Management and mitigation of sinkholes on karst lands: an overview of practical applications

When karst lands are developed for residential or commercial purposes, sinkholes are to be properly managed or mitigated. This paper discusses various types of sinkholes and their possible formation mechanisms, presents some guidelines for sinkhole management, and summarizes several engineering measures for sinkhole remediation. Because a sinkhole is often not an isolated feature but a component of an integrated groundwater and surface water system, knowledge of the sinkhole geology and hydrology is essential in selection of the proper management tools and remediation options. Adverse effects including flooding, additional sinkholes, and groundwater contamination can result from poorly managed or improperly repaired sinkholes.     

湖南宁乡大成桥充水矿山疏干区岩溶系统水气压力监测及突变特征

湖南煤炭坝煤矿是我国著名的大水矿山,开采标高已降至-400 m,每小时排水量11 000 m3。长期的疏干排水,已形成面积达219.19 km2的地下水降落漏斗。以往的调查资料表明,矿山疏干诱发的岩溶塌陷主要发生在疏干开始、地下水位下降到基岩面附近、矿坑发生突水突泥灾害等3个阶段,在疏干区应该无诱发因素导致岩溶塌陷的发生。但近年来煤炭坝煤矿疏干区大成桥的岩溶塌陷特征表明,尽管相关部门采取了一系列处置措施,但岩溶塌陷仍然频繁发生。为了进一步揭示该地区岩溶塌陷发育规律,使处置决策更加科学化,作者所在团队选择大成桥为典型区,通过岩溶系统地下水气压力监测,分析诱发岩溶塌陷的动力来源及其变化规律。结果表明,疏干区岩溶管道裂隙系统中水气压力突变现象极为明显,年最大变幅达54.72 m,瞬时水气压力变化速率最大为70.6 cm/min,造成这一现象的主要原因是气爆、地下洞穴（溶洞、土洞）垮塌。      

The influence of karst features on environmental studies in Turkey

 The carbonate rocks of Turkey, which underlie about one third of the country, possess major water resources with great potential for electricity generation and water supplies. The ongoing development of karst features, especially in the southern part of Turkey, demonstrates specific environmental problems that occur in many karst water supply projects. Karst aquifers, springs, sinkholes, dolines, poljes and other karst features are of great importance from the standpoint of karst water resources and environmental research studies. In karst regions, conservation and protection of groundwater resources for both qualitative and quantitative evaluations is possible only when the catchment area is determined accurately. Since the catchment area in karst terrains is not limited by the surface drainage boundaries and the groundwater flows through well-developed coduits or fissures, the equations used in non-karstic areas cannot be applied to such karstic regions. Studies on the development of karst features and its environmental impacts in Turkey are of recent origin. Therefore, many unreliable methods are being applied in karstic areas. For example, the use of "shallow holes or sinkholes and fault zones" for septic water waste disposal or as sewage by those who are not familiar with karst, sometimes causes very serious problems of extensive groundwater pollution. This paper discusses the development of different karstic features in Turkey and case studies on its environmental impacts. Received: 27 December 1995 · Accepted: 10 July 1996     

Impact of karst water on coal mining in North China

Coalfields in North China encompass more than ten Provinces. They contain six to seven coal seams in the Permo-Carboniferous strata. The lower three seams account for 37% of the total reserves and are threatened with intrusion of karst water from the underlying Ordovician limestone. Hundreds of water inrush incidences have occurred, in which a large amount of water suddenly flows into tunnels or working faces under high potentiometric pressure. Over 50 mines have been flooded over the last 30 years. Large-scale dewatering or depressurizing of the karst aquifer was considered essential to avoid water inrushes and keep the mines safely operational. This practice, however, has caused sinkholes, dry springs, water supply shortage, and groundwater contamination in the surrounding areas. One alternative water control measure is to make full use of the rock layer between the coal seam and the karst aquifer as a protective barrier to prevent or constrain water flow from the underlying aquifer into the mines. Grouting is effective when the hydrogeological conditions are favorable to this technique. Proper design of the grouting program and experience of the contractor are also important for a successful application.     

不同补给条件下裂隙-管道介质间水流交换的示踪试验研究

为探究岩溶含水系统中裂隙-管道介质间不同补给方式下水流交换情况,在实验室内借助高精度摄像仪和有色示踪剂对其进行可视化观测。设计多组试验对单独补给裂隙、共同补给、裂隙和落水洞分开同时补给三种补给方式下水流交换情况进行探讨,从而定性地分析水流交换情况。试验结果表明:落水洞对裂隙水扩散的影响随裂隙距离落水洞的距离增大而减小;相较于共同补给情况,单独补给裂隙情况下落水洞对裂隙水扩散影响较大;在分开同时补给情况下裂隙与落水洞补给水量相同时,仅呈现裂隙对落水洞的单向补给。     

Legal impediments to utilizing groundwater as a municipal water supply source in karst terrain in the United States

Many jurisdictions presently utilize, or are now considering the utilization of, high-volume wells as a municipal water supply source. Withdrawal of groundwater in karst regions implicates rights to use groundwater and possible interference with other rights of nearby landowners. Drought conditions and increased population contribute to an increased incidence of legal disputes over the use of groundwater as a municipal water supply source in karst regions. High-volume pumping of groundwater may cause land subsidence, including sinkholes, drying of springs and/or streams and loss in value of nearby land. This paper examines the legal causes of action available to landowners adversely affected by high-volume groundwater pumping: groundwater rights, "loss of lateral and subjacent support", nuisance, and "takings". The author concludes that the law fails to include environmental and geoscience considerations. State legislatures should consider legislative changes to unify legal and scientific principles.     

Formation mechanism of large sinkhole collapses in Laibin,Guangxi, China

On June 3, 2010, a series of karst sinkholes occurred at Jili village surrounded by Gui-Bei highway, Wu-Ping highway and Nan-Liu High-Speed Railway in Laibin, Guangxi, China. The straight-line distances from an large sinkhole pit, 85 m in diameter and 38 m in depth, to the above mainlines are 200, 600 and 500 m, respectively. Several investigation methods including geophysical technology, borehole and well drilling, groundwater elevation survey and hydrochemistry analysis of groundwater were used to study the formation mechanisms of these sinkholes. Based on the results, the spatial distribution of the Jili underground river was confirmed with a strike of SN along the middle Carboniferous limestone bedrock and the Quaternary deposits controlled the sinkhole formation. In addition, both historical sinkhole events and analysis of the groundwater–air pressure monitoring data installed in the underlying karst conduit system indicate that sinkholes in this area are more likely induced by extreme weather conditions within typical karst geological settings. Extreme weather conditions in the study area before the sinkhole collapses consisted of a year-long drought followed by continuous precipitation with a daily maximum precipitation of 442 mm between May 31 and June 1, 2010. Typical geological conditions include the Jili underground river overlain by the Quaternary overburden with thick clayey rubble. Especially in the recharge zone of the underground river, a stabilized shallow water table was formed in response to the extreme rainstorm because of the presence of the thick clayey rubble. When the underground conduit was flooded through the cave entrance on the surface, air blasting may have caused the cave roof collapse followed by formation of soil cavities and surface collapses. Borehole monitoring results of the groundwater–air pressure monitoring show that the potential karst sinkhole can pose threats to Shanbei village, the High-Speed Railway and the Wu-Ping highway. Local government needs to be aware of any early indicators of this geohazard so that devastating sinkholes can be prevented in the future. The results also suggest that groundwater–air pressure monitoring data collected both the Quaternary deposits and the bedrock karst system provide useful indicators for potential sinkhole collapses in similar karst areas where sinkholes usually occur during rainy season or karst groundwater level is always under the rockhead.     

Characterization of the shallow groundwater system in an area with thin soils and sinkholes

Door County, Wisconsin, is a region of karst topography underlain by Silurian dolomite bedrock. Numerous sinkholes intercept much of the surface runoff and act as sites for direct groundwater recharge. The clay-rich and impermeable Upper Ordovician Maquoketa formation separates the dolomite aquifer from the deeper aquifers and appears to be a factor in groundwater circulation and karst formation Thin glacial drift and Quaternary materials overlie the dolomite and are hydrologically connected with it The interactions of surface and groundwater, and the role of solution features in water interchange were studied in a small drainage basin. This basin contains several large sinkholes and a nearby spring complex Mapping identified many additional sinks and swallets in surface drainage routes Water flowing into two sinks was traced and found to have a residence time of several hours. Water flowing into sinkholes and from the spring was sampled to identify the quality and seasonal trends in composition of the shallow groundwater Water quality parameters monitored include magnesium, sodium, potassium, chloride, phosphorous, nitrate and ammonia, nitrogen, alkalinity, pH, turbidity, and specific conductance. Nitrate levels were found to increase 5 to 6 times during periods when there was zero input through sinkhole recharge sites. Nitrate levels approached the 10 mg/l NO₃ ⁻-N limit set by the U.S. Public Health Service for drinking water In this basin sandy soils are most susceptible to sink development, whereas clay-rich soils have a lesser number of sinks. It appears, however, that a network of bedrock solution features exists under all soils The loss of soil into sinkholes has impacted groundwater quality and reduced agricultural productivity through a reduction in tillable acreage and water retention capacity.     

贵州冗赖水库岩溶成库条件分析

冗赖水库位于珠江流域的北盘江与南盘江两大水系之间的高原岩溶台地,左右岸外侧均存在低邻槽谷,坝址下游存在底部发育落水洞的大型岩溶海子,水库成库难度大,当地人饮水问题突出。通过岩溶水文地质调查、钻探、物探、连通试验等手段,从地形条件、地层岩性、地质构造、水文地质条件、岩溶发育特征等方面,对冗赖水库成库条件进行了分析论证。认为水库库盆底部依托隔水性岩体,不存在库水渗漏问题,但水库两岸受分水岭地下水位低、断层破碎带及岩溶发育等影响,存在库水渗漏问题,同时库首两岸可能存在顺平缓岩层面、溶蚀裂隙等产生渗漏问题。因此建议采用垂直防渗方式,防渗标准（透水率）小于3 Lu或防渗帷幕下限接稳定地下水位以下10 m,遇到溶洞等地质缺陷时应查明其分布特征,并根据实际情况降低防渗底线。      

Travel time based approach for the assessment of vulnerability of karst groundwater: the Transit Time Method

Karst aquifers represent important water resources in many parts of the world. Unfortunately, karst aquifers are characterised by high contamination risks. This paper presents a travel time based method for the estimation of karst groundwater vulnerability. It considers (1) physics-based lateral flow within the uppermost weathered zone (epikarst) in a limestone-dominated region and (2) high velocities of vertical infiltration at discrete infiltration points (e.g. sinkholes) or lines (e.g. dry valleys, faults). Consequently, the Transit Time Method honours the actual flow path within the unsaturated zone of a karst aquifer system. A test site in Northern Jordan was chosen for the demonstration of the assessment technique, i.e. the catchment area of the Qunayyah Spring north of the capital Amman. The results demonstrate that zones of highest vulnerability lie within valleys and nearby main fault zones. It also reveals that regions, categorised as protected areas by other methods due to thick unsaturated zones, contribute to a major degree to the total risk.     

Multi-tracer investigation of groundwater residence time in a karstic aquifer: Bitter Lakes National Wildlife Refuge, New Mexico, USA

Several natural and anthropogenic tracers have been used to evaluate groundwater residence time within a karstic limestone aquifer in southeastern New Mexico, USA. Natural groundwater discharge occurs in the lower Pecos Valley from a region of karst springs, wetlands and sinkhole lakes at Bitter Lakes National Wildlife Refuge, on the northeast margin of the Roswell Artesian Basin. The springs and sinkholes are formed in gypsum bedrock that serves as a leaky confining unit for an artesian aquifer in the underlying San Andres limestone. Because wetlands on the Refuge provide habitat for threatened and endangered species, there is concern about the potential for contamination by anthropogenic activity in the aquifer recharge area. Estimates of the time required for groundwater to travel through the artesian aquifer vary widely because of uncertainties regarding karst conduit flow. A better understanding of groundwater residence time is required to make informed decisions about management of water resources and wildlife habitat at Bitter Lakes. Results indicate that the artesian aquifer contains a significant component of water recharged within the last 10–50 years, combined with pre-modern groundwater originating from deeper underlying aquifers, some of which may be indirectly sourced from the high Sacramento Mountains to the west.     

Roadway construction in karst areas: management of stormwater runoff and sinkhole risk assessment

In karst-rich regions, it is inevitable that roadways cross karst landscapes. Road building across such terranes faces environmental and engineering challenges because of impacts on water quality from stormwater runoff and concerns of sinkhole collapse under or near roadways. When highway runoff drains rapidly into subsurface conduit networks through open sinkholes and/or sinking streams, the impact of the runoff on the karst aquifer can be qualitatively evaluated by mixing cell models. Formulation of a comprehensive stormwater runoff management plan prior to roadway construction can minimize the associated adverse impacts. The commonly used best management practices help manage the stormwater runoff effectively in some sites. Site-specific management plans are preferable for other sites because of concerns of flooding and land stability. Proactive measures should be taken to identify areas of the greatest sinkhole collapse risk along the proposed route and the associated groundwater drainage patterns.     

基于表层岩溶带调控的峰丛洼地低影响开发构建

岩溶峰丛洼地地区石漠化、饮水困难和水污染等环境问题高发,生态环境十分脆弱。低影响开发概念的引入有助于规范开发行为,促进水资源的高效利用,降低石漠化和地下河污染风险。根据水文条件和开发方式岩溶洼地空间分为坡耕地水土流失敏感区、表层岩溶泉水源地敏感区和落水洞污染输入敏感区。低影响开发模式总体是在3类敏感区实现5个管理目标。坡耕地敏感区的低影响开发目标设置为降低农田耗水量和减少水土流失,开发途径是减少蒸发和调控坡面洪水径流。表层岩溶泉敏感区的管理目标是降雨－径流资源化利用和饮用水安全保障,通过实施雨水收集回用工程和设置水源地保护区来实现。落水洞敏感区需要通过设置径流缓冲区和沉淀过滤池来预防污染物进入。我国南方石漠化地区探索和总结出以表层岩溶带降雨－径流管理为特征的低影响开发模式。该模式要求峰丛顶部留置生态保护区涵养水源。岩溶洼地底部为落水洞排洪预留缓冲区,利用岩溶裂缝设置下凹式绿地,实现自然渗透和净化。“峰”、“洼”之间过渡区划定水源地保护区边界,同时设法增加雨水资源化利用率,补充生态和生活缺水量。低影响开发模式也适用于峰丛洼地发育的东南亚和中美洲等地区。      

贵阳观山湖区至白云区地下水有机污染现状与防治对策

文章按水文地质条件将全区划分为12个地下水系统,并选择43组控制性水点分丰枯两季进行有机样品采集和测试,在此基础上对研究区地下水中有机污染物的检出、超标、分布及来源均进行了分析。结果显示,参评的86组地下水样品中,有32组检出有机污染物;27种参评有机组分中,10种有机组分存在不同程度的检出,其中,三氯甲烷检出25次,检出率29.07%,其余组分检出率均低于5%;仅有1,2二氯丙烷超标1次,超标率低;区内地下水有机污染物检出浓度较低,超标率低,处于轻度污染阶段;12个系统中,有9个系统发现有机物污染物检出;检出点多分布于工矿企业的下游地段,排污河渠两侧;污染物多来源于中小型工矿企业,以污染物通过落水洞、天窗等进入含水层为主要污染途径;地下水系统排泄区的近源污染多发,危害程度大。针对上述污染特征,提出加强对中小企业污染源的集中管理,加大污水管网建设力度等对策建议。      

花梨隧道岩溶水文地质条件及危险性评估

花梨隧道是瓮开高速的控制性工程,其地质构造及岩溶水文地质条件较为复杂。采取现场地质调查、钻探、测量、室内岩土物理力学指标试验、电法物探等综合勘察手段,分析花梨隧道含水层岩性组合特征、可溶岩体系分布特征及岩溶水系统性,查清了其岩溶水文地质条件,并对涌突水危险性进行了分级评价。结果表明:（1）花梨隧道地表出露的可溶岩与非可溶岩,分为泥质粉砂岩组成的非可溶岩与灰岩组成的可溶岩两个体系;（2）花梨隧道预测正常涌水量为32 126.4 m3·d-1,隧道最大涌水量应按预测涌水量的2~6倍考虑;（3）花梨隧道可溶岩段内岩溶涌突水危险性总体为中等危险,其中极高危险段占总长度的16%。      

湖南郴州地区岩溶塌陷分布规律及其影响因素浅析

通过地质环境调查,分析湖南郴州地区岩溶塌陷分布规律及其影响因素,结果表明:(1)1980-1983年为岩溶塌陷盛发期,平均8.5个?年-1;2012-2020年塌陷发生频率增加,平均5.88个/年;岩溶塌陷主要发生在3-7月份雨季;(2)低丘冲沟中发生塌陷54个,占塌陷总数的55.67％;岩溶平原中发生塌陷40个,占4...     

The hydrologic effects of intense groundwater pumpage in east-central Hillsborough County,Florida, U.S.A.

Well problems, water shortages, local flooding, and induced sinkholes have been periodic problems for residents in east-central Hillsborough County, Florida. This agricultural area has experienced dramatic short-term water-level declines in the Floridan aquifer from seasonal groundwater withdrawals. The sudden declines in the potentiometric surface have been caused from intense irrigation pumpage, primarily for frost and freeze protection and fruit setting. Citrus and strawberry crops are protected from occasional freezes by the application of warm groundwater to maintain minimum soil temperatures of 32°F(0°C). Local residents with inadequately constructed wells lose their source of water when the potentiometric surface is lowered to depths where their wells do not function. Some residents have lost their water supply for a week or more, and many have incurred damage to their pumps. The drawdown of the potentiometric surface in some areas has induced sinkholes causing property damage for some residents and concern for others. In addition, the high application rates for frost and freeze irrigation have created run-off problems resulting in local flooding to some residents. Fortunately, there has been no damage to resident homes from the flooding or sinkholes. This report summarizes the area's hydrogeology, and the consequences of heavy freeze irrigation. A finite-difference, numerical model is used to quantify the regional impacts to the potentiometric surface of the Floridan aquifer from estimated irrigation pumpage. Management recommendations for alleviating the problems are also discussed in the report.     

西南表层岩溶带土壤中砷的迁移规律实验与模拟

岩溶地下河是我国西南地区的重要水源,工业生产过程中产生的砷污染物,除通过落水洞等直接进入并污染地下水外,还会在表层岩溶带溶缝、溶隙内吸附、滞留及富集,并在特定条件下再次迁移,成为"稳定次生污染源".以广西某砷污染事件为例,采用窄缝槽物理模型装置进行砷的动态吸附、解吸实验,并结合地球化学模拟研究砷污染物在表层岩溶带土壤中的迁移规律.实验结果显示表层岩溶带对砷的吸附以物理吸附（扩散过程）为主,相比吸附过程而言解吸速率则显得缓慢,而酸溶液相比去离子水可促进砷的解吸过程.地球化学模拟结果表明土壤矿物中以针铁矿对砷的吸附贡献最大,而酸溶液通过溶蚀针铁矿等矿物削弱对砷的吸附能力.因此在西南岩溶地区,表层岩溶带系统一旦纳入砷污染物,则解吸过程缓慢,易形成砷污染物的滞留、富集;而酸雨作用下砷的解吸、迁移过程加快,则会提高地下水系统的污染风险.      

青木关岩溶槽谷地下水水源地固有脆弱性评价

岩溶地下水脆弱性评价是基于保护岩溶含水层从而有效地管理和利用地下水提出的有效方法和手段。我国西南岩溶区大多数地区缺少应有的地下水保护带,地下水比较容易受到污染。通过采用改进的斯洛文尼亚模式,考虑四个因子:覆盖层(O)、径流特征(C)、降雨条件(P)、岩溶发育程度(K),对重庆市青木关岩溶槽谷地下水水源地的固有脆弱性进行了定量评价。结果表明:流域范围内12.6%为高脆弱性地区;43%为中等脆弱性;44.4%为低脆弱性区域。消水洞及周边100m和消水河及其两边10m,以及岩溶管道发育地区为高脆弱性区。大部分岩溶区为中等脆弱性区。砂岩地区为低脆弱性地区。评价结果与实际吻合。该评价结果为各级决策部门合理规划利用和保护地下水资源提供简单明了的科学依据。该方法对于川东岩溶槽谷地区脆弱性评价有推广价值。      

武汉市岩溶塌陷的演化机理研究

基于武汉市易发生的29处岩溶塌陷,从岩溶、覆盖层和地下水3方面分析了岩溶塌陷的内部结构;通过现场监测和数值模拟,分析了降雨、钻探和桩基施工的输入作用,并探讨了武汉市岩溶塌陷的演化机理。结果表明:（1）“上黏下砂”的盖层结构、浅部岩溶发育、孔隙水与岩溶水具良好水力联系是塌陷形成的基础条件;（2）自然环境下开口岩溶上方土洞扩展存在水力潜蚀和应力集中破坏两个演化阶段;（3）钻探和桩基施工联通孔隙水和岩溶水的瞬间,孔壁周边松散砂土快速进入临界水力梯度而破坏。桩基施工在覆盖层内的振动荷载和超孔隙水压力,易造成覆盖层整体破坏。在岩溶区施工产生的冲击作用可使岩溶水和孔隙水形成不同步波动,两者存在高水头差,致使覆盖层内砂层在压力差作用下破坏。