Environmental magnetic and magnetic fabric studies in LakeWaynewood, northeastern Pennsylvania, USA: Evidence for changes inwatershed dynamics     

M.T. Cioppa  K.P. Kodama 《Journal of Paleolimnology》2003,29(1):61-78

An environmental magnetic and magnetic fabric study of sedimentscollected from Lake Waynewood, a post-glacial lake in the PoconoMountains of Pennsylvania, USA, provided a history of the lake's watersheddynamics over the past 3500 years. Two 5 m long, Mackereth coresof lake sediments and three watershed soil profiles were analyzed magnetically.Paleosecular variation and ¹⁴C measurements allowed timing ofchanges in the lake's watershed which are documented by changes in ARM,SIRM,, S-ratio, SIRM/, ARM/ and ARM/SIRMdowncore. Prior to 2900 years BP, there is little evidence for allogenicinflux. Dramatic changes in mineral magnetic properties and a strong AARmagnetic fabric appear approximately 2900 years BP, suggesting major changes inwatershed conditions, either in the hydrologic regime or in vegetative cover.Between 2900 and 1800 yrs BP, large variations in magnetic mineralogy areapparent, whereas about 1800 years BP, a single sediment source began todominate the magnetic mineralogy. About 100–200 years ago, conditionsagain changed, probably due to clearcutting and settlement of the watershed.Topsoil erosion appears to have dominated the magnetic signal. S and Mnconcentration downcore indicate that there is little evidence for reductiondiagenesis having caused the changes observed in magnetic mineral type andconcentration, except in the top 10 centimeters of the sediment column.  相似文献   

LANDSLIDE POTENTIALITY OF THE TSENGWEN RESERVOIR WATERSHED, TAIWAN     

Chin-yu LEE Professor  Department of Soil  Water Conservation  National Pingtung University of Science  Technology  Pingtung    Taiwan  R.O.C. 《国际泥沙研究》2004,(2)

To recognize the geographical characteristics of the landslide areas will be helpful for the watershedmanagement in the reservoir watershed. According to the quantitative analysis, we'll take differentscores and weighting for the potential parameters of the landslide areas in the Tsengwen reservoirwatershed, and in the meanwhile, we'll extract the different factors, including the slope, aspect,altitude, soil and geological textures etc., and the results shown as maximum one--day rainfall, ratio offorests and average relief is the most affecting parameters on the potential risk map of landslide areas.  相似文献   

评再版的《集水区经营》论丛     

冯海燕 《山地学报》2006,24(6):775-776

对再版的《集水区经营》论丛进行较详尽的评介。认为该论丛作者为水土保持研究和水土保持工作者提供了较为完整的、行之有效的集水区经营理念和借鉴模式,具有较高的指导性和可借鉴性。  相似文献   

Effect of climatic change on snowmelt runoffs in mountainous regions of inland rivers in Northwestern China   总被引：3，自引：0，他引：3  

WANG Jian  LI Shuo 《中国科学D辑(英文版)》2006,49(8):881-888

Snow is one of the most active natural elements of snow cover through its high albedo, variation of the the cryosphere on the earth surface. Its unique proper- snow cover distribution and frozen soils in regional ties, such as areal extent, surface albedo, and snow scales not only affect local climate and environments, depth are important parameters in global energy bal- but also feedback to large-scale, or even global cli- ance models. On global and terrestrial scales, a large matic change th…  相似文献   

Interbasin groundwater flow and groundwater interaction with surface water in a lowland rainforest, Costa Rica: A review     

David P. Genereux  Michael Jordan   《Journal of Hydrology》2006,320(3-4):385-399

This paper reviews work related to interbasin groundwater flow (naturally occurring groundwater flow beneath watershed topographic divides) into lowland rainforest watersheds at La Selva Biological Station in Costa Rica. Chemical mixing calculations (based on dissolved chloride) have shown that up to half the water in some streams and up to 84% of the water in some riparian seeps and wells is due to high-solute interbasin groundwater flow (IGF). The contribution is even greater for major ions; IGF accounts for well over 90% of the major ions at these sites. Proportions are highly variable both among watersheds and with elevation within the same watershed (there is greater influence of IGF at lower elevations). The large proportion of IGF found in water in some riparian wetlands suggests that IGF is largely responsible for maintaining these wetlands. δ¹⁸O data support the conclusions from the major ion data. Annual water and major ion budgets for two adjacent watersheds, one affected by IGF and the other not, showed that IGF accounted for two-thirds of the water input and 92–99% of the major ion input (depending on the major ion in question) to the former watershed. The large (in some cases, dominating) influence of IGF on watershed surface water quantity and quality has important implications for stream ecology and watershed management in this lowland rainforest. Because of its high phosphorus content, IGF increases a variety of ecological variables (algal growth rates, leaf decay rate, fungal biomass, invertebrate biomass, microbial respiration rates on leaves) in streams at La Selva. The significant rates of IGF at La Selva also suggest the importance of regional (as opposed to small-scale local) water resource planning that links lowland watersheds with regional groundwater. IGF is a relatively unexplored and potentially critical factor in the conservation of lowland rainforest.  相似文献   

LAND USE READJUSTMENT IN THE COMPREHENSIVE WATERSHED MANAGEMENT IN CHINA     

DING Lianzhen 《国际泥沙研究》1997,(1)

I.~onUCTIONChinaisamongthecountrieswhichsufferthemostserioussoilerosionintheworld.Soilconservationstudiesstartedearlyinthe1930's.AlterthefoundingofthePeople'sRepublicofChinain1949,moreeffortshavebeenmadetothesoilconservation.However,becauseofthecrucialnaturalconditionsintheseriouslyerodedregionsandtheimpactsofhumanactivitiesincludingthegrowthofPOpulationdensity,thesituationwasnotmuchimproveduntilthe1980's,whenthecomprehensivewatershedmanagementforsoilandwaterconservationwascarriedoutinlar…  相似文献   

UPLAND EROSION MODELING WITH CASC2D-SED     

Rosalía ROJAS 《国际泥沙研究》2002,17(4)

1 INTRODUCTION Erosion and sedimentation embody the processes of detachment, transport, and deposition of soil particles. Erosion and subsequent deposition can cause major problems. Erosion reduces productivity of cropland, sediment degrades water quality and may carry soil adsorbed polluting chemicals. Deposition in irrigation canals, stream channels and reservoirs reduces structural capacity and requires costly removal. Ideally, an erosion model should describe the physical processes…  相似文献   

基于DEM的流域水系分维估算方法探讨   总被引：16，自引：5，他引：16  

吕爱锋  陈嘻  王纲胜 《干旱区地理》2002,25(4):315-320

分形理论是现代数学的一个新的分支，是一种新世界观和方法论。分形理论与地学的结合，极大地推动了地理学的发展。介绍了分形理论在水文学研究中的应用和发展，介绍了利用Arc/Info，以DEM为数据源提取流域信息的方法。提供了一种将分形理论、GIS技术和流域地貌模型巧妙耦合，分别用基于覆盖法的分维估算方法和基于Horton定理的分维估算方法计算了马连河流域水系分形维数。这种方法与传统方法相比，具有易于操作、高效等优点。  相似文献   

流域科学研究中的观测和模型系统建设   总被引：6，自引：5，他引：1  

李新  程国栋 《地球科学进展》2008,23(7):756-764

流域是地球系统的缩微,是自然界的基本单元。流域科学从基础研究角度可以被看作是地球系统科学研究方法在流域尺度上的具体体现;从流域综合管理的应用角度看,流域科学是在流域尺度上通过对自然资源和人类活动的优化配置而为可持续发展服务的应用科学。流域观测系统和模型系统的建设是发展流域科学的前提。提出了建立遥感—地面观测一体化的、覆盖流域能水和生物化学循环及社会经济活动的流域观测系统的设想,规划了系统各组成部分,以高效、高分辨率、高精度、多尺度、集成和现代化为流域观测系统的基本衡量准则。流域模型系统可概括为“水—土—气—生—人”集成模型的发展,[JP2]应该科学目标和流域管理目标并重,既要发展具有综合模拟能力的流域集成模型,也要建成流域水土资源和社会经济资源可持续利用决策支持系统。流域集成模型应由分布式水文模型、陆面过程模型、地下水模型、渠系模型、动态植被模型和社会经济模型构成。  相似文献   

地理探测器方法下甘肃白龙江流域景观破碎化与驱动因子分析   总被引：6，自引：0，他引：6  

张金茜  巩杰  柳冬青 《地理科学》2018,38(8):1370-1378

基于GIS技术、景观格局指数、主成分分析和地理探测器的方法,定量分析了1990~2014年甘肃白龙江流域的景观破碎化及其驱动因子。结果表明：1990~2014年甘肃白龙江流域景观破碎化程度先增加后降低;研究期间流域东南部的景观指数变化最为剧烈和复杂,主要是文县和武都区;人类干扰（人类活动强度和土地利用类型）和地形因子（高程、坡度和坡向）对景观破碎化空间分异的影响显著不同,其中人类干扰是景观破碎化空间分异的主要驱动因子。  相似文献