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981.
海平面上升的淹没效应和岸滩冲淤对潮间带湿地面积影响的分离估算 总被引:1,自引:0,他引:1
海平面上升的淹没效应导致潮间带湿地面积损失,泥沙淤积可以抵消海平面上升的影响而使潮间带湿地面积持续增长。潮间带湿地面积的实际变化取决于这两个因素的抗衡。本文通过对崇明东滩固定断面高程的重复测量,结合海平面上升速率和潮间带坡度,尝试分离海平面上升和泥沙淤积两因子对潮间带湿地面积变化的影响。结果表明,2005~2010年间,泥沙淤积使崇明东滩潮间带湿地面积增加1.79km2(平均0.36km2/a),而相对海平面上升的"淹没"效应导致崇明东滩潮间带湿地面积损失约0.44~0.64km2(0.09~0.13km2/a),潮间带面积实际增长1.15~1.35km2(0.23~0.27km2/a)。今后几十年,受全球海平面加速上升和长江入海泥沙进一步减少的影响,崇明东滩潮间带湿地的净淤涨速率可能进一步下降,崇明东滩湿地的开发利用将面临新的挑战。 相似文献
982.
在地质灾害详细调查的基础上,基于GIS平台以地质灾害点密度为依据生成初步地质灾害易发性区划图.从诱发地质灾害的内部因素出发将地层岩性、地形坡度、地貌类型、植被覆盖率、多年降雨量分级后,叠加到初步易发性区划图中,生成了地质灾害气象预警区划基图.以降雨作为诱发地质灾害的主导外在因素,重新对泾川县进行了地质灾害气象预警区划,... 相似文献
983.
2000—2007年中国东部地区城市土地集约利用分析 总被引:1,自引:0,他引:1
本文以中国东部地区10省市87个城市为研究对象,利用层次分析法构建城市土地集约利用评价的指标体系,分析2000-2007年城市土地集约利用变化的规律,并建立城市土地集约利用指标值与影响因子之间的多元回归模型,寻找影响城市土地集约利用变化的差异。研究结果表明:①从人口承载、经济投入与经济产出的角度构建了评价指标体系,经济产出成为城市土地集约利用的主要影响因素。②北京市城市土地集约利用指标值均值的变化最大,其他东部9省市各城市土地集约利用指标值均值的变化趋势类似,变化相对平缓。广东城市土地集约利用指标均值的标准差最大,海南城市土地集约利用指标值的标准差起伏最大。③多数城市土地集约利用指标值均分布在0.1000~0.2000之间。④构建了城市土地集约利用指标值与各影响因子之间的多元回归模型,72个城市通过了规定条件的检验。 相似文献
984.
LI Xian-zhou LIU Li-hua YANG He-ting NING Wei-kun FAN Wen 《东北亚地学研究》2005,8(1):142-145
There are rich natural resources of natural mineral drugs in eastern Jilin Province. Systematic resource investigation can elevate fractional conversion of this area' s mineral ,drugs resources superiority. Research on natural mineral drugs of this area can upgrade the translation rate of resource superiority and accelerate the development of local medical industry, especially, it can provide scientific data for founding the strategic design of Chinese traditional medicine's trademark ofJilin Changbai Mountain. Since the resource of mineral drugs can not be regenerated, it must be exploited scientifically, utilized reasonably and protected effectively its sustaining application. 相似文献
985.
Lower Permian formations within the Buqingshan Mountains (A'nyemaqen ophiolitic zone, eastern sector of the eastern Kunlun) were formed in the following paleogeodynamic environments (from north to south): (1) shelf and slope of a passive continental margin in a marginal sea; (2) partially Permian metamorphic rocks of subduclion-accretion complexes and volcanogenic rocks of an ensimatic island arc, of the age limited from above by the Asselian - Sakmarian; and (3 ) an island arc slope and oceanic trench. Subduction-accretion complexes and the island arc volcanites are overlain with a sharp angular unconformity by a carbonate-conglomerate sequence, which presents as local molasse of the Early Permian age. Based on fusulinids from the basal limestone, the age of the local molasse is first defined as the Yakhtashian-Bolorian, i.e. Artinskian-Kungurian (?). The thorough investigations revealed that the initial closure of the eastern Paleotethys within the eastern Kunlun corresponded to the Sakmarian-Yakhtashian (Artinskian) boundary, whereas in the western Paleotethys sector (Northern Pamirs) the closure occurred considerably earlier, prior to the Late Bashkirian. Thus, the idea that the Paleotethys in the eastern Kunlun reached its maximum width in the Permian, is highly questionable. During the Early Permian the A'nyemaqen branch of the Paleotethys intensely decreased. Beginning from the Bolorian (Kungurian) and up to the end of the Permian this branch represented its relict in the form of a marginal sea depression. It may be suggested that the Paleotethys closure in the A'nyemaqen took place gradually from the west to the east and covered a long period from the Late Carboniferous to the terminal Early Permian. 相似文献
986.
LI Xian-zhou LIU Li-hua YANG He-ting MING Wei-kun FAN Wen College of Material Science Technology Jilin University Changchun Jilin China Chaoyang Science Technology Union Changchun Jilin China 《东北亚地学研究》2005,(Z1)
There are rich natural resources of natural mineral drugs in eastern Jilin Province. Systematic resource investigation can elevate fractional conversion of this area' s mineral drugs resources superiority. Research on natural mineral drugs of this area can upgrade the translation rate of resource superiority and accelerate the development of local medical industry, especially, it can provide scientific data for founding the strategic design of Chinese traditional medicine's trademark of Jilin Changbai Mountain. Since the resource of mineral drugs can not be regenerated, it must be exploited scientifically, utilized reasonably and protected effectively its sustaining application. 相似文献
987.
Fuyuan An Tianyuan Chen Xiangzhong Li Xiangjun Liu Yixuan Wang Zongyan Chen E Chongyi 《地球表面变化过程与地形》2021,46(12):2421-2436
This study investigated a series of dammed lakes and downstream-adjacent alluvial fans in the upstream to middle reaches of the Golmud River in the eastern Kunlun Mountain, on the north-eastern Qinghai-Tibetan Plateau (QTP). An optically stimulated luminescence (OSL) chronology shows the sediments of five dammed lakes developed from c. 45–40, 30–25, 18–14, and 12–8 ka, corresponding to MIS 3b, late MIS 3a, Last Deglaciation, and early Holocene, respectively. The remote sensing data show these dammed lakes have a total area of 109.4 km2, with the lake volume of more than 4.0 km3. Symmetric alluvial fans from north–south tributary valleys produced OSL ages of c. 61–52, 42–31, 26–20, and 16–10 ka, corresponding to glaciation periods: the MIS 3c and MIS 3a, MIS 2, and the Last Deglaciation. This suggests that glacial activity is responsible for the alluvial fan development, where dammed rivers occurred first, but lake formation did not take place synchronously until later periods of strong hydrologic activity, resulting from northward intrusions of the Indian summer monsoon (ISM) or glacier melt. Thus, the blocking pattern is that river valleys were dammed during periods of glacial activity and lakes formed during wet periods. The lake formation and subsequent drainage may have resulted in: (i) impeded headwater incision and strengthening of downstream dissection; (ii) enriched the halite and potash in the distal Qarhan Salt Lake through hydrologic and hydrochemical processes of abundant water input, the salt lake expansion, salt redissolution from playa and final resedimentation during later dry periods. The alluvial-dammed lake pattern in the mountain-basin systems of eastern Kunlun Mountain offers a model for assessing the linkages between monsoon dynamics, geomorphic processes and distal salt lake evolutions in other arid regions. 相似文献
988.
The traditional data envelopment analysis(DEA), bootstrap-DEA and Malmquist models are employed to measure different tourism efficiencies and their spatial characteristics of 61 cities in six coastal urban agglomerations in eastern China. The following conclusions are drawn.(1) The comprehensive efficiency(CE) of urban tourism using the bootstrap-DEA model is lower than the CE level using the DEA-CRS model, which confirms the significant tendency of the DEA-CRS model to overestimate results.(2) The geometric CE averages of urban tourism in the Yangtze River Delta(YRD) and the Pearl River Delta(PRD) have changed from ineffective to effective since 2000, the averages in the Beijing-TianjinHebei(BTH) and the Shandong Peninsula(SDP) have changed from ineffective to moderately effective since 2000, and those in the Central and Southern Liaoning(CSL) and the West Bank of Taiwan Strait(WBTS) have been ineffective since 2000.(3) The CE values of urban tourism in the PRD, the YRD, the BTH and the SDP have been slightly affected by the pure technical efficiency(PTE), whereas the CE values in the CSL and the WBTS have been slightly affected by the scale efficiency(SE) since 2000.(4) Spatially, the range of geometric averages of the total factor productivity(TFP) for the PRD, the YRD, the BTH, the SDP, the WBTS and the CSL has decreased sequentially, while the one for most cities in six urban agglomerations has exhibited a downward trend since 2000.(5) Collectively, the natural conditions, the economic policies and the tourism capital drive the SE change of urban tourism of the CSL and the WBTS. The tourism enterprises for increasing returns to scale and imitating innovative technology have an effect on the CE change of urban tourism in the BTH and the SDP. The tourism market competition drives the PTE change of urban tourism in the PRD and the YRD. Although the PTE and the SE of urban tourism in six coastal urban agglomerations suffer from uncertain events, the CE maintained overall sound momentum since 2000. 相似文献
989.
990.
The response of the upper-ocean temperatures and currents in the tropical Pacific to the spatial distribution of chlorophyll-a and its seasonal cycle is investigated using a coupled atmosphere-ocean model and a stand-alone oceanic general circulation model.The spatial distribution of chlorophyll-a significantly influences the mean state of models in the tropical Pacific.The annual mean SST in the eastern equatorial Pacific decreases accompanied by a shallow thermocline and stronger currents because of shallow penetration depth of solar radiation.Equatorial upwelling dominates the heat budget in that region.Atmosphere-ocean interaction processes can further amplify such changes. The seasonal cycle of chlorophyll-a can dramatically change ENSO period in the coupled model.After introducing the seasonal cycle of chlorophyll-a concentration,the peak of the power spectrum becomes broad,and longer periods(>3 years) are found.These changes led to ENSO irregularities in the model. The increasing period is mainly due to the slow speed of Rossby waves,which are caused by the shallow mean thermocline in the northeastern Pacific. 相似文献