A preliminary study on sediment flux in the Changjiang Delta during the postglacial period

During the last 7000 years since the Changjiang Delta was formed, how much sediment brought by the Changjiang River remained in the modern Changjiang Delta? And how much sediment was delivered into the sea and adjacent coasts? These are very important que…     

Magnetic properties of tidal flat sediments of the Yangtze Estuary and its relationship with particle size

Since the 1970s, environmental magnetism has found extensive applications in diverse research areas of geoscience[1]. In China, a lot of environmental magnetic studies have been carried out on loess, lake and marine sediments for the purpose of paleoclima…     

CLOBAL CHARM OF THE CHANGJIANG RIVER DELTA

1SPLENDOROFHISTORICALCULTURE InChina,theChangjiang(Yangtze)RiverDelta①gen-erallymeansanadvancedproductivityandculture,whichaffectsdeeplynotonlythewholeChinabutal-sotheAsian-Pacificregion,evenEuropeandAfrica. 1.1CradlefortheCommunicationandPropagationofCivilization ThedevelopmentcourseoftheChangjiangRiverDelta'scultureisdevious,buttheNeolithicHemuduCultureexcavatedinYuyaoCityofZhejiangProvinceindicatestheadvancedpaddyriceculture;MajiabangCulture5000aB.P.andEastBridgeRuin…     

Application of swat model in the upstream watershed of the Luohe River

1INTRODUCTIONIntheHuanghe(Yellow) Riverbasin, soilerosionisaseriousproblem,whilerunoffandsedimentyieldsim-ulation hasnotbeenextensivelystudiedonthebasisofGIS(GeographicInformationSystem) and dis-tributedhydrologicalmodel.Inthisstudy,theLushiwatershed,whichislocatedattheupstreamoftheLushiHydrologicalStationintheLuoheRiver—thebiggesttributary oftheHuanghe Riveranddown-streamofXiaolangdiDam,isselectedasthestudyarea.ThelevelofsoilerosioninLushiwatershedismoderatein theHuangheRiverbas…     

发展我国知识经济的理论思考

发展我国知识经济 ,必须以邓小平“科学技术是第一生产力”思想为理论基石 ,符合社会主义市场经济特征的激励知识创新活动的“经济组织”为基本前提。在此基础上 ,构建起符合我国国情的由相互联系、制约和影响的九大要素为基本框架的知识创新机制 ,是当前社会经济环境条件下的最优制度安排。     

“新经济地理学”与经济地理学的分异与对立

最近几年来,由于经济全球化的趋势,西方经济学家又开始对经济地理学产生兴趣。“新经济地理学”或“地理经济学”应运而生。首先介绍经济学家克鲁格曼的“新经济地理学”理论框架和方法,综述西方地理学家对所谓“新经济地理学”的评价,最后概述经济地理学最近的发展以及地理学家对新经济地理学理解。     

中扬子区海相沉积盆地性质研究

分析了中扬子区海相沉积盆地基底和层序充填特性;研制了M判别图解,研究了沉积盆地的性质,认为盆地基底具有三分性,盆地层序充填具有阶段性和分区性,沉积盆地主体具有克拉通盆地的特点和性质。     

嘉陵江流域水保治理前后沿程水沙变化研究

嘉陵江为长江上游重要支流,是长江三峡水库重要的洪水和泥沙来源地。20世纪50年代初至80年代末,多年平均径流量701亿m3,多年平均悬移质输沙量近1.4亿t;“长治”工程的实施,对控制流域水土流失起到了较为明显的积极作用。以流域内主要控制站大量的实测水文气象资料为依据,重点研究了全流域水保治理前后的水沙变化情况及规律。     

A River Water Quality Model for Chlorophyll and Dissolved Oxygen that Accommodates Zebra Mussel Metabolism

The development, testing and application of a dynamic two-dimensional (longitudinal-vertical) mass balance model for dissolved oxygen (DO) and chlorophyll (Chl) for rivers is documented that for the first time accommodates both the oxygen demand and filtering effects of zebra mussels. The test system is a phytoplankton-rich section ( 15 km long) of the Seneca River, NY, that is believed to represent an upper bound of the impact of this exotic invader. Changes in common measures of water quality of the river brought about by the zebra mussel invasion are reviewed and related longitudinal patterns in DO, Chl, and Secchi disc transparency are documented. Model testing is supported by comprehensive measurements of DO, Chl, and various forcing conditions over a three-month period, and independent determinations of several model coefficients. Wide variations in the areal consumption rate of DO (ZOD; g·m^–2·d^–1) and filtering rate (m³·m^–2·d^–1) of zebra mussels, as determined through model calibration, occurred over the study period. Values of ZOD in areas with dense zebra mussel populations at times (e.g., > 50 g·m^–2·d^–1) were an order of magnitude greater than the sediment oxygen demand associated with organically enriched deposits. The value of determinations of these fluxes from model calibration procedures is evaluated within the context of the limitations of protocols presently available to support independent specification of these rates. Model analyses are conducted to evaluate the relative magnitude of source and sink processes for DO and Chl, the potential operation and implications of feedback from low DO levels on oxygen consumption by zebra mussels, and the sensitivity of model simulations to selected sources of uncertainty and variability. Model projections of oxygen resources of the river are presented in a probabilistic format in evaluating reductions in zebra mussel biomass that would be necessary to eliminate violations of standards and regain assimilative capacity.