Natural Hazards - Due to excessive harvesting of underground water resources in many important aquifers inside Iran, ground subsidence is occurring at different speeds. In present study, InSAR... 相似文献
Occurrence of drought, as an inevitable natural climate feature, cannot be ceased while happening. However, costs of the consequences could be alleviated using mature scientific integrated approaches. To reduce the amount of damage, it is required to provide “Contingency” and “Mitigation” action plans. For this reason, development of efficient operating instructions for various regions based on weather conditions and field studies is needed as well as having a sophisticated understanding of socioeconomic situations. This paper describes an approach to provide the first national agricultural drought risk management plan for a river basin in Iran country as a pilot. The study lasted for 3 years as a national technical research project for the “soil conservation and watershed management research institute.” To reach the objectives, besides holding workshops and specialized think-tank meetings, field researches were done. Based on the socioeconomic data sources in the basin and the results of meetings by participation of local managers and residents, the final plan was developed. Moreover, in order to carry out this research, different climatic, agricultural and local information were collected in the watershed. In the next steps, potential risks and vulnerabilities of various agricultural sectors due to the hazard were evaluated. In this study, a nine-step approach to develop an agricultural drought risk management plan proposing different scientific–managerial phases based on the latest experts’ opinions, released international scientific best practices, and existing conditions governing the region was followed. With respect to the average income of US$ one million from agriculture and animal husbandry in the river basin, total drought loss varies from US$ 86,000 to US$ 258,000 for a range of light to very intense drought conditions, respectively. The setup of these nine executive phases defined monitoring, forecasting, and warning steps in working teams and managed the subprograms in partnership with stakeholders and decision-makers to mitigate the rate of drought damage from 30 to 47% (depending on the severity of the drought condition).
The Upper Triassic-Middle Jurassic sedimentary succession in the Tabas Basin, with a thickness of about 1600 m, provides a case showing geochemical property changes through the Triassic-Jurassic boundary. The studied section (Kamarmacheh Kuh) is composed of the marine Nayband Formation (Norian-Rhaetian) overlain by siliciclastic sediments of Ab-e-Haji Formation (Lower Jurassic-Aalenian). Detailed geochemical analyses were conducted on selected samples from both formations and the results were used to infer paleo-depositional conditions. Most of the studied samples contain <1 wt% TOC composed mostly of oxidized organic matter with insignificant generative potential. Extract analysis of four representative samples indicate that the rocks also contain minor amounts of preserved algal organic matter along with a secondary contribution of higher plant organic matter from the adjacent watershed. Biomarker analyses show subtle variations in the relative contribution of land plant material that are consistent with the widespread occurrence of coal seams in the upper parts of the Nayband and basal parts of the Ab-e-Haji formations. Although the samples from the Kamarmacheh Kuh Section have low source potential, the extractable hydrocarbons indicate that conditions existed that were conducive to organic matter preservation and that regions of the Tabas Basin with higher primary productivity or lower sedimentation rates may have greater potential. 相似文献
An updated Lagrangian finite element formulation of a three-dimensional annular section beam element is presented for large displacement and large rotation dynamic analyses of flexible riser structures. In this formulation a new linearization method is used to avoid inaccuracies normally associated with other linearization schemes. The effects of buoyancy force as well as steady state current loading are considered in the finite element solution for riser structures response. The formulation has been implemented in a nonlinear finite element code and the results are compared with those obtained from other schemes reported in the literature. 相似文献
In the present study, Cu (II) ions removal from aqueous solution was intensified by exciting magnetic nanoparticles under inert gas, magnetic field and combination of these two mixing methods in a T-type microchannel. The flow patterns and liquid–liquid two-phase mass transfer were studied in three different magnet distances from mixing channel (3, 6 and 10 mm) and also in the presence of different inert gas flow rates (1, 3 and 5 mL/min). Depending on the mixing method and the flow rate of both phases, several distinct flow patterns were observed including slugs, droplet, parallel and dispersed flows. The performances of mixing techniques for mass transfer enhancement based on relative removal efficiency ratio (λ) and mass transfer coefficient ratio (γ) were compared with simple layout (without nanoparticles, magnetic field and inert gas). The results showed that simultaneous using of inert gas and magnetic field can drive the nanoparticles as mixer. Liquid–liquid mass transfer with 27–62% enhancement in E and 235–285% in KLa compared with plain one was observed. 相似文献
The spatial distribution of residual light non-aqueous phase liquid (LNAPL) is an important factor in reactive solute transport
modeling studies. There is great uncertainty associated with both the areal limits of LNAPL source zones and smaller scale
variability within the areal limits. A statistical approach is proposed to construct a probabilistic model for the spatial
distribution of residual NAPL and it is applied to a site characterized by ultra-violet-induced-cone-penetration testing (CPT–UVIF).
The uncertainty in areal limits is explicitly addressed by a novel distance function (DF) approach. In modeling the small-scale
variability within the areal limits, the CPT–UVIF data are used as primary source of information, while soil texture and distance
to water table are treated as secondary data. Two widely used geostatistical techniques are applied for the data integration,
namely sequential indicator simulation with locally varying means (SIS–LVM) and Bayesian updating (BU). A close match between
the calibrated uncertainty band (UB) and the target probabilities shows the performance of the proposed DF technique in characterization
of uncertainty in the areal limits. A cross-validation study also shows that the integration of the secondary data sources
substantially improves the prediction of contaminated and uncontaminated locations and that the SIS–LVM algorithm gives a
more accurate prediction of residual NAPL contamination. The proposed DF approach is useful in modeling the areal limits of
the non-stationary continuous or categorical random variables, and in providing a prior probability map for source zone sizes
to be used in Monte Carlo simulations of contaminant transport or Monte Carlo type inverse modeling studies. 相似文献
The state of periodic loading and the interval of periodic roof weighting have an important role in geomechanical stability and, hence, in the continuity of longwall mining operations. In this paper, the mechanism of roof caving in longwall mining—together with the effect of engineering and geomechanical properties of surrounding rock masses on the magnitude and timing of periodic loading—is studied. For this purpose, a longwall mine is first modeled using Phase2 software, and then, by simulating the roof caving process, the periodic roof weighting intervals is calculated. Based on the numerical modeling, the first roof weighting interval and the periodic roof weighting interval are calculated as 27.2 and 12.1 m, respectively. Sensitivity analysis is then applied to determine the effect of changes in the mechanical properties of the rock mass, especially in the main roof and immediate roof. The results of the analysis show that as GSI and quality of the immediate roof increases, the periodic roof weighting interval also increases. Hence, the applied algorithm in this research study can effectively be utilized to calculate the periodic roof weighting interval in the longwall mining method. 相似文献
Natural Resources Research - This contribution proposes a spatially weighted factor analysis (SWFA) to recognize effectively the underlying mineralization-related feature(s) in geochemical signals.... 相似文献
In the design process of berm breakwaters, their front slope recession has an inevitable rule in large number of model tests, and this parameter being studied. This research draws its data from Moghim’s and Shekari’s experiment results. These experiments consist of two different 2D model tests in two wave flumes, in which the berm recession to different sea state and structural parameters have been studied. Irregular waves with a JONSWAP spectrum were used in both test series. A total of 412 test results were used to cover the impact of sea state conditions such as wave height, wave period, storm duration and water depth at the toe of the structure, and structural parameters such as berm elevation from still water level, berm width and stone diameter on berm recession parameters. In this paper, a new set of equations for berm recession is derived using the M5'' model tree as a machine learning approach. A comparison is made between the estimations by the new formula and the formulae recently given by other researchers to show the preference of new M5'' approach. 相似文献
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