Development of storm hyetographs for flood forecasting in the Kingdom of Saudi Arabia

This paper presents the derivation of the design storm hyetograph patterns for the Kingdom of Saudi Arabia based on real rainfall events from meteorological stations distributed throughout the Kingdom. Two thousand twenty-seven rainfall storms for a 20–28-year period were collected and analyzed covering 13 regions of the Kingdom. Four distinct dimensionless rainfall hyetograph patterns have been obtained over the Kingdom, while two patterns have been obtained for each individual region because of the lack of data for long-duration storms in individual regions. The resulting dimensionless rainfall patterns for each region can be used to develop storm hyetographs for any design duration, total rainfall depth and return period. It has been shown that the developed storm hyetographs have different features from other storm patterns that are commonly used in arid zones. The study recommends using these curves for the design of hydraulic structures in Kingdom of Saudi Arabia and regions alike.     

Analysis of pervasive precipitation in similar gradient areas of Iran

Precipitation is a major climatic element with high spatial variations. Temporal and spatial variations may differ in large and small scales. It is, therefore, of utmost importance to study areas with similar gradients in terms of precipitation patterns in order to shed light on the complexities of precipitation variations. In the present study, attempts were made to identify areas with similar gradients experiencing the same precipitation pattern over a 50-year period (1964–2013). To this end, data were collected from synoptic stations in Iran in two phases (i.e., 1434 stations in the first phase and 673 stations in the second one). Alexanderson’s technique was adopted to examine sudden changes in precipitation patterns. The results showed that five regions with similar gradients could be identified in terms of precipitation patterns: negative and high variations, negative and moderate variations, positive and high variations, positive and moderate variations, and little or no variations. The distribution of such regions indicated that the regions with positive trends experienced more annual variations and had further spatial distribution. Furthermore, the findings revealed that the regions with negative precipitation patterns experienced more sudden changes in comparison with those with positive precipitation patterns. Additionally, more variations were observed in the precipitation patterns in recent years.     

干旱区土壤种子库的研究进展

土壤种子库在连接过去、现在和将来的植物种群和群落的结构和动态中起着重要的生态和进化作用,对保护和恢复干旱区植被起着重要的作用。从土壤种子库的研究方法、数量特征、分布格局、时空动态、与地上植被关系、年龄结构及影响因素等方面论述了干旱区土壤种子库研究的若干进展,展望了干旱区土壤种子库的研究趋势。     

半干旱区景观格局与生态水文过程研究进展

景观格局和生态水文过程之间具有紧密的联系和相互作用,在半干旱地区这种联系尤为显著,是地球科学研究的重要前沿领域.尺度效应在两者关系中起重要作用,不同尺度下两者相互作用机制有很大差异.归纳总结了半干旱地区景观格局与生态水文过程的研究现状与进展,包括二者相互作用机理、影响因素、干扰、尤其是人为干扰对这种相互作用的影响,以及模型模拟等.以尺度为线索,在斑块、坡面和流域尺度进行展开.最后,提出了半干旱地区景观格局与生态水文过程研究中存在的问题、热点和趋势,包括物理机制、干扰后的恢复机制、模型发展、流域尺度集成及尺度转换.     

Decline of the mid‐ to late Holocene forests in China: climatic change or human impact?

Fossil pollen data from China indicate continued forest decline during the mid‐ to late Holocene in most regions north of the Yangtze River. The earliest forest decline can be detected ca. 5000 yr BP in the middle and lower Yellow River regions. North, northeast and northwest from this region, forest decline became progressively later, and almost no decline took place in the northernmost part of northeast China and in the remote areas of west China during the last 5000 yr. Climate changes could hardly account for the temporal and spatial patterns of the forest decline. Instead, anthropogenic disturbance may have been of overwhelming importance. Ancient agriculture and high‐density settlement expanded outward from the middle and lower Yellow River regions in similar patterns to those of forest change. This study also indicates that land‐use and land‐cover changes may have started in the early stage of Chinese civilization in an extensive area of the country. Copyright © 2000 John Wiley & Sons, Ltd.     

Validating the demarcation of eco-geographical regions: a geostatistical application

Eco-geographical regional system is important for the study of global environmental changes and sustainable development, and it serves as a scientific basis for rationally managing and sustainably utilizing ecosystems and natural resources, such as constructing healthy eco-environments and making policies of environmental management. This paper explained the necessity of validation in the demarcation of eco-geographical regions, which is difficult and may be achieved with some assumptions and presumptions because of the existence of transition zones. Also in this paper, we explored the use of geostatistics in validating regions and boundaries using a case study in Qinghai-Tibet Plateau on the basis of normalized difference vegetation index (NDVI) data. The results show that: (1) eco-geographical regions have different spatial complexity and spatial heterogeneity [i.e. different characteristic values (nugget/sill, fractal) of NDVI], and regions with similar patterns of temperature and moisture have similar mean NDVI values and spatial characteristics [i.e. similar spatial characteristic values (nugget/sill, fractal) of NDVI]. Thus, based on the similarity of spatial heterogeneity or spatial patterns of distribution, demarcations of eco-geographical regions with similar conditions of temperature and moisture, such as IID1 (Ngari montane desert-steppe and desert zone), IID2 (Qaidam montane desert zone), and IID3 (Northern slopes of Kunlun montane desert zone), meet the regional validation requirement. (2) Based on the comparison of spatial heterogeneity or spatial patterns of distribution, the boundary between IIA/B1 (Western Sichuan–eastern Xizang montane coniferous forest zone) and IB1 (Golog–Nagqu high-cold shrub–meadow zone) meets the boundary validation requirement. This boundary guarantees high similarities in an intra-region and high differences in inter-regions, because the value of fractal dimension is the minimum in buffer 1. Furthermore, this paper discussed the application of geostatistics in the choice of index system for boundaries of eco-geographical regions and the determination of region size. The results indicate that the application of geostatistics in eco-geographical regional system is broad, and such researches can serve for obtaining more reasonable and applicable eco-geographical regionalization schemes.     

Population shifts and local democratic representation in Eastern Germany

The shift to market forces in East Germany has fundamentally reconfigured its social and economic geography. In particular, spatial inequalities between localities and regions have re-emerged forcefully in response to new values, expectations and preferences. Increased mobility through private transport, changing job opportunities, educational choices and desire for new housing qualities have inter alia created new parameters for the population's lives. The responses i.a. in the form of migration have altered demographic structures and spatial patterns of the population considerably, often varying significantly over relatively short distances within and between regions. After initial population losses generally through outmigration from East to West Germany, population losses in cities occurred in favour of suburban areas, and rural depopulation in favour of the cities; creating a highly differentiated basis for future development through new urban-rural contrasts and differences between urban regions. This paper will outline some of these processes and demonstrate their effects on the already-considerable inequalities inherited from communism. Attention will also be given to the effects of changing population structures and patterns on local government and the future prospects for an indigenously supported, sustainable economic development for regions and the likely pathways of transformation and adjustment. This revised version was published online in July 2006 with corrections to the Cover Date.     

Scale Transitions in Fracture and Active Fault Networks

Detailed box counting analysis was conducted of (1) fractures observed in exposures of the Devonian Shale in the central Appalachians Valley and Ridge Province of West Virginia, (2) several fracture patterns presented in the literature, and (3) active faults mapped throughout the main island (Honshu) of Japan. Box curves reveal, with few exceptions, that most naturally occurring fracture patterns are characterized by nonfractal behavior. In many cases, two linear regions separated by an abrupt transition are observed in the logN/logr box curves. The small-scale (larger r) features generally have higher fractal dimension than do the larger scale features in the pattern. Transitions from one region to another are usually abrupt. These transitions are not associated with sampling problems or other data limitations. In some cases three or more linear regions may appear. Box counting analysis of model fracture patterns indicate that transitions are related to the dominant spacing of individual sets or to the dominant fragment size in the network. This study provides detailed documentation of scale invariant features in natural fracture and active fault patterns. Although the relationship of the geometrical properties of a pattern to the location of transitions is understood in terms of the models, to understand the physical mechanisms responsible for these transitions deserves further study.     

研究微量元素区域分散与富集规律的新方法

本文从实际资料出发初步探讨了多年来一些区域化探工作者使用传统的浓度克拉克值来估计不同地质单元不同元素的富集与贫化规律的问题。提出了以元素的区域背景平均值代替地壳克拉克值计算区域浓集系数的新方法,研究微量元素的区域空间分布规律,取得了较好的效果。     

全球早、中寒武世藻类生物地理分区初探

澄江生物群、凯里生物群、加拿大布尔吉斯生物群和西伯利亚藻群中均有丰富的藻类化石。根据前寒武纪宏观藻类的分布以及凯里生物群和布尔吉斯页岩生物群中藻类和后生动物的相似性，讨论了前寒武纪至中寒武世期间生物地理分区的控制因素。对几个生物群中的藻类化石和后生动物化石的对比研究发现,在相近的纬度范围内, 动植物化石组合特征非常相似; 而纬度明显差异时, 藻类生物群及后生动物群也具有明显的差异。由于后生生物在前寒武纪至中寒武世期间具有低的演化程度和分异能力，因此生物地理分布的主要控制因素是古纬度。而Schopf (1976)的生物地理分区模式不适合这一时期的生物地理分区。结合前寒武纪至中寒武世后生生物化石的分布情况，建立了前寒武纪-中寒武世时期的生物地理分区模式。这个模式较好地解释了分布在北美大陆和华南大陆上的寒武纪生物群相似的原因。     

Coevolution of Brachiopod Paleobiogeography and Tectonopaleogeography during the Early–Middle Permian

A comprehensive compilation and systematic analysis of known early and middle Permian brachiopod faunas shows that the early Permian brachiopod faunas comprise three realms, six regions, and eleven provinces, while those of the middle Permian comprise three realms, four regions, and eight provinces. A comparison and analysis of brachiopod faunal patterns reveal a coevolution between global brachiopod paleobiogeography and tectonopaleogeography during the early–middle Permian. Although temperature/latitude is the main factor controlling the formation of three realms, tectonopaleogeographic factors determine the temperature/latitude in which the continents were located. The ‘continental barrier' of Pangea, as a ‘central axis' continent, divided the three realms into six regions, which indicates that the formation of biogeographic regions was controlled mainly by the tectonopaleogeographic factors. The evolution of tectonopaleogeography was sometimes a long-term process, so that the biogeographic regions(or provinces) controlled by tectonopaleogeography displayed relative stability. Shifts in the nature of biogeographic provinces(e.g., from cool water to warm water, and vice versa), extensions or narrowing of geographical ranges, and recombinations of some provinces were all related to regional tectonic evolution. The study of the coevolution between brachiopod paleobiogeography and tectonopaleogeography not only accounts for the formation mechanisms of brachiopod paleobiogeographic patterns during the early–middle Permian, but also provides evidences for the locations and configurations of oceans and plates(blocks) during this period.     

Lamellar structures in low-calcium orthopyroxenes

Clinoenstatite lamellae are found to be distributed in three distinct patterns that define three microstructural types. There are regions of the crystal devoid of lamellae and these correspond to ordered or O-orthopyroxene. When the lamellae are present but not in any periodic arrangement, disordered or D-orthopyroxene is identified. In some areas, the lamellae are spaced periodically and these are regions of “superlattice” orthopyroxene. These microstructural types explain all previous X-ray results on orthopyroxenes. Microstructural differences between low and high calcium orthopyroxenes are discussed.     

A worldwide test of three long-term premonitory seismicity patterns—a review

Worldwide analysis of the clustering of earthquakes has lead to the hypothesis that the occurrence of abnormally large clusters indicates an increase in probability of a strong earthquake in the next 3–4 years within the same region. Three long-term premonitory seismicity patterns, which correspond to different non-contradictory definitions of abnormally large clusters, were tested retrospectively in 15 regions. The results of the tests suggest that about 80% of the strongest earthquakes can be predicted by monitoring these patterns.Most of results concern pattern B (“burst of aftershocks”) i.e. an earthquake of medium magnitude with an abnormally large number of aftershocks during the first few days. Two other patterns, S and Σ often complement pattern B and can replace it in some regions where the catalogs show very few aftershocks.The practical application of these patterns is strongly limited by the fact that neither the location of the coming earthquake within the region nor its time of occurrence within 3–4 years is indicated. However, these patterns present the possibility of increasing the reliability of medium and short-term precursors; also, they allow activation of some important early preparatory measures.The results impose the following empirical constraint on the theory of the generation of a strong earthquake: it is preceded by abnormal clustering of weaker earthquakes in the space-time-energy domain; corresponding clusters are few but may occur in a wide region around the location of the coming strong earthquake; the distances are of the same order as for the other reported precursors.     

黄河源区气候变化的环境效应研究

以黄河源区气象台站的降水和气温资料以及玛多、达日、玛曲、唐乃亥和兰州水文站的径流资料为基础, 分析研究了该区降水、气温、水文变化趋势, 并对研究区的土地利用现状变化及原因进行了探讨. 结果表明: 在年代际变化趋势上, 黄河源区气温总体上呈升温态势, 降水呈减少趋势, 径流量也表现为减少趋势.土地利用现状的变化表明人类活动对研究区生态湿地的干预增强.自然因素和人类活动的综合作用, 使得黄河源区生态环境进一步恶化, 亟需进行人工干预, 保护和改善黄河源区生态湿地环境.     

Strengthening foundations of seismically weak buildings on sandy soils in Denizli,Turkey

Rare earth elements (REE) have been extensively used to indicate for material provenance since they behave conservatively and mainly transport in particulate form during earth surface processes. Nevertheless, the application of REE for material provenance study has to be cautious because grain size and mineral fractionations can alter bulk compositions of weathered sediments. Central Asia is one of the most important dust source regions globally and numerous studies on REE compositions of surface materials have been conducted. In this study, REE compositions of various materials from this area are summarized to explore the existing REE-related problems. Overall, chondrite-normalized REE patterns for many surface materials are so uniform that they cannot serve as reliable approaches in tracing material source regions. In contrast, great variations of REE compositions occur among different materials that are derived even from the same parent rock due to influences of grain-size distributions and heavy minerals. For the same reason, small-scale loess around the Tibetan Plateau has different upper continental crust (UCC)-normalized REE patterns compared to those of typical loess. Therefore, great cautions should be made when UCC-normalized REE patterns and REE ratios are utilized to investigate material provenance. Finally, some suggestions are proposed for such studies in future.     

金矿区水中几种状态金在不同气候带的地球化学分布

通过对4个金矿区的水化学测量,发现水中不同状态金分布在不同地域气候带下呈规律性变化,初步建立水中不同状态金异常分布模式,为水化学预测隐伏金矿提供依据     

Order amid sparse data: Patterns of lake level changes in North America during the Late Quaternary

Water-level fluctuations in closed-basin lakes can be used to reconstruct past hydrological changes, and the recognition of spatially coherent patterns in lake behavior provides evidence for changes in climate. The geological records of water level in many lakes, particularly those in arid regions, are by nature incomplete. The fragmentary nature of the data poses special problems for comparison of records and identification of regions where lakes behave similarly. An unconventional method of assessing similarity in the behavior of lakes is used with multidimensional scaling to place lakes in a low-dimensional space. Weights are used to reflect the amount of information available for each particular comparison. The similarity measure is based on evidence for changes in lake depth between successive time intervals and on independent evidence for the direction of change at any given time. Groups (clusters) of lakes in the low-dimensional space are identified by mutual proximity. The method was applied to a set of 65 Late Quaternary lake-level records from North America. About one-third of the lakes had too little weight to be placeable, about one-third were in clusters, and about one-third showed unique behavior. Those lakes which clustered showed four distinct types of record, characteristic of well-defined geographic regions. This ability to distinguish spatially coherent patterns on internal evidence alone strengthens the basis for using lake-level records for regional palaeoclimatic reconstructions.     

Review: Progress in permafrost hydrogeology in China

Groundwater in China’s permafrost region is vital for humans and cold-climate ecosystems. Permafrost responses to global warming have significantly changed the spatio-temporal patterns and distribution of properties associated with the groundwater system. The main areas of current and past studies on permafrost hydrogeology in China include four aspects: groundwater distribution and dynamics in permafrost regions, interplay between groundwater and permafrost, the impact of permafrost degradation on groundwater, and the regional effect of groundwater changes on the environment in permafrost regions. Over the last 10 years, the development and use of coupled heat-transport and groundwater models have focused on the hydrogeology of permafrost, and on groundwater development and distribution in permafrost regions. Progress in groundwater-related research on issues surrounding permafrost regions of China are comprehensively summarized and discussed in this review paper, which should provide a theoretical basis for further study of the groundwater system and its effects on the ecological environment under climate change.     

Advances in travel geometry and urban modelling

Urban travel geometry is a generalization of patterns of movement in cities and regions where route configuration and prevailing traffic speeds constrain or direct movement in distinctive and repeatable patterns. In this paper we use these properties to construct time surfaces on which distance equates to the time of travel in the urban plane. Such surfaces can be two- or three-dimensional and are useful in the study of urban structure, locational analysis, transport planning and traffic management. A particular niche addressed in this paper is non-conformal time surface transformations in which speed or the cost of travel is constrained according to co-ordinate directions. It is argued that such models may be more suited to gridded and orbital-radial cities than previously used conformal transformations. After explaining the rationale behind the approach, a mathematical basis is developed and several calibrated examples are provided based on regions in the UK. The paper concludes with some examples of potential applications, and an annex provides a detailed mathematical framework. This revised version was published online in August 2006 with corrections to the Cover Date.