1) I. A. H. S. / A. I. H. S.

Abstract

A simple method is used to study the response of runoff in the Sahel to climate change. The statistical characteristics of rainfall are calculated over the western part of the Sahel for the period 1961–1990, using the BADOPLU network. Daily rainfall is simulated using a Markov process with Weibull distribution for rainfall depths. Runoff is modelled using a conceptual SCS model and the curve numbers are calculated for West Africa. Climate change is provided by simulations using the Arpège GCM (Scenario A1B), and a perturbation method is used on the parameters which describe the rainfall. Changes in rainfall are assumed to occur through increases in frequency, not intensity. Using Arpège, runoff is mainly found to increase, in depth and in number of events, by the end of the 21st century. Changes in evaporation and land use are not included in the analysis. The impact of this 21st century potential climate change (rainfall) on the runoff is found to be of the same magnitude as the impact of changes in land use.     

Localized versus wide-ranging effects of the post-Soviet wars in the Caucasus on agricultural abandonment

Wars are frequent and can affect land use substantially, but the effects of wars can vary greatly depending on their characteristics, such as intensity or duration. Furthermore, the spatial scale of the effects can differ. The effects of wars may be localized and thus close to conflict locations if direct mechanisms matter most (e.g., abandonment because active fighting precludes farming), or wide-ranging, e.g., farther away from conflict locations, if indirect mechanisms predominate (e.g., no access to agricultural inputs). Our goal was to quantify how the very different wars in the Caucasus region during post-Soviet times most likely affected agricultural abandonment at different scales. We analyzed data on conflict locations plus Landsat-derived land-cover data from 1987 to 2015, and applied matching statistics, difference-in-differences estimators, and logistic panel regressions. We examined the localized versus wide-ranging effects of the different wars on permanent agricultural abandonment and inferred to direct and indirect mechanisms that may have resulted in agricultural abandonment. While permanent agricultural abandonment was overall surprisingly limited across the Caucasus, up to one third of abandonment was most likely related to the wars. Among the wars, the war in Chechnya was by far the most intense and longest, but its effect on abandonment was similar to the less intense and relatively short war in Abkhazia. 47 % and 45 % of agricultural abandonment was related to each war, respectively. The reason was that the effect of the war in Chechnya was more localized, and abandonment occurred near conflict locations, in contrast to Abkhazia, where the effect was wide-ranging and abandonment occurred farther away from conflict locations. In contrast, the war in South Ossetia showed no significant effect on abandonment, and the war in Nagorno-Karabakh had the surprising pattern that abandonment was higher where no war had occurred. For each of the wars, abandonment was predominately related to the nearest conflict locations, but in Abkhazia additional conflict locations within 10 km further increased the probability of abandonment. We infer that the direct mechanisms of the war such as bombing, and active fighting most likely resulted in a localized effect close to conflict locations in Chechnya and in Nagorno-Karabakh. However, in Nagorno-Karabakh subsidies for new settlers after the war, (i.e., a positive wide-ranging effect), potentially reduced the amount of abandonment there. In contrast, negative wide-ranging effects such as refugee movements and post-war restrictions on their return is related to broad-scale abandonment in Abkhazia. In summary, permanent agricultural abandonment was not necessarily higher in a war with a high overall intensity. Instead, the effect of a given war varied in scale, and was related to the relative importance of direct and localized versus indirect and wide-ranging mechanisms, including postwar events and policies, which is likely the case for other wars, too.     

遵义市岩溶地下水环境的空间信息统计组合分析

应用空间信息统计分析理论与方法来分析遵义市岩溶地下水环境,对遵义市城区岩溶地下水中的硫酸盐(SO42-)、氨氮(NH4+)、亚硝酸盐(NO2-)、硝酸盐(NO3-)等离子作克里格(Kriging)估值等值线图,并根据等值线图对4种离子的空间分布特征及范围、空间变化规律进行分析评价。     

河姆渡早期文化发展间断原因新考

通过对浙江余姚市田螺山遗址剖面系统采样,在前人研究的基础上,采用地层学的研究方法,通过地层对比、古地磁、孢粉与微古分析、14C测年等手段,认为河姆渡早期文化发展中断可能是由于海啸或风暴潮灾害作用的结果。     

时空一体化框架下时空异常探测

：提出一种时空一体化的时空异常探测方法,首先基于时空统计学与聚类分析构建一体化时空邻近域。进而, 发展兼顾时空相关与异质性的时空异常度量方法。最后,采用一种3步骤的策略探测时空异常。应用本文方法探测中国 陆地区域33年(1970年—2002年)的年平均气温时空数据中的时空异常,探测结果具有较好的可靠性,反映时空数据的时 空一体化特征。同时,对时空异常的产生机理与实际意义进行分析和解释。     

基于"当前"统计模型的载体速度计算

本文通过分析描述载体运动的"当前"统计模型,设计了基于"当前"统计模型计算载体速度的自适应卡尔曼滤波算法.利用航空飞行实验中获得的相位观测值,进行时序差分得出相位率,并对其组双差,获得计算速度的双差多普勒频移值,使用设计的算法进行计算分析,同时与常加速度模型的滤波结果做了比较.结果表明在静态和动态情况下,"当前"统计模...     

Characteristics of intensity change in tropical cyclones affecting the South China Sea from 1977 to 2007

The best track data of tropical cyclones (TCs) provided by Regional Specialized Meteorological Center (RSMC) Tokyo for the South China Sea (SCS) from 1977 to 2007 are employed to study the spatiotemporal variations (for a period of 12 hours) and the rapid (slow) intensification (RI/SI) of TCs with different intensity. The main results are as follows. (1) Over this period, the tropical storms (TSs) and severe tropical storms (STSs) mostly intensify or are steady while the typhoons (TYs) mostly weaken. The stronger a TC is initially, the more observation of its intensification and the less its variability will be; the more observation of its weakening is, the larger its variability will be. (2) The TC intensifies the fastest at 0000 UTC while weakening the fastest at 1200 UTC. (3) In the intensifying state, TSs, STSs, and TYs are mainly active in the northeastern, central-eastern, and central SCS respectively. The weakening cases mainly distribute over waters east off Hainan Island and Vietnam and west off the Philippines. Some cases of TSs and STSs weaken over the central SCS. (4) The RI cases form farther south in contrast to the SI cases. The RI cases are observed in regions where there are weaker vertical shear and easterly components at 200 hPa. The RI cases also have stronger mid-and lower-level warm-core structure and smaller radii of 15.4 m/s winds. The SI cases have slightly higher SST.     

Assessment of the natural and anthropogenic sources of chemical elements in alluvial soils from the Drava River using multivariate statistical methods

The objectives of this study are as follows: (a) an assessment of the geochemical background signature of the Drava Valley before the industrial revolution; (b) an evaluation of anthropogenic geochemical influences on the alluvial plains and river terraces in the valley; and (c) a determination of the spatial distribution of trace elements in the alluvial soils of the Drava River downstream of the Austrian–Slovenian border to the confluence of Mura and Drava Rivers.     

张掖市城市湿地土壤盐分、pH值和含水量的空间异质性分析

基于区域变量化理论,运用传统统计学和地质统计学方法,以张掖市城市湿地为研究区,定量分析湿地土壤盐分、pH值和含水量的空间异质性.结果表明:土壤盐分较高,呈一定的碱化趋势;盐分属于强变异程度,pH值属于弱变异程度,含水量属于中等变异程度;根据半方差函数理论模型分析,盐分受结构性因素较大影响表现为强空间相关性,pH值受随机...     

On the long-term response of marine structures

This paper addresses some important issues related to the estimation of long-term extreme responses of marine structures. Several convolution models to establish the long-term distribution of a marine structure response parameter are available in the literature. These methods are typically based either on all short-term peaks, all extreme short-term peaks or all short-term upcrossing rates. The main assumptions and simplifications of the five models most usually found in the literature are discussed in this paper. A linear single-degree-of-freedom (SDOF) system along with a bi-lognormal probability model for significant wave heights and zero-crossing wave periods have been used for numerical tests. An improved approach to efficiently evaluate the long-term convolution integrals is also proposed in this paper. It is shown that a combination of the Inverse First Order Reliability Method (IFORM) and an Importance Sampling Monte Carlo Simulation (ISMCS) approach can be used to obtain a very good result for the exact solution of long-term integrals.