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BJARNE HOLM JAKOBSEN M.Sc. 《Geografisk tidskrift / udgivet af Bestyrelsen for Det Kongelige danske geografiske selskab》2013,113(1):17-32
Jakobsen, Bjarne Holm: Pedoiogisk kortlægning og jordbundsbonitering i et geestrandområde ved Tønder. Geografisk Tidsskrift 81: 17–32. København, Juni 1, 1981. The result is presented of a detailed pedological survey of the geest at the margin of the Tønder Marsh-Area. Maps showing the parents sediments, the pedology and the drainage class have been constructed. Furthermore a soil capability map is shown using the land valuation principles of the Federal Republic of Germany. 相似文献
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苏北潮滩湿地植被对沉积物N、P含量的影响 总被引：20，自引：7，他引：13
文章对比分析了植被和沉积物中N、P垂向分布和季节变化,探讨不同植被对潮滩湿地N、P动态变化的影响。分析表明:潮滩湿地的分带性差异使N、P在潮滩湿地各地带有不同的分布规律和季节性变化特性,植被尤其是有较高地下生物量的互花米草和芦苇在整个潮滩湿地N、P的分布以及季节变化中起重要作用,潮滩植被主要是通过N、P在体内的主动转移,植物对沉积物中N、P的吸收以及富集死亡的地下根茎中分解矿化后释放的N、P来影响沉积物中N、P分布的; 1~4月通过枯落生物量回归到地面的N、P总量分别达到149.4 t和18.2 t,对整个湿地生态系统的生源物质循环以及生态环境产生很大影响。 相似文献
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根据石码站1980年以来多年潮位统计资料,分析九龙江口南港潮位变化及其原因．结果表明,近十多年来,南港低潮位持续下降,而高潮位变化不大,2005年平均潮差达4．0m以上．大量挖取砂和径流量减少是导致低水位下降的主要原因．南港已成为受潮汐影响明显的河口潮流段,其深度基准面应按照海区性质,选用理论最低湖面． 相似文献
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基于非结构三角形网格的FVCOM(Finite-Volume Coastal Ocean Model)海洋数值模式,对白令海峡及其邻近海域的潮汐、潮能进行数值模拟研究。模拟结果同验潮站和实测海流资料符合良好,较好地反映了白令海峡及其邻近海域的潮汐、潮流分布特征和运动状况。根据计算结果绘制了主要分潮的同潮图和潮流椭圆图,对该海域潮汐潮流特征进行了系统分析。结果表明,白令海陆架区、白令海峡和楚科奇海主要以M2分潮为主,而在诺顿湾海域以K1分潮为主,M2分潮潮流在白令海陆架东南部及阿纳德尔湾较强,K1分潮潮流在诺顿湾潮流达到最大值。在此基础上,对其潮汐能的传播与耗散进行分析,结果发现研究海域潮能通量较小,主要分潮在研究海域潮能耗散总量约为751 MW,M2潮能耗散占该总量的52%,K1潮能耗散占38%,潮能进入白令海陆架后,M2分潮主要在圣劳伦斯岛以南陆架区耗散,K1分潮主要在诺顿湾海区耗散。 相似文献
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黄河三角洲潮滩潮沟近期变化遥感监测 总被引：13，自引：1，他引：12
作者选用1986年和2001年两个时相的Landsat TM/ETM+影像,结合遥感、地理信息系统 (GIS) 和分形理论研究了黄河三角洲典型河口岸段潮滩潮沟的发育演变。结果表明：近15年来,挑河口~106站和现行水河口(1976~1996年黄河入海口,下同)~甜水沟岸段分维值D增大,呈顺向演替;其余岸段分维值均减小,表现为逆向演替。人工围垦挤占了大面积潮滩,人工岸线不断向海扩展,其最大推进速率达0.8 km/yr;同时,潮沟长度缩短,最严重的岸段每年减少14.9 km。通过分析表明,人类活动已成为影响三角洲潮滩发育的重要因子,其导致整个三角洲的潮滩体系严重退化,自然形成的潮沟时空谱系不复存在;另外,发育时间长短、入海泥沙、海浪和潮流对潮滩发育演变亦非常重要。目前,黄河三角洲潮滩可分为河口滩、潮控滩、浪控滩和人控滩4大类型。 相似文献
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根据历史和实测资料研究慈溪市海岸变化过程及其成因,结果表明:1)距今约2 500 a慈溪全境已形成南丘北海、中部为滨海平原的地貌格局;2)慈溪滩涂属于淤涨型滩涂,自宋代以来已修建11道海塘,新中国成立前海岸线平均每年向外推移25 m,之后则达到50~100 m;3)慈溪滩涂形成演变的影响因子包括地形约束、河川径流和人类活动等,近代人类活动的作用强度越来越大;4)西三闸附近涨潮潮位增高和庵东滩面淤高、扩大是西三潮沟形成的主要动力因素,其诱因是大规模的人类活动。西三潮沟的整治原则应是“因势利导,围涂治沟”。鉴于目前西三潮沟东西两侧都已完成直堤工程,建议在钱塘江连续丰水年时抛石筑坝,彻底截断西三潮沟。 相似文献
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中国海陆过渡带——岸海洋环境特征与变化研究 总被引：7，自引：2，他引：5
海岸海洋是陆地与海洋过渡的地带,位居亚洲与太平洋之交的中国海岸类型丰富,河海交互作用与人类活动影响使海岸海洋环境与作用过程独具特色.河流的贯通作用,使得全球变化与人类活动对河流流域的作用,亦在海岸海洋地区表现出来,并对海洋环境形成显著的影响.历史与现实实例表明,在海岸海洋的开发利用中需重视研究海陆交互过渡带环境特征,尽... 相似文献
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Effect of the Earth's ellipticity on the lunar tidal potential 总被引：1，自引：0，他引：1
R A. Dahlen 《Geophysical Journal International》1993,113(1):250-251
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An ephemeris for gravity tide predictions at the nanogal level 总被引：3，自引：0，他引：3
J. B. Merriam 《Geophysical Journal International》1992,108(2):415-422
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A. Palumbo 《Geophysical Journal International》1986,84(1):93-99
Summary. A method for the determination of lunar and solar daily components of earthquakes is proposed. Its application to the most intense earthquakes with epicentres in Italy (from 1900 to 1983) provides for the first time large and significant lunar and solar tidal terms. The absence of significant results from the analysis of 9157 world-wide large shocks processed according to the proposed method and to routine spherical harmonic techniques indicates that the Italian earthquakes are locally tidally triggered. 相似文献
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长江口拦门沙河段潮滩表层沉积物分布特征(英文) 总被引：2，自引：0，他引：2
Sediment samples with high spatial resolution (432 samples in total) and flow data were collected on the tidal flats in the mouth-bar region of the Yangtze Estuary. The data was collected in July 2005, July 2006 and May 2007. The samples were analyzed with a particle sizer, resulting in the sediment distribution. The grain sizes and related parameters were analyzed. The results were presented in a ternary diagram. The sediment mainly consisted of sand, silty sand, sandy silt, sand-silt-clay, silt and clayey silt. And sand skeletons and clay matrices were found. At Nanhui Shoal, silt skeletons could be identified as well. Furthermore, the results were discussed per shoal. Although some depth dependencies were found per shoal, no general relation was found. The results are as follows: sediment located at these tidal flats of the Yangtze Estuary was mainly composed of sand, silty sand and silt. The median grain size in sediment was relatively complex with a range from 2.5 φ to 8 φ. The distributions of sorting coefficients ranging from 1 to 2 were in agreement with median sizes. It was suggested that sediment of the tidal flats was coarser and better sorted or finer and worse sorted. The skewness in sediment distribution varied from 0.1 to 0.8. In addition, the distributions of sorting coefficient and skewness in sediment at Chongming Eastern Shoal, Hengsha Eastern Shoal and Jiuduan Shoal were of similar characteristics because there were closely positive correlated relationships among these parameters. However, due to the location difference between Nanhui Southern Shoal and Eastern Shoal, the values of sorting coefficient and skewness had relatively large distinctions. The tracks of sediment transport could be described based on the distributions of sediment, which might reveal sediment transport controlled by two dominant hydrodynamic factors of current and wave. It was appreciable that coarser sediment with lower sorted coefficient was affected by dominant ebb current action and intense wave action resulted from rapidly dissipated wave energy. Moreover, due to the effects of obstructed branches, guided current and broken wave actions of the Deep Water Channel Project, grain-size in sediment located at two sides of the groyne was of uneven distribution characteristics. 相似文献
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《Norsk geografisk tidsskrift. Norwegian journal of geography》2012,66(2):65-73
In a sloping hay meadow, situated on phyllitic soils in the fjord region of western Norway, shade from solitary trees in the lower meadow and from high tree cover on the upper slopes has reduced the number of indicators of traditional management, which include vulnerable hay-meadow species. However, the number of additional species, for example, forest species, was higher in shade from solitary trees than in the open; the areas under the crowns may have functioned as refuges for forest species in former days, when wooded hay meadows, comprising small woodlots, solitary trees and shrubs, were widespread in the region. Indicators of traditional management were more frequent in dry plots than in moist plots, but most species in this group occurred in moist plots too. To keep the habitat area for these species as large as possible and at the same time restore the former well-managed tree-layer of the meadow, the removal of large Fraxinus excelsior and Alnus incana specimens from the upper slopes and reduction of the crowns of solitary Taxus baccata and Prunus domesticus on the lower slopes is recommended. 相似文献
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Integrating remote sensing, geographic information system (GIS) and fractal theory, change characteristics of tidal flats and tidal creeks in the Huanghe (Yellow) River Delta over the period of 1986-2001 were discussed. The results show that evolutions of tidal fiats throughout the Huanghe River Delta are influenced by various factors, and that progressive succession and regression of tidal flats concur in different coastal segments of the delta. Human activities have played an increasingly important role in the succession process of tidal flats. Due to land reclamation in coastal zones of the delta in the last 15 years, lots of tidal flats were occupied, the artificial coastline migrated seaward (the maximum change rate was 0.8 kmyr^-1) and tidal creeks became sparser (the highest decreasing rate of length of tidal creeks was 14.9 kmyr^-1). Except for two coastal segments from the Tiaohe Estuary to the 106 Station and from the south of the Huanghe River mouth to the north of the Xiaodao River Estuary,fractal dimension values of tidal creeks in the remaining coastal segments of the delta decreased. In addition, the time dimension, sediment fluxes into the sea, waves and tidal-currents have profound influences on the evolution process of tidal flats. Four types of tidal flats-river-dominated tidal flats,tide-dominated tidal flats, wave-dominated tidal flats and man-dominated tidal flats can be identified.Owing to the intensification of human activities in coastal zones of the delta, man-dominated tidal flats have become the main kind of tidal flats. 相似文献
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1987年8月—31日在剑桥大学地球科学院分别举行了地质及固体地球物理工作组会议及混合会议.两天的会议主席都由新西兰人担任.地质工作组会议内容包括:1.开幕.自我介绍;2.圣迭戈会议提案采纳及执行情况;3.本次会议新议题:a.地质制图,主要确认专家组会议提出的协调分工、统一图例、在大剖面协作中统一比例尺等事项;b.地圈—生物计划设想;c.南极地球科学研究回顾与展望;d.工作组向SCAR的年度报告;4.第5届国际地球科学讨论会总结;5.第6届国际南极地球科学讨论会,审议了日本在圣迭戈会议上提出的建议,经表决同意下届讨论会将于1991年在日本东京或其他城市举行(原建议为1992年),并通过了讨论会内容及分组方法;6.各成员国国家年度报告;中 相似文献
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大、小潮日闽江口短叶茳芏+芦苇沼泽甲烷排放通量日变化特征 总被引：2，自引：0，他引：2
利用"静态箱-悬浮箱-气相色谱法",分别在小潮日(2010年4月4～5日和9月2～3日)和大潮日(2010年4月14～15日和9月9～10日),在闽江口鳝鱼滩湿地的中高潮滩过渡区短叶茳芏(Cyperus malaccensis)+芦苇(Phragmites australis)沼泽中,取样并测定了该沼泽24h的甲烷排放通量,并同步对潮水水位、温度等环境因子进行了观测。研究结果表明,不论大、小潮日,总体上,沼泽是甲烷排放源,白天的甲烷排放通量大于夜间;4月、9月的2个小潮日的甲烷排放通量分别为4.43mg/(m2·h)和8.13mg/(m2·h),2个大潮日的甲烷排放通量分别为1.39mg/(m2·h)和3.25mg/(m2·h),小潮日甲烷排放通量明显大于大潮日;大潮日,涨落潮阶段的沼泽水-气界面甲烷排放通量低于非涨落潮阶段;温度和潮水水位是控制甲烷排放通量日变化的重要环境因子。 相似文献
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江苏沿海滩涂围垦耕地质量演变趋势分析 总被引：11，自引：1，他引：10
淤涨型沿海滩涂作为中国重要湿地和耕地后备资源,承担着生态保护、社会保障、经济发展等多重服务功能。选取江苏中部淤涨型滨海滩涂开展实证分析,分析围垦年限为0~40年滩涂垦区耕地质量因子空间差异,采用“时空代换”方法揭示滨海滩涂围垦后耕地质量的演变趋势,为沿海滩涂围垦区耕地资源可持续利用提供决策参考。结果表明：江苏中部沿海滩涂土壤总体呈现盐碱度高、养分贫瘠等特征且土壤理化性质变异程度高,土壤质地呈现显著南北和陆海梯度特征。滩涂垦区围垦初期地形、植被状态和围垦后滨海滩涂转变为耕地路径对耕地质量演变趋势均具有重要影响。沿海滩涂转为耕地路径由垦区自然条件、开发主体、开发规模等因素共同作用,江苏中部沿海滩涂转为耕地路径已从“盐生植被→养殖水体→耕地”转变为“盐生植被→耕地”,该转变缩短了滩涂转为耕地的周期,但同时也带来围垦滩涂撂荒闲置现象。围垦后沿海滩涂土壤逐步向耕地土壤转变,耕地质量因子演变趋势可分为四种：上升型,如土壤全磷、有效磷、粘粒含量;下降型,如土壤砂粒含量;下降—上升型,如有机质、全氮、碱解氮和CEC;上升—下降型,如土壤盐分和pH。围垦初期,滩涂土壤脱离海水环境,土壤有机质发生矿化过程呈现下降趋势,土壤盐分和pH受到蒸发和蒸腾作用急剧上升;围垦中期,受到人类耕作作物秸秆等有机物输入以及施肥的影响,土壤有机质、养分等呈现上升趋势,土壤盐分和pH呈现下降趋势;围垦后期,耕地质量因子受到耕作管理影响存在一定幅度的波动,由于沿海滩涂垦区耕地形成时间短,耕地质量对耕作管理等因素敏感度高。 相似文献
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P. M. Davis P. A. Rydelek D. L. Agnew A. T. Okamura 《Geophysical Journal International》1987,90(1):233-244
Summary. We have analysed the east-west tilt components, O1 , K1 , N2 , M2 and S2 from a continuously recording tiltmeter located in Uwekahuna Vault on Kilauea Volcano, Hawaii, for the period 1971—79. Detailed analysis of the M2 component gives values of 30.9 ± 2.0 (95 per cent) nrad and 116.0 ± 2.0° for the amplitude and phase, respectively, compared to values of 48.5 nrad and 139.4° for the equilibrium tide. the total theoretical tide, found by summing the equilibrium and load tides, amounts to 37.2 nrad at a phase of 121.7°. the 20 per cent discrepancy with that observed may be due to an inaccurate cotical chart, cavity effects in the vault, strain—tilt coupling or an inappropriate solid earth model. In the vicinity of Hawaii (≤ 3°) two independent cotidal charts give almost identical results for the near field ocean load. At greater distances, we use the Schwiderski (1978) cotidal chart. We estimate that local cavity and strain—tilt coupling effects are less than 12 per cent owing to the agreement between geodetically determined and instrumental tilt but we can not rule out regional effects. Assuming these are small and the cotical charts correct, we find that the M2 results are brought into satisfactory agreement if, instead of using an average oceanic earth model in the (< 75 km) vicinity of Hawaii, we use an earth model with nearly one-half the oceanic rigidity. Such a low upper mantle and crustal rigidity is consistent with Kilauea's position above the thermal upwelling associated with the Hawaiian hotspot. 相似文献