数据同化在海洋生态模型中的应用和研究进展

将数据同化方法引入海洋生态系统动力学模型研究,利用现有的观测数据,获得最佳的模式参数、初始场或提高状态模拟,是当前多学科交叉研究的热门领域。本文依据国内外研究进展,主要就海洋生态模型研究中所采用的变分伴随、卡尔曼滤波、模拟退火法方法进行了介绍,总结了数据同化在我国的海洋生态系统研究中的现状和发展趋势。     

营口港扩建工程悬浮物对海域环境影响分析

以营口港扩建工程为例,在潮流模拟计算基础上,利用悬浮物扩散模型分析论证了海域施工过程中悬浮物对海域水质及海洋生物的影响。结果表明:施工期对悬浮物影响范围仅局限于港区防波堤范围内,对港区外海域环境影响较小。     

0509号台风暴雨过程分析与暴雨灾害评估

针对2005年8月8～10日辽宁区域性台风暴雨过程,以常规气象资料、自动站资料及卫星云图资料为基础进行分析。结果表明:暴雨是台风、副热带高压与西风槽相互作用的结果,较好的水汽条件是产生台风暴雨的重要条件之一,低空急流是水汽输送的通道,也是台风暴雨的明显特征之一;结合单站气压连续变化以及云系变化判断“麦莎”登陆时间地点;应用基于概率分析的暴雨事件快速评估模型对暴雨灾害进行评估,评估表明暴雨过程为三级暴雨灾害,属中度级别。     

新疆生态系统健康遥感评估及关键驱动因子研究

作为我国陆地面积最大的省级行政区,新疆维吾尔自治区具有多样的生态系统结构和丰富的动植物物种资源,是我国西北地区重要的生物多样性热点研究区域.通过以新疆维吾尔自治区为研究对象,结合区域特点和定量遥感数据实时、易获取、周期性等优势,选取归一化植被指数、动物物种丰富度、干旱度、人类扰动指数四类单因子指标,依据"活力-组织-恢...     

Ring foundation on elastic subgrade: an analytical solution for computer modelling using the Lagrangian multiplier method

In the practice of geotechnical engineering, the case of a ring footing carrying a set of concentrated point loads is a common problem. At times, the induced vertical and angular displacements for the ring footing need to be evaluated at a relatively precise level. By making use of the governing set of equations derived for the case of a general curved beam, expressions that can be easily implemented in modern computing software are derived for the vertical and angular displacements of a ring footing of rectangular cross section as functions of the radial position. The loading case considered is a vertical point load, and the soil is modelled as elastic. Estimates of the displacements have been shown for a common range of practical applications. The behaviour for a set of concentrated loads may be evaluated using the derived equations through direct superposition. Nonlinear finite element analysis is used to evaluate the vertical deflection and angular twist of the ring foundation. Numerical analysis performed for three ring foundations with different radii and cross sections is reported to validate the accuracy of the derived analytical solution. Copyright © 2016 John Wiley & Sons, Ltd.     

Towards developing sediment quality assessment guidelines for aquatic systems: An Australian perspective

Sediment at the sediment‐water interface of natural and man‐made waterways forms an integral part of the ecosystem because it is affected by a continuous flux of physical, chemical and biological components between the sediment, interstitial water and the overlying water column. Aquatic sediments contain records of past and present urban and rural runoff, chemical discharges and spills. In recent years sediment quality has received increasing attention following identification of the role of sediment as both a sink for pollutants and as a contaminant source with potential impacts on the quality of receiving waters. Research has indicated that the processes leading to remobilization of contaminated sediments in upstream reaches of a waterway may, through time, exert a significant influence on water quality in the downstream reaches. This, together with the cumulative effects due to contaminant input from point and non‐point source discharges, have dramatic effects on water quality and thus on ecosystem structure and functioning.

The problems associated with elevated concentrations of many hazardous organic and inorganic compounds have resulted in the establishment of aquatic sediment quality criteria and management guidelines in many overseas countries, with the objectives being the reduction and elimination of adverse environmental effects and human health risks associated with contaminated sediments. Whereas more than 70% of the Australian population is clustered around the coastal waterways, little is known about the role of sediments as a repository of environmental pollutants and/or as a source of adverse impacts on water quality and the health of our rivers. The paucity of knowledge on the quality of aquatic sediment highlights the need for the development of coherent guidelines for sediment quality assessment and management of contaminated sites, which are consistent with Australian environmental conditions and land use features.

A comparative evaluation of sediment quality information from eight coastal rivers along the east coast of Australia, presented in this paper, indicates the possibility for establishing a framework for regional sediment quality assessment. This may be achievable by using textural and compositional attributes of bottom sediments in depositional areas to develop databases on the loading and concentration trends of nutrients and contaminants. Regional variability in sediment quality determinants are shown to reflect the influence of catchment hydrology, lithology and land use on nutrient and contaminant concentration trends. Locally, the loading and partitioning behaviour of sediment‐bound contaminants is largely controlled by the nature and the extent of interactions occurring at the sediment‐water interface within individual depositional units.

The concept of ‘Sediment Effect Zone’ is introduced to provide a compartmental approach to the characterization of aquatic sediments and depositional environments in different hydrologic zones. This approach offers a rational basis for follow‐up chemical and biological assessments to establish sediment quality standards and management guidelines. Because of the complex influences of environmental, methodological and statistical factors on defining the sediment variability, the need for implementing proper quality control measures from early stages of design of a sediment quality assessment program is highlighted.     

PRINCIPES FONDAMENTAUX DE LA THEORIE DU MOUVEMENT DES EAUX SOUTERRAINES

ABSTRACT

In southeastern Arizona, almost all summer rainfall results from widely-scattered high-intensity afternoon or evening thunderstorms of limited areal extent. For eleven years of record on the Walnut Gulch Experimental Watershed, Tombstone, Arizona, about 70 percent of the annual rainfall of 11 1/2 inches and over 95 percent of the annual runoff occurred in July, August, and early September. In contrast, about 5 percent of the rainfall occurred in the previous 3 months, and about 25 percent in the remaining 6 1/2 months.

Therefore, summer rainfall, although highly variable, represented the most dependable source of water to the Walnut Gulch watershed. On the average, significant rainfall was recorded on some part of the watershed on 40 percent of the days in the critical July-August period. The maximum frequency was 3 out of every 4 days in 1955, and the minimum 3 out of every 10 days in 1960.

The wettest year was 1955, with a continuous rainy period of 47 days; whereas, the driest was 1960, with the longest rainy period lasting only 5 days. The longest summer drought during the period of record occurred in 1962, when no rain fell for 17 days in August, following a 14-day rainy period in late July.

As yet, there are not enough data to determine reliable expectancies for summer rainy or drought periods.     

Organic matter of the Mulhouse Basin, France: a synthesis

The lower Oligocene evaporite sequence of the Mulhouse Basin (France) contains organic matter-rich marl deposits. These marls display an overall cyclic variation of sedimentation rate, organic carbon content, hydrogen index and selected molecular parameters over a 30 m thick stratigraphic interval. The integration of all sedimentological and geochemical parameters has allowed the reconstruction and characterization of the paleoenvironment of deposition. The marls were deposited in a perennial lake that was at times connected to the sea. Two organic facies end members could be assigned to a lake stage with a marine connection and a lake stage that received dominantly continental water input. The overall stratigraphic variation in the organic matter content is interpreted to reflect the adaptation of the Oligocene flora to the changing paleoclimate and environmental conditions.     

层状含水系统R—C电网络模拟方法

本文论述了R-C电网络模型的基本原理及模拟装置,分析了不同类型的层状含水系统。根据榴似性原理,建立了不同类型的电网络模型。在此基础上,预测了内蒙古某露天煤矿的矿坑疏干涌水量,取得了比较满意的结果。