Flood risk mapping and crop-water loss modeling using water footprint analysis in agricultural watershed,northern Iran

Natural Hazards - Spatial information on flood risk and flood-related crop losses is important in flood mitigation and risk management in agricultural watersheds. In this study, loss of water bound...     

Comparison of conventional and Monte Carlo simulation-based probabilistic seismic hazard analyses for Shiraz city,southern Iran

Estimation of ground-motion amplitudes of different hazard levels is of paramount importance in planning of urban development of any metropolis. Such estimation can be computed through a probabilistic seismic hazard analysis (PSHA). This paper concentrates on the PSHA of an area located in Shiraz city, southern Iran. The area includes whole of Shiraz city (i.e., one of the largest and most populous cities of Iran) and its outskirts. Conventional and Monte Carlo simulation-based approaches are utilized to perform the PSHA of the studied area. Two areal seismic source models are delineated, and thence seismicity parameters of all zones associated with their corresponding uncertainties are computed. Uncertainties in ground-motion prediction are accounted for via three ground-motion prediction equations (GMPEs) within the logic tree framework. These GMPEs are applied to estimate bedrock ground shaking (V_s30?=?760 m/s) for several return periods (i.e., 75, 475, 975, and 2475 years). In general, the results of the two abovementioned PSHA approaches show relatively similar results. However, the Monte Carlo simulation-based approach overpredicts bedrock spectral accelerations at periods of 0.4–2.5 s compared to the conventional PSHA approach for return periods of 475, 975, and 2475 years.     

Improved target illumination at Ludvika mines of Sweden through seismic-interferometric surface-wave suppression

In mineral exploration, new methods to improve the delineation of ore deposits at depth are in demand. For this purpose, increasing the signal-to-noise ratio through suitable data processing is an important requirement. Seismic reflection methods have proven to be useful to image mineral deposits. However, in most hard rock environments, surface waves constitute the most undesirable source-generated or ambient noise in the data that, especially given their typical broadband nature, often mask the events of interest like body-wave reflections and diffractions. In this study, we show the efficacy of a two-step procedure to suppress surface waves in an active-source reflection seismic dataset acquired in the Ludvika mining area of Sweden. First, we use seismic interferometry to estimate the surface-wave energy between receivers, given that they are the most energetic arrivals in the dataset. Second, we adaptively subtract the retrieved surface waves from the original shot gathers, checking the quality of the unveiled reflections. We see that several reflections, judged to be from the mineralization zone, are enhanced and better visualized after this two-step procedure. Our comparison with results from frequency-wavenumber filtering verifies the effectiveness of our scheme, since the presence of linear artefacts is reduced. The results are encouraging, as they open up new possibilities for denoising hard rock seismic data and, in particular, for imaging of deep mineral deposits using seismic reflections. This approach is purely data driven and does not require significant judgment on the dip and frequency content of present surface waves, which often vary from place to place.     

Regional improvement of global geopotential models using GPS/Leveling data

Studia Geophysica et Geodaetica - Global geopotential models are widely used in the remove-compute-restore technique for local gravity field modeling. In this paper, a method for regional...     

A Hybrid Particle Swarm Optimization and Genetic Algorithm for Model Updating of A Pier-Type Structure Using Experimental Modal Analysis

China Ocean Engineering - Conventional design of pier structures is based on the assumption of fully rigid joints. In practice, the real connections are semi-rigid that cause changes in dynamic...     

Geological and Geophysical Studies of Sulfide Copper Mineralization in the Dochileh Area: An Example of Manto‐Type Deposit in the Sabzevar Zone,Iran

The Dochileh stratiform copper deposit in the Sabzevar Zone of northeastern Iran is hosted in the basaltic sequence of the Upper Eocene age. The host rock displays two hydrothermal events: zeolite–carbonate alteration that is a stratigraphic–lithologic feature and chlorite and chlorite/ferruginous alterations in the local mineralized structures. Ore formation is related to both hydrothermal events and occurs in both stratiform and vein mineralization types. Mineralization consists of main chalcocite with variable amounts of bornite, chalcopyrite, native copper, malachite, and cuprite minerals, which occur as hydrothermal breccias, and disseminated, vein, and veinlet forms. Geophysical field studies using resistivity and induction polarization (IP) methods were conducted along nine survey lines in the area. As a result of modeling and interpretation of the acquired geophysical data, high values of IP and resistivity corresponding to mineralization were observed at two depth levels: 0–20 m and more than 40 m. Based on these geological and geophysical investigations, six locations for drilling exploration boreholes were proposed. Drilling data confirmed the mineralization containing high copper values in the two depth levels: the vein‐type mineralization in the surface and shallow depth level, and the stratiform mineralization at the deeper level. Fluid inclusion studies in calcite and quartz from stratiform‐ and vein‐type mineralization show the evidence of mixing, and a linear dilution trend during the ore formation occurred at a wide range of temperatures: 121–308°C and 80–284°C, respectively, and varying salinities of between 3.2–16.8 and 0.8–22 wt% NaCl equivalents. The stable isotope composition of δ³⁴S that falls in a range of ?2.4 to +25.0‰ could be considered biogenetic sulfur from bacterial sulfate reduction and leaching of sulfur from hosting basalt. The δ¹³C values of calcite vary between ?0.6 and ?7.6‰, suggesting a major contribution of marine carbonates associated with igneous carbonates, and the δ¹⁸O_SMOW values of calcite are between +15.2 and +19.9‰, suggesting a contribution of δ¹⁸O‐rich sedimentary rocks and δ¹⁸O‐poor meteoric water. Copper and sulfide‐rich hydrothermal fluid have flowed upward through the local faults and permeable interbeds within the Eocene volcanic sequence and have formed the mineralized veins and horizons. The geophysical results have detected the local faults as the channel ways for mineralization.     

Seismic hazard analysis and local site effect of the 2017 Mw 7.3 Sarpol-e Zahab,Iran, earthquake

Natural Hazards - A strong earthquake occurred on November 12, 2017, in Sarpol-e Zahab city, western Iran, with the moment magnitude ( $$M_{{\text{w}}}$$ ) of 7.3 and a focal depth of...     

Bedload resistance in supercritical flow

The movement of bedload in subcritical flow produces additional roughness as compared to flow in a rigid bed. The magnitude of this bed load roughness is proportional to the thickness of the sediment layer moving along the bed, the particle size and the sediment concentration. In a supercritical flow, however, further resistance is expected due to the momentum absorption by the high flow velocity. In this study the effect of sediment movement on the flow resistance in supercritical flow was experimentally investigated. The experiments included flows over smooth and rough beds carrying sediment of mean diameters D50=2.80, 5.42 and 7.06 mm in a rigid rectangular channel. The results show that the sediment transport may increase the friction factor by up to 90% and 60% in smooth and rough beds, respectively. Bedload extracts its momentum from the flow, which causes a reduction of near bed flow velocity and steeper velocity gradient near the bed resulting in an increase in shear velocity as well as in roughness height. The increase in friction factor is directly related to bedload concentration and particle size.     

Physical modeling into outflow hydrographs and breach characteristics of homogeneous earthfill dams failure due to overtopping

The main objective of the present study is to introduce new empirical equations for the determination of breach geometrical dimensions and peak outflow discharge(Q_p).Therefore,a historic failure database of 109 embankments was collected and examined.The most important factors that affect the breach evolution,including grading size,hydraulic,and outflow characteristics are also studied.Some of the parameters used for the determination of Q_p and average breach width(Bave)have a significant effect on the erosion process,but they are less reflected in the technical literature.To study the behavior of noncohesive soils during overtopping,15 physical tests were performed at the laboratory,and the effects of interfering parameters were investigated.The experimental output hydrograph was used to simulate the hydrographs resulting from the failure of real dams,and recent artificial intelligence techniques along with linear and nonlinear regression models were employed.The area-time analysis of the laboratory hydrographs shows that the soil particle size and the characteristics of reservoir-basin significantly affect the rate of breach formation and outflow discharge.New relationships are introduced,based on the breach characteristics,by a combination of historical and experimental data,as well as case studies conducted on the hypothetical failure of 10 operational dams.The mathematical model is also used to simulate the process of breach evaluation.Based on statistical indices,comparison of the results,and sensitivity analysis,the developed equations can better express the susceptibility of materials to erosion and their application can minimize downstream vulnerabilities.     

Titanium‐in‐biotite thermometry in porphyry copper systems: Challenges to application of the thermometer

Empirical geothermometer dealing with Ti solubility in the Fe‐Mg biotites was originally proposed for biotites in graphitic, peraluminous metapelites containing ilmenite or rutile that equilibrated roughly at 4–6 kbar. Given that biotites are abundant in the porphyry copper systems, this geothermometer has frequently been used for the determination of magmatic–hydrothermal temperatures in the porphyry copper systems. Common associations of porphyry copper deposits (PCDs), that is, low Al content of biotite, biotite chloritization (causes the biotite to become more magnesian and to lose Ti), and biotite formation by amphibole replacement, as well as disequilibrium, local equilibrium, or re‐equilibration of biotites, especially through potassic alteration, may provide significant uncertainty in the temperatures estimated a by Ti‐in‐biotite geothermometer. In addition, besides the calibration range of thermometer for pressure (400–600 MPa), the temperatures of major sulfide precipitation in PCDs (>~400°C) does not fit with the temperature range of thermometer calibration (480–800°C). Worth noting, as confirmed by fluid inclusion data in the Sarkuh PCD, regardless of presence of mineralogical requirements, obtained temperatures of sulfide mineralization using Ti in biotite thermometer could be overestimated. This may be due to the difference between general conditions of sulfide mineralization and calibration range of Ti in the biotite thermometer for pressure and temperature, as well as the metaluminous nature of biotites in PCDs.