A test of TOPMODEL'a ability to predict spatially distributed groundwater levels

TOPMODEL was calibrated to a small catchment using precipitation and runoff data. Acceptable fits of simulated and observed runoff were obtained during both the calibration and validation periods. Predictions of groundwater levels using this calibration did not agree well with observations at the 37 points within the catchment where groundwater levels were measured, including three locations with continuous recordings. Groundwater level observations at one single point in time, however, sufficed to calibrate new topographic–soil indices that improved the prediction of the local groundwater levels at the observed tubes. This suggests that spatially distributed calibration data are necessary to exploit reliably TOPMODEL's ability to predict spatially distributed hydrology. The mean or recalibrated transmissivity values at these 37 points differed from the catchment mean as determined by the precipitation–runoff calibration. Thus, while groundwater information can help in predicting groundwater levels at specific locations, increasing the number of local groundwater level measurements is not sufficient to improve the spatially distributed representation of subsurface flow by TOPMODEL for the catchment as a whole, as long as the groundwater information is not integrated in the precipitation–runoff calibration. © 1997 John Wiley & Sons, Ltd.     

地壳分展模式

本文旨在综合分析早期经典的和近年来提出的陆壳的９种分层模式,既包括地球物理的,也包括构造变形、变质和物质成分的,指明它们之间的联系和区别。结合地质和地球物理的最新进展,本文对这些模式进行了评介,对莫霍面、下地壳组分及反射下地壳的地质意义提出了看法．这些模式,尤其是近年来提出的大陆壳分层的几种模式无疑对地质和地球物理学家进一步认识和了解陆壳的复杂地质作用、地壳和地球的演化及早寒武纪地质是有益的．     

Modelling groundwater level variations by learning from multiple models using fuzzy logic

Modelling time series of groundwater levels is investigated by three fuzzy logic (FL) models, Sugeno (SFL), Mamdani (MFL) and Larsen (LFL), using data from observation wells. One novelty in the study is the re-use of these three models as multiple models through the following strategies: (a) simple averaging, (b) weighted averaging and (c) committee machine techniques; these are implemented using artificial neural networks (ANN). These strategies provide some evidence that (i) multiple models improve on the performance of individual models and those using committee machines perform better than the other two options; and (ii) committee machine models produce defensible modelling results to develop management scenarios. The study investigates water table declines through management scenarios and shows that in this aquifer water use has higher impacts on water table variations than climatic variations. This provides evidence of the need for planned management in the study area.     

Is anthropogenic land subsidence a possible driver of riverine flood-hazard dynamics? A case study in Ravenna,Italy

We investigate possible changes in flood hazard over a 77-km² area around the city of Ravenna. The subsidence rate in the area, naturally a few mm year^?1, increased dramatically after World War II because of groundwater and natural gas extraction, exceeding 110?mm year^?1 and resulting in cumulative drops larger than 1.5?m. The Montone–Ronco river system flows in the southern portion of the area, which is protected against frequent flooding by levees. We performed two-dimensional simulations of inundation events associated with levee breaching by considering four different terrain configurations: current topography and a reconstruction of ground elevations before anthropogenic land subsidence, both neglecting and representing the main linear infrastructures (e.g. roads, artificial channels). Results show that flood-hazard changes due to anthropogenic land subsidence (e.g. significant changes in computed water depth and velocity) are observed over less than 10% of the study area and are definitely less important than those resulting from construction of the linear infrastructures.     

四级联动的海域使用管理信息系统建设关键技术研究

海域管理信息系统即是"数字海洋"八大业务系统之一,也是海域动态监视监测系统建设的核心内容。论文在明确四级联动海域使用管理信息系统建设目标的基础上,提出其总体结构,然后探讨其实现的关键技术,即坐标统一问题、数据存储备份问题、海量数据传输与共享、视频数据获取与远程指挥和多S集成等。     

Derivation and application of new equations for radiation stress and volume flux

In this paper, new expressions of radiation stress and volume flux for long waves have been analytically derived by inclusion of higher-order surface elevations up to the sixth-order. To quantify these expressions, surface elevations along a beach are first simulated using the fully nonlinear Boussinesq-type model COULWAVE. Then, based on the large amount of numerical data, new equations for radiation stress and volume flux are statistically formulated. The research unveils the essential roles of the Ursell parameter, Irribarren number and wave steepness described by the local wave height, wave length and bottom slope. The study shows the importance of nonlinear wave properties in wave-induced currents and mean water levels (set-up/down). The higher-order formulations produce lower values for radiation stress and volume flux than calculated from the lower-order and linear waves. Case studies suggest that the new formulations produce an accurate estimation for mean water level. However, improvement on the computed current profiles is marginal for some cases. This implies that the accurate prediction of the current profile would require more than just the proposed improvement of the radiation stress and volume flux.     

台湾海峡及邻近海域主要无脊椎动物食性特征及其食物关系研究

对台湾海峡及邻近海域14种主要经济无脊椎动物的胃含物进行了鉴定分析。结果表明：这些无脊椎动物对饵料生物无明显的选择性，均为混合食性。其食性类型可分为：游泳生物食性类型、游泳动物和底栖动物混合食性类型、底栖生物和浮游动物食性类型、底栖生物食性类型、浮游动物和游泳动物食性类型。10种甲壳动物和4种头足类的营养级范围分别为1．64～2．60级和2．04～2．88级。除周氏新对虾(Metapenaeus joyneri)、角突仿对虾(Parapenaeopsis cornuta)和鹰爪虾(Trachypenaeus curdrostris)属第二营养层次的杂食性动物外，其它的均属第三营养层次的肉食性动物。拥剑梭子蟹(Portunus haanii)、秀斑好(Caarybdis feriatus )、哈氏仿对虾(Parapenaeopsis harduickii)和杜氏枪乌贼(Loligo duvaucelii)的食物生境宽度较大，它们对各种饵料生物的利用更趋均衡。4种头足类之间、3种蟹类之间食物重叠显著。长尾类、短尾类、鱼类和腹足类是台湾海峡主要无脊椎动物营养层次能量传递中的关键功能类群。     

渤、黄、东海高营养层次重要生物资源种类的营养级研究

利用2000年和2001年2次大面调查所收集的11970个胃含物样品分析结果,计算了黄海和东海生态系统高营养层次35个重要生物资源种类的营养级,同时,结合对渤海和黄海39个种类营养级历史数据的修正,讨论研究了我国海洋高营养层次生物资源种类营养级的研究策略和计算方法。主要研究结果为：(1)渤海重要生物资源种类营养级的变化范围为3．12～4．9,黄海为3．2～4．9,东海为3．29～4．55。近年来各海域高营养层次的营养级呈下降趋势,如渤海从1959年的4．1下降到1998～1999年的3．4,黄海从1985～1986年的3．7下降到2000～2001年的3．4;(2)高营养层次营养级波动主要是由于群落种类组成变化及单种类营养级年间波动引起的,而单种类营养级年间波动又直接与群体个体变小以及摄食食物的低营养层次化有关。因此,高营养层次的营养级变化是认识海洋生态系统生物生产动态的重要指标,需要对其进行长期和系统的监测;(3)建议在今后的研究中,根据简化食物网的概念,对占生物量绝对多数的重要生物资源种类的营养级进行重点研究并采用国际通用的标准划分计算营养级。     

Hydrological identification of drought

The problem of drought identification is considered from a primarily hydrological viewpoint. The problems related to the definition, identification and prediction of drought have not yet been solved. Although rainfall data are analysed as the main indicator and characteristic of drought, other characteristics resulting from a rainfall deficit are also important. A time unit of one month was selected as the most suitable for analysis. Special attention was paid to the selection of truncation levels with respect to their influence on the results of drought identification. Three methods for drought identification were applied to a series of monthly rainfall data in Osijek from January 1882 to December 1990: (1) run analysis; (2) a discrete Markov process; and (3) the percentile method. Although the results of these three methods are encouraging, different methods yielded similar results. Some drawbacks of the application of distribution curves are discussed. Drought events should be identified using a number of different procedures.     

Relict shoreline features at Cockburn Island,Ontario

Cockburn Island, Ontario (45°55′ N, 83°20′ W), holds at least six sets of elevated lake bluffs, scarps and bar deposits that mark distinctive water planes above the Nipissing Great Lakes water plane (∼198 m). These relict shoreline features occur at elevations that correspond closely with the elevations of others at nearby St. Joseph Island and in eastern upper Michigan. Together, the elevations and relative locations of steep relict bluffs suggest a proto-Cockburn Island once interrupted the surface of proglacial Lake Algonquin. The islet appears to have emerged and grown through a period of uplift and a sequence of lowering water levels. The highest relict shoreline (280.2 m) is correlated with the Main phase of Lake Algonquin. Lower shorelines at Cockburn Island cannot be correlated consistently, so additional work is required. This is the seventh in a series of ten papers published in this special issue of Journal of Paleolimnology. These papers were presented at the 47th Annual Meeting of the International Association for Great Lakes Research (2004), held at the University of Waterloo, Waterloo, Ontario, Canada. P.F. Karrow and C.F.M. Lewis were guest editors of this special issue.