三峡库区腹地山区农业景观格局动态变化与转型

山区农业景观格局动态分析有利于厘清农业景观发展的动态轨迹与方向,对农地用途的合理规划和管理有重要意义。本文提出了山区农业景观格局转型理论框架,并在三峡库区草堂溪流域进行了实证研究,从整体—微观的角度解析2000—2018年期间,以坡耕地、撂荒地和果园为代表的农业景观格局转型特征。研究发现：① 果园沿河谷的扩张和撂荒地在较高海拔处的扩张明显压缩了坡耕地的空间,这导致区域景观多样性的整体增强,而在局部地形上的差异明显,斑块破碎但聚集度增强;② 研究区农户耕种范围内的农业景观格局转型主要表现为耕—果转换型、综合型、部分撂荒型和撂荒型4种模式,各模式揭示了山区农业景观格局的不同发展阶段;③ 在以社会经济因素为主的驱动下,三峡库区山区的农业景观格局转型具有双向性,表现为以传统均衡分布的纯粮种植景观向河谷生态经济双赢的经果林景观和较高海拔的撂荒地转变。研究结果揭示了近年来中国山区农业景观格局演变的独特性,对库区山区农村土地利用和农业生态系统的深入认识以及库区乡村发展和生态环境的改善均有启示意义。     

KINEMATIC WAVE MODELLING OF VERTICAL MOVEMENT OF SNOWMELT WATER THROUGH A SNOWPACK

Vertical movement of snowmelt water through snowpacks is modelled by applying the kinematic wave theory. Analytical solutions are obtained for moisture flux, particle velocity, time history and velocity of meltwater front and total moisture content for a single melt event assuming that the melt rate is constant. These solutions are extended to the case involving more than one event. © 1997 by John Wiley & Sons Ltd.     

碳酸盐岩样品中镍和钪的电感耦合等离子体质谱分析与干扰校正方法

电感耦合等离子体质谱法(ICP-MS)已在碳酸盐岩微量元素测试中得到了广泛应用.然而,采用ICP-MS分析碳酸盐岩中含量较低的Ni(1.6～50.5μg/g)和Sc(0.3～6μg/g)时,信号值会受到高含量CaO(可高达56％)和MgO(可高达21％)的显著干扰,使测试值远高于真实值,从而无法获得准确的待测元素含量....     

城市地区浅层地温能评价方法探讨

随着地源热泵技术的成熟,我国城市地区浅层地温能利用正在快速发展,为了保证浅层地温能的有效开发和可持续利用,应对浅层地温能资源进行评价。浅层地温能资源包括浅层地温能可利用量和储存量。浅层地温能利用环境评价和经济评价是资源评价中的必要内容。资源计算成果为城市区域浅层地温能开发利用规划和地源热泵工程提供依据。     

波流相互作用与波动传播模态

波和流是大气中两种最基本的运动形式,两者之间的相互作用可以导致千变万化的天气现象。波流相互作用理论是大气动力学的基本理论之一,该理论的研究具有重要的理论价值和科学意义。波流相互作用的研究主要包括两方面:一方面是可以描述基本气流对波强迫作用的“波作用”（守恒）方程的研究,另一方面是可以描述波对基本气流反馈作用的E-P通量以及波形变、传播等理论的研究。波流相互作用的研究不仅在理论上已取得重要进展,例如, E-P通量的提出,剩余环流的引进,广义E-P通量的出现,三维E-P通量的建立,波作用守恒方程、波动突变、波流稳定性结构、波形变及其大圆路径、低频波遥相关等理论的发展,而且在实际应用上也取得丰硕成果,如科学地解释了赤道平流层东西风准两年振荡、极地平流层爆发性增温、瞬变波对阻高的维持和高空急流加速以及大气低频波遥相关等,特别是为预测行星波的传播,研究风暴轴和诊断分析实际大气中波能集中区和发散区提供了理论基础和科学方法。作者从小振幅和有限振幅扰动两方面回顾了国内外波流相互作用和低频波传播理论的研究进展,重点介绍了大尺度环流系统波流相互作用和波动传播模态的最新研究成果,提出了不同动力、热力背景下多尺度波流相互作用机理及其理论模型,建立了非线性大气动力学突变及其稳定性结构等理论。相对来说,热源强迫和地形强迫引起的波流相互作用中稳定性问题的研究一直比较薄弱,特别是关于大气水分循环过程和青藏高原等复杂大地形影响下不同尺度系统波流相互作用的研究,这也是未来波流相互作用研究的一个重要内容。     

西南天山柯坪推覆构造东段晚第四纪变形样式与缩短速率

柯坪推覆构造的变形量和变形速率对于认识中国大陆的地球动力学过程有重要意义,但晚第四纪以来的变形特征与缩短速率是众多研究中的薄弱环节。文中通过大量的野外调查、探槽开挖、变形地貌面实测与阶地堆积物的测年,分析了柯坪推覆构造普昌断裂以东部分的晚第四纪变形样式、变形量和缩短速率。晚第四纪以来,研究区在地表和近地表的变形主要通过2种形式表现出来:低角度逆断层运动和新褶皱的弯曲变形。这些变形主要由最新地貌面的隆升和缩短来实现。研究区存在2个变形强度大的地段,缩短速率西段为1·32mm/a;东段为1·39mm/a     

土地覆被及生态服务价值变化的多时间尺度模拟——以四川省渔子溪流域为例

根据渔子溪流域1986年和1994年的遥感影像土地覆被解译资料为基础,建立了模拟渔子溪流域生态环境变化的Markov Chain模型和Patch-dynamics模型,并以2002年遥感影像资料作为验证数据对模型进行了误差分析。以此为基础,分别以1年和8年的时间尺度对渔子溪流域土地覆被及其生态服务价值的变化进行了模拟,结果表明,时间尺度对模拟结果具有显著影响：在1年和8年的模拟尺度下,以Markov Chain模型得到的流域生态服务价值在1986~2018年间变化的相对误差为20%;不同土地覆被类型在不同步长下模拟结果的相对误差不一样,表明不同土地覆被类型变化的特征时间尺度不一样,以Patch-dynamics模型的模拟结果为例,步长为1年比步长为8年的相对误差大的土地覆被类型为耕地 (-8.2%/-5.6%)、有林地 (-0.5%/-0.4%)、草地 (0.7%/0.4%) 和居民建设用地 (-29.9%/-16.4%),它们的年际变化较大,其变化趋势不稳定,受到人为偶然因素的影响明显;而相对误差较小的土地覆被类型为灌木林 (-1.5%/-1.7%) 和永久冰雪覆盖 (27.3%/41.9%),它们的变化趋势较为稳定,主要受比较稳定的自然因素的影响。研究还表明,采用Markov Chain模型的模拟结果与采用Patch-dynamics模型的模拟结果总体上是一致的,但后者的模拟结果更稳定、更可靠。     

酒泉盆地早白垩世沉积相特征与构造样式浅析

通过对酒泉盆地早白垩世的构造样式、沉积相特征研究,认为早白垩世酒泉盆地呈现NE向的伸展构造。     

THE MAXIMUM LIKELIHOOD ESTIMATION OF b-VALUE IN MAGNITUDE-FREQUENCY RELATION AND ANALYSIS OF ITS INFLUENCING FACTORS

b-value in the magnitude-frequency(G-R)relationship plays a vital role in seismicity research and seismic hazard analysis, and the most commonly used techniques to simulate it are least square approach and maximum likelihood method. Least square method is simple and easy to apply, therefore widely used in China. However, many researches show that there exist some limits in least square estimation of b-value. Earthquakes with different magnitudes are not equally weighted in this method, and larger events have higher weights, so b-value is vulnerable to the fluctuation of several big earthquakes; meanwhile, least square method needs to divide magnitude intervals artificially. With a small sample size, data points could be not enough if the magnitude interval is too wide, and events in a magnitude interval may be lacking if it is divided to be too narrow. Especially for incremental G-R relationship, it is possible that N(M_i)equals 0 in an interval with large magnitude, so log(N(M_i))loses meaning and has to be ignored, resulting in a low b-value. Therefore, under certain conditions, maximum likelihood method is recommended as an effective substitution or supplementary for least square estimation of b-value. Among numerous previous researches on maximum likelihood estimation of b-value, lots of equations have been provided, based on varied implicit assumptions and different ways of solution. A brief overview is first presented for these equations, and classification and summary are provided based on whether taking account of the effect of binned magnitude, with finite maximum magnitude, using unequal observation periods for different magnitude intervals, and with analytic solution or not. Following this, a total of 6 influential factors are analyzed, such as binning magnitude, measurement errors of magnitude, sample size, magnitude span, minimum completeness magnitude and fore- and aftershocks. At last, reasonable suggestions are provided for using those equations properly. The equations of Aki(1965), Utsu(1965), Page(1968)and Kijko and Smit(2012)are based on assumption that magnitudes are continuous random variables, and have no corrections for this, so these equations are not recommended here. For simplicity, the equations of Utsu(1966)or Tinti and Mulargia(1987)can be used, but magnitude span should be greater than 2.5 due to without finite maximum magnitude in the formulas. For researchers having capability to write code and calculate numerically, Weichert(1980)or Bender(1983)'s algorithm could be utilized. Especially when it is required to apply data with different observation periods for varied magnitudes, the formula of Weichert(1980)is recommended. This study contributes to more accurately understand and use different formulas of estimating b-value by maximum likelihood technique, which can be used as reference for peers.     

DETERMINATION OF SLIP RATE ON THE SOUTHERN SEGMENT OF THE ANNINGHE FAULT

The Anninghe Fault has been suggested as an important segment of the fault system along the eastern boundary of the Sichuan-Yunnan faulted block in the southeastern region of the Tibetan plateau. Reliable determination of the Late Quaternary slip rate on the Anninghe Fault is very helpful and significant for revealing deformation mechanism and kinematic characteristics of the Sichuan-Yunnan faulted block, which further helps us understand fault activity and seismic potential of the region. However, previous studies were focused mainly on the northern segment of the Anninghe Fault, while slip rate on its southern segment has been less studied. Therefore, in this paper, we chose two sites at Dashuigou and Maoheshan on the southern segment of the Anninghe Fault, and used high-resolution images of unmanned aerial vehicle (UAV)photogrammetry technology, detailed field survey, multiple paleoseismic trenching and radiocarbon dating methods to constrain slip rate on the southern fault segment of the Anninghe Fault. Specifically, we suggest that the slip rate at the Dashuigouo site is narrowly constrained to be~4.4mm/a since about 3^￣￣300a^￣￣BP based on a linear regression calculation method, and speculate that a slip rate of 2.6~5.2mm/a at the Maoheshan site would be highly possible, although we poorly constrained the whole deformation amount of the two branch faults at the Maoheshan site from multiple paleoseismic trenching. The data at the two sites on the southern segment show a consistent slip rate compared with that of the northern segment of the Anninghe Fault. Moreover, considering a similar paleoseismic recurrence interval on the two segments of the Anninghe Fault from previous studies, we further suggest that the fault activity and deformation pattern on the two segments of the Annignhe Fault appears to be well consistent, which is also in agreement with the regional tectonic deformation.