基于农户生计资产视角的土地生态安全定量评估

甘肃民勤县面临的生态安全危机已经受到人们的普遍关注。以2010-2014年农户生计资产视角,借助生态足迹原理和生态压力指数的方法,对民勤县典型村的土地生态安全状况进行定量评估。结果表明：（1）将农户生计资产归纳为自然资产、物质资产、人力资产、金融资产和社会资产,在一定程度上反映了不同农户生计类型拥有不同的生计资产;（2）2010-2014年民勤县典型村不同生计类型的人均生态足迹和人均生态承载力变化明显,呈盈余状态;（3）2010-2014年民勤县典型村土地生态安全处于较安全状态。     

干旱区土壤有机碳含量与土壤理化性质相关分析

干旱区土壤碳库是全球碳库的重要组成部分,在全球碳循环中起着重要作用.本文根据干旱区土壤相关数据资料,分析土壤有机碳与土壤理化性质相关性,为干旱区碳循环提供理论依据.结果表明:土壤有机碳含量与土壤营养成分和交换性阳离子含量呈显著正相关,与土壤pH值和容重呈显著负相关.此外,干旱区土壤也存在相当比例的无机碳,土壤有机碳和无机碳含量呈显著负相关,二者间关系还需要结合母质、生物气候条件、人类活动影响进行进一步说明.     

Simulation of snowmelt runoff in ungauged basins based on MODIS: a case study in the Lhasa River basin

It is theoretically and practically significant to conduct snowmelt runoff simulations and hydrological research for high-elevation regions. The Lhasa River basin, an ungauged basin, is a typical alpine headwater region where snowmelt runoff contributes significantly to its stream flow. In this study, the snowmelt period, defined by the snow cover curves obtained at different altitudinal zones based on Moderate-Resolution Imaging Spectroradiometer (MODIS) and Digital Elevation Model data, occurred from March 6 to July 12 in the basin. The snowmelt processes were simulated with the Snowmelt Runoff Model (SRM) in 2002 and 2003 for calibration and validation, respectively. The coefficients of determination (R ² ) were 0.86 and 0.87 for calibration and validation, respectively, and the Nash–Sutcliffe coefficients were both 0.80, which indicate reasonable performances in simulating hydrological processes in the Lhasa River basin. The simulated snowmelt at altitudes below 5,000 m accounts for most of the snowmelt. And the simulated snowmelt runoff contributed 3–6 % to the total runoff. The sensitivity of individual parameters was analysed and ranked as follows: α and γ > C _S  > C _R  > T _crit . In short, the SRM based on MODIS remotely sensed data performed well for the ungauged Lhasa River basin.     

北京市地震应急避难场所减灾能力评价体系的研究

北京市地震应急避难场所是我国建设最早、数量最多的,根据国家和地方的建设标准和规范,现有地震应急避难场所部分建设项目与权威的国家建设标准要求相比较而言,还存在超标与不足,因此定量和综合的能力评价势在必行.本文采用层次分析法,针对应急避难场所各种能力,梳理出3个层次、18个因素,并通过专家调查方式得到各因素的权重,形成减灾能力评价体系.文中以北京市朝阳区的应急避难场所为例进行了评价,并给出了其完善的建议.初步可认为,本文提出的地震应急避难场所减灾能力评价体系具有较好的可操作性,对避难场所的建设和完善具有一定的指导意义.     

Active source monitoring at the Wenchuan fault zone: coseismic velocity change associated with aftershock event and its implication

With the improvement of seismic observation system, more and more observations indicate that earthquakes may cause seismic velocity change. However, the amplitude and spatial distribution of the velocity variation remains a controversial issue. Recent active source monitoring carried out adjacent to Wenchuan Fault Scientific Drilling (WFSD) revealed unambiguous coseismic velocity change associated with a local M_s5.5 earthquake. Here, we carry out forward modeling using two-dimensional spectral element method to further investigate the amplitude and spatial distribution of observed velocity change. The model is well constrained by results from seismic reflection and WFSD coring. Our model strongly suggests that the observed coseismic velocity change is localized within the fault zone with width of ~120 m rather than dynamic strong ground shaking. And a velocity decrease of ~2.0 % within the fault zone is required to fit the observed travel time delay distribution, which coincides with rock mechanical experiment and theoretical modeling.     

High efficient parallel numerical surface wave model based on an irregular quasi-rectangular domain decomposition scheme

To achieve high parallel efficiency for the global MASNUM surface wave model, the algorithm of an irregular quasi-rectangular domain decomposition and related serializing of calculating points and data exchanging schemes are developed and conducted, based on the environment of Message Passing Interface (MPI). The new parallel version of the surface wave model is tested for parallel computing on the platform of the Sunway BlueLight supercomputer in the National Supercomputing Center in Jinan. The testing involves four horizontal resolutions, which are 1°×1°, (1/2)°×(1/2)°, (1/4)°×(1/4)°, and (1/8)°×(1/8)°. These tests are performed without data Input/Output (IO) and the maximum amount of processors used in these tests reaches to 131072. The testing results show that the computing speeds of the model with different resolutions are all increased with the increasing of numbers of processors. When the number of processors is four times that of the base processor number, the parallel efficiencies of all resolutions are greater than 80%. When the number of processors is eight times that of the base processor number, the parallel efficiency of tests with resolutions of 1°×1°, (1/2)°×(1/2)° and (1/4)°×(1/4)° is greater than 80%, and it is 62% for the test with a resolution of (1/8)°×(1/8)° using 131072 processors, which is the nearly all processors of Sunway BlueLight. When the processor’s number is 24 times that of the base processor number, the parallel efficiencies for tests with resolutions of 1°×1°, (1/2)°×(1/2)°, and (1/4)° ×(1/4)° are 72%, 62%, and 38%, respectively. The speedup and parallel efficiency indicate that the irregular quasi-rectangular domain decomposition and serialization schemes lead to high parallel efficiency and good scalability for a global numerical wave model.     

The porosity origin of dolostone reservoirs in the Tarim,Sichuan and Ordos basins and its implication to reservoir prediction

Origin of dolostone remained a controversial subject, although numerous dolomitization models had been proposed to date. Because of the dolomitization’s potential to be hydrocarbon reservoirs, one debatable issue was the role of dolomitization in porosity construction or destruction. Based upon case studies of dolostone reservoirs in various geological settings such as evaporative tidal flat (Ordos Basin, NW China), evaporative platform (Sichuan Basin, SW China), and burial and hydrothermal diagenesis (Tarim Basin, NW China), here we systematically discuss the origin of porosity in dolostone reservoirs. Contrary to traditional concepts, which regarded dolomitization as a significant mechanism for porosity creation, we found two dominant factors controlling reservoir development in dolostones, i.e., porosity inherited from precursor carbonates and porosity resulted from post-dolomitization dissolution. Actually, dolomitization rarely had a notable effect on porosity creation but rather in many cases destroyed pre-existing porosity such as saddle dolostone precipitation in vugs and fractures. Porosity in dolostones associated with evaporative tidal flat or evaporative platform was generally created by subaerial dissolution of evaporites and/or undolomitized components. Porosity in burial dolostones was inherited mostly from precursor carbonates, which could be enlarged due to subsequent dissolution. Intercrystalline porosity in hydrothermal dolostones was either formed during dolo- mitization or inherited from precursor carbonates, whereas dissolution-enlarged intercrystalline pores and/or vugs were usually interpreted to be the result of hydrothermal alteration. These understandings on dolostone porosity shed light on reservoir prediction. Dolostone reservoirs associated with evaporative tidal flat were laterally distributed as banded or quasi-stratified shapes in evaporite-bearing dolostones, and vertically presented as multi-interval patterns on tops of shallowing-upward cycles. Dolostone reservoirs associated with evaporative platform commonly occurred along epiplatforms or beneath evaporite beds, and vertically presented as multi-interval patterns in dolostones and/or evaporite-bearing dolostones of reef/shoal facies. Constrained by primary sedimentary facies, burial dolostone reservoirs were distributed in dolomitized, porous sediments of reef/shoal facies, and occurred vertically as multi-interval patterns in crystalline dolostones on tops of shallowing-upward cycles. Hydrothermal dolomitization was obviously controlled by conduits (e.g., faults, unconformities), along which lenticular reservoirs could develop.     

Spatio-temporal analysis of the melt onset dates over Arctic sea ice from 1979 to 2017

The melt onset dates(MOD) over Arctic sea ice plays an important role in the seasonal cycle of sea ice surface properties, which impacts Arctic surface solar radiation absorbed by the ice-ocean system. Monitoring interannual variations in MOD is valuable for understanding climate change. In this study, we investigated the spatio-temporal variability of MOD over Arctic sea ice and 14 Arctic sub-regions in the period of 1979 to 2017 from passive microwave satellite data. A set of mathematical and ...     

海洋测绘学科体系及其专业建设的探讨

海洋测绘的核心任务是为国民经济建设、国防建设和科学研究等提供基础的海洋地理空间信息服务.本文探讨了海洋测绘的学科体系、学科意义、特点及与其他学科的关系,阐述了上海海洋大学海洋测绘专业建设的“特色、创新和务实”理念,总结了在师资队伍建设、教学环境建设、教学改革等方面的初步成果.     

江汉盆地新沟油田新沟嘴组盐韵律多级划分及其地质意义

江汉盆地为中国东部典型的中、新生代盐湖盆地,近些年在新沟油田古近系新沟嘴组发现致密油藏,储集层主要为与盐韵律相关的白云岩和粉砂岩层。为了探究盐韵律的发育特征及其意义,作者以岩心精细观察为基础,结合测录井、分析化验资料,根据盐矿物种类、剖面结构和厚度,对新沟嘴组盐韵律发育规模进行了不同级别的划分,对各级韵律的剖面特征进行了描述,并对其形成机理进行了分析。在此基础上,从古气候及油气2个角度探讨了盐韵律的地质意义。盐韵律的形成是湖平面上升-下降不断变化的直接响应。新沟嘴组盐韵律中广泛发育广温相盐类矿物白云石、方解石,指示江汉盆地古近系新沟嘴期的气候特征为古温度介于寒冷和炎热之间的过渡型半干旱-干旱气候;一个完整的盐韵律可以形成一个生储盖组合,对油气生成、储集和保存具有重要意义。