Shallow sediment transport flow computation using time-varying sediment adaptation length   总被引：1，自引：0，他引：1  

Jaan Hui PU  Khalid HUSSAIN  Song-dong SHAO  Yue-fei HUANG 《国际泥沙研究》2014,29(2):171-183

Based on the common approach,the adaptation length in sediment transport is normally estimated astemporally independent.However,this approach might not be theoretically justified as the process of reaching the sediment transport equilibrium stage is affected by the flow conditions in time,especially for fast moving flows,such as scour-hole developing flows.In this study,the two-dimensional（2D） shallow water formulation together with a sediment continuity-concentration（SCC） model were applied to flow with mobile sediment boundary.A timevarying approach was proposed to determine the sediment transport adaptation length to simulate the sediment erosion-deposition rate.The proposed computational model was based on the Finite Volume（FV） method.The Monotone Upwind Scheme of Conservative Laws（MUSCL）-Hancock scheme was used with the Harten Lax van Leer-contact（HLLC） approximate Riemann solver to discretize the FV model.In the flow applications of this paper,a highly discontinuous dam-break,fast sediment transport flow was used to calibrate the proposed timevarying sediment adaptation length model.Then the calibrated model was further applied to two separate experimental sediment transport flow applications documented in the literature,i.e.a highly concentrated sediment transport flow in a wide alluvial channel and a sediment aggradation flow.Good agreement with the experimental data were obtained with the proposed model simulations.The tests prove that the proposed model,which was calibrated by the discontinuous dam-break bed scouring flow,also performed well to represent rapid bed change and steady sediment mobility conditions.  相似文献   

Assessment of Heavy Metal Contamination in Soil and Groundwater at Leather Industrial Area of Kasur,Pakistan   总被引：1，自引：0，他引：1       下载免费PDF全文

Muhammad Afzal  Ghulam Shabir  Samina Iqbal  Tanveer Mustafa  Qaiser Mahmood Khan  Zafar Mahmood Khalid 《洁净——土壤、空气、水》2014,42(8):1133-1139

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Evaluation of the effect of water management interventions on water level of Gaza coastal aquifer     

Mazen Abualtayef  Ghada Abdel Rahman  Ismael Snounu  Khalid Qahman  Hasan Sirhan  Ahmed Khaled Seif 《Arabian Journal of Geosciences》2017,10(24):555

Gaza coastal aquifer (GCA) is the most precious natural source where it is the only source of water for different uses. Groundwater crisis in Gaza includes two major folds: shortage of water supply and contamination. The extraction of groundwater currently exceeds the aquifer recharge rate. As a result, the groundwater level is falling continuously leading severely deterioration of GCA. The main objective of this study is to analyze and evaluate the current and proposed water resources management plans and their effect on the water level of GCA. In this respect, the available quantities of rainfall that could be harvested and infiltrated from different types of land-use based on existing and planned situations are studied using GIS tool and numerical models for GCA using V-MODFLOW environment for simulating four scenarios: (i) existing management practice (no action scenario), (ii) proposed Palestinian Water Authority (PWA) stormwater infiltration plan, (iii) proposed Gaza Emergency Technical Assistance Program (GETAP) interventions, and (iv) combination between second and third scenarios. The management scenarios were tested with the calibrated flow model for the target period between 2016 and 2040. The simulation results of existing management practice scenario show that there are several depression zones in Gaza Strip; in southern part from ??18 to ??24 m MSL in 2020 and 2040, in the northern part from ??7 to ??12 m MSL in 2020 and 2040, and in the middle regions experienced a small decline in groundwater level. The simulation results of proposed PWA scenario indicate similar depression zones as per first scenario but with good enhancement of water level, ??17 to ??18 m MSL in the southern part and ??3 to ??6 m MSL in the northern part in 2020 and 2040, respectively. The simulation results of GETAP intervention scenario show a positive impact on groundwater level. The results of fourth scenario show good enhancement of water level, in which the water level in the northern part ranges from +?3 to +?6 m MSL in 2020 and 2040, while in the south part ranges from ??15 to +?4 MSL in 2020 and 2040.  相似文献   

Biodegradation of cyanide and evaluation of kinetic models by immobilized cells of <Emphasis Type="Italic">Serratia marcescens</Emphasis> strain AQ07     

K. I. Karamba  S. A. Ahmad  A. Zulkharnain  N. A. Yasid  A. Khalid  M. Y. Shukor 《International Journal of Environmental Science and Technology》2017,14(9):1945-1958

Immobilized form of Serratia marcescens strain AQ07 was experimented for cyanide biodegradation. Cyanide degradation (200 ppm) was achieved after 24-h incubation. Three parameters were optimized which included gellan gum concentration, beads size, and number of beads. In accordance with one-factor-at-a-time method, cyanide removal was optimum at 0.6% w/v gellan gum gel, 0.3-cm-diameter beads, and 50 beads number. It was able to withstand cyanide toxicity of 800 ppm, which makes it very suitable candidate in cyanide remediation. Beads reusability indicates one-cycle ability. The first cycle removed 96.3%, while the second removed 78.5%. Effects of heavy metals at 1.0 ppm demonstrated that mercury has a considerable effect on bacteria, inhibiting degradation to 61.6%, while other heavy metals have less effect, removing 97–98%. Maximum specific degradation rate of 0.9997 h^?1 was observed at 200 ppm cyanide concentration. Gellan gum was used as the encapsulation matrix. ?-picoline-barbituric acid spectrophotometric analytical method was used to optimize the condition in buffer medium integrated with potassium cyanide via one-factor-at-a-time and response surface method. The range of cyanide concentrations used in this research, specific biodegradation rate was obtained to model the substrate inhibition kinetics. This rate fits to the kinetic models of Teisser, Aiba and Yano, which are utilized to elucidate substrate inhibition on degradation. One-factor-at-a-time approach parameters were adopted because it removes more cyanide compared to response surface methodology modules. The predicted biokinetic constant from this model suggests suitability of the bacteria for use in cyanide treatment of industrial waste effluents.  相似文献   

Hydrogeophysical investigations for assessing the groundwater potential in part of the Peshawar basin,Pakistan     

Sher Muhammad  Perveiz Khalid 《Environmental Earth Sciences》2017,76(14):494

A large number of valleys and basin systems are present in the northwestern part of the Himalayas in Pakistan which form significant aquifers in the region. Hydrogeophysical investigations in the western part of Nowshera District, a part of the intermontane Peshawar basin, were undertaken to help to determine the availability of groundwater resources in the region. Thirty vertical electrical resistivity soundings (VES) were acquired using a Schlumberger expanding array configuration with a maximum current electrode spacing (AB/2) of 150 m in delineating the groundwater potential in the study area. The results of the interpreted VES data using a combination of curve matching technique and computer iterative modeling methods suggest that the area is underlain by 3 to 5 geo-electric layers. The interpretation results showed that the geo-electrical succession consists of alluvium comprising of alternating layers of clay, silty clay, fine to coarse sands, sand with gravels and gravels of variable thickness. High subsurface resistivity values are correlated with gravel–sand units and low resistivity values with the presence of clays and silts. The modeled VES results were correlated with the pumping tests results and lithological logs of the existing wells. The pumping test suggests the transmissivity of the aquifer sediments is variable corresponding to different sediments within the area. The gravel–sand intervals having high resistivity value show high transmissivity values, whereas clay–silt sediments show low transmissivities. It is concluded that majority of the high resistive gravel–sand sediments belong to an alluvial fan environment. These gravel–sand zones are promising zones for groundwater abstraction which are concentrated in the central part of the study area.  相似文献   

Temporal shoreline change and infrastructure influences along the southern Red Sea coast of Saudi Arabia     

Omar A. Alharbi  Michael R. Phillips  Allan T. Williams  Tony Thomas  Mohammed Hakami  Jehad Kerbe  Abdoul Jelil Niang  ElSayed Hermas  Khalid Al-Ghamdi 《Arabian Journal of Geosciences》2017,10(16):360

Jizan is one of the Saudi Arabian coastal cities endowed with diverse natural settings, which includes Ash Shuqayq in the north, Turfah in the centre and Jizan in the South. This work analysed specific environmental characteristics, such as spits, sabkhas and wadis. Assessments used Landsat imagery to examine coastal change between 1973 and 2011. The cumulative temporal change identified regression trends given by coefficients of determination that explained a significant percentage of data variation for Jizan (R ² = 69%) and Turfah (R ² = 72%), while Ash Shuqayq was insignificant (R ² = 14%). Inter-survey results predicted future change, although trends were not significant, i.e. Jizan (R ² = 22%), Turfah (R ² = 14%) and Ash Shuqayq (R ² = 3 and 61% with outlying value removed). Aerial photos showed regional coastal changes, which included a maximum accretion of 36.4 m and maximum erosion of 12.9 m. These are scientifically effective techniques to monitor regional coastal change, i.e. erosion and accretion and identified rates of 0.59, 1.80 and 3.53 myr^?1 for Ash Shuqayq, Turfah and Jizan. Changes were linked to infrastructure developments, e.g. tourism, port development and natural causes, e.g. spit formations and wadi outfalls.  相似文献   

Response of infilled frames using pseudo-dynamic experimentation     

Khalid M. Mosalam  Richard N. White  Gustavo Ayala 《地震工程与结构动力学》1998,27(6):589-608

An accurate and practical testing technique to study seismic performance of multi-storey infilled frames is formulated. This technique is based on the pseudo-dynamic method which can provide an acceptable approximation of the dynamic performance of structures under the influence of earthquake excitation. The pseudo-dynamic experimental technique is outlined and applied for testing a two-bay, two-storey gravity load designed steel frame infilled with unreinforced concrete block masonry walls. From the discussion of the results, the dynamic performance of the tested structure is assessed. © 1998 John Wiley & Sons, Ltd.  相似文献   

Application of a mixture distribution of extreme values to earthquake magnitudes in Iraq and conterminous regions     

Khalid J. Fahmi  Jamal N. Al Abbasi 《Geophysical Journal International》1991,107(2):209-217

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Spatio‐temporal distribution of actual evapotranspiration in the Indus Basin Irrigation System          下载免费PDF全文

Umar Waqas Liaqat  Minha Choi  Usman Khalid Awan 《水文研究》2015,29(11):2613-2627

Strategic planning of optimal water use requires an accurate assessment of actual evapotranspiration (ET_a) to understand the environmental and hydrological processes of the world's largest contiguous irrigation networks, including the Indus Basin Irrigation System (IBIS) in Pakistan. The Surface Energy Balance System (SEBS) has been used successfully for accurate estimations of ET_a in different river basins throughout the world. In this study, we examined the application of SEBS using publically available remote sensing data to assess spatial variations in water consumption and to map water stress from daily to annual scales in the IBIS. Ground‐based ET_a was calculated by the advection‐aridity method, from nine meteorological sites, and used to evaluate the intra‐annual seasonality in the hydrological year 2009–2010. In comparison with the advection‐aridity, SEBS computed daily ET_a was slightly underestimated with a bias of ?0.15 mm day^?1 during the kharif (wet; April–September) season, and it was overestimated with a bias of 0.23 mm day^?1 in the rabi (dry; October–March) season. Monthly values of the ET_a estimated by SEBS were significantly (P < 0.05) controlled by mean air temperature and rainfall, among other climatological variables (relative humidity, sunshine hours and wind speed). Because of the seasonal (kharif and rabi) differences in the water and energy budget in the huge canal command areas of the IBIS, ET_a and rainfall were positively correlated in the kharif season and were negatively correlated during the rabi season. In addition, analysis of the evaporation process showed that mixed‐cropping and rice–wheat dominated areas had lower and higher water consumption rates, respectively, in comparison with other cropping systems in the basin. Basin areas under water stress were identified by means of spatial variations in the relative evapotranspiration, which had an average value of 0.59 and 0.42 during the kharif and the rabi seasons, respectively. The hydrological parameters used in this study provide useful information for understanding hydrological processes at different spatial and temporal scales. Results of this study further suggest that the SEBS is useful for evaluation of water resources in semi‐arid to arid regions over longer periods, if the data inputs are carefully handled. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Optimization of Preparative Separation and Purification of Total PolyphenoJs from Sargassum tenerrimum by Column Chromatography     

Samee Haider  LI Zhenxing  LIN Hong  Khalid Jamil 《青岛海洋大学学报(英文版)》2009,(4):425-430

Polyphenols from the ethanol extracts of Sargassum tenerrimum （ST） with potent antiallergic effects were studied to optimize separation process through column chromatography. The adsorption and desorption characteristics of three widely used adsorbents： macroporous resin, silica gel, and polyvinylpolypyrrolidone （PVPP）, were critically evaluated respectively and studied for the optimization of preparative separation of polyphenols. Static operations on these adsorbents showed that macroporous resin had the best adsorption and desorption capability among the three adsorbents. Dynamic adsorption and desorption with macroporous resin packed column were also conducted to optimize the parameters such as： with the optimal values shown in brackets, the concen- tration of extract solution （4 times diluted）, pH value （6-7）, adsorption speed （3BVh-1, bed volumes/per hour）, concentration of ethanol （80%）, elution speed （3 BV ht） and elution volume （7 BV）. The chromatographic process so optimized gave a purity of 62.43% from the crude polyphenols, providing a promising basis for large scale preparation of bioactive polyphenols upon further scaling up tests.  相似文献