晋陕峡谷地区岩溶地下水的同位素及水化学分析

本文研究采用同位素和水化学分析的方法对本地区 2个泉域即天桥和柳林泉域的地下水系统进行分析。研究发现 :(1)天桥泉域北部大部分地区岩溶地下水主要接受了大气降水的补给 ,同时在局部地区也接受了地表水的补给 ;天桥泉域南部岩溶地下水接受了不同高程的大气降水的补给 ,迳流较为活跃。 (2 )柳林泉域岩溶水系统存在浅部和深部 2个子系统 ,来自这 2个系统的地下水互相混合 ,形成了排泄区较为复杂的地下水化学类型     

Intensive exploitation of a karst aquifer leads to Cryptosporidium water supply contamination

Groundwater from karst aquifers is an important source of drinking water worldwide. Outbreaks of cryptosporidiosis linked to surface water and treated public water are regularly reported. Cryptosporidium oocysts are resistant to conventional drinking water disinfectants and are a major concern for the water industry. Here, we examined conditions associated with oocyst transport along a karstic hydrosystem, and the impact of intensive exploitation on Cryptosporidium oocyst contamination of the water supply. We studied a well-characterized karstic hydrosystem composed of a sinkhole, a spring and a wellbore. Thirty-six surface water and groundwater samples were analyzed for suspended particulate matter, turbidity, electrical conductivity, and Cryptosporidium and Giardia (oo)cyst concentrations. (Oo)cysts were identified and counted by means of solid-phase cytometry (ChemScan RDI^®), a highly sensitive method. Cryptosporidium oocysts were detected in 78% of both surface water and groundwater samples, while Giardia cysts were found in respectively 22% and 8% of surface water and groundwater samples. Mean Cryptosporidium oocyst concentrations were 29, 13 and 4/100 L at the sinkhole, spring and wellbore, respectively. Cryptosporidium oocysts were transported from the sinkhole to the spring and the wellbore, with respective release rates of 45% and 14%, suggesting that oocysts are subject to storage and remobilization in karst conduits. Principal components analysis showed that Cryptosporidium oocyst concentrations depended on variations in hydrological forcing factors. All water samples collected during intensive exploitation contained oocysts. Control of Cryptosporidium oocyst contamination during intensive exploitation is therefore necessary to ensure drinking water quality.     

Ein Speicher-Durchfluss-Modell für die Abflussbildung im Oberjura-Karst der Schwäbischen Alb

Upper Jurassic karstified limestones in southern Germany are characterized by a dual-porosity system. Here we present a new model that describes the basic processes from recharge to discharge. While recharge is distributed to both main conduits and fractures, only minor amounts of the total runoff reach the karst system directly (direct runoff) while most water infiltrates into the fractured matrix. This mechanism expels pre-event water from the fissured matrix and into karst conduits. Additionally, matrix storage exponentially decreases during baseflow conditions. Altogether, direct runoff, pre-event water and baseflow fill the karst system and make up the spring discharge. Based on a time series of 40 years of recharge data, the model simulates daily changes of groundwater volumes within the two storage systems. Prerequisites are recession coefficients for baseflow and conduits. A distribution coefficient calculates the amount of direct runoff and a second coefficient the amount of pre-event water. Calculated discharges were in good agreement with the spring hydrograph.     

基于相空间重构与神经网络耦合的岩溶泉流量预测模型

岩溶水系统是受水文、地质、地形地貌、植被、人类活动等多种因素影响的非线性动力系统。本文利用重构相空间与神经网络,建立重构相空间与神经网络耦合的泉流量预测模型;通过对黑龙洞泉域泉流量的预测可知,所建立的耦合模型精度高。     

Enhanced vulnerability assessment in karst areas by combining mapping with modeling approaches

The objective of this work is to facilitate a sustainable regional planning of water resources in karst areas by providing a conceptual framework for an integrative vulnerability assessment. A combined mapping and modeling approach is proposed, taking into account both spatial and temporal aspects of karst groundwater vulnerability. The conceptual framework comprises the delineation of recharge areas, vulnerability mapping, numerical flow and transport modeling and the integration of information into a combined vulnerability map and time series. The approach is illustrated at a field site in northwest Switzerland (Gempen plateau). The results show that the combination of vulnerability mapping and numerical modeling allows the vulnerability distribution, both in the recharge and discharge areas, to be identified, and at the same time, the time dependence of karst groundwater vulnerability to be assessed. The combined vulnerability map and time series provide a quantitative basis for drinking water management and for regional planning.     

锦屏大河湾磨房沟泉流量衰减规律研究

为了研究磨房沟泉岩溶水系统含水介质结构特征，同时确定工程对岩溶环境的影响程度，对磨房沟泉多年出口流量进行了衰减分析。结果表明，磨房沟泉含水介质由管道状大溶隙和细小溶隙组成，在衰减过程中前者主要起导水的作用，后者则为主要的储水空间。衰减曲线的年际变化表明泉域受工程影响大，建议今后的引水隧洞施工宜采用以堵为主，堵排结合的工程治理措施。     

西南喀斯特小流域地下水数值模拟

本文以位于西南典型喀斯特地区的贵州普定后寨河流域为研究对象,采用等效连续导水介质体概化方法建立喀斯特流域地下水数值计算模型.运用MODFLOW中的排水沟渠子程序包以及河流子程序包,构建考虑地表河与地下河系统与含水层地下水流交换水动力过程模拟方法,分析后寨河流域地下水流运动特征,估算含水层补排水量.模型计算的地下水位动态...     

Modellierung der Hydraulik von Karstgrundwasserleitern – Eine Übersicht

The modelling of groundwater flow in karst aquifers is a challenge due to the extreme heterogeneity of its hydraulic parameters and the duality in their discharge behaviour, i.e. rapid response of highly conductive karst conduits and delayed drainage of the low-permeability fractured matrix after recharge events. Classical single continuum models cannot reproduce the observed high transport velocities and the characteristic discharge hydrographs, i.e. rapid increase and slow recession. The prediction of short-term and long-term water resources and the assessment of the vulnerability of the karst groundwater to contamination demand, however, quantitative simulation tools. This review paper presents available modelling tools, employed for in karst systems, ranging from lumped parameter (global) models to distributive modelling concepts, including a critical evaluation.     

Karstentwässerung im Kaisergebirge (Tirol, Österreich) – Abgrenzung hydrographischer Einzugsgebiete durch Kombination hydrogeologischer Untersuchungen mit Isotopenmethoden und hydrologischer Modellierung

Water resources investigations in karstic mountainous regions face the difficulty that the hydrological catchment boundaries are usually not identical with the orographic catchment boundaries. In this study an integrative method is presented that combines different sources of hydrogeological information and results of distributed water balance modelling to identify hydrological catchment boundaries and subsurface water ways in a karstic mountainous region. The different information comprises, in addition to meteorological and hydrographic data, region-wide point measurements of discharge, field surveys, isotope data, tracer tests, spring discharge data, soil and geological surveys and mapping, etc. The study was set-up in the Kaisergebirge mountain range in Tyrol/Austria, using the well known model MIKE SHE. Based on the additional information, the original model structure was adjusted to the specific situation in the karst, e.g. by introducing a bypass-flow within the unsaturated zone. The modelling results based on the orographic catchments were evaluated in terms of closure and—equally important—non-closure of the water balance. Spatial patterns of simulated hydrologic quantities are interpreted in light of the different sources of information. As a result, a regional map of surplus and deficit between observed and simulated runoff was drawn and combined with the additional information to form a general conceptual model of karst water flow directions and the location and altitude of the contributing recharge area in the high-alpine region. The results of the study provide a valuable basis for the assessment and protection of karst water resources for water supply.     

Investigating epikarst using low-frequency GPR: example from the Gran Sasso range (Central Italy)

A realistic 3D view of the epikarst is key to understanding karst groundwater phenomena. Ground penetrating radar proved to be highly effective for investigating the epikarst of a sinkhole located in the Gran Sasso karst range (central Italy). Two different low-frequency antennae (100 MHz bistatic shielded and 40 MHz bistatic unshielded) were used. The radar signal interpretation was correlated with field observations of the epikarst and borehole data. Two radar anomaly surfaces were identified, which were correlated with the top and bottom of the epikarst surface. The shape of the two surfaces correlates well with the surface topography of the study sinkhole and with the orientation of its main joints and karren. The work indicated that such a 3D reconstruction could be usefully applied to karst aquifer vulnerability studies.      

Implications of land disturbance on drinking water treatability in a changing climate: Demonstrating the need for “source water supply and protection” strategies

Forests form the critical source water areas for downstream drinking water supplies in many parts of the world, including the Rocky Mountain regions of North America. Large scale natural disturbances from wildfire and severe insect infestation are more likely because of warming climate and can significantly impact water quality downstream of forested headwaters regions. To investigate potential implications of changing climate and wildfire on drinking water treatment, the 2003 Lost Creek Wildfire in Alberta, Canada was studied. Four years of comprehensive hydrology and water quality data from seven watersheds were evaluated and synthesized to assess the implications of wildfire and post-fire intervention (salvage-logging) on downstream drinking water treatment. The 95th percentile turbidity and DOC remained low in streams draining unburned watersheds (5.1 NTU, 3.8 mg/L), even during periods of potential treatment challenge (e.g., stormflows, spring freshet); in contrast, they were elevated in streams draining burned (15.3 NTU, 4.6 mg/L) and salvage-logged (18.8 NTU, 9.9 mg/L) watersheds. Persistent increases in these parameters and observed increases in other contaminants such as nutrients, heavy metals, and chlorophyll-a in discharge from burned and salvage-logged watersheds present important economic and operational challenges for water treatment; most notably, a potential increased dependence on solids and DOC removal processes. Many traditional source water protection strategies would fail to adequately identify and evaluate many of the significant wildfire- and post-fire management-associated implications to drinking water “treatability”; accordingly, it is proposed that “source water supply and protection strategies” should be developed to consider a suppliers’ ability to provide adequate quantities of potable water to meet demand by addressing all aspects of drinking water “supply” (i.e., quantity, timing of availability, and quality) and their relationship to “treatability” in response to land disturbance.     

洛阳盆地浅层地下水资源数值模拟评价

水资源的不合理利用、地下水的过渡开采导致了洛阳盆地水环境的恶化。本文结合洛阳盆地水文地质条件运用数学模型对盆地的浅层孔隙地下水资源进行模拟评价。结果表明:建立二层结构的非均质三维非稳定流数学模型,经模型识别和校正,所选参数是基本合理的,可以比较准确地模拟洛阳盆地第四系浅层地下水系统。盆地地下水补给主要为降水及灌溉入渗补给,地下水排泄主要为人工开采,占总排泄量的75.82%,因此调整和优化现状地下水开采方案,合理开采地下水资源显得尤为必要。     

Kalirückstandshalde Sollstedt (Thüringen): Untersuchungen zur Ausbreitung der Haldenlösung im Rötkarst

The Sollstedt potash waste pile has been deposited without a basement layer on the Middle Bunter and Roethian. Therefore, a part of the salts dissolved by meteoric water infiltrates into the groundwater. The strongly mineralized waste pile seepage water spreads not only into the Middle Bunter but also into the Roethian, which is generally considered an aquitard, because in this area the Roethian is strongly karstic. This study demonstrates that there is a relationship between the seepage water and the strongly mineralized springs surrounding the stockpile. In particular, the strong mineralization of the Silze spring, which is situated in the supposed direction of groundwater flow, can be attributed to mixing with the seepage water. From the calculated water and salt balances, it is concluded that the major part of the seepage water which previously infiltrated in the Roethian infiltrates directly into the Middle Bunter. This suggests a preferential but locally limited permeability of the Roethian in the horizontal and vertical directions.     

Complexity‐reduced in the hydroclimatological modelling of aquifer's discharge

Climate variability induces considerable interannual fluctuations in spring discharge, especially in mountain areas, where groundwater is recharged mainly by rain and snow melt. This study presents the discharge climatological model (DISCLIM), which was developed to test a complexity‐reduced approach to perform historical reconstruction in the lack of physical assumptions. The Mount Cervialto aquifer (Southern Italy) is the test site, where a powerful karst spring is monitored since the 1920s and is very sensitive to climatic conditions. DISCLIM incorporates seasonal precipitation and climate indicators only. Despite its simplicity, DISCLIM has been able to well estimate the yearly fluctuations of discharge hydrological, explaining about 90% of the interannual variability at the calibration stage, and more than 80% at validation stage. This means that DISCLIM can be easily used for estimating the discharge in historical times, when no all the hydrological balance data are available for the purpose.     

Numerische Modellierung der Grundwasserströmung im Einzugsgebiet der Gallusquelle unter Festlegung eines Drainagesystems

Groundwater flow in karst systems is mainly determined by the efficacy of the drainage through karst conduits. A great challenge for the numerical modelling of such groundwater flow consists in the lack of knowledge about this drainage system. Here, an approach is presented deriving the conduit network for the spring catchment Gallusquelle, central Swabian Alb, from different geographic information. Using this conduit network the transient groundwater flow in the catchment was simulated numerically applying the software ROCKFLOW (Wollrath & Helmig, SM-2 Strömungsmodell für inkompressible Fluide, Theorie und Benutzerhandbuch. Technischer Bericht Institut für Strömungsmechanik, Universität Hannover, 1991). The influence of different parameters on the hydraulic behaviour of the karst system could be demonstrated in a parameter study by means of simulated spring discharge and groundwater tables. In particular, the superposition of drainage behaviour and intermediate storage of groundwater from the conduits in the matrix along with recharge events could be derived in dependence of the varied parameters.     

Land-sea mercury transport through a modified watershed, SE Brazil

River management has altered the land-sea transport of water, sediments, and chemical compounds with profound impacts on the structure of continental and costal ecosystems. Understanding riverine transport across modified watersheds allow for better assessment of the influence of river management on material fluxes to coastal waters. Here, we assess the quantitative and qualitative aspects of mercury (Hg) transport across a modified watershed by diversion of Paraíba do Sul River waters into Sepetiba Bay, Brazil. We measured concentrations and speciation of Hg in water samples collected at sites within the modified watershed. These data, together with water discharge and sediment load from numerical models and measurements were used to estimate mass balances. In the Sepetiba watershed, mercury is mainly associated with suspended sediments (90%) and therefore Hg flux displayed the characteristic trend of downstream reduction due to trapping efficiency of particulate load by successive reservoirs. The mass balance suggests that the major source of mercury to Sepetiba Bay is the erosion of soil-derived particles from the drainage basin rather than mercury diverted from Paraíba do Sul River watershed.     

基于流固耦合分析的富水隧道外水压力与限量排放标准研究

隧道衬砌结构外水压力和限量排放标准是岩溶山区隧道工程建设关注的焦点。以某富水隧道为依托,借助FLAC~(3D)软件通过流固耦合数值分析,对富水隧道衬砌结构合理的外水压力取值和限量排放标准进行研究。分析了围岩无注浆条件下隧道外水压力随排水量的变化规律,进而提出了基于结构安全的隧道外水压力取值和地下水排放标准,同时分析了围岩注浆条件下隧道外水压力随注浆圈厚度和地下水排放量的变化规律,提出不同注浆厚度条件下地下水排放标准和合理的注浆圈厚度取值。     

Delivery and impact bypass in a karst aquifer with high phosphorus source and pathway potential

Conduit and other karstic flows to aquifers, connecting agricultural soils and farming activities, are considered to be the main hydrological mechanisms that transfer phosphorus from the land surface to the groundwater body of a karstified aquifer. In this study, soil source and pathway components of the phosphorus (P) transfer continuum were defined at a high spatial resolution; field-by-field soil P status and mapping of all surface karst features was undertaken in a > 30 km² spring contributing zone. Additionally, P delivery and water discharge was monitored in the emergent spring at a sub-hourly basis for over 12 months. Despite moderate to intensive agriculture, varying soil P status with a high proportion of elevated soil P concentrations and a high karstic connectivity potential, background P concentrations in the emergent groundwater were low and indicative of being insufficient to increase the surface water P status of receiving surface waters. However, episodic P transfers via the conduit system increased the P concentrations in the spring during storm events (but not >0.035 mg total reactive P L⁻¹) and this process is similar to other catchments where the predominant transfer is via episodic, surface flow pathways; but with high buffering potential over karst due to delayed and attenuated runoff. These data suggest that the current definitions of risk and vulnerability for P delivery to receiving surface waters should be re-evaluated as high source risk need not necessarily result in a water quality impact. Also, inclusion of conduit flows from sparse water quality data in these systems may over-emphasise their influence on the overall status of the groundwater body.     

某岩溶塌陷成因分析及危险性预测

岩溶塌陷具有分布广、发生频繁、产生条件复杂、预测困难、作用因素众多、形成机制的多样性、多变性和复杂性以及灾后治理费用昂贵等特征。对研究区岩溶塌陷的成因进行了分析,确定了岩溶条件、地下水条件、地形地貌条件、覆盖层条件、人类工程活动这5个塌陷因子,通过模糊综合分析法,利用excel算法对模糊综合分析法权重进行便捷计算,实现了对研究区岩溶塌陷的危险性分区,对岩溶塌陷危险性进行了评价。     

解析法与数值法预测石硐沟铅锌银矿矿坑涌水量

基于石硐沟铅锌银矿为水文地质条件复杂的岩溶裂隙充水矿床,利用解析法和数值法分别建立了模型,对其矿坑涌水量进行了计算,以提高矿坑涌水量预测的准确性,为进一步的防治水提供了依据。