Groundwater simulation using a numerical model under different water resources management scenarios in an arid region of China

Groundwater plays an important role in the economic development and ecological balance of the arid area of northwest China. Unfortunately, human activity, for example groundwater extraction for irrigation, have resulted in excessive falls in groundwater level, and aquifer overdraft in the oasis, disrupting the natural equilibrium of these systems. A groundwater numerical model for Minqin oasis, an arid area of northwest China, was developed using FEFLOW software to simulate regional groundwater changes under transient conditions. The vertical recharge and discharge (source/sink terms) of the groundwater models were determined from land-use data and irrigation systems for the different crops in the different sub-areas. The calibrated model was used to predict the change for the period from 2000 to 2020 under various water resources management scenarios. Simulated results showed that under current water resources management conditions groundwater levels at Minqin oasis are in a continuous drawdown trend and groundwater depth will be more than 30 m by 2020. Reducing the irrigation area is more effective than water-saving irrigation to reduce groundwater decline at Minqin oasis and the annual groundwater budget would be −0.978 × 10⁸ m³. In addition, water-diversion projects can also reduce the drawdown trend of groundwater at Minqin oasis, and the groundwater budget in the Huqu sub-area would be in zero equilibrium if the annual inflow into the oasis was enhanced to 2.51 × 10⁸ m³. Furthermore, integrative water resources management including water-diversion projects, water-saving irrigation, and reducing the irrigation area are the most effective measures for solving groundwater problems at Minqin oasis.     

Mechanism and geo-mechanics models of landslides triggered by 5.12 Wenchuan Earthquake

Due to the extremely high magnitude, long duration, and the complicated geo-environment in the disaster area, the great 5.12 Wenchuan Earthquake not only produced a huge number of landslides and rockfalls, but also involved complicated dynamic processes. These processes are quite different from the characteristics of landslides and rockfalls under general gravitational force, and presently human knowledge is very poor in this field. In order to describe the special dynamic processes, some terms such as shattering-cracking, shattering-sliding, shattering-falls and ejection are defined in this paper. Combined with slope structures, a mechanism classification system of strong earthquake-triggered landslide and rockfall is suggested, which is divided into 5 categories and 14 types. This paper also analyzes the basic characteristics, dynamic processes and geo-mechanics conceptual models of some typologies, especial the type of shattering-sliding for most large-scales landsides. This paper initially reveals the formation mechanism, geo-mechanics models and dynamic features of landslides and rockfalls triggered by the great Wenchuan Earthquake.     

Analysis on the dynamical process of Donghekou rockslide-debris flow triggered by 5.12 Wenchuan earthquake

Among the geo-hazards caused by the great Wenchuan Earthquake, the rapid and long runout rockslide-debris flow is of primary concern due to the large volume of displaced material and the resultant catastrophic impacts to the landscape and socioeconomic structure. In order to analyze the dynamical process of this kind of geo-hazard, the Donghekou rockslide-debris flow is given as an example in this paper. This event, which killed 780 people, initiated at an elevation of 1300 m with a total long run-out distance of more than 2400 m. The slide mass is mainly composed of dolomite limestone and siliceous limestone of Sinian system, together with carbon slate and phyllite of Cambrian. During the processes from slide initiation to the final cessation of slide movement, five dynamic stages took place, here identified as the initiation stage, the acceleration of movement stage, the air-blast effect stage, the impact and redirection stage and the long runout slidematerial accumulation stage. Field investigations indicate that due to the effects of the earthquake, the dynamics of the Donghekou rockslide-debris flow are apparently controlled by geologic and tectonic conditions, the local geomorphological aspects of the terrain, and the microstructural and macroscopic mechanical properties of rocks which compose the slide mass. These three main factors which dictate the Donghekou rockslide-debris flow dynamics are discussed in detail in this paper, and significant results of field investigations and tests of materials are presented. The above dynamical processes are analyzed in this paper, and some useful conclusions have been gained.     

河西古代金银开采史话

甘肃河西走廊有悠久的开采金银矿的历史。采金至少始于唐代,鼎胜于清代;采银主要在明代。采金范围包括今酒泉、张掖、武威等地区。清代,敦煌金矿,曾是我国最大的金矿。本文不仅探讨了河西开采金银的历史,而且列举了古代具体产地数十处,对当前河西寻找金银矿亦有一定的参考价值。     

Generation of hazard-consistent ground motion

This paper presents an integrated approach for evaluating seismic hazard and establishing ground motion at a site. In this approach, we combine the advantage of probabilistic and deterministic seismic hazard analyses and generate synthetic ground motion by considering the characteristics of seismic source, path attenuation, and local soil condition. Furthermore, uncertainties in seismic and soil parameters are taken into account. The proposed approach can be used to establish site-specific ground motion for engineering applications.     

中国近代铜矿开发概貌

本文总结了我国清末至民国初期（１８４０－１９２０）长达８０年的铜矿开发概貌，按现行政区划共涉及１２个省．对各省的铜矿，既扼要探讨历史沿革，又尽量地汇集具体产铜地名及有关地质矿产信息，对了解和研究近代中国铜矿开发史，系统地总结现代中国铜矿床的由来，都有一定的意义．     

太行山东麓层状云微物理特征的飞机观测研究

本文利用“太行山东麓人工增雨防雹作业技术试验”的飞机和地面雷达观测数据,重点研究分析了2018年5月21日一次典型西风槽天气系统影响下的层状云微物理特征。结果表明,?5°C层的过冷水含量低于0.05 g m?3,冰粒子数浓度量级101～102 L?1。冰粒子数浓度高值区主要以针状和柱状冰晶为主。这可能低层是Hallett-Mossop机制和其他冰晶繁生机制共同作用下所产生的冰晶碎片在冰面过饱和条件下凝华增长所形成的。冰粒子数浓度低值区的冰晶形状基本以片状或枝状为主。?5°C层的冰雪晶增长主要以凝华和聚并增长为主,凇附过程很弱。零度层附近云水含量峰值区的液态水占比达到70%以上。云水含量峰值区的粒子主要以直径10～50 μm的云滴为主,伴随着少量聚合状冰晶。零度层其他区域的过冷水含量维持在0.05 g m?3左右,冰晶形态主要以聚合状、凇附状及霰粒子为主。液水层则主要以球形液滴及半融化状态的冰粒子为主。垂直探测表明:零度层以上的冰雪晶数浓度呈现随高度递增的趋势。在发展稳定的层状云内,混合层的过冷水含量很低,冰粒子主要通过凝华和聚并过程增长,云体冰晶化程度较高。而在发展较为旺盛的层状云区里过冷水含量也较高,大量液滴的存在也表明混合层冰-液相之间的转化不充分。不同温度层的粒子谱显示,冷水含量高值区的冰粒子平均浓度比过冷水低值区高,但平均直径比过冷水低值区小。     

Exhumation history and preservation of the Jiaojia giant gold deposit,Jiaodong Peninsula

Science China Earth Sciences - The Jiaojia giant gold deposit is the largest gold deposit in China, with a total gold reserve of approximately 1200 t. Until now, the knowledge of the exhumation...     

品种主要农艺性状与夏玉米机收指标相关分析

籽粒含水量是影响夏玉米机收的主要指标。研究与收获期籽粒含水量相关的品种农艺性状及不同脱水类型品种产量差异,对于机收品种选育有重要参考意义。为此,于2015年和2016年在河南省鹤壁农业气象试验站,选择24个当前主要种植品种为供试材料,采取统一授粉,连续测定分器官含水量变化及收获期品种农艺性状,进行籽粒脱水相关性状研究。结果表明,籽粒含水量的动态变化与茎秆、穗轴和苞叶含水量均呈极显著正相关,收获期籽粒含水量与株高呈显著负相关,与穗轴直径、雄穗分枝数、百粒重、果穗长、果穗粗、果穗大小、种皮厚度、粒长和籽粒体积呈显著正相关。不同脱水类型品种产量差异显著,成熟期籽粒含水量与产量呈显著正相关。     

Performance of various predicted GNSS global ionospheric maps relative to GPS and JASON TEC data

When using predicted total electron content (TEC) products to generate preliminary real-time global ionospheric maps (GIMs), validation of these ionospheric predicted products is essential. In this study, we evaluate the accuracy of five predicted GIMs, provided by the international GNSS service (IGS), over continental and oceanic regions during the period from September 2009 to September 2015. Over continental regions, the GPS TEC data collected from 41 IGS continuous tracking stations are used as a reference data set. Over oceanic regions, the TEC data from the JASON altimeter are used for comparison. An initial performance comparison between the IGS combined final GIM product and the predicted GIMs is also included in this study. The evaluation results show that the predicted GIMs produced by CODE outperform the other predicted GIMs for all three validation results. The accuracy of the 1-day predicted GIMs, produced by the IGS associate analysis centers (IAACs), is higher than that of the 2-day predicted GIMs. Compared to the 2-day UPC predicted GIMs, the 2-day ESA predicted GIMs are observed to have slightly worse performances over ocean regions and better positioning performances over continental regions.