Analysis of groundwater level trend in Jakham River Basin of Southern Rajasthan

Groundwater accounts for about half of the water use for irrigation in India.The fluctuation pattern of the groundwater level is examined by observing rainfall replenishment and monitoring wells.The southern part of Rajasthan has experienced abrupt changes in rainfall and has been highly dependent on groundwater over decades.This study presents the impact of over-dependence on groundwater usage for irrigation and other purposes,spatially and temporally.Hence,the objective of this study is to examine the groundwater level trend by using statistical analysis and geospatial technique.Rainfall factor was also studied in groundwater level fluctuation during 2009-2019.To analyze the influence of each well during recharge or withdrawal of groundwater,thiessien polygonswere generated from them.In the Jakham River basin,75 wells have been identified for water level trend study using the Mann-Kendall statistical test.The statistics of trend analysis show that 15%wells are experiencing water level decline in pre-monsoon,while very low percentage of wells have such trend during post-monsoon season.The average rate of water level decline is 0.245 m/a in pre-monsoon and 0.05 m/a in post-monsoon.The aquifer recharge potential is also decreasing by year.it is expected that such type of studies will help the policy makers to adopt advanced management practices to ensure sustainable groundwater resource management.     

Sea level in the Mediterranean Sea: seasonal adjustment and trend extraction within the framework of SSA

The sea level change is a crucial indicator of our climate. The spatial sampling offered by satellite altimetry and its continuity during the past years are the major assets to provide an improved vision of the Mediterranean sea level changes. In this paper, an automatic signal extraction approach, based on Singular Spectrum Analysis (SSA), is utilized for analysis and seasonal adjustment of the Mediterranean Sea level series. This automatic approach enables us to overcome the difficulties of visual identification of trend constituents that sometimes we encounter when using the conventional SSA method. The results indicate that the Mediterranean mean sea level is dominated by several harmonic components. The annual signal is particularly strong and almost covers 73.62 % of the original sea level series variation whiles its amplitude is about 15 cm. The extracted trend also indicates that the Mediterranean main sea level has significantly been raised during the period 1993–2012 by 2.44?±?0.4 mm yr^?1. As an important consequence, considering the current situation, if this trend continues, the Mediterranean Sea level will be raised about 22 cm by the end of this century, which makes a dramatic effect on several issues such as land, flora, fauna, and people activities established along the Mediterranean coastlines.     

农村住宅建设与防震减灾

本文通过对当前我国农村住宅建设中存在的诸多问题的阐述,从中分析农村住宅抗震性能差的原因,并提出自己的观点、建议。     

Novel basin modelling concept for simulating deformation from mechanical compaction using level sets

As sedimentation progresses in the formation and evolution of a depositional geologic basin, the rock strata are subject to various stresses. With increasing lithostatic pressure, compressional forces act to compact the porous rock matrix, leading to overpressure buildup, changes in the fluid pore pressure and fluid flow. In the context of petroleum systems modelling, the present study concerns the geometry changes that a compacting basin experiences subject to deposition. The purpose is to track the positions of the rock layer interfaces as compaction occurs. To handle the challenge of potentially large geometry deformations, a new modelling concept is proposed that couples the pore pressure equation with a level set method to determine the movement of lithostratigraphic interfaces. The level set method propagates an interface according to a prescribed speed. The coupling term for the pore pressure and level-set equations consists of this speed function, which is dependent on the compaction law. The two primary features of this approach are the simplicity of the grid and the flexibility of the speed function. A first evaluation of the model concept is presented based on an implementation for one spatial dimension accounting for vertical effective stress. Isothermal conditions with a constant fluid density and viscosity were assumed. The accuracy of the implemented numerical solution for the case of a single stratigraphic unit with a linear compaction law was compared to the available analytical solution [38]. The multi-layer setup and the nonlinear case were tested for plausibility.     

地球化学勘查的新技术及发展趋势

近几年,地球化学勘查无论从技术层面还是思想层面都得到迅速发展,主要包括:解决了几种特殊景观区普遍存在的有机质和风成砂等因素对异常的干扰问题;电地球化学、地气溶胶地球化学、金属元素活动态地球化学等深穿透地球化学勘查技术在寻找隐伏矿的理论和应用上逐渐趋于成熟;构造地球化学勘查技术成为隐伏矿定位预测评价中的关键技术之一,并形成一套完整的勘查技术流程;人工神经网络分析等地球化学数据处理新方法不断发展;建立了多目标区域地球化学调查体系,实现了资源调查与环境调查并举。未来,地球化学勘查将在农业、土地利用规划、坏境预警和保护等领域得到越来越多的应用。     

超前地质预报系统的提出及其发展方向

总结了超前地质预报的作用和发展现状,分析了超前地质预报认识上的误区和各种探测设备存在的问题。提出了超前地质预报系统的概念,阐述了隧道所在地区地质分析技术、隧道不良地质体超前预报技术、重大施工地质灾害临近警报技术包含的内容。系统的工作步骤为,利用地质分析技术结论以及地质复杂程度分级标准对探测区段的围岩进行地质复杂程度分级,针对不同级别的地质复杂程度,制定与其对应的超前地质预报系统方案,并注意现场工作中动态控制的应用。以厦门海底隧道F3风化深槽为例,对超前地质预报系统的内容及工作步骤进行了应用。提出了超前地质预报系统的发展方向。研究旨在完善超前地质预报工作,使超前地质预报结果在现场施工过程中能真正起到指导性的作用,最大程度地减少地质灾害造成的人员伤亡和财产损失     

The rheid concept in geotectonics

Abstract

The rheidity of a substance is defined as that property which determines whether it will behave as a fluid or solid for a particular experiment. It may be measured for given conditions of temperature, pressure, and shear stress, by that time for which the shear must be maintained for the deformation by viscous flow to exceed by one thousand times the elastic deformation. When loads are maintained for longer than the rheidity, the substance deforms as a fluid, and the elastic terms of the deformation equation may be neglected as insignificant. The rheidity of ice, salt, gypsum and serpentine are respectively of the order of a fortnight, a year, ten years and ten thousand years. Glaciers, salt domes, gypsum extrusions, and post-magmatic re-intrusion of serpentine are examples of rheid behaviour. Geological and astronomical evidence indicates that the rheidity of the mantle of the earth varies from tens of thousands of years at the top to hundreds of years at the base. Since tectonic loads are maintained from ten thousand to ten million years, the mantle of the earth behaves as a fluid for all geotectonic phenomena. The rheidity of the crust varies from 10⁵ to 10⁹ years, and hence the crust behaves as a solid for many tectonic processes. Geosynclinal materials and orogenic zones have, in general, shorter rheidities. and many fluid phenomena occur. Crystalline schists undergo rheid folding in the cores of orogens. Rheid folding, in spite of its appearance of extreme complexity, obeys simple geometrical laws, the understanding of which allows the complexly attenuated and contorted folds to be projected and extrapolated from fragmentary data. The universal contortion of the Archaean gneisses, which is usually regarded as evidence of intense shortening, does not necessarily imply much shortening or intense diastrophism.     

Flow of top coal and roof rock and loss of top coal in fully mechanized top coal caving mining of extra thick coal seams

This study investigates the flow and caving characteristics of top coal and roof rock, as well as top coal loss pattern in the fully mechanized top coal caving mining of extra thick coal seams. The two dimensional discrete element numerical simulation software program, particle flow code (PFC), is used for the simulation of top coal caving and the inversion analysis. The original locations, distribution, and migration pattern of caved top coal and lost coal were obtained. The analysis shows that in the initial site of caving, the caved bodies are in the form of arc shaped strips in front of the working face. During the caving, caved bodies of different heights move towards the lower rear of the face at different speeds. The lost coal and caved roof rock are originally located at the interface between coal seam and roof, the lost coal is mainly distributed in the goaf on the floor. Behind the support, the caved top coal bodies originally are arc shaped strips, with the highest points located at the midline of the caving opening. The strips are more curved near the goaf than those near the support. During top coal caving, the strips successively cave, with the adjacent outer strip replacing the caved one. The variations of top coal loss and waste rock ratio with time reflect the different phases of top coal caving. In order to improve coal recovery and limit the amount of caved roof rock, the waste rock ratio should be controlled below 10 %. When the waste rock ratio reaches this value, the caving opening should be closed. This paper provides theoretical bases for the improvement of top coal recovery in the fully mechanized top coal caving mining of extra thick coal seams.     

中国地热资源现状及发展趋势

中国地热资源禀赋良好,分布广泛且具有明显的规律性和地带性。本文系统总结了国内取得的地热资源勘查开发成果:浅层地热能资源在全国范围内普遍分布,我国336个地级以上城市规划区范围内浅层地热能资源年可开采量折合标准煤7亿吨;水热型地热资源年可开采量折合标准煤19亿吨;干热岩远景资源量折合标准煤856万亿吨。阐明了有代表性的水热型地热资源成因机制和干热岩资源成藏模式。地热开发利用技术发展迅速,浅层地热能和水热型地热资源利用量逐年攀升,但在地热资源成藏模式研究、勘查开发及管理利用等方面仍有亟须突破的技术瓶颈和需要改进的环节。文章分析了存在问题并提出了我国地热发展战略路线,下一步应加强热源机理与控热构造研究,推进地热探测技术和开发利用示范,开展重点地区浅层地热能、水热型地热资源勘查评价,完善干热岩勘查开发技术体系,推动地热产业健康有序发展。