滨海新区填海造陆的地形地貌环境演变影响分析          下载免费PDF全文

乔吉果  许冬  梁昊  宫少军  赵卫  宋学山 《海洋开发与管理》2018,35(5):36-40

填海造陆对海岸环境的影响主要体现在改变海岸线长度与形态及直接吹填沙导致近海海底地形地貌变化~([1]),这些变化影响着海岸带规划管理和可持续发展,具有重要的理论和现实意义。文章利用滨海新区遥感影像及其海图资料,对该区域近30年海岸线变迁、围填海演变及海底地形信息进行了提取,并对其具体进程和驱动因素进行了研究。研究表明:30年间,滨海新区海岸线变迁是向海洋推进,且推进的趋势越来越明显,岸线长度增长趋势愈发明显,变迁面积较大。针对填海造陆引起围堤基底冲刷问题,笔者建议对中度冲刷区采取防护工程措施、岸外消浪工程和加强动态监测等措施防止泥沙向航道下移。  相似文献   

青藏高原腹地多年冻土区地表反照率的季节变化及主要影响因子     

孙琳婵  赵林  李韧  肖瑶 《山地学报》2020,(1):9-18

准确获取青藏高原地表反照率的季节变化特征对高原地表能水循环研究具有重要意义。本文利用青藏高原多年冻土区西大滩和唐古拉2007年的气象及辐射数据,运用相关分析方法研究了太阳高度角、积雪及活动层冻融过程对地表反照率变化的影响。结果显示:冷暖季降雪过程中地表反照率的变化差异较明显;地表无积雪覆盖期间,地表反照率与气温和表层土壤含水量呈反相关关系。利用多元回归分析法构建了以积雪日数和气温为影响因子的月均地表反照率计算回归方程,经检验与观测值对比平均相对误差为7.1%,可用于青藏高原北部地表反照率的估算。  相似文献   

国内外大城市的城市森林时空变化对比研究   总被引：1，自引：0，他引：1  

段倩雯  谈明洪 《地理科学进展》2020,39(3):410-419

城市森林在减弱噪声、净化空气、调节城市气温等方面具有十分重要的作用。中国城市正处于快速发展阶段,对国内外大城市的城市森林现状及其时空变化进行对比分析可为中国城市森林的建设提供理论借鉴。跨区域城市森林对比研究的主要困难在于城市区域定义的差异导致不同城市之间可比性差。论文利用强度梯度法,基于夜间灯光影像及GlobeLand30地表覆盖产品,提取12个国内外大城市2000年和2010年的城市森林数据,探究其时空变化。结果表明,从现有城市森林量看,城市森林覆盖率及人均城市森林面积在发达国家城市中普遍偏高,而在亚洲发展中国家城市中非常低,例如纽约的人均城市森林面积高达316.5 m ²,而上海、新德里和雅加达则低于2 m ²。从时间变化看,2000—2010年城市森林面积增长率在发达国家城市中均小于70%,而在大部分发展中国家城市超过了100%。城市森林增加的最主要来源是城市面积扩张,减少的主要原因是转为硬化地面和城市草地。按照基于缓冲区分析得到的城市森林空间分布格局,这些城市可以分为3类：中心城区高、周边城区低(北京、首尔),中心城区低、周边城区高(广州、东京、圣保罗等),整个城区均低(上海、新德里、雅加达)。最后,基于对比结果为中国城市森林未来的发展提供了建议。  相似文献   

Diatom blooms and associated vegetation shifts in a subarctic peatland: responses to distant volcanic eruptions?          下载免费PDF全文

U. Kokfelt  R. Muscheler  A. Mellström  E. Struyf  M. Rundgren  S. Wastegård  D. Hammarlund 《第四纪科学杂志》2016,31(7):723-730

  相似文献   

近百年来大亚湾沉积物有机质的沉积记录及对人为活动的响应   总被引：1，自引：1，他引：0  

曲宝晓  宋金明  袁华茂 《海洋学报》2018,40(10):119-130

通过对沉积物中粒度组成、总有机碳（TOC）、总氮（TN）、碳氮比（TOC/TN）和碳、氮稳定同位素丰度（δ13C、δ15N）等的分析，结合沉积年代学信息与端元混合模型结果，解析了百年尺度下大亚湾沉积物中不同来源有机质的演变过程及控制因素。结果表明，大亚湾沉积物特性在20世纪70年代末至80年代初发生了显著改变:在此之前，TOC、TN、δ13C和δ15N表现稳定，陆源与海源有机碳的比例维持在3∶7，而自此之后，TOC与TN含量显著升高，TOC/TN持续下降，在1980—2000年和2010年至今都出现了陆源有机碳比例升高，海源有机碳比例降低的现象。上述显著变化表明大亚湾海洋环境自20世纪70年代末至80年代初已经发生了重大变化。近20年来GDP与沉积柱中TN和δ15N呈现出的显著正相关，与TOC/TN呈现出的显著负相关，表明沿岸经济的迅猛增长，水产养殖业的快速发展，周边人口的急速增加等人为活动，是造成大亚湾生态环境变化的重要原因。未来的研究应更密切关注人为活动对海湾生态环境的影响，通过法律法规约束行为，加强海湾生态环境保护与修复治理工作。  相似文献   

Climatic Changes Dominant Interannual Trend in Net Primary Productivity of Alpine Vulnerable Ecosystems     

YANG Yihan  WANG Junbang  LIU Peng  LU Guangxin  LI Yingnian 《资源与生态学报(英文版)》2019,10(4):379-388

The Three-River Headwaters (TRH), which is the source area of Yangtze River, Yellow River and Lancang River, is vulnerable and sensitive, and its alpine ecosystem is considered an important barrier for China’s ecological security. Understanding the impact of climate changes is essential for determining suitable measures for ecological environmental protection and restoration against the background of global climatic changes. However, different explanations of the interannual trends in complex alpine ecosystems have been proposed due to limited availability of reliable data and the uncertainty of the model itself. In this study, the remote sensing-process coupled model (GLOPEM-CEVSA) was used to estimate the net primary productivity (NPP) of vegetation in the TRH region from 2000 to 2012. The estimated NPP significantly and linearly correlated with the above-ground biomass sampled in the field (the multiple correlative coefficient R² = 0.45, significant level P < 0.01) and showed better performance than the MODIS productivity product, i.e. MOD17A3, (R² = 0.21). The climate of TRH became warmer and wetter during 1990-2012, and the years 2000 to 2012 were warmer and wetter than the years1990-2000. Responding to the warmer and wetter climate, the NPP had an increasing trend of 13.7 g m^-2 (10 yr)^-1 with a statistical confidence of 86% (P = 0.14). Among the three basins, the NPP of the Yellow River basin increased at the fastest rate of 17.44 g m^-2 (10 yr)^-1 (P = 0.158), followed by the Yangtze River basin, and the Lancang River, which was the slowest with a rate of 12.2 g m^-2 (10 yr)^-1 and a statistical confidence level of only 67%. A multivariate linear regression with temperature and precipitation as the independent variables and NPP as the dependent variable at the pixel level was used to analyze the impacts of climatic changes on the trend of NPP. Both temperature and precipitation can explain the interannual variability of 83% in grassland NPP in the whole region, and can explain high, medium and low coverage of 78%, 84% and 83%, respectively, for grassland in the whole region. The results indicate that climate changes play a dominant role in the interannual trend of vegetation productivity in the alpine ecosystems on Qinghai-Tibetan Plateau. This has important implications for the formulation of ecological protection and restoration policies for vulnerable ecosystems against the background of global climate changes.  相似文献   

GRACE̽��ǿ���������仯   总被引：1，自引：0，他引：1  

邹正波  罗志才  李辉  申重阳  周新 《大地测量与地球动力学》2010,30(2):6-9

????GRACE??????????????????й??????????????????仯?????????????仯???????δ??????????????仯???????????????????????????????????Χ???仯???????????????????Ms8.0?????????????????仯???????????????о?????????????????????????????????????????????????????????仯????????  相似文献   

吹填土自重沉淤阶段孔隙水压力消散的试验研究     

宋晶  王清  孙铁  李晓茹  张中琼  焦志亮 《岩土力学》2010,31(9):2935-2940

利用真空预压法处理吹填土时,细颗粒常堵塞排水管,导致土体排水不畅。为提高吹填土固结效率,采用自重沉淤排水与加负压排水固结相结合的方式在室内进行吹填土固结试验。试验第一阶段用排水管作为吹填土自重沉淤的竖向排水通道;第二阶段以装入中粗砂的排水管作吹填土排水通道,同时也是压力传递通道。试验监测到吹填土固结过程中不同位置孔隙水压力的变化,通过监测数据着重研究自重沉淤排水阶段吹填土的固结规律。借助渗流平衡方程确定吹填土在自重沉淤阶段孔隙水压力变化主要由排水管中水位、单位土面积控制,解释自重沉淤阶段孔隙水压力变化机理。同时,为了减小由于排水距离远近造成的固结不均,利用自重沉淤与加压固结结合的方法使吹填土达到较为理想的固结效果,将砂井设计理论与孔隙水压力变化曲线相结合确定排水管有效排水范围等效直径,为实际工程提供排水管间距的设计参数。  相似文献   

云南省工业试点县耕地数量变化特征及其驱动力分析——以兰坪县为例     

秦国真  杨润高 《云南地理环境研究》2010,22(5):82-87

根据兰坪县2001～2008年的统计资料,对兰坪县耕地数量变化的影响因素进行了研究。应用灰色关联分析的方法,定量地诊断出各影响因素与耕地数量变化的关联度,然后依据关联度的大小,从诸因素中找出主要影响因素以及次要影响因素,并在此基础上提出建议,以促进耕地资源的可持续利用。研究表明：总人口的增加,农业科技的应用和农业经济结构的调整以及经济的发展是近8年来兰坪县耕地面积变化的主要影响因素。  相似文献   

Intense diurnal surface currents in the Bay of La Paz,Mexico     

Oleg Zaytsev  Alexander B. Rabinovich  Richard E. Thomson  Norman Silverberg 《Continental Shelf Research》2010

Currents in the northern Bay of La Paz were examined using an 8-month Acoustic Doppler Current Profiler (ADCP) record collected in the upper 185 m of the water column during 2007. Flow variability was dominated by tidal motions, which accounted for 43% (33% diurnal, 10% semidiurnal) of the total kinetic energy. The tidal motions had a pronounced vertical structure dominated within a shallow (∼30 m thick) surface layer by intense counterclockwise (CCW) rotary S₁ diurnal radiational currents that were highly coherent with the counterclockwise seabreeze. Motions within the semidiurnal frequency band were primarily associated with significant counterclockwise S₂ radiational tidal currents, which were also coherent with the seabreeze. Both S₁ and S₂ tidal ellipses in the upper layer were aligned perpendicular to the bay entrance with mean semi-major axes of 55 and 20 cm/s, respectively. Below the surface layer, tidal currents decayed rapidly to relatively weak, clockwise rotary barotropic motions. In contrast to those for radiational harmonics, tidal ellipses of the gravitational constituents (M₂, K₁ and O₁) were oriented cross-bay. Energy within the diurnal frequency band in the surface layer was dominated by a coherent component (barotropic, phase-locked baroclinic and radiational), which accounted for roughly 65% (59% from S₁ alone) of the total diurnal kinetic energy. Of the remaining diurnal band energy, 18% was associated with an incoherent baroclinic component and 17% with a background noise component. Below 30 m depth, the corresponding estimates are 40%, 32% and 28%, respectively. The persistent, surface-intensified CCW rotary currents observed at the mooring site are assumed to be forced by strong CCW seabreeze winds in the presence of a “slippery” low-density surface layer. This response may be further augmented by topographic narrowing at the bay entrance and by the close proximity of the diurnal and inertial frequency bands in the region.  相似文献