左江中游岩溶峰林区河流交互带水化学特征与控制因素

岩溶交互带是连接岩溶含水层与地表河流的重要通道,对河流和地下水水质具有重要的保护作用。本研究选取左江中游岩溶峰林区河流交互带为研究对象,在丰水期(8月下旬)和平水期(10月下旬)对交互带内机井的水化学进行现场测试分析,并结合地下水流动系统理论探讨左江两侧岩溶交互带空间分布特征和控制因素。研究结果表明:左江水的电导率(EC)较小、Ca^2+、HCO3^-浓度较低,两岸机井中增高;pH、温度、DO的变化则相反,呈现出左江高,两岸机井中降低;交互带内形成了具有DO、pH值梯度、温度梯度、Ca^2+和HCO3^-梯度的混合区。左岸岩溶区补给径流面积大,地下水流动系统范围大,流线密集,岩溶十分发育,形成岩溶管道系统;右岸为左江包围的河间地块,地下水流动系统范围小,补给面积有限,流线稀疏,岩溶发育深度和强度受到限制。左江两岸不同规模的地下水流动系统导致两岸岩溶发育强度明显不同,造成河流交互带范围的巨大差异,左岸的范围大于1000m,而右岸的范围在200m以内,左岸是右岸的5倍以上。本研究有助于左江沿岸地下水的开发利用和水质保护。     

岩溶洞穴交互带概念的提出及其在水资源管理中的意义

岩溶地区以管道流为主的地下水补给、径流与排泄常常引起地下水与地表水间快速且频繁的交互与转化,并因此引发水环境退化问题。文章引用并拓展地表水文学和水文生态学中交互带的概念,提出南方岩溶地区管道流与其他类型水体交互的场所为岩溶洞穴交互带,并依据交互带的水流类型和交互方式,划分为泉口交互带、天窗交互带、落水洞交互带和管道交互带4种类型;且以泉口交互带和天窗交互带为重点,采用水文和水化学在线监测、现场测试、流量测量,结合水化学、浮游生物和微生物等的分析鉴定,剖析了交互带的水文、水化学特征和水生生物群落结构及其与水环境的关系。研究发现:岩溶洞穴交互带的水文功能有弱化趋势;泉口交互带的污染物降解能力明显,水化学功能尚能发挥作用;水生生物功能在退化,主要是由水文功能弱化导致的。水文功能弱化是岩溶洞穴交互带环境功能退化的重要原因。建议在岩溶地区的水文地质和环境地质工作中重视交互带,探索交互带的探测和监测技术,通过有效管理改善交互带的环境功能。      

岩溶关键带及其碳循环研究进展

岩溶关键带的范畴包含了大气-(降水)-植被-土壤-裂隙-基岩-水组成的“碳-水-钙”循环强烈的表层岩溶带以及岩溶管道-洞穴-地下河-隔水层组成的巨大岩溶地下空间,岩溶关键带碳循环是岩溶地球系统科学研究的前沿方向。总结概括了岩溶地球系统科学发展至今的岩溶关键带范畴内碳循环及其对大气CO2源汇效应的研究成果,包括早期碳运移模型、当前主流的区域岩溶碳汇量的计算方法和结果以及“生物碳泵”的新发现等,讨论了当前岩溶碳循环研究框架过于单一或不一致以及碳周转时间尺度等问题,提出应对岩溶关键带碳输入、赋存以及碳输出的各个环节做出系统化监测,通过联网在线高分辨率监测站点的建设以及“3S”技术实现点位到区域的研究,使岩溶碳汇在全球碳循环模型中的重要性更具说服力。     

桂南陇瑞洼地浅层岩溶自然电场特征剖析

岩溶洼地地下水渗透流在一定的渗透压力作用下,通过洼地土层过滤后沿碳酸盐岩溶蚀裂隙网络或孔隙下渗补给岩溶管道或地下河等深层岩溶水,便会产生离子导电岩土层的自然极化现象和自然电场,这种自然电场的研究方法可用于洼地浅层岩溶水的探测。研究结果表明,陇瑞洼地浅层岩溶发育带产生的自然电场实测值的平面等值线在洼地中心部位上出现了场幅值-60～-80 mV、带宽约40 m的带状异常,异常带由北至南呈似“S”状分布;自然电位梯度实测值的平面等值线在岩溶发育带顶部在地面投影中心线附近出现由负值向正值过度的“零值”异常带,“零值”异常带平面分布位置的变化指示了洼地浅层岩溶发育的平面差异与变化。以第18测线为例,陇瑞洼地浅层岩溶自然电位在剖面上分布满足位函数分布特征,即自然电位在浅层岩溶带顶部（615/18测点附近）取得极小值,在极小值的两侧由于逐渐远离岩溶发育带自然电位幅值逐渐减弱,直至趋近于零;自然电场梯度在浅层岩溶带顶部（615/18测点）附近出现由负值向正值过度的“零点”异常,呈似中心对称曲线。水文地质监测钻孔在不同深度揭露了浅层溶洞、溶隙和断层破碎带,从而验证了自然电场法探测岩溶洼地浅层岩溶水资源的有效性。      

岩溶地下水系统防污性能评价方法

岩溶水系统结构复杂,不同类型岩溶区具有不同的岩溶水文地质特征,其地下水系统防污性能评价必须采用不同指标体系的评价模型。本文在对不同类型岩溶区发育特征分析基础上,分别就现有评价模型在不同类型岩溶区的适应性进行了分析,认为:埋藏型岩溶区可采用专门用于承压含水层防污性能评价的PTHQET模型进行评价,而对于补给区局部裸露的浅埋藏性岩溶区建议采用COP模型进行评价;EPIK模型适用于南方裸露岩溶区;北方裸露型岩溶区因表层岩溶带发育程度弱,亦可采用COP模型进行评价。针对覆盖型岩溶的特殊性,在欧洲模型基础上提出了PLEIK评价模型,评价因子包括保护性盖层(P)、土地类型与利用程度(L)、表层岩溶带发育强度(E)、补给类型(I)和岩溶网络发育情况(K);突出了P(保护性盖层)和L(土地利用类型)两个因子的作用,并赋予各因子比欧洲模型更丰富的内涵,同时采用多种可替代参数确定各因子量值,最后给出了防污性能指数计算方法与分级标准。     

中国含油气盆地的古岩溶成因类型

<正> 近年来,在鄂尔多斯、渤海湾、塔里木盆地等深埋藏碳酸盐岩中的油气勘探相继取得了重大突破,在埋藏深度约二三千米的碳酸盐岩中发现了高产古岩溶储集层。由于这类储集规律十分复杂,勘探开发有一定难度,为此从1996年起,国家“九五”重点科技攻关项目“中国大中型气田勘探开发研究(96—110)”特设立了油气田碳酸盐岩古岩溶与深岩溶专题研究。该专题研究识别出了多种多样的古岩溶成因类型。(1)鄂尔多斯盆地古岩溶包括早期“层状岩溶”、中期“膏     

油气田古岩溶与深岩溶研究新进展

项目来源：国家“九五”重点科技攻关项目“中国大中型气田勘探开发”研究专题 起止时间： 1996年—2000年 项目负责人：夏日元 主要完成人：夏日元唐健生罗伟权邓自强关碧珠 承担单位：中国地质科学院岩溶地质研究所 古岩溶是指地质历史时期而非现代营力环境下形成的岩溶；深岩溶则为不受地表侵蚀基准面控制环境条件下的深埋藏岩溶作用。近年来，鄂尔多斯盆地、渤海湾盆地及塔里木盆地等深埋藏碳酸盐岩中的油气勘探相继取得了重大突破，在埋藏深度大于2000～3000m的碳酸盐岩中发现了高产古岩溶储集层。由于储集空间主要为岩溶孔洞、裂缝等，非均质性明显，空间分布规律复杂，加之碳酸盐岩储层经历了漫长的岩溶作用过程(既有地质历史时期近地表环境下的古岩溶作用，又经历了长期逐渐被埋藏过程中深岩溶作用的叠加与改造)，造成油气储集规律十分复杂，给勘探、开发带来了一定难度。为此，从1996年起，国家“九五”重点科技攻关项目“中国大中型气田勘探开发研究(96—110)”特设立了油气田碳酸盐岩古岩溶与深岩溶专题研究。 专题研究采用古水文地质综合方法、溶蚀作用地球化学物理和数学模拟、岩石地球化学测试、岩溶储层介质结构定量评价和预测等技术手段，系统研究了鄂尔多斯盆地和渤海湾盆地奥陶系碳酸盐岩古岩溶和深岩溶的形成条件、影响控制因素和发育特征，揭示了不同时期岩溶作用的机制、发育演化特征及其与油气富集关系，识别出多种多样的古岩溶成因类型： (1)鄂尔多斯盆地古岩溶包括早期“层状岩溶”、中期“膏溶”和晚期“断裂系统岩溶”三个发育演化阶段。“膏溶”作用起关键作用，古岩溶地貌形态对油气富集有明显的控制作用； (2)深岩溶包括压释水岩溶和热水岩溶两种类型。压释水岩溶是指在压力差驱动下，上覆煤系地层成岩压实过程中释放出来的酸性水，通过渗流窗口侵入古风化壳产生对流循环而形成的岩溶。具有“水平渗流”、“侧向渗流—对流循环”、“纵向对流循环”三种发育模式，与烃类运移、聚集的关系为：早期为烃类改善运移通道，中期改造贮存空间，晚期对储集体形成封闭； (3)热水岩溶为奥陶系古风化壳深埋藏后，受燕山运动构造热事件影响，古地温梯度明显增高，呈承压状态向上运移的具有溶蚀能力的深循环热水对可溶岩所产生的溶蚀作用。热水岩溶主要经历了深循环对流热水形成、溶蚀与白云岩化作用两大阶段，对油气藏的形成具有建设性作用； (4)渤海湾盆地黄骅坳陷奥陶系碳酸盐岩岩溶发育主要经历了三个演化阶段：①加里东晚期—海西早期裸露古岩溶；②印支—燕山早期裸露和浅埋藏古岩溶：③燕山晚期—喜山期埋藏深岩溶。通过研究，建立了向斜翼部侵蚀洼地排泄型、向斜轴部山间洼地排泄型、山前浅埋藏断陷盆地型等三种古岩溶发育模式，以及倾斜垒式断块压释水作用、深埋褶断凸起构造压释水作用、深大断裂带高位掀斜断块热水作用等三种深岩溶发育模式。 (5)建立了各类古岩溶和深岩溶发育演化模式，提出了岩溶型油气储层定量评价和预测的模拟勘探技术，预测了三处有利勘探块区，取得了一定社会经济效益。     

我国南方表层岩溶带及其对岩溶水的调蓄功能

表层岩溶带是地表强烈岩溶化过程的产物,为表层碳酸盐岩各种岩溶个体形态和微形态组合构成的不规则带状的岩溶带,在我国南方岩溶区广泛分布。表层岩溶带对岩溶水的调蓄表现在两个方面: 一是增加入渗补给量;二是延缓降雨后雨水在岩溶水系统停留的时间,并形成了表层岩溶泉。表层岩溶带对岩溶水的调蓄功能大小主要与表层岩溶带的结构、岩层产状、地表覆盖情况和降雨性质有关。石漠化环境与森林环境的表层岩溶带对岩溶水的调蓄功能差异很大。石漠化地区,表层岩溶带泉的出流时间短,动态非常不稳定;表层岩溶带对岩溶管道泉调蓄能力弱,泉水动态与降雨动态一致。森林环境表层岩溶泉则多为常流泉,水文动态比较稳定。表层岩溶带形成的表层岩溶泉为开采深部岩溶水困难的峰丛山区的居民饮水提供了重要的水源,但只有恢复了岩溶石山区森林生态,才能实现表层岩溶泉应有的供水功能。      

中国西南岩溶关键带结构与物质循环特征

岩溶关键带调查研究的目标是揭示岩溶生态系统的动态平衡和演化机制,旨在为经济社会提供资源环境服务的可持续管理对策,指出在合理的人为活动下增强岩溶关键带韧性的办法及修复受损部位的有效途径。碳酸盐岩作为可溶岩,赋予了岩溶关键带在结构上及物质循环过程中的岩石圈-生物圈相互作用等方面的若干特殊性。该文以中国西南岩溶区为例,总结了诸多学者的研究成果,揭示了从桂林岩溶区到重庆武隆岩溶区,岩溶关键带发育厚度由几米逐渐增厚至1 000 m的区域差异; 岩溶关键带的垂向物质循环过程以土壤-表层岩溶带为中心环节,而在横向上则呈现“岛屿状”镶嵌分布特征,地表生态具脆弱性; 岩溶关键带碳循环过程包括岩溶碳循环和生态碳循环两部分,碳汇则由植物碳汇、土壤碳汇和岩溶碳汇组成,初步估算其碳汇通量为64.36 t/(km²·a)。     

特殊的地表岩溶形态及成因探讨

对金沙江溪洛渡电站区二叠系下统( P1 )灰岩岩溶发育规律综合研究后发现: 本区内的岩溶洼地多为“半边岩溶洼地” ;岩溶漏斗四周为玄武岩碎块的“特殊类型岩溶漏斗” ;分布于1100m高程的岩溶湖也多是顺岩层走向发育的岩溶湖。      

Applying a modified conduit flow process to understand conduit-matrix exchange of a karst aquifer

Due to the high heterogeneity and complexity of water flow movement for multiple karst water-bearing mediums,the evaluation,effective development,and utilization of karst water resources are significantly limited.Matrix flow is usually laminar,whereas conduit flow is usually turbulent.The driving mechanisms of water exchange that occur between the karst conduit and its adjacent matrix are not well understood.This paper investigates the hydrodynamic characteristics and the mechanism of flow exchange in dual water-bearing mediums(conduit and matrix)of karst aquifers through laboratory experimentation and numerical simulation.A karst aquifer consisting of a matrix network and a conduit was proposed,and the relationship between the water exchange flux and hydraulic head differences generated from the laboratory experiments was analyzed.Two modes of experimental tests were performed with different fixed water level boundaries in the laboratory karst aquifer.The results indicate that the water exchange capacity was proportional to the square root of hydraulic head differences.The linear exchange term in the conduit flow process(CFP)source program was modified according to experimental results.The modified CFP and the original CFP model experimental data results were compared,and it was found that the modified CFP model had better fitting effects.These results showed that the water exchange mechanism between conduit and matrix is very important for solid-liquid interface reaction,water resource evaluation,and understanding of karst hydrodynamic behavior.     

Comparison of a karst groundwater model with and without discrete conduit flow

Karst aquifers exhibit a dual flow system characterized by interacting conduit and matrix domains. This study evaluated the coupled continuum pipe-flow framework for modeling karst groundwater flow in the Madison aquifer of western South Dakota (USA). Coupled conduit and matrix flow was simulated within a regional finite-difference model over a 10-year transient period. An existing equivalent porous medium (EPM) model was modified to include major conduit networks whose locations were constrained by dye-tracing data and environmental tracer analysis. Model calibration data included measured hydraulic heads at observation wells and estimates of discharge at four karst springs. Relative to the EPM model, the match to observation well hydraulic heads was substantially improved with the addition of conduits. The inclusion of conduit flow allowed for a simpler hydraulic conductivity distribution in the matrix continuum. Two of the high-conductivity zones in the EPM model, which were required to indirectly simulate the effects of conduits, were eliminated from the new model. This work demonstrates the utility of the coupled continuum pipe-flow method and illustrates how karst aquifer model parameterization is dependent on the physical processes that are simulated.     

Interconnection of karst systems and flow piracy through karst collapse in layered carbonate rocks

A new mode of interconnecting karst systems separated by impermeable bed due to karst collapse was discovered in the study of dam site in Guizhou, South China. Karst flow may be diverted from conduits in one layer to another, thus forming a connected karst system. Comprehensive methodology and techniques used in the investigation included surface geological surveys, geophysical investigations, special drilling, and tracer tests. In the stage of preliminary study, the karst conduits were considered to be developed separately along individual karstified layers. However, further investigation shows that karst collapse may be associated with conduit and cavern development, damaging the impermeable bed and its watertight function. Accordingly, a new pattern of karst conduit system was reestablished. The results obtained enable the dam designer to plan a reliable alternative for seepage protection.     

Inference of the structure of karst conduits using quantitative tracer tests and geological information: example of the Swiss Jura

Karst aquifers are known for being particularly heterogeneous with highly transmissive conduits embedded in low permeability volumes of rock matrix. Artificial tracer experiments have been carried out in a complex karst aquifer of the folded Jura Mountains in Switzerland with the aim of deciphering the conduit organisation. It is shown that tracer experiments with multiple injection points under different flow conditions can lead to useful information on the conduits’ structure. This information has been combined with data from structural geology, spring hydrology, and speleological observations. A conceptual model of the conduit network shows that a detailed inference of the conduit organisation can be reached: geology controls conduit location and orientation; spring hydrology, including temporary springs, constrains conduit elevations and relative hydraulic heads in the aquifer subsystems; and tracer tests identify major flow paths and outlets of the system and dilution caused by non-traced tributaries, as well as the presence of secondary flow routes. This understanding of the Aubonne aquifer structure has important implications for the future management of the groundwater resource. Similar approaches coupling geological information, spring hydrology, and multi-tracer tests under various flow conditions may help to characterise the structure of the conduit network in karst aquifers.     

岩溶IGCP国际合作30年与岩溶关键带研究展望

全球岩溶类型多样,对环境变化敏感,资源与环境问题突出,是地球关键带监测与研究的重点,IGCP661项目的执行为岩溶区关键带类型划分与监测对比研究提供了契机和国际合作平台。近30年岩溶IGCP执行始终强调岩溶系统与人类活动环境的相互作用,其轨迹实际上与地球系统科学到地球关键带理念是一脉相承的。IGCP299提出了岩溶形态组合概念,揭示各种岩溶形态与其形成环境之间的因果关系。岩溶动力系统(IGCP379), 岩溶生态系统(IGCP448)概念的提出有助于我们更好地理解岩溶系统的整体功能,及系统内水、生物地球化学过程、人类活动的相互作用,进而形成了一整套岩溶动力学研究方法体系。开辟了岩溶记录与全球变化、碳循环与应对气候变化、石漠化形成演变与生态修复等研究新领域,并取得了丰硕的研究成果,有力地推动了现代岩溶学的发展。      

Karst rivers’ particularity: an example from Dinaric karst (Croatia/Bosnia and Herzegovina)

The very complex system of sinking, losing and underground transboundary Karst rivers, lakes and aquifers in the central part of the deep and bare Dinaric karst in Croatia and Bosnia and Herzegovina is analysed. The groundwater and surface water are hydraulically connected through numerous karst forms which facilitate the exchange of water between the surface and subsurface. A complex underground conduit system is an inherent characteristic karst system analysed. Groundwater and surface water exchange with both adjacent and distant aquifers through underground routes or inflows from surface streams and artificial reservoirs. Because of a complex surface and underground karst features, which strongly influenced its hydrological and hydrogeological regime, the main open stream flow, with a longitude of about 106 km, undergoes eight name changes. In this paper, it is noted as “the eight-name river”. In fact, it represents one river with losing, sinking and underground stream sections. Different surface and underground karst forms play crucial roles in the way the water flowing over the surface and on the underground sections of its catchment. The analysed area is full of varied and often spectacular surface landforms, including for example the Blue and Red Lakes and the Kravice Waterfall. The analyses made in the paper show the existence of a decreasing trend of mean annual discharges on the eight-name river, which can cause numerous problems in the regional water resource management of this transboundary river and catchment.     

Relative importance and chemical effects of diffuse and focused recharge in an eogenetic karst aquifer: an example from the unconfined upper Floridan aquifer, USA

Karst aquifer studies often focus on allogenic water inputs and large conduit flow. However, diffuse recharge can be significant, particularly in unconfined eogenetic karst aquifers that retain high matrix permeability. This study examines an unconfined region of the upper Floridan aquifer (USA) that hosts a sinking stream, its resurgence, and a large conduit system. Daily diffuse recharge was approximated using a water-budget method and ranged from 17% of precipitation during a low precipitation year to >53% during the highest precipitation year, illustrating the highly variable nature of diffuse recharge in this region. The total allogenic input via the sinking stream over the 5 years of the study was significantly larger than the volume of diffuse recharge. However, only about 2% of the allogenic recharge flows from the conduit into the surrounding aquifer. That flow is restricted to storm events when hydraulic heads in the conduits exceed those in the surrounding aquifer. The estimated volume of dissolution is similar for allogenic recharge and diffuse recharge to the unconfined region surrounding the conduits, but dissolution from the diffuse recharge is distributed over a larger area than dissolution from allogenic recharge. These results exemplify how recharge type impacts flow and water–rock interactions in eogenetic karst aquifers.     

A Leaky-Conduit Model of Transient Flow in Karstic Aquifers

Karst Flow Model (KFM) simulates transient flow in an unconfined karstic aquifer having a well-developed conduit system. KFM treats the springshed as a two-dimensional porous matrix containing a triangulated irregular network of leaky conduits. The number and location of conduits can be specified arbitrarily, perhaps using field information as a guide, or generated automatically. Conduit networks can be tree-like or braided. Rainwater that has infiltrated down from the surface leaks into the conduits from the adjacent porous matrix at a rate dictated by Darcy’s law, then flows turbulently to the spring via the conduits. KFM is calibrated using the known steady state; geometry and recharge determine the steady fluxes in the conduits, and the head distribution determines conduit gradients and sizes. Spring flow can vary with time due to spatially and temporally variable recharge and due to prescribed variations in the elevation of the spring. KFM is illustrated by four examples run on a test aquifer consisting of 27 nodes, 42 elements, and 26 conduits. Three examples (drought, uniform rainstorm, storm-water input to one element) are simulations, while the fourth uses data from a spring-basin flooding event. The qualitative fit between the predicted and observed spring discharge in the fourth example provides support of the hypothesis that the dynamic behavior of a karst conduit system is an emergent property of a self-organized system, largely independent of the locations and properties of individual conduits.     

晋西南峨嵋台塬的岩溶水系统及岩溶水资源潜力

本文通过分析峨嵋台塬的地质结构和岩溶水补给的自然条件,提出:(1)峨嵋台塬岩溶水具独立的地下水系统特征,北边界为里望断裂,南边界为临猗断裂,西边界为沿黄河东岸延展的夹马口—小梁断裂,东边界为稷王山东麓泥页岩带和变质岩体;(2)岩溶水主要来自稷王山裸露区大气降水,少量排向河津—侯马盆地和运城盆地,大量沿临猗断裂带向黄河方向迳流排泄,排泄量不到东王岩溶泉流量的10%;(3)峨嵋台塬岩溶水潜力有限。