Geochemistry of the thermal springs of Mount Taftan,southeastern Iran     

Ata Shakeri  Farid Moore  Mazda Kompani-Zare 《Journal of Volcanology and Geothermal Research》2008

Thermal and cold water chemistry from the southern flank of Mount Taftan was investigated in order to discriminate among hydrochemical facies, isotopic characteristics, geothermal reservoir and identify the major geochemical processes that affect water composition.  相似文献   

Crop Residues Mulch as Organic Weed Management Strategy in Maize          下载免费PDF全文

Azhar Mahmood  Muhammad Zahid Ihsan  Abdul Khaliq  Saddam Hussain  Zahid Ata Cheema  Muhammad Naeem  Ihsanullah Daur  Hafiz Athar Hussain  Fahad Alghabari 《洁净——土壤、空气、水》2016,44(3):317-324

  相似文献   

Development and application of a stochastic optimization model for groundwater management: crop pattern and conjunctive use consideration   总被引：2，自引：2，他引：0  

Ata Joodavi  Mohammad Zare  Masoud Mahootchi 《Stochastic Environmental Research and Risk Assessment (SERRA)》2015,29(6):1637-1648

The need for irrigation water in arid and semi-arid regions is mostly supplied by groundwater. Furthermore, the agricultural development in these areas is not generally based on a comprehensive plan, which can cause aquifers depletion. On the other hand, to properly manage an aquifer and to have an optimal crop plan, the stochastic nature of the different parameters of a groundwater system such as groundwater recharge and water demands should be taken into consideration. In this paper, we develop an explicit stochastic optimization model for Firouzabad aquifer in Iran. This formulation is based on the first and second moment analysis for groundwater head which has been initially proposed for surface water resources management by Fletcher and Ponnambalam. We extend the model to create a new random withdrawal policy for conjunctive use setting in which the randomness in available precipitation is taken into account. The interesting point is that the model provides the respective probabilities of shortage and surplus without imposing the extra decision variables into the optimization model. A genetic-based algorithm is used to solve the stochastic nonlinear and non-convex formulation. The outcome results indicate that the current crop pattern should be changed, that is, the allocated areas of some crops have to be meaningfully reduced. Finally, to validate our model efficiency, we demonstrate that how much close the statistical characteristics obtained from the optimization model are to those estimated from the Monte Carlo simulation. Furthermore, the optimal benefits obtained using the proposed optimization model are as suitable as the benefits achieved using the corresponding Monte Carlo-based optimization model.  相似文献   

Assessing Submerged Vegetation Roughness in Streambed under Clear Water Condition Using Physical Modeling     

Hosna Shafaei  Amini  Ata  Shirdeli  Azim 《Water Resources》2019,46(3):377-383

Water Resources - Roughness coefficient, also called Manning’s coefficient, is one of the most important hydraulic parameters in the rivers. This coefficient, in addition to the flow...  相似文献   

Combining Arc-GIS and OWA model in flooding potential analysis (case study: Meshkinshahr city)     

Ghaffari Gilandeh  Ata  Sobhani  Behrooz  Ostadi  Elnaz 《Natural Hazards》2020,102(3):1435-1449

Natural Hazards - “Streets have been turned into rivers”; this is a news headline which we have been hearing more often recently and refers to the floodwaters flowing into cities....  相似文献   

The effects of uniform and nonuniform pile spacing variations on local scour at pile groups     

Ata Amini  Nina Solaimani 《Marine Georesources & Geotechnology》2018,36(7):861-866

Pile groups are frequently used to support bridge decks. Scour in the vicinity of piles is the main cause for the bridges failure. In this research, to address the effects of uniform and nonuniform pile spacing on the equilibrium scour depth, laboratory experiments were carried out under steady clear-water conditions. For this purpose, scour depth produced by pile group with various pile spacing and arrangement was investigated using a laboratory flume. Flume bed was covered by uniform sediments with a median size of 0.9?mm and 0.2?m thickness. Flow discharge and velocity as well as scour depth were recorded in each experiment and the data were analyzed. The results showed that the pile spacing influences the local scour depth and with increase in uniform and transverse (perpendicular to the flow) spacing, the maximum scour depth was reduced. The pile spacing variation in line with the flow has a minor effect on scour depth. In addition, the pile spacing perpendicular to the flow was with the most influences on scour depth. The results of this research can be used by engineers to optimize the design of bridges.  相似文献   

Surface load dynamic solution of saturated transversely isotropic multilayer half-space     

Ata Jafarzadeh  Morteza Eskandari-Ghadi 《国际地质力学数值与分析法杂志》2019,43(9):1655-1685

This paper treats the dynamic response of a multilayered transversely isotropic fluid saturated poroelastic half-space under surface time-harmonic traction. The governing system of partial differential equations is uncoupled with the use of a set of physically meaningful and complete potential functions that decompose different body waves in a saturated poroelastic transversely isotropic medium. After expressing the equations in the Hankel-Fourier domain, a proper algebraic factorization is applied to generate reflection and transmission matrices for decomposed waves. All responses including displacements, stresses, and pore fluid pressure for both general patch load and point load are presented in the form of semi-infinite line integrals. The verification of the method is confirmed with the degeneration of the solutions presented here to the existing solutions for dried both homogeneous and multilayered elastic half-spaces as well as poroelastic half-space. Selected numerical results are depicted to investigate the effects of layering and pore pressure on responses of a transversely isotropic poroelastic medium. The load distribution effects are studied by comparison of the patch and point load responses. Also, resonance notion and effective parameters on this phenomenon such as layering system and anisotropy contrast are discussed. Significant influence of materials and layering configuration on number and amplitude of resonances depicted through the numerical evaluation.  相似文献   

Prediction of soil temperature using regression and artificial neural network models   总被引：3，自引：0，他引：3  

Mehmet Bilgili 《Meteorology and Atmospheric Physics》2010,110(1-2):59-70

In this study, monthly soil temperature was modeled by linear regression (LR), nonlinear regression (NLR) and artificial neural network (ANN) methods. The soil temperature and other meteorological parameters, which have been taken from Adana meteorological station, were observed between the years of 2000 and 2007 by the Turkish State Meteorological Service (TSMS). The soil temperatures were measured at depths of 5, 10, 20, 50 and 100 cm below the ground level. A three-layer feed-forward ANN structure was constructed and a back-propagation algorithm was used for the training of ANNs. In order to get a successful simulation, the correlation coefficients between all of the meteorological variables (soil temperature, atmospheric temperature, atmospheric pressure, relative humidity, wind speed, rainfall, global solar radiation and sunshine duration) were calculated taking them two by two. First, all independent variables were split into two time periods such as cold and warm seasons. They were added to the enter regression model. Then, the method of stepwise multiple regression was applied for the selection of the “best” regression equation (model). Thus, the best independent variables were selected for the LR and NLR models and they were also used in the input layer of the ANN method. Results of these methods were compared to each other. Finally, the ANN method was found to provide better performance than the LR and NLR methods.  相似文献   

Groundwater recharge estimation in arid hardrock‐alluvium aquifers using combined water‐table fluctuation and groundwater balance approaches          下载免费PDF全文

Azizallah Izady  Osman A.E. Abdalla  Ata Joodavi  Akbar Karimi  Mingjie Chen  Andrew Tompson 《水文研究》2017,31(19):3437-3451

This paper proposes an approach to estimate groundwater recharge using an optimization‐based water‐table fluctuation method combined with a groundwater balance model in an arid hardrock‐alluvium region, located at the Oman–United Arab Emirates border. We introduce an “effective hardrock thickness” term to identify the percentage of the considered hardrock thickness in which effective groundwater flow takes place. The proposed method is based upon a Thiessen polygon zoning approach. The method includes subpolygons to represent specific geologic units and to enhance the confidence of the estimated groundwater recharge. Two linear and 1 nonlinear submodels were developed to evaluate the model components for the calibration (October 1996 to September 2008) and validation (October 2008 to September 2013) periods. Long‐term annual groundwater recharge from rainfall and return flow over the model domain are estimated as 24.62 and 5.71 Mm³, respectively, while the effective groundwater flow circulation is found to occur in the upper 7% of the known hardrock thickness (42 m), confirming conclusions of previous field studies. Considering a total difference in groundwater levels between eastern and western points of the study area of the order of 220 m and a 12‐year monthly calibration period, a weighted root mean squared error in predicted groundwater elevation of 2.75 m is considered quite reasonable for the study area characterized by remarkable geological and hydrogeological diversity. The proposed approach provides an efficient and robust method to estimate groundwater recharge in regions with a complex geological setting in which interaction between fractured and porous media cannot be easily assessed.  相似文献   

Periodicities in Solar Flare Index for Cycles 21 – 23 Revisited     

A. Kilcik  A. Özgüç  J. P. Rozelot  T. Ataç 《Solar physics》2010,264(1):255-268

The periodic analyses of solar flare data have been carried out by different authors for about three decades. Controversial results appear as depending on the analysis techniques and investigated time periods. Considering that different authors applied different methods to different data sets, it seems necessary to reanalyze the periodicity of solar flare index with a unified method. In this study we used two new methods to investigate the periodic behavior of solar flare index data, first for individual cycles 21, 22 and 23, and then for all of them. We used i) the multi taper method with red- and white-noise approximations, and ii) the Morlet wavelet transform for periodicity analysis. Apart from the solar rotation periodicity of about 27 days which is of obvious significance and is found in all examined cycles with at least a 90% significance level, we obtained the following prominent periods: 152 days for cycle 21, 73 days for cycle 22, and 62 days for cycle 23. Finally, we compare our results with the ones previously found. We emphasize the fact that a lesser number of periodicities is found in the range of low frequencies (long periods) while the higher frequencies show a greater number of periodicities. This result might be useful for better predictions of the solar cycles.  相似文献