Assessment of drought hazard impact on wheat cultivation using standardized precipitation index in Iran

The assessment of drought hazard impacts on wheat cultivation as a strategic crop in Iran is essential for making mitigation plans to reduce the impact of drought. Standardized precipitation index has gained importance in recent years as a potential drought indicator and is being used more frequently for assessment of drought hazard in many countries. In the present study, the calculated standardized precipitation index for 48 stations dataset in the 30-year time scale fulfilled 30 statistical matrices. The drought hazard index map was produced by sum overlaying the spatial representations of 30 statistical matrices and categorized into four levels of low, moderate, high, and very high, which demonstrated probability of drought occurrences of 10–20 %, 20–30 %, 30–40 %, and 40–50 %, respectively. Finally, after the general division of zonal statistics in drought hazard index map of Iran, major drought hazard zones were geographically classified into five zones. The statistical analysis showed a significant correlation (R ²?=?0.701 to 0.648) between drought occurrences and wheat cultivation including surface area and total production for these drought hazard zones.     

Surface water quality contamination source apportionment and physicochemical characterization at the upper section of the Jakara Basin, Nigeria

The present study investigates the surface water quality of three important tributaries of Jakara Basin, northwestern Nigeria to provide an overview of the relationship and sources of physicochemical and biological parameters. A total of 405 water samples were collected from 27 sampling points and analyzed for 13 parameters: dissolved oxygen (DO), 5-day biochemical oxygen demand (BOD₅), chemical oxygen demand (COD), suspended solids (SS), pH, ammonia-nitrogen (NH₃NL), dissolved solids (DS), total solids (TS), nitrates (NO₃), chloride (Cl), phosphates (PO₄), Escherichia coli (E. coli) and fecal coliform bacteria (FCB). Pearson’s product–moment correlation matrix and principal component analysis (PCA) were used to distinguish the main pollution sources in the basin. Four varimax components were extracted from PCA, which explained 84.86, 83.60, and 78.69 % of the variation in the surface water quality for Jakara, Tsakama, and Gama-Kwari Rivers, respectively. Strong positive loading included BOD₅, COD, NH₃NL, E. coli, and FCB with negative loading on DO attribute to a domestic waste water pollution source. One-way ANOVA revealed that there was no significant difference in the mean of the three water bodies (p?>?0.05). It is therefore recommended that the government should be more effective in controlling the point source of pollution in the area.     

Assessment of bioclimatic comfort conditions based on Physiologically Equivalent Temperature (PET) using the RayMan Model in Iran

In this study thermal comfort conditions are analyzed to determine possible thermal perceptions during different months in Iran through the Physiologically Equivalent Temperature (PET). The monthly PET values produced using the RayMan Model ranged from ?7.6°C to 46.8°C. Over the winter months the thermal comfort condition (18–23°C) were concentrated in southern coastal areas along the Persian Gulf and Oman Sea. Most of the country experienced comfort conditions during the spring months, in particular in April, while during the summer months of July and August no thermal comfort conditions were observed. In November coastal areas of the Caspian Sea had the same physiological stress level of thermal comfort as April. The map produced showing mean annual PET conditions demonstrated the greatest spatial distribution of comfortable levels in the elevation range from 1000 to 2000 meter a.s.l., with annual temperatures of 12–20°C and annual precipitation of under 200 mm. The statistical relationship between PET conditions and each controlling parameter revealed a significant correlation in areas above 2000 meter, annual temperature over 20°C and annual precipitation of 200–400 mm with a correlation coefficient (R ²) of 0.91, 0.97 and 0.96, respectively.     

Trend analysis of groundwater using non-parametric methods (case study: Ardabil plain)

In the present study, the trends in groundwater level and fifteen hydro-geochemical elements at 32 piezometric stations located in the Ardabil plain of the northwest of Iran were analyzed using the non-parametric Mann–Kendall method after removing the effect of significant lag-1 serial correlation from the respective time series by pre-whitening. The magnitudes of trends were computed using the Sen’s estimator method. The homogeneity of trend was tested using the method proposed by van Belle and Hughes as well. Results showed that significant (α < 0.1) negative trends in groundwater level were witnessed for all but five stations of the Ardabil plains during the last 22 years from 1988 to 2009. The groundwater levels over Ardabil plain have declined at the rate of about 18 cm/year, with the strongest decline (1.93 m/year) witnessed at Khalife-loo-sheikh station. The results of homogeneity of trends showed that trends were homogeneous for months but not for stations. Strong positive trends were detected in the groundwater quality concentration across the whole plain. Decline in groundwater level and increase in geochemical elements in the groundwater were attributed to the human activities in the Ardabil plain located in the northwest of Iran.     

利用支持向量分类(SVC)估算断层深度和特征选择(英文)

地下断层深度的估算是重力解释难题之一,我们试利用支持向量分类(SVC)法进行计算。使用正演和非线性反演技术,通过相关误错使检测地下断层深度成为可能。但必要有一个深度初始猜测值,而且这猜测值通常不是由重力资料得。本文我们介绍以SVC作为利用重力数据估算断层深度的一种手段。在这项研究中,我们假设一种地下断层深度可归为一种类型,SVC作为一个分类算法。为了有效地利用此SVC算法,我们基于一个正确的特征选择算法去选择正确的深度特征。本次研究中我们建立了一套基于不同深度地下断层的合成重力剖面训练集,用以训练用于计算实际的地下断层深度的SVC代码。然后用其它合成重力剖面训练集测试我们训练的SVC代码,同时也用实际资料验证了我们的训练SVC代码。     

Reservoir operation using system dynamics under climate change impacts: a case study of Yamchi reservoir,Iran

This paper proposes a decision support system for Yamchi reservoir operation in semi-arid region of Iran. The paper consists of the following steps: Firstly, the potential impacts of climate change on the streamflow are predicted. The study then presents the projections of future changes in temperature and precipitation under A2 scenario using the LARS-WG downscaling model and under RCP2.6, RCP4.5, and RCP8.5 using the statistical downscaling model (SDSM) in the northwestern of Iran. To do so, a general circulation model of HadCM3 is downscaled by using the LARS-WG model. As a result, the average temperature, for the horizon 2030 (2011–2030), will increase by 0.77 °C and precipitation will decrease by 11 mm. Secondly, the downscaled variables are used as input to the artificial neural network to investigate the possible impact of climate change on the runoffs. Thirdly, the system dynamics model is employed to model different scenarios for reservoir operation using the Vensim software. System dynamics is an effective approach for understanding the behavior of complex systems. Simulation results demonstrate that the water shortage in different sectors (including agriculture, domestic, industry, and environmental users) will be enormously increased in the case of business-as-usual strategy. In this research, by providing innovative management strategies, including deficit irrigation, the vulnerability of reservoir operation is reduced. The methodology is evaluated by using different modeling tests which then motivates using the methodology for other arid/semi-arid regions.     

1997年伊朗中东部加恩-比尔兼德(GheanBirjiand)Zirkuh余震序列分析

分析了由当地地震台网记录的1997年伊朗加恩-比尔兼德(Ghean-Birjiand)Zirkuh余震序列. 基于余震的分布，可以判断出一垂直的北西南东走向的断层，其长度90 km. 加恩比尔兼德Zirkun地震的断层破裂明显地表现为起始于震中区，单方向地向东南方向传播. 沿断层的余震分布剖面显示，余震分布的深度范围可达20 km. 表明地震活动发生在上地壳，这一地区地震发生层的厚度20 km. 余震的分布表明，在主震的震源过程中块体西部是断层的上盘. 余震的时空分布表现出两个显著的空区，与地表断裂中所见到的间断一致. 可以得出这样的结论: 在主震和余震过程中第一个空区起着障碍体的作用，而第二个空区较深的部位在主震或余震的过程中发生了破裂. 地震后的前10天, 其余震的时间频次衰减图象遵循修正的大森关系，而此后的余震序列非常好地遵循大森模型.      

Seawall case studies and failure analysis of sloped concrete walls under static and dynamic loads

Concrete seawalls are structures in coastal facilities for shore and slope protections. Owing to several advantages of sloped or inclined walls such as minimum soil disturbance and less required earthworks, they can be considered as an appropriate alternative to vertical cantilever retaining walls. The combination of slab and strip semideep foundation instead of heel–toe slab foundations increases their capability for stability, erosion control, and storm wave energy dissipation. In this paper, three case studies from seawalls in which failure has occurred are presented and discussed. Technical performance of sloped walls against different internal and external instability factors is investigated, and comparisons are made between vertical and sloped (inclined) walls with respect to geotechnical and structural aspects through parametric study. Analysis indicates that the sloped retaining walls perform better from technical, practical, and economical standpoints. It was found that for identical static and dynamic loads, including earthquake and wave loads, inclined walls provide relatively higher safety factors against different criteria and exhibit more stable and practical performance compared with commonly used walls in practice. The case studies in this paper illustrate causes of failure in each case and gives suggestions for improving instability prevention of walls against static and dynamic loads.     

Geomorphological investigation of possible impact evidences for the crater-shaped structure of Zirouki in Samsour Desert, SE Iran

Despite the extensive records on geomorphological studies in Iran, meteorite impact craters have so far not been considered in to account. Based on both remote sensing technique and field work we have recognized the circular structure of Zirouki crater in the Samsour desert, southeast of Iran, which if confirmed as an impact structure, would be the third impact structure candidate in the Middle East after the Wabar craters in Saudia Arabia and Jebel Waqf as Suwwan in Jordan. Geomorphological investigation of the possible impact structure of Zirouki crater was done based on multi criteria methodology including of geological, topographical, geophysical and petrographical studies. Among different studies, topographical investigation indicated that the crater shape morphology was quite obvious with a central uplift projection; as well geophysical pattern provided very strong evidence for possible impact structure, indicating the presence of circular negative gravity anomaly at the whole of the crater.     

Erratum to: A spatio-temporal three-dimensional conceptualization and simulation of Dera Ismail Khan alluvial aquifer in visual MODFLOW: a case study from Pakistan

The Gour Oumelalen area exposes Paleoproterozoic (1.9 Ga) marbles and calc-silicate granulites. Some marbles show a specific mineralogy characterized by the presence of a highly aluminous clinopyroxene with Al₂O₃ content exceeding16 wt%. This clinopyroxene shows a marked zoning with a hedenbergitic core rimmed by fassaite. Phase relations are expressed by spectacular reaction textures in calc-silicate granulites as Opx + Cpx + Pl + H₂O  == > Grt + Qtz ± Am and Cpx + Ilm + Pl ± Mt = > Grt + Qtz + Spn. In olivine-bearing marbles, clinopyroxene and dolomite occur around olivine and calcite. According to thermodynamic modeling in the Na₂O–CaO–FeO–MgO–Al₂O₃–SiO₂–H₂O–TiO₂–Fe₂O₃ (NCFMASHTO) system, the first stage of metamorphism is located at 800 °C and 6–7 kbar, which is followed by an increase in pressure at 9–10 kbar and 800 °C and an isobaric cooling at 680 °C. The deduced anticlockwise P–T path is consistent with a granulitic metamorphism occurring in an active continental margin context.