that most of data are either slightly scale forming or corrosive water or slightly corrosive but non-scale forming, and 75% of the wells are suitable for construction purposes (have SO4 2? concentrations <300 mg/L). The groundwater reaches alarming situation, where almost chemically unsuitable for drinking purposes and the water to be used after proper treatment such as desalination. 相似文献
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Alsharifa Hind Mohammad Hahn Chul Jung Taleb Odeh Chandrashekhar Bhuiyan Hussam Hussein 《Arabian Journal of Geosciences》2018,11(5):103
This article assesses drought status in the Yarmouk Basin (YB), in northern Jordan, using the Standardized Precipitation Index (SPI), the Standardized Water-Level Index (SWI), and the Percent Departure from Normal rainfall (PDNimd) during the years 1993–2014. The results showed that the YB suffers from frequent and irregular periods of drought as variations in drought intensity and frequency have been observed. The SPI results revealed that the highest drought magnitude of ??2.34 appeared at Nuaimeh rainfall station in 1991. This station has also experienced severe drought particularly in years 1995, 1999, 2005, and 2012 with SPI values ranging from ??1.51 to ??1.59. Some other rainfall stations such as Baqura, Ibbin, Khanasiri, Kharja, Mafraq police, Ramtha, Turra, and Umm Qais have also suffered several periods of drought mostly in 1993. The SWI results show the highest extreme drought events in 2001 in Souf well while other extreme drought periods were observed at Wadi Elyabis well in 1994 and at Mafraq well in 1995. As compared to SPI maps, our SWI maps reflect severe and extreme drought events in most years, negatively impacting the groundwater levels in the study area. 相似文献