甘肃东部引水灌溉工程引起的负效应及其防治

对甘肃东部引水灌溉工程引起的地面塌陷、滑坡、土壤盐渍化等负效应进行了分析,并提出了一定的防治措施.     

Oil spill fishery impact assessment modeling: The fisheries recruitment problem

A model to assess the impact of oil spill on fisheries, consisting of an oil spill fates model, a continental shelf hydrodynamics model, an ichthyoplankton transport and fates model, and a fish population model, has been applied to the Georges Bank-Gulf of Maine region to estimate the impact of oil spills on several important commercial fisheries. The model addresses direct impacts of oil on a fishery through hydrocarbon-induced egg and larval mortality. This early life stage mortality is estimated by dynamically mapping the spatial intersection of the surface and subsurface oil concentrations resulting from the spill with the developing eggs and larvae. Ichthyoplankton entering an area with hydrocarbon concentrations in excess of a specified threshold are assumed lost. Model output is given in terms of differential catch, comparing the non-impacted and the hydrocarbon impacted fisheries. Difficulties in establishing stock-recruit relationships, and the inability to predict first year survival even one year ahead make the quantification of absolute catch losses impossible. Output of the model system discussed here is therefore limited to relative rather than absolute catch losses.The paper is organized to demonstrate first the importance of the recruitment question to impact estimation, second that a modeling methodology is necessary to evaluate impacts given the magnitude of unexplained observed recruitment variability, and third a stochastic solution to the problem which places impact estimates in the context of a probability distribution. Lastly, the model system is applied to the problem of attaining better early life history mortality estimates, to ultimately improve impact estimation capabilities.     

Faroe Bank Channel overflow 1995–2005

The Faroe Bank Channel (FBC) is the deepest passage across the Greenland–Scotland Ridge and there is continuous overflow of dense water through the channel, which provides a substantial contribution to the global thermohaline circulation. Since November 1995, Acoustic Doppler Current Profilers (ADCPs) have been moored at the sill of the channel continuously, except for short annual servicing periods. In addition to this, CTD sections have regularly been occupied across the channel and instruments, recording temperature and salinity, have been moored for short periods. These observations demonstrate that the channel, due to its small width, can be monitored fairly well with only one ADCP mooring and they allow the generation of a time-series of overflow volume flux for the 1995–2005 period. The kinematic overflow flux, defined solely from the velocity field, was found to have an average value of 2.1 ± 0.2 Sv with a seasonal and with inter-annual variations of approximately 10% amplitude, but with no discernible trend for the whole period. The average flux of water with potential density exceeding 27.8 kg m⁻³ was found to be 1.9 ± 0.3 Sv with average properties: θ = 0.25 °C, S = 34.93, γ_θ = 28.01 kg m⁻³ for this period. No evidence was found for a weakening overflow flux, but the salinity of the FBC-overflow, especially the warmer parts, has increased substantially during the period, which implies an increased average density on the order of 0.01 kg m⁻³. Previous observations of a helical cross-channel circulation are confirmed and may explain the thin pycnocline layer, but shear-instability induces intensive mixing that puts a lower limit on the layer thickness. Critical control at one point of the sill cross-section, rather than friction, seems to govern the overflow dynamics and simple layered models can explain much of the observed features as well as the seasonal variation, but potential vorticity, as defined for a single overflow layer, is not conserved. A previously suggested 1950–2000 weakening of the FBC-overflow, which was partly based on a subset of the data presented here, is not supported by the full dataset.     

关于80年代闽南─台湾浅滩渔场中上层渔获量变动原因的初探

近来，1986年中上层渔获量达7．4333万t，1987年史创历史记录高达12．07万t，并且1983年（厄年）金色小沙丁鱼产量也达到1．9587万t，仅次于历史最高水平的1971年的产量，但到1988半的产量仅为2778t，占中上层渔获量3．21％，从而从历史上第一位下降到第4位[1]，如此渔获量变动，其原因何在呢？笔者试就从海洋环境变异，捕捞力度等诸因素合理解释中上层渔获量变功，为科学管理和合理开发中上层鱼类资源寻找理论依据。     

中国南方早中三叠世岩相古地理

在各基于剖面的地层学及定量岩石学研究的基础上,采用单因素分析综合作图法,编制出了中国南方早中三叠世飞仙关期(印度期)、嘉陵江期(奥伦期)、雷口坡期(安尼期)和天井山期(拉丁期)的各种单因素基础图件及定量岩相古地理图。在这种古地理图中,各一、二、三级古地理单元的确定都有定量的单因素数据为依据。各期岩相古地理的特征可概括为陆海相间,台盆相间,台中有盆,盆中有台,台中有滩和坪,台盆间有斜坡。各期岩相古地理有明显的继承性和发展性。从早三叠世飞仙关期到中2叠世天井山期,是一个较大的海退过程。这种定量的岩相方地理图,为中国南方中下三叠统的油气勘探提供了科学依据。     

山东平邑“12·25”石膏矿坍塌事故救灾中的水文地质保障

在山东平邑"12·25"石膏矿坍塌事故搜救过程中,为保证搜救人员和被困矿工免受水害,开展了水文地质应急调查,发现了新的充水水源和充水通道,通过高频率水位动态监测,准确确定了不同充水通道的渗漏状态。在此基础上,采取突水事故预警、充水水源疏干降压、采空区积水排放、封堵涌水通道(4号竖井)等针对性措施,保证了井下被困矿工和搜救人员免遭水害,幸存矿工在井下被困36天后经大口径钻孔成功提升获救。     

多道瞬态面波法与微动法联合推断岩溶塌陷区覆盖层的结构和厚度分布

为了大尺度范围内获取岩溶塌陷典型调查区覆盖层的结构和厚度分布,采用多道瞬态面波法与微动法,对柳州市柳城县东泉公社幅岩溶塌陷重点调查区进行了野外观测,根据微动法提取的特征频率与地层厚度的关系,结合已知钻孔资料,得出覆盖层厚度与特征频率的函数关系,获取了覆盖层的厚度分布,根据面波的频散特性,得出覆盖层的横波速度分布,获取了覆盖层的结构分布,结合得出的覆盖层结构和厚度分布,推断出测区内发育4条断层或溶沟等局部构造。研究表明,利用微动法提取的特征频率和面波的频散特性,可以有效地推断出塌陷区覆盖层的结构和厚度分布。      

基于地下水动力特征监测的岩溶塌陷预警阈值探索——以广州金沙洲岩溶塌陷为例

监测预警是岩溶塌陷地质灾害防治领域急需解决的技术难题。文章在总结当前岩溶塌陷监测预警研究现状的基础上,以广州金沙洲地区岩溶塌陷监测为例,通过对不同岩溶塌陷阶段地下水动力条件监测数据分析,发现数据异常值反映了不同工况地下水动态和岩溶塌陷发展阶段的突变关系,以此为基础,通过曲线拟合和残差分析确定了岩溶塌陷预警的置信带。通过对比分析异常值出现最多次数时间,最大及最小异常值出现时间和实际岩溶塌陷发生时间,验证了运用异常数据分析法进行岩溶塌陷预警是可行的,监测数据间隔越密,捕获的异常值越多,预警越准确。      

南宁地铁施工降水诱发岩溶塌陷条件及安全防控措施

抽排地下水是触发岩溶塌陷的重要因素,但抽排地下水诱发岩溶塌陷的临界参数及安全防控措施研究较少。文章以南宁市地铁4号线体育中心东地铁站为例,分析其施工降水诱发岩溶塌陷的条件。根据崩解试验及管道流试验,得出非饱和土体和饱和土体的岩溶塌陷发育临界条件参数,并提出地表阻水、控制土体含水量高于14.65%、控制抽水量小于4.4 m3· d-1 3种安全措施防止岩溶塌陷发生。