寒区和干旱区水文研究的回顾和展望

寒区和干旱区水文研究冰川,积雪,冻土,高寒山区和山前地带已初步形成了较完整的观测实验和研究体系,８０年代以来,在冰川融水径流,出山径流形成的观测实验,寒区水文过程,冰川作用流域水文过程和大气过程相互关系。乌鲁木齐地区的水资源问题,气候对水资源的影响,高亚洲冰冻圈水文,冰川洪水和融雪径流以及干旱区水文等方面已取得了多项研究成果,近年来,寒区和干旱区水文水资源的研究在内陆河流域水资源合理开发利用与社会     

长江-黄河源寒区径流时空变化特征对比

长江源区比黄河源区寒冷而干燥, 年径流量仅为黄河源区的60%, 径流年内分配较黄河源区均匀性差, 丰水年与枯水年比例基本相当, 而黄河源区枯水年占较大优势. 近40 a来长江源区径流量总体上呈明显的递减趋势, 黄河源区径流量则呈现略微增长趋势. 长江源区径流量以8～9 a的周期变化较为显著, 黄河源区径流量则以7～8 a周期比较显著. 对寒区径流变化的主要影响因子分析表明, 长江源区温度因子对径流年际变化影响大于黄河源区, 而降水因子影响相对较小, 长江源区寒区水文环境对径流影响较大是造成长江、黄河源区径流差异形成的主要原因.     

寒冷地区热棒技术的研究与应用

由于热棒具有极强的单向导热性能, 被广泛用来冷却地基、强化冻土与大气间热交换, 解决基础冻胀、融沉等热力过程中工程问题. 从热棒在国内外冻土工程的综合应用、热棒传热影响因素以及热棒应用的工程设计参数, 评述和回顾了寒冷地区热棒技术的研究和应用, 并讨论了热棒技术综合应用的发展前景.工程实践表明, 热棒在寒冷地区具有广泛的工程应用前景, 不仅可以应用于寒区公路、铁路、 输油管线工程等大型线性工程, 而且也可应用于机场、房屋等工业与民用建筑, 同时还可以用于低温储藏库修建、机场跑道融雪等. 青藏铁路修建以来, 热棒在我国得到了最广泛的应用, 同时热棒与保温材料、块碎石护坡/护道等联合构成了新的综合结构措施.     

Spatial and temporal distribution of groundwater recharge in northern Nigeria

Moisture samples obtained from unsaturated-zone profiles in sands from northern Nigeria were used to obtain recharge estimates using the chloride (Cl) mass-balance method and to produce records of past recharge and climatic events. Recharge rates range from 14–49 mm/year, on the basis of unsaturated-zone Cl values and rainfall chemistry measured over eight years at three local stations. The unsaturated-zone results also provide a record of the changing recharge and climatic events of the past 80 years; this record compares quite well with modelling results using precipitation data from Maiduguri, especially for the late 20th-century period of drought. The best fit for the model is made, however, by using a lower mean rainfall Cl (0.65 mg/l) than that obtained from the mean of the field results (1.77 mg/l Cl). This result implies that the measured rainfall Cl probably overestimates the depositional flux of Cl, although the lower value is comparable to the minimum of the measured rainfall Cl values (0.6 mg/l Cl). Recharge estimates made using these lower Cl values range from 16–30 mm/year. The spatial variability was then determined using results from 360 regional shallow wells over 18,000 km². Using the revised rainfall estimate, the Cl balance indicates a value of 43 mm for the regional recharge, suggesting that either additional preferential flow is taking place over and above that from the vadose one, or that the regional recharge represents inputs from earlier wetter periods. These recharge estimates compare favourably with those from hydraulic modelling in the same area and suggest that the recharge rates are much higher than values previously published for this area. High nitrate (NO₃) concentrations (NO₃-N>Cl) preserved under aerobic conditions in the vadose zone reflect secondary enrichment from N-fixing vegetation, as occurs elsewhere in the Sahel. Electronic Publication     

Comparison of tropical,carbonate and temperate,siliciclastic tidally dominated sedimentary deposits: Examples from the Australian continental shelf

Surficial deposits of the tidally influenced Australian shelf seas exhibit a variation in fades related to energy gradient. These deposits comprise a high energy gravelly facies, a mobile sand sheet facies and a low energy muddy sand facies. Such a facies distribution conforms generally with the existing model of continental shelf tidal sedimentation, derived for the west European tidal seas. However, the carbonate rich and mainly warm water deposits of the Australian shelf differ from the mainly quartzose and temperate cold‐water deposits of the European type case in terms of: (i) the role of seagrasses in trapping fine‐grained sediment; and (ii) the relative importance of the production of carbonate mud by mechanical erosion of carbonate grains. Seagrasses in Spencer Gulf, Gulf of St Vincent and Torres Strait are located in regions of strong tidal currents, associated with bedforms and gravel lag deposits. Thus, in the case of tropical carbonate shelves, seagrass deposits containing fine‐grained and poorly sorted sediments are located in close proximity to high energy gravel and mobile sand facies. In contrast, the European model (for temperate, siliciclastic shelves) places facies in a regional gradient with a wide separation (in the order of 50–100 km).

Of the locations reviewed, the Gulf of St Vincent, Bass Strait, southern Great Barrier Reef, Torres Strait and Gulf of Carpentaria exhibit zones of carbonate mud accumulation. The production and winnowing of carbonate mud from the mobile sand facies is a factor that must be taken into account in the assessment of a sediment budget for this facies, and which is of relatively greater importance for carbonate shelves. Insufficient data are presently available from the macrotidal North West Shelf to test the applicability of the model to this region.     

Groundwater recharge: an overview of processes and challenges

Since the mid-1980s, a relative explosion of groundwater-recharge studies has been reported in the literature. It is therefore relevant to assess what is now known and to offer further guidance to practitioners involved in water-resource development. The paper summarizes current understanding of recharge processes, identifies recurring recharge-evaluation problems, and reports on some recent advances in estimation techniques. Emphasis is accorded to (semi-)arid regions because the need for information is greatest in those areas – groundwater is often the only water source, is vulnerable to contamination, and is prone to depletion. Few studies deal explicitly with groundwater recharge in temperate and humid zones, because recharge is normally included in regional groundwater investigations as one component of the water balance. The resolution of regional water-balance studies in (semi-)arid areas is, in contrast, often too low to quantify the limited recharge component with sufficient precision. Despite the numerous studies, determination of recharge fluxes in (semi-)arid regions remains fraught with uncertainty. Multiple tracer approaches probably offer the best potential for reliable results in local studies that require 'at-point' information. However, many investigations indicate that these approaches are not straightforward, because in some cases preferential flow contributes as much as 90% of the estimated total recharge. Tracer results (e.g. Cl^–, ³H) must therefore be interpreted with care in areas with multi-modal flow in the vadose zone. Moreover, accurate estimation of total chloride deposition is essential, and tritium may be influenced by vapour transport at low flux rates. In addition, paleoclimatic and paleohydrological conditions may cause discrepancies between measured actual processes and calculated long-term averages. The frequently studied issues of localized recharge and spatial variability need not be a problem if concern is with regional estimates. The key for practitioners is the project objective, which dictates whether 'at-point' or area-/groundwater-based estimation methods are appropriate. Many indirect (wadi) recharge studies reported in the literature are site specific; the relationship between 'at point' hydraulic properties and channel-reach losses demands further investigation. Electronic Publication     

黄河、长江源区降水变化的水汽输送和环流特征

利用黄河、长江源区气象站的降水资料和NCEP/NCAR再分析气候资料,分析了黄河、长江源区降水的年际变化,对黄河、长江源区典型多雨年与少雨年的500 hPa位势高度和风场、600 hPa流场、大气水汽含量和水汽输送进行了合成和对比分析.结果表明:黄河和长江源区的降水在近50 a的长期变化趋势都不明显,但在最近10 a黄河源区的降水有明显的减少趋势.而长江源区的降水则有明显的增加趋势;江河源区在多雨与少雨年有明显的环流差异特征,在多/少雨年,500 hPa蒙古低压减弱/加强,西风风速减弱/增强,600 hPa高原辐合线偏北/南,江河源区大气水汽含量增加/减少,西南季风的偏南水汽输送增加/减少.使得江河源区有较多/少的水汽来源,从而降水增多/减少;黄河和长江源区有相似的多雨与少雨年环流差异特征,只是差异程度不同,长江源区多雨与少雨年环流特征差异的强度不及黄河源区.     

水源地勘察评价分类体系的构建及其意义

本文简要回顾了水源地的分类历史,分析了科学分类的基本原理及其分类流程,就水源地的分类目标、分类原则、分类对象、分类指标等进行了探讨,构建起了地表水与地下水既相容统一又相互独立的水源地分类体系,并对水源地分类方案的特点进行了简要介绍.     

Regional Population and Employment Change in Australia 1991–2001: Inertia in the Face of Rapid Change?

Analyses of the patterns of national population change have been influenced by the US experience where major differences between a older north and a newer south are prominent in many studies. The current paper argues that these perspectives overlook some inertia in the pattern of population and jobs. Drawing upon US and European experience the paper explores the pattern of change in Australia. There it finds that population has favoured newer locations but that gains in share of national population have not been large. At the same time some of the older regions have maintained population share, or at worst recorded small declines. That broad insight is enriched by sectoral analysis where it is clear that only the retail sector has experienced the large gains in new regions; employment change in other sectors showed the links with population change are weak. The paper concludes that simple notions of new region population and employment gains are oversimplified and overlook the substantial development around established centres. In particular it is possible that the old regions are re-structuring their spatial form and spilling over statistical boundaries and so actually maintaining established role in national networks.     

Research Advance of Shrub Dendrochronology in the Cold and Arid Regions of China

Along with the booming of dendrochronology in China, the woody species for the tree-ring study have expanded gradually from tree species to the shrub and dwarf shrub species in the last decades. The zonal woody species in the vast alpine mountains, arid desert areas and arid regions in China are mostly shrubs and semi-shrubs, which is very important to understand the process of regional evolution, environmental protection and ecological recovery. In this paper, the shrub species which have been studied on tree rings in cold and arid areas of China were collected and sorted, and the fundamental research advances were presented, which include the shrub tree ring identification, radial growth characteristics, and chronology construction by different parameters. The applications of shrub dendrochronology to the subjects in eco-response, paleoclimate reconstruction, hydrological process, ecological study of artificial forest and ecological restoration were also presented. The prospect of shrub dendrochronology in the future was also discussed.     

青藏高原多年冻土地区公路路基变形

通过对现场实体工程的长期监测资料和路基破坏机理分析研究,使我们对沥青路面对多年冻土的严重影响,导致多年冻土的升温与退化,使路基产生较严重的不均匀下沉变形,及其它所引起的一系列路基病害问题的发生发展过程有了较为系统和深刻认识,取得了大量现场实测资料及研究成果.讨论了高温多年冻土地区冻土路基的变形特征,以及冻土路基变形与工程地质条件的关系,给出了路基随地温波动变化而发生的变形过程。     

冻土动力学研究的现状及展望

随着我国"一带一路"倡议发展主线的逐步开展,寒区交通运输工程必将得到广泛的建设。为确保寒区工程构筑物在动荷载作用下的长期稳定,对冻土动力学相关理论与实践问题的研究迫切地需要做出解答。冻土动力学主要研究的是动荷载作用下冻土的强度、变形和稳定性问题。通过归纳和总结,阐述了冻土动力学在动力学参数、动强度、动应力-应变关系、动蠕变特征及蠕变模型、冻土场地地震反应特性、冻土区桩基结构动力特性、列车荷载下冻土路基的动力响应等7个方面的研究进展及成果,并结合各方向的发展趋势进行了展望。     

Geo-hazards with characteristics and prevention measures along the coastal regions of China

China has more than 18,000 km long coastline. Along the coastline, there are various configurations of topography, geomorphology, and geology condition. In the coastal regions, geological disasters, including seawater intrusion, coast scouring, land subsidence, karst collapse, soil erosion, collapse-landslide-debris flow (CLDF), and human activity-induced disasters, occur frequently. All of these disasters have their own forming causes, characteristics, and distribution regions. Seawater intrusion and coast scouring only occur in the coastal regions while the others occur in both coastal regions and in-land regions. Land subsidence occurring in the coastal region is of larger scale and entails greater economic loss than that occurring in the in-land region. For the other disasters, although the scale of disaster in the coastal regions is smaller than that happened in the in-land regions, the economic loss in the former case is greater than that in the latter. This is because populations are dense and economy is developed along the coastal regions of China. To mitigate the disasters and reduce the economic loss, countermeasures are discussed.     

内蒙古东部及邻区石炭纪—二叠纪构造地层格架与形成环境

构造带内的地层建造和区域展布主要受大地构造背景和古地理环境的双重控制。突出构造地层学方法,进行综合地层学研究,重点地层剖面实测与修订前人资料相结合,在恢复大地构造演化和沉积相分析的基础上,重新划分内蒙古东部及邻区石炭纪—二叠纪地层分区,并建立构造地层格架。2条构造线将研究区分隔成3个地层分区。西拉木伦河断裂南侧（华北地层分区）出露大陆边缘坳陷沉积和陆内裂陷槽充填,称为康保-赤峰地层小区。查干敖包-阿荣旗断裂至黑河一线北侧（兴安地层分区）属西伯利亚板块,呈现边缘坳陷沉积和裂陷槽充填的陆块南缘称东乌-龙江地层小区;而陆内坳陷沉积的北部范围称额尔古纳地层小区。2条构造线之间为板块增生带（内蒙草原地层分区）,自然分隔成锡林郭勒地层小区、科尔沁地层小区和松-辽地层小区,发育多岛洋-海槽-残余海槽的复杂环境。通过论述各岩组划分、对比和沉积相归属,构造地层格架尽可能反映当时的大地构造格局和沉积环境演变。     

干旱区陆面过程和大气边界层研究进展

干旱区陆面过程和大气边界层不仅与气候、生态、水资源密切相关,而且影响我国气候格局和东亚大气环流,是一个十分重要的研究领域,近20多年已取得了比较系统的研究进展.从干旱区陆面热力和水分过程特征、干旱区大气边界层结构特征、干旱区陆面过程参数及其参数化公式、非均匀下垫面大气边界层理论、干旱城市大气边界层特征与污染机理等方面归纳总结了干旱区陆面过程和大气边界层领域取得的部分研究进展.并且,认为科学试验的代表性、复杂下垫面的影响、尺度转化、地表能量不平衡、极端天气过程的相互作用、水分过程的复杂性等问题是干旱区陆面过程和大气边界层研究领域的突出问题和未来研究重点.     

Lateral thinking: 2-D interpretation of thermochronology in convergent orogenic settings

Lateral motion of material relative to the regional thermal and kinematic frameworks is important in the interpretation of thermochronology in convergent orogens. Although cooling ages in denuded settings are commonly linked to exhumation, such data are not related to instantaneous behavior but rather to an integration of the exhumation rates experienced between the thermochronological ‘closure’ at depth and subsequent exposure at the surface. The short spatial wavelength variation of thermal structure and denudation rate typical of orogenic regions thus renders thermochronometers sensitive to lateral motion during exhumation. The significance of this lateral motion varies in proportion with closure temperature, which controls the depth at which isotopic closure occurs, and hence, the range of time and length scales over which such data integrate sample histories. Different chronometers thus vary in the fundamental aspects of the orogenic character to which they are sensitive. Isotopic systems with high closure temperature are more sensitive to exhumation paths and the variation in denudation and thermal structure across a region, while those of lower closure temperature constrain shorter-term behaviour and more local conditions.Discounting lateral motion through an orogenic region and interpreting cooling ages purely in terms of vertical exhumation can produce ambiguous results because variation in the cooling rate can result from either change in kinematics over time or the translation of samples through spatially varying conditions. Resolving this ambiguity requires explicit consideration of the physical and thermal framework experienced by samples during their exhumation. This can be best achieved through numerical simulations coupling kinematic deformation to thermal evolution. Such an approach allows the thermochronological implications of different kinematic scenarios to be tested, and thus provides an important means of assessing the contribution of lateral motion to orogenic evolution.     

青藏铁路多年冻土路基稳定性及防治措施研究

青藏铁路冻土路基的稳定性是多年冻土区列车安全运营的重要保证．影响路基稳定性的主要因素是路基地温场的变化、路基两侧地表水以及地下水（冻结层上水、冻结层间水）和地层含冰量大小,即冻土路基防护措施的强弱和水热影响程度．保证冻土路基稳定性的防治原则是减少太阳辐射和周围环境的水影响,易采用路基两侧排水、增加片（碎）石护坡（道）、...     

内蒙古东部及邻区石炭纪—二叠纪构造地层 格架与形成环境

构造带内的地层建造和区域展布主要受大地构造背景和古地理环境的双重控制。突出构造地层学方法,进行综合地层学研究,重点地层剖面实测与修订前人资料相结合,在恢复大地构造演化和沉积相分析的基础上,重新划分内蒙古东部及邻区石炭纪—二叠纪地层分区,并建立构造地层格架。2条构造线将研究区分隔成3个地层分区。西拉木伦河断裂南侧（华北地层分区）出露大陆边缘坳陷沉积和陆内裂陷槽充填,称为康保-赤峰地层小区。查干敖包-阿荣旗断裂至黑河一线北侧（兴安地层分区）属西伯利亚板块,呈现边缘坳陷沉积和裂陷槽充填的陆块南缘称东乌-龙江地层小区;而陆内坳陷沉积的北部范围称额尔古纳地层小区。2条构造线之间为板块增生带（内蒙草原地层分区）,自然分隔成锡林郭勒地层小区、科尔沁地层小区和松-辽地层小区,发育多岛洋-海槽-残余海槽的复杂环境。通过论述各岩组划分、对比和沉积相归属,构造地层格架尽可能反映当时的大地构造格局和沉积环境演变。     

高密度电法勘探在西部戈壁地区的应用

高密度电阻率法是基于岩土电学性质差异的一种勘探方法.目前在我国东南被广泛应用,但在西部戈壁地区的应用难度较大.根据试验讨论接地电阻的影响和装置类型的选取,并总结高密度电法在戈壁地区使用的效果和局限性.同时提出戈壁地区高密度电法的使用建议,以提高数据获取和解释的准确性.     

Comparative analysis of groundwater formation in arid and super-arid deserts (with examples from Central Asia and northeastern Arabian Peninsula)

Groundwater formation within arid and super-arid deserts is discussed through comparative analysis. Although fresh groundwater is being formed in both types of deserts, mainly from infiltrated surface runoff, in arid deserts, infiltration is currently taking place, whereas in super-arid areas, it occurred mainly in the Pleistocene pluvial epoch. Groundwater discharge conditions are also different. In arid deserts, the discharge occurs mainly through transpiration by phreatophytes, which form phyto-hydrogeological ecosystems where the dominant factor is an interaction between groundwater and vegetation, with transpiration reaching over hundreds of mm/year and the thickness of the groundwater evaporation zone extending over 10 m. Active subsurface water exchange does not favor the preservation of Pleistocene fossil groundwater. Super-arid deserts, however, have an extremely scarce vegetative cover (low, if any), physical evaporation, a thin zone of evaporation influence, and slow water outflow. Favorable conditions therefore exist for the preservation of relict low-mineralized waters. Furthermore, arid and super-arid deserts differ by types of groundwater accumulation and horizontal and vertical zonalities. In arid deserts, hydrogeological problems are connected with the anthropogenic influence upon groundwater, and with control on rational use of surface water and groundwater. In super-arid deserts, the basic problem is depletion of fossil groundwater.