线路漏电影响的实用化定量估算方法

本文提出了造成长期以来不能定量评价 Ps 漏电误差的关键问题及其解决办法的理论依据,推导出全线路最大可能漏电误差的理论计算公式,指出其应用条件,并给出实验验证结果和台站线路漏电误差的计算实例.      

地电阻率观测中线对地漏电干扰场的定量化研究

根据电法勘探的基本原理．参考已推导出的线对地漏电的基本公式．给出了《地电观测技术规范》允许漏电电流最大值时的电阻率相对误差三维分布图及平面等值线图，并讨论了其分布特征；同时给出了不同位置ρｓ相对变化１．５％时的漏电电流三维分布图及平面等值线图；粗略地给出了外线路绝缘电阻的允许范围，为提高地电台站布设的经济效益提供了较好的理论依据。     

一种地电阻率场地干扰的快速检测方法

对2018年洛阳地震台地电阻率观测区域出现的1次典型漏电干扰进行分析。经初步分析、干扰源模拟定位、干扰源现场调查等,确定干扰源的位置。通过对此次干扰的分析与排查,归纳总结出一种便利、快速的干扰检测定位方法。     

乌加河地震台地电阻率干扰形态识别

选取乌加河地震台2015-2018年地电阻率观测资料,分析数据异常变化,结合观测环境及实地调查,发现存在降雨、雷电、金属管线、农田灌溉、设备漏电等影响因素,对比分析并总结各类干扰曲线形态、变化幅度、影响时间、干扰频次等特征,以便正确认识并排除地电阻率干扰,为地震异常信息识别提供帮助。     

高邮地震台地电阻率观测精度干扰原因分析及排除方法

对高邮台地电NS向ρs的观测精度在2002-07-24雷雨后出现降低的现象进行了分析排查，发现是一交流接触器在遭雷击时烧坏，导致交流电三相中的一相对地漏电，与变压器中的零线形成回路所致。从而排除了配电房漏电的干扰。保证了观测资料的质量。     

阳原地震台的改造建设--地电阻率观测中的干扰及排除

阳原台地电阻率观测受外界影响非常严重，因而严重影响了观测资料的精度，使资料质量大大降低。本文通过实验和研究，找到了影响资料观测精度的因素：(1)漏电；(2)电极老化；(3)稳流源输出不稳定；(4)降雨；(5)风扰，并分别加以排除。     

交直流漏电在地电阻率观测中的判定——以定西地震台电阻率干扰排查为例

随着城镇化的扩张,地电阻率观测场地受到多种干扰影响,对甄别地电阻率异常信息带来了困难。2017年9月,甘肃省定西地震台地电阻率在四川九寨沟7.0级地震后出现了突变,巡查观测场地时发现距离东西道测量电极(N_3)70 m处有变压器接地线。经检测,该线带有18.5 A的电流,排除漏电后测值恢复到背景值。     

集宁地电观测系统故障检查及处理

对集宁2017年4月1日-5月31日地电阻率原始观测数据曲线常规分析发现,NS、EW测道数值差异明显,采用电测深曲线进行对比分析,发现2测道电阻率数值基本一致。在同场范围内,地电阻率与电测深曲线应同步变化。对集宁地电阻率布极区、观测环境、观测系统、装置系统进行系列检查、测试,发现NS测道导线线芯与导线铠导通,导线铠与避雷箱箱体接触导致线路漏电,造成数值出现误差。通过对外线路以及电极引线等进行优化改造,集宁地电阻率观测数据恢复正常。     

降雨对大柏舍地电台地电阻率观测的影响

选取大柏舍地电台2011—2019年地电阻率观测数据和降雨量资料,分析降雨对地电阻率观测的影响,利用影响系数理论,对结果进行分析探讨。结果表明,由于大柏舍地电台表层介质影响系数较小且为负值,小幅降雨对该台地电阻率短期影响不明显,仅自然电位差受到干扰;大范围强降雨时,地电阻率和自然电位差均受到影响;因ZD8B仪地电阻率观测系统架空线路漏电,导致EW向分量呈阶降变化,且比用于背景场观测的ZD8M仪变化幅度大。     

地震地电阻率观测改进方法研究电测井技术的移植应用与数值模型分析

现有的地震地电阻率观测系统需要较大的环境保护区（2——5km2）．随着各地的经济发展,地电观测的环境受到越来越大的影响,造成部分台站连续多年的地电前兆观测受到严重的干扰．为了减小观测环境保护区范围,有效地抑制来自地面的观测环境改变及城市地铁、轻轨运行时漏电产生的干扰,提出了将三侧向石油电测井技术移植到地震地电阻率前兆监测领域,以提高地电前兆观测的抗干扰能力和前兆信息的监测能力．电测井有限元数值模型的计算结果表明,该方法可有效测量出地层的电阻率变化,对来自地表的干扰有较强抑制能力．分析还表明,该方法可有效抑制来自轻轨、地铁的漏电干扰．      

Estimation of potential changes in the ecosystem of Lake Ladoga in the 21st century under the impact of anthropogenic and climatic factors

The effect of potential climate changes on the ecosystem of Lake Ladoga at different levels of anthropogenic load is studied using mathematical models. The Lake Ladoga year-round circulation corresponding to potential climate changes in the lake catchment area is reproduced. The year-round regime of functioning of the lake ecosystem is reproduced using ecosystem models. The potential changes in the lake ecosystem due to changes in the phosphorus load within the limits observed in 1961–1983 are found to be more essential than those due to prognostic changes in climate.     

位错引起的大地水准面变化

从动态的观点介绍了大地水准的物理意义。用数值分析方法计算了常见的几种断层位错导致的大地水准面局部变化的分布图像,并着 断层位错的倾角与大地水疰同变化 之间的关系。     

黄河流域气候与农业种植面积变化对径流的影响

根据黄河流域1960—2005年5个水文站逐日流量、77个气象站1959—2013年逐日降水数据,结合流域内主要农作物种植面积及大型水库资料,全面探讨气候与农业面积变化及人类活动对黄河流域径流变化的影响.研究表明:黄河流域所有流量分位数总体呈下降趋势,并于1980s中后期到1990s中期发生突变.降水变化是黄河流域径流变化的主要影响因素.在考虑不同流量分位数情况下,农作物种植面积变化对不同分位数径流变化的影响也有差异性.花园口站农作物种植面积变化对径流量量级和可变性均有显著影响;其余4站各项气候变化与农作物种植指标参数较大,虽均未达到10%的显著性水平,但仍会对径流的量级变化产生影响.对唐乃亥站,农作物耕作面积的下降减少了灌溉用水,在0.5流量分位数时有高达60%增加径流量的间接作用.对于头道拐站,农作物耕作面积的增加使得流域总蒸发量增加,灌溉用水增加,在0.3流量分位数时有高达40%减少径流量的间接作用.该研究为气候变化与人类活动影响下黄河流域水资源优化配置提供重要理论依据.     

Modeling studies of tidal dynamics and the associated responses to coastline changes in the Bohai Sea,China

Over the past 30 years, reclamation projects and related changes have impacted the hydrodynamics and sediment transport in the Bohai Sea. Three-dimensional tidal current models of the Bohai Sea and the Yellow Sea were constructed using the MIKE 3 model. We used a refined grid to simulate and analyze the effects of changes in coastline, depth, topography, reclamation, the Yellow River estuary, and coastal erosion on tidal systems, tide levels, tidal currents, residual currents, and tidal fluxes. The simulation results show that the relative change in the amplitude of the half-day tide is greater than that of the full-day tide. The changes in the tidal amplitudes of M₂, S₂, K₁, and O₁ caused by coastline changes accounted for 27.76–99.07% of the overall change in amplitude from 1987 to 2016, and water depth changes accounted for 0.93–72.24% of the overall change. The dominant factor driving coastline changes is reclamation, accounting for 99.55–99.91% of the amplitude changes in tidal waves, followed by coastal erosion, accounting for 0.05–0.40% of the tidal wave amplitude changes. The contribution of changes in the Yellow River estuary to tidal wave amplitude changes is small, accounting for 0.01–0.12% of the amplitude change factor. The change in the highest tide level (HTL) is mainly related to the amplitude change, and the correlation with the phase change is small. The dominant factor responsible for the change in the HTL is the tide amplitude change in M2, followed by S2, whereas the influence of the K1 and O1 tides on the change in the HTL is small. Reclamation resulted in a decrease in the vertical average maximum flow velocity (V_VAM) in the Bohai Sea. Shallower water depths have led to an increase in the V_VAM; deeper water depths have led to a decrease in the maximum flow velocity. The absolute value of the maximum flow velocity gradually decreases from the surface to the bottom, but the relative change value is basically constant. The changes in the tidal dynamics of the Bohai Sea are proportional to the degree of change in the coastline. The maximum and minimum changes in the tidal flux appear in Laizhou Bay (P-LZB) and Liaodong Bay (P-LDB), respectively. The changes in the tidal flux are related to the change in the area of the bay. Due to the reduced tidal flux, the water exchange capacity of the Bohai Sea has decreased, impacting the ecological environment of the Bohai Sea. Strictly controlling the scale of reclamation are important measures for reducing the decline in the water exchange capacity of the Bohai Sea and the deterioration of its ecological environment.     

Sensitivity of a seismically active reservoir to low-amplitude fluctuations: Observations from Lake Jocassee,South Carolina

Relation between water level changes and pattern of seismicity is an important consideration in studies of Reservoir Induced Seismicity (RIS). Sensitivity of the Regions around Lake Jocassee to small fluctuations in the lake level is presented in this paper. The seismic source regions in the area around the lake seem to be sensitive to changes in the lake level as small as 1 to 1.5 m. Although such changes may produce stress changes of the order of only 0.1 bar, their influence on the spatial pattern of earthquakes seems to be quite perceptible. Observations of this type may help understand the threshold values of pore pressure/effective stress changes that can activate fault zones under high fluid pressure.     

理塘毛垭温泉水温异常研究

1975-2005年间，四川省理塘毛垭温泉水温变化与地震有一定的对应.地热变化异常与地震的密切关系已被较多震例所证实. 2005年2月25日（温泉水温53 ℃）～3月14日（温泉水温26.9 ℃），毛垭温泉水温下降了26.1 ℃，2月水温月均值54.1 ℃、3月水温月均值30.7 ℃，下降了23.4 ℃，这一现象引起了地震系统各级领导和专家的高度重视.2005年3月中国地震局监测预报司在成都主持召开了南北地震带紧急震情会商会.根据会议决定，四川省地震局预报研究所组织了“毛垭温泉水温异常专题研讨会”，针对毛垭温泉水温下降异常，将30年来的资料进行了系统全面的分析，对于毛垭温泉的地震地质背景、温泉的热源、水温异常与强地震的关系作了较深入的研究，并且重点研究了水温下降异常特征与川滇两省强震的关系，对于毛垭温泉未来水温的三种动态变化趋势和近期川滇两省的强震趋势进行了探讨。     

Pressure effects on regional mean sea level trends in the German Bight in the twenty-first century

The effect of large-scale atmospheric pressure changes on regional mean sea level projections in the German Bight in the twenty-first century are considered. A developed statistical model is applied to climate model data of sea level pressure for the twenty-first century to assess the potential contribution of large-scale atmospheric changes to future sea level changes in the German Bight. Using 78 experiments, an ensemble mean of 1.4-cm rise in regional mean sea level is estimated until the end of the twenty-first century. Changes are somewhat higher for realisations of the special report on emission scenarios (SRES) A1B and A2, but generally do not exceed a few centimeters. This is considerably smaller than the changes expected from steric and self-gravitational effects. Large-scale changes in sea level pressure are thus not expected to provide a substantial contribution to twenty-first century sea level changes in the German Bight.     

四川水氡测值突跳异常与地震

在四川开展水氡前兆观测的初期,部分水氡点的水氡测值突跳异常很好地对应了其可预测范围内的中强以上地震。水氡测值突跳异常曾作为松潘—平武和盐源—宁蒗等地震预报的重要依据。但在水氡观测至今的完整时间段内,水氡突跳异常总体表现出对应率低,漏报率高的现象。多次预报攻关研究结果显示,水氡观测的异常表现是多种多样的,水氡测值突跳异常只是其中的表现之一。在今后四川及邻区的中强以上地震预报实践中,水氡测值突跳异常仍可作为地震短临预报的重要参考。     

中国大陆井水位与水温动态对汶川M_S 8.0地震的同震响应特征分析

分析了汶川MS8.0地震在中国大陆引起的水位、水温同震变化特征,对比研究了2007年9月12日印尼苏门答腊MS8.5远震和汶川MS8.0近震在四川及其附近地区引起的水位、水温同震变化差异,结果表明:汶川地震在中国大陆引起的水位同震变化以上升为主,同时水位上升与下降的井点空间分布表现出一定的分区性;水位、水温同方向阶变的井点数比例高于两者反方向阶变井点数比例,当水位同震变化为振荡型时,水温以下降型为主;相对于远震,近震引起的水位、水温同震变化井点数量增加,无变化井点数量减少;所有井水位和大多数井水温同震阶变的方向都不因地震的远近、大小、震源机制或地震方位的变化而改变,个别发生水温同震升降方向变化的井点是由于水的自流状态和水位同震阶变由振荡转为阶变的改变所引起;水位同震升降性质受控于当地的地质构造环境和水文地质条件,而水温同震变化还与地震波引起的井孔中水的运动方式、水温探头放置的位置等因素有关,其机理更为复杂     

A new method for modelling flow duration curves and predicting streamflow regimes under altered land-use conditions / Une nouvelle méthode de modélisation des courbes de débits classés et de prévision des régimes d'écoulement sous conditions modifiées d'occupation du sol

Abstract

The impact of changes in land-use/cover on streamflow at short time scales is evaluated by examining the changes in the flow duration curve (FDC) before and after land-use/cover change. The FDC characterizes the relationship between the magnitude and frequency and hence provides the complete range of streamflow over time. Two issues need to be considered in predicting the FDC due to land-use changes: (a) the appropriate parametric form of the FDC that enables application of the same expression of FDCs before and after the changes; and (b) the ability of parameters to capture and characterize the effect of land-use changes. In this paper, we propose a model which is a four-parameter double power form as a function of the FDC, where the two hydrological parameters represent the mean annual flow ([Qbar]) and the cease-to-flow point (τ expressed as a percentage), while the other two parameters (α and β) determine the shape of the FDC. The properties of this function are investigated in order to assign parameters to cope with the land-use changes. The model is used for several typical catchments in Australia for demonstration.