Input data resolution‐induced uncertainty in watershed modelling

The temporal‐spatial resolution of input data‐induced uncertainty in a watershed‐based water quality model, Hydrologic Simulation Program‐FORTRAN (HSPF), is investigated in this study. The temporal resolution‐induced uncertainty is described using the coefficient of variation (CV). The CV is found to decrease with decreasing temporal resolution and follow a log‐normal relation with time interval for temperature data while it exhibits a power‐law relation for rainfall data. The temporal‐scale uncertainties in the temperature and rainfall data follow a general extreme value distribution and a Weibull distribution, respectively. The Nash‐Sutcliffe coefficient (NSC) is employed to represent the spatial resolution induced uncertainty. The spatial resolution uncertainty in the dissolved oxygen and nitrate‐nitrogen concentrations simulated using HSPF is observed to follow a general extreme value distribution and a log‐normal distribution, respectively. The probability density functions (PDF) provide new insights into the effect of temporal‐scale and spatial resolution of input data on uncertainties involved in watershed modelling and total maximum daily load calculations. This study exhibits non‐symmetric distributions of uncertainty in water quality modelling, which simplify weather and water quality monitoring and reducing the cost involved in flow and water quality monitoring. Copyright © 2011 John Wiley & Sons, Ltd.     

MSDP软件在单台数字地震记录分析中的应用

根据MSDP分析软件的基本功能和测震分析常用方法,结合Dimas分析软件的使用经验,从台站工作的实际出发,以单台地震震相分析整个流程的形式,总结了在MSDP下地震震相的单台分析识别方法.利用这些方法,有助于提高地震台站工作人员震相分析识别的工作效率.     

Numerical simulation of deep-hole resistivity anomaly caused by drilling construction in Xinfengjiang geoelectric station

The Xinfengjiang reservoir in Guangdong Province, is one of the large reservoirs that have triggered earthquakes of magnitude greater than 6. Numerous earthquakes have occurred since the impoundment of the reservoir, making it one of the most active seismic zones in south China. In 2015, a set of deep-hole resistivity anomalies was observed in the Heping geoelectric station in Dongyuan county, located near the Xinfengjiang reservoir. After a field investigation, we found that a planned well drilling construction of new measuring channels was being carried out during that corresponding period of time. After careful comparison and analysis on the basis of the collected raw data, we had a reason to believe that drilling construction, rather than the inducement of the Xinfengjiang reservoir, was the main culprit for those unusual georesistivity values. So as to verify the above conjecture, we constructed a series of 3D finite element models based on the geological and hydrological information around Heping station and analyzed the drilling disturbances, respectively. Some significant conclusions were finally drawn according to the precise numerical simulation. This study gives a good example by combining numerical simulation with engineering practice as a way to understand the root cause of georesistivity anomalies in reality.     

基于实地调研的中国西南地区不同震级人员死亡数量研究

地震是造成人员死亡最严重的自然灾害之一,震后对人员死亡等灾情的快速评估是地震应急响应和救援的关键。总结经验发现,在地震前进行预评估工作是提高震后灾情快速评估精度和时效性的有效手段。通过对62次发生在我国西南地区的历史震例分析后发现,当地震震级小于4.5级时,基本不会造成人员死亡情况。本研究利用我国云南和四川部分区县的实地调研数据,发现地震人员死亡数与震级存在指数函数关系,由此构建了针对各个区县的地震人员死亡人数指数函数估算模型,并计算了回归系数。基于该模型,获得了5.0～8.0级地震人员死亡数查找表(以0.5级为间隔),用于辅助震后快速评估工作。     

鄱阳湖汇流顶托对长江汉口水位影响的量化分析

为定量评估汇流顶托对水位变化的影响,本文从水文过程仿真及顶托响应评价入手,提出了一种汇流顶托对水位影响的量化分析方法,并以长江汉口江段为例,开展了鄱阳湖汇流顶托对长江汉口江段水位影响的量化评价,结果表明:改进提出的长江汉口江段水文仿真模型,经参数优选后确定性系数可达0.98以上,总量相对误差绝对值在3%以内,较好地再现了水文变化过程;通过响应指数定义及水文过程模拟,研制了汉口多值型水位流量关系响应特征曲线,揭示了鄱阳湖与长江水位变化的关联性机制;经2016和2020年洪水实例分析,汉口江段长历时高洪水位主要受长江来水及鄱阳湖汇流顶托共同驱动,二者合力贡献可达83.3%以上,其中鄱阳湖汇流顶托贡献率在35%左右.其余因素(如区间洪水、沿江排涝等)亦助推高洪水位形成,部分时段贡献可达近34.4%.本文提出的顶托量化分析方法,可定量评估因顶托效应引起的水位变化,为解析河段高洪水位成因机制提供了有效的技术支撑.     

Effects of variable attribute weights on landform classification

This paper focuses on the attribute weight issue and advocates use of modi?able attribute weights in terrain‐based environmental analysis and classi?cation. A question was asked: ‘How much will the result of a terrain‐based environmental analysis be affected if the weights of used terrain attributes are changed?’ The literature on landform classi?cation and the fuzzy k‐means method was reviewed in particular to help clarify the background and importance of this weight assignment issue. As an example, the effects of modifying attribute weights were evaluated for fuzzy k‐means landform classi?cation in a case study area. A total of 102 classi?cations were compared with each other and with a soil map, and comparison methods were speci?cally designed to evaluate the differences between these classi?cations. The results show that fuzzy k‐means landform classi?cation is sensitive to weight adjustments of adopted terrain attributes. The sensitivity is particularly high when the attribute weights started to be tuned away from the standard (i.e. uniform) weight of one. Better matching between landform classi?cation and a soil map may be produced when attribute weights are tuned. In all, we advocate the widespread adoption of an exploratory attitude in assigning attribute weights for environmental analysis and classi?cation. Copyright © 2006 John Wiley & Sons, Ltd.     

发展与不发展南海扰动的能量收支与转换特征

利用多年逐月海温距平和区风应力距平观测资料,运用线性回归和ＥＯＦ分析方法,分析了ＥＮＳＯ相联系的热带太平洋典型风应力异常场结构。结果显示,与ＥＮＳＯ线性相关的风应力异常场在时间尺度上表现为低频变化,在水平结构上主要表现为四个典型分布。     

阳宗海冬瓜营古地震剖面(英文)

对冬瓜营古地震剖面研究的结果表明:阳宗海附近西支小江活断层上,近两千五百年以来至少发生过五次七级以上强震,它们的碳14年代分别为距今118±95年(b.p.)距今445±95年(b.p.);距今1347±213年(b.p.);距今1930±135年(b.p.);>距今2359±213年(b.p.)。其中,剖面记录的最晚两次古地震事件与历史记载的嵩明、宜良间1833年八级大地震和宜良1500年七级强震还能够相对应,说明该剖面记录的古地震事件可信度较高,具有一定的参考使用价值。     

Three-dimensional Q structure in Jiashi earthquake region of Xinjiang

3-D S-waveQ structure in Jiashi earthquake region is inverted based on the attenuation of seismic waves recorded from earthquakes in this region in 1998 by the Research Center of Exploration Geophysics (RCEG), CSB, and a rough configuration of deep crustal faults in the earthquake region is presented. First, amplitude spectra of S-waves are extracted from 450 carefully-chosen earthquake records, called observed amplitude spectra. Then, after instrumental and site effect correction, theoretical amplitude spectra are made to fit observed amplitude spectra with nonlinear damped least-squares method to get the observed travel time overQ, provided that earthquake sources conform to Brune’s disk dislocation model. Finally, by 3-D ray tracing method, theoretical travel time overQ is made to fit observed travel time overQ with nonlinear damped least-squares method. In the course of fitting, the velocity model, which is obtained by 3-D travel time tomography, remains unchanged, while onlyQ model is modified. When fitting came to the given accuracy, the ultimateQ model is obtained. The result shows that an NE-trending lowQ zone exists at the depths of 10–18 km, and an NW-trending lowQ zone exists at the depths of 12–18 km. These roughly coincide with the NE-trending and the NW-trending low velocity zones revealed by other scientists. The difference is that the lowQ zones have a wider range than the low velocity zones. Foundation item: Joint Seismological Science Foundation of China (957-07-414) and State Key Basic Research Development and Programming Project (95-13-02-02). Contribution No. RCEG200105, Research Center of Exploration Geophysics, China Seismological Bureau.     

丹东形变观测洞室改造

“十五”期间,为了新增水管仪、伸缩仪,丹东地震台对形变观测洞室进行了环境改造,新建了仪器基墩,解决了建造仪器基墩过程中遇到的施工难题,为水管仪和伸缩仪运行提供了良好的观测条件。文中介绍的方法对其他台站建造仪器基墩有一定借鉴意义。