Thickness estimation of the Longbasaba Glacier: methods and application     

GuangLi He  JunFeng Wei  Xin Wang 《寒旱区科学》2020,12(6):477-490

A total of 71,177 glaciers exist on the Qinghai-Tibet Plateau, according to the Randolph Glacier Inventory (RGI 6.0). Despite their large number, glacier ice thickness data are relatively scarce. This study utilizes digital elevation model data and ground-penetrating radar thickness measurements to estimate the distribution and variation of ice thickness of the Longbasaba Glacier using Glacier bed Topography (GlabTop), a full-width expansion model, and the Huss and Farinotti (HF) model. Results show that the average absolute deviations of GlabTop, the full-width expansion model, and the HF model are 9.8, 15.5, and 10.9 m, respectively, indicating that GlabTop performs the best in simulating glacier thickness distribution. During 1980-2015, the Longbasaba Glacier thinned by an average of 7.9±1.3 m or 0.23±0.04 m/a, and its ice volume shrunk by 0.28±0.04 km³ with an average reduction rate of 0.0081±0.0001 km³/a. In the investigation period, the area and volume of Longbasaba Lake expanded at rates of 0.12±0.01 km²/a and 0.0132±0.0018 km³/a, respectively. This proglacial lake could potentially extend up to 5,000 m from the lake dam.  相似文献   

深圳市近20年城市景观格局演变及其驱动因素   总被引：1，自引：0，他引：1  

吴健生  罗可雨  赵宇豪 《地理研究》2020,39(8):1725-1738

基于深圳市1996—2015年土地利用数据,利用景观指数、景观转移矩阵和景观扩张指数等方法探究了深圳市近20年景观格局时空变化、主要景观类型转移和建筑用地扩张模式,最后使用Binary Logit模型考察了市级和区级建筑用地景观扩张的主要驱动因素。结果表明：① 1996—2015年,深圳市建筑用地景观优势性逐步增强,面积增加15.81%,以蔓延式（61.9%）和填充式（36.27%）扩张为主;② 1996—2006年为城市化快速扩张期,建筑用地扩张呈集中开发形态,景观多样性和均匀性增加,城市扩张中心略微向北部和东部移动,2006—2015为城市化低速过渡期,景观破碎化加剧,城市扩张重心向北部和西部偏移;③ 在市级尺度上,GDP密度和人口密度对建筑用地景观扩张有显著正影响,生态控制线、高程、坡度和至道路的距离有着显著负影响。每单位生态控制线范围、坡度的增加分别将使建筑用地景观扩张的机会比率将平均减少到原来0.8168倍、0.8841倍。各驱动因素表现出区域和尺度差异性,GDP对宝安区、南山区和坪山区,人口增长对宝安区、龙华区,以及交通可达性对大鹏新区、龙岗区驱动分别最为突出。研究结果可以为中国城市快速扩张过程中的景观格局变化提供科学实践。  相似文献   

Lack of mitochondrial genetic structure in the endangered giant clam populations of Tridacna maxima (Bivalvia: Cardiidae: Tridacninae) across the Saudi Arabian coast     

Ben Othmen Abdelwahe  Abhary Mohame  Deli Temim  Ouanes Zouhour  Alhuwaiti Nour  Dimassi Najet  Mansour Lamjed 《海洋学报(英文版)》2020,39(2):28-37

The present investigation focuses on population genetic structure analysis of the endangered giant clam species Tridacna maxima across part of the Red Sea,with the main aim of assessing the influence of postulated potential barriers to gene flow(i.e.,particular oceanographic features and marked environmental heterogeneity)on genetic connectivity among populations of this poorly dispersive bivalve species.For this purpose,a total of 44 specimens of T.maxima were collected from five sampling locations along the Saudi Arabian coast and examined for genetic variability at the considerably variable mitochondrial gene cytochrome c oxidase I(COI).Our results revealed lack of population subdivision and phylogeographic structure across the surveyed geographic spectrum,suggesting that neither the short pelagic larval dispersal nor the various postulated barriers to gene flow in the Red Sea can trigger the onset of marked genetic differentiation in T.maxima.Furthermore,the discerned shallow COI haplotype genealogy(exhibiting high haplotype diversity and low nucleotide diversity),associated with recent demographic and spatial expansion events,can be considered as residual effect of a recent evolutionary history of the species in the Red Sea.  相似文献   

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胡守超  伍吉仓  孙亚峰 《大地测量与地球动力学》2009,29(3):95-99

????(Stacking)??????????????PCA????Karhunen??Loeve???(KLE)??3?????????????????????????12??GPS????????5?????????????С?????????3???????????Ч???????????????????д????????????????????????????????????????÷?Χ???в????  相似文献   

基于GIS城镇空间扩展的评价研究——以来安汊河新区为例     

胡明星  权亚玲 《四川测绘》2009,32(5):195-199

通过对来安汉河新区总体概念规划的实践，本文在新区空间扩展评定中建立了评价分类的指标体系、确定了指标因子分级，并采用特尔斐法和层次分析法相结合的方法计算出评价指标因子权重值。在此基础上采用多因子综合评价方法，在GIS数据库中计算出每个单元的综合评价值，并依据该值进行等级划分，评定出汉河新区空间扩展范围和具体位置，为新区空间扩展的规划提供了科学根据。  相似文献   

The effects of urbanization on ecosystem services for biodiversity conservation in southernmost Yunnan Province,Southwest China   总被引：1，自引：1，他引：1  

Cheng  Fangyan  Liu  Shiliang  Hou  Xiaoyun  Wu  Xue  Dong  Shikui  Coxixo  Ana 《地理学报(英文版)》2019,29(7):1159-1178

Journal of Geographical Sciences - Urbanization can profoundly influence the ecosystem service for biodiversity conservation. However, few studies have investigated this effect, which is...  相似文献   

The basic law of the formation and expansion in urban agglomerations   总被引：2，自引：3，他引：2  

Fang  Chuanglin 《地理学报(英文版)》2019,29(10):1699-1712

Journal of Geographical Sciences - Urban agglomerations are formed when a country is in the advanced stages of industrialization and urbanization. They are highly integrated groups of cities that...  相似文献   

Urban expansion in Xiongan New Area since 1975     

Fang Liu  Zengxiang Zhang  Xiao Wang 《国际地球制图》2013,28(14):1568-1583

Abstract

Although urban expansion has been extensively studied at different scales in China, relatively little attention has been paid to the county scale. Xiongan New Area (XNA) was selected as the study area and its urban expansion processes from 1975 to 2017 were retrieved using remote sensing and GIS technology, and its spatial-temporal characteristics of urban expansion were revealed from the aspects of basic characteristics of urban expansion, urban spatial morphological evolution, interactions of urban lands, and assessments of the imbalanced degree of population-land urbanization. Results indicated that urban lands in XNA expanded significantly. Cultivated lands were the first land source for urban expansion. Urban lands mainly adopted the edge-expansion, which rendered the urban fringes to be complex and irregular. The interaction of three counties in XNA was strengthened successively, especially after the implementation of the ‘New Urbanization’ strategy. Population-land urbanization was inharmonious but has improved from moderate to mild imbalance.  相似文献   

华北平原“杨上粮下”现象的驱动机制——以河北省文安县为例   总被引：2，自引：0，他引：2  

赵宇鸾  李秀彬  辛良杰  郝海广 《地理研究》2012,31(2):323-333

以Landsat5TM遥感影像、农户调查数据和统计数据为基础数据,运用3S技术提取了案例区河北省文安县1995～2007年土地利用变化信息,分析了杨树扩张的时空格局;并从农户杨树种植决策行为视角,运用数理统计、投入产出法分析了杨树扩张占地的驱动因素。结论如下:(1)杨树林地扩张幅度大、速率快。(2)杨树扩张所用土地92.14%来源于耕地,"杨上粮下"现象突出。(3)杨树扩张速率的空间差异显著。杨树扩张受生产要素、土地产品市场及政策因素的综合驱动,其中劳动力因素和经济因素起主要作用。(4)非农从业人员比率和农民年人均收入越高,杨树扩张速度越快。在劳动力由富余转为相对稀缺的情况下,农户为提高经济收益,倾向选择耗工少,劳动生产率较大的杨树,是杨树扩张占地的根本原因。  相似文献   

城市空间形态的最低成本-周期扩张规律——以昆明为例   总被引：2，自引：0，他引：2  

吴启焰  陈辉  Belinda Wu  曾文 《地理研究》2012,31(3):484-794

城市形态演化反演城市土地利用模式的转变,是内部最低成本土地利用模式驱动力的外部表达。这一城市空间格局演变遵循本文提出的"外部扩张,内部填充"相互交替总体规律。它既是集聚与扩散驱动因子作用的结果,也是植入与再植入的"扬弃"选择过程的交互作用产物。基于最低成本—周期扩张模型的假设,本文选取昆明建成区近现代的影像资料,运用形态学的视角分析城市空间结构的变迁,探寻城市形态演化规律。结果表明:(1)从城市形态演变的一般理性微观、宏观过程来看,城市形态变迁在统计学上遵循最低成本—周期扩张规律假设;(2)在最低成本—周期扩张模型内,公共投资与基层设施建设变动及其要素替代效应对形态的周期性扰动响应是其核心作用机制。  相似文献