{"id":37796,"date":"2026-02-13T11:06:28","date_gmt":"2026-02-13T10:06:28","guid":{"rendered":"https:\/\/www.vtei.cz\/2026\/02\/vyuziti-termometrie-pro-vyhledavani-mineralnich-pramenu-marianske-lazne-a-karlovy-vary-2\/"},"modified":"2026-02-26T16:42:08","modified_gmt":"2026-02-26T15:42:08","slug":"application-of-thermometry-in-the-exploration-of-mineral-springs-marianske-lazne-and-karlovy-vary","status":"publish","type":"post","link":"https:\/\/www.vtei.cz\/en\/2026\/02\/application-of-thermometry-in-the-exploration-of-mineral-springs-marianske-lazne-and-karlovy-vary\/","title":{"rendered":"Application of thermometry in the exploration of mineral springs \u2013 Mari\u00e1nsk\u00e9 L\u00e1zn\u011b and Karlovy Vary"},"content":{"rendered":"

ABSTRACT<\/h2>\n

Thermometry is a\u00a0non-invasive technique suitable for detecting hidden mineral water springs. Its applicability was evaluated in\u00a0two contrasting hydrogeological settings: Mari\u00e1nsk\u00e9 L\u00e1zn\u011b, characterized by cold, CO\u2082-rich mineral springs, and Karlovy Vary, dominated by thermal springs.<\/p>\n

In\u00a0Mari\u00e1nsk\u00e9 L\u00e1zn\u011b, the\u00a0objective was to identify previously undocumented springs. Ground thermometry with a\u00a0thermal infrared (TIR) camera proved highly effective. The\u00a0survey was supplemented by measurements of\u00a0free dissolved CO\u2082 (H\u00e4rtl tube), temperature, electrical conductivity, and pH. A\u00a0total of\u00a0131 thermal anomalies were recorded along 20 km of\u00a0watercourses, 14 of\u00a0which were confirmed as new mineral springs. The\u00a0actual number of\u00a0springs is likely higher, as CO\u2082 analyses are limited in\u00a0springs strongly diluted by surface water.<\/p>\n

In\u00a0Karlovy Vary, the\u00a0aim was to localize and quantify wild thermal springs (up to 73.4 \u00b0C) within\u00a0the\u00a0bed of\u00a0the\u00a0Tepl\u00e1 river, which influence the\u00a0equilibrium of\u00a0the\u00a0entire spring system. TIR imaging was ineffective due to rapid dilution by river water. Therefore, point temperature measurements were performed in\u00a0a\u00a0regular grid over a\u00a01,300\u00a0m\u00b2 area of\u00a0the\u00a0riverbed. This approach revealed 14 untapped so-called wild thermal springs. In\u00a0parallel with water temperature measurements, electrical conductivity was also continuously recorded, and at the\u00a0end of\u00a0the\u00a0mapping a\u00a0summary discharge balance of\u00a0the\u00a0springs was attempted, unsuccessfully, using a\u00a0FlowTracker device based on water flow measurements in\u00a0the\u00a0Tepl\u00e1. Ultimately, the\u00a0total yield of\u00a0the\u00a0wild springs in\u00a0the\u00a0study area, that is, in\u00a0the\u00a0vicinity of\u00a0the\u00a0V\u0159\u00eddlo springs, was estimated at 2\u20133\u00a0l\/s. This estimate is based on long-term changes in\u00a0pressure conditions within\u00a0the\u00a0V\u0159\u00eddlo structural system.<\/p>\n

The\u00a0results of\u00a0both thermometric surveys demonstrate that, when an appropriate workflow is applied, thermometry represents a\u00a0highly versatile and effective method for the\u00a0qualitative assessment of\u00a0mineral water discharges. However, for successful application, the\u00a0methodology must always be adapted to the\u00a0specific hydrogeological and hydrological conditions of\u00a0the\u00a0site. The\u00a0results of\u00a0both partial surveys provided information on the\u00a0distribution of\u00a0mineral springs and will serve as a\u00a0basis for defining the\u00a0protection of\u00a0spring structures.<\/p>\n

INTRODUCTION<\/h2>\n

In\u00a0hydrogeological practice, thermometry is most commonly used to identify concealed inflows of\u00a0groundwater into surface waters. It represents an alternative to simple discharge measurements in\u00a0a\u00a0watercourse, where differences in\u00a0flow are assumed to be caused by groundwater inflow. Thermometry is based on the\u00a0premise that groundwater usually exhibits a\u00a0more stable temperature throughout the\u00a0year compared with the\u00a0more variable temperatures of\u00a0surface water\u00a0[1]. The\u00a0temperature of\u00a0groundwater in\u00a0the\u00a0near-surface zone of\u00a0the\u00a0geological environment approaches the\u00a0mean annual air temperature and increases with depth below ground as a\u00a0result of\u00a0the\u00a0geothermal gradient. This thermal contrast creates anomalies in\u00a0watercourses or receiving waters at locations where groundwater emerges\u00a0[2], which can be detected using probe thermometers, cameras recording in\u00a0the\u00a0infrared thermal spectrum (TIR), or standard conductometers with a\u00a0temperature sensor, both through in\u00a0situ measurements and remote sensing\u00a0[3]. The\u00a0thermal contrast can be understood as a\u00a0natural non-conservative tracer. Its advantage lies primarily in\u00a0its ubiquity, natural occurrence, non-invasive nature, and ease of\u00a0detection, which enables rapid mapping\u00a0[4]. Unlike conservative tracers, whose concentrations are directly related to mixing ratios\u00a0[5], the\u00a0quantitative interpretation of\u00a0thermal anomalies in\u00a0terms of\u00a0discharge estimation is indirect and complex\u00a0[6]. The\u00a0measured temperature signal is influenced by the\u00a0temperature of\u00a0groundwater, surface water, the\u00a0degree of\u00a0mixing with surface water, and heat exchange with the\u00a0atmosphere, which depends, inter alia, on the\u00a0thermal capacity of\u00a0water. For these reasons, thermometry is considered a\u00a0qualitative, or in\u00a0some cases semi-quantitative, method.<\/p>\n

The effectiveness of detecting a thermal signal is directly related to the magnitude of the temperature difference (\u2206T). Under conditions in the Czech Republic, thermometric surveys are most effective in winter, when relatively warm groundwater contrasts with cold water in streams or receiving waters. However, diurnal temperature fluctuations are also important. Surveys conducted at night or under complete cloud cover minimise disturbing effects [3]. Detection is further influenced by seasonal variability in stream discharge: at higher flows, the detection threshold increases and sensitivity decreases. In general, better results can be achieved under calm conditions and during periods without recent precipitation, which tends to homogenise the temperature of the water column. Heat exchange is influenced by conduction, convection, and radiation, as well as by transport processes, predominantly advection, whereby heat is transported with the movement of groundwater and, respectively, surface water [6]. The second main transport mechanism is thermal dispersion, which arises as a result of differing flow velocities [7]. Although it is sometimes simplified or neglected in models, particularly at low flow velocities, dispersion can be important for the accurate interpretation of heat transport processes [7]. The combination of these processes determines the size, shape, and intensity of the thermal signal. In qualitative assessments, it is assumed that the intensity and size of a thermal signal reflect the discharge or temperature of a spring (a larger or more pronounced anomaly approximately corresponds to higher discharge or\u00a0a\u00a0higher inflow temperature)\u00a0[6]. The\u00a0shape of\u00a0the\u00a0thermal signal is influenced by flow direction and mixing dynamics\u00a0[8]. In\u00a0quantitative applications, the\u00a0main\u00a0difficulty is the\u00a0aforementioned non-conservative nature of\u00a0the\u00a0\u201ctracer\u201d. It is necessary to take into account the\u00a0thickness of\u00a0the\u00a0water column above the\u00a0discharge point, the\u00a0degree of\u00a0mixing, the\u00a0velocity of\u00a0surface water flow, and the\u00a0influence of\u00a0atmospheric conditions. There is no universal calibration for quantification, and each site must therefore be assessed individually [9, 10].<\/p>\n

Experience with the\u00a0use of\u00a0thermometry for locating concealed springs is extensive both internationally and within\u00a0the\u00a0Czech context. However, in\u00a0the\u00a0field of\u00a0natural medicinal resources, this method has not yet become part of\u00a0routine practice, and experience with its application remains limited. Thermometry was used, for example, in\u00a0the\u00a0mapping of\u00a0the\u00a0tectonic structure of\u00a0western Bohemia, including the\u00a0wider surroundings of\u00a0Mari\u00e1nsk\u00e9 L\u00e1zn\u011b. This work was carried out between 1984 and 1988, and areas such as the\u00a0Pott valley in\u00a0Mari\u00e1nsk\u00e9 L\u00e1zn\u011b were surveyed using thermometric methods\u00a0[11]. The\u00a0results, however, were intended primarily to verify the\u00a0hypothesis that abundant groundwater discharges are tectonically predisposed, while issues related to natural medicinal resources were largely not addressed, reportedly also due to the\u00a0low sensitivity of\u00a0the\u00a0detectors available at that time. In\u00a0Karlovy Vary, so-called commission inspections using thermometry were conducted in\u00a01980\u00a0[12], but their purpose was not to quantify measurements; rather, they served as reconnaissance of\u00a0the\u00a0site in\u00a0connection with ongoing remediation works. Measurement data from these inspections in\u00a0Karlovy Vary are not available.<\/p>\n

OBJECTIVES<\/h2>\n

The\u00a0main\u00a0objective of\u00a0the\u00a0thermometric survey in\u00a0both Mari\u00e1nsk\u00e9 L\u00e1zn\u011b and Karlovy Vary (Fig.\u00a01<\/em>) was to identify previously unknown mineral water discharges. Knowledge of\u00a0the\u00a0spatial distribution of\u00a0mineral springs is crucial for the\u00a0appropriate design of\u00a0both preventive and remedial protection measures, including those related to already recorded and exploited discharges. A\u00a0partial objective was to describe the\u00a0specific aspects of\u00a0the\u00a0application of\u00a0thermometry in\u00a0the\u00a0exploration of\u00a0mineral water outlets, with two contrasting sites deliberately surveyed in\u00a0order to verify the\u00a0applicability of\u00a0the\u00a0method across a\u00a0broader range of\u00a0conditions. The\u00a0Mari\u00e1nsk\u00e9 L\u00e1zn\u011b area is spatially extensive and is characterised by discharges of\u00a0cold mineral waters enriched with free dissolved (hereafter f. d.) CO\u2082, whereas the\u00a0Karlovy Vary area is spatially limited and typical of\u00a0thermal water discharges. Mari\u00e1nsk\u00e9 L\u00e1zn\u011b was selected because the\u00a0search for cold mineral springs places higher demands on the\u00a0applied technology, which ultimately results in\u00a0a\u00a0higher explanatory value of\u00a0the\u00a0outcomes obtained from testing thermometry in\u00a0mineral spring detection. Sub-objectives were defined separately for each site.<\/p>\n

\"\"<\/a>Fig.\u00a01. Areas studied with thermometric survey<\/h6>\n

Sub-objectives for the\u00a0Mari\u00e1nsk\u00e9 L\u00e1zn\u011b site<\/h3>\n

The\u00a0sub-objective was to use newly identified mineral water springs for sampling and, on this basis, to better understand spatial patterns in\u00a0their composition. The\u00a0current concept of\u00a0the\u00a0hydrochemical zonation of\u00a0mineral waters is based solely on data from recorded springs\u00a0[13]. The\u00a0significance of\u00a0identifying additional, less abundant, unrecorded mineral springs or seepages is also related to the\u00a0requirement of\u00a0the\u00a0Slavkovsk\u00fd les Protected Landscape Area (PLA) to register and protect mineral water springs as a\u00a0whole, regardless of\u00a0whether or not they have designated protection zones. Without knowledge of\u00a0their location and physical and chemical properties, it is not possible to ensure effective protection of\u00a0discharging mineral waters. This is also closely linked to the\u00a0question of\u00a0the\u00a0tectonic control of\u00a0water chemistry and the\u00a0spatial distribution of\u00a0springs.<\/p>\n

Sub-objectives for the\u00a0Karlovy Vary site<\/h3>\n

The\u00a0sub-objective of\u00a0the\u00a0thermometric measurements in\u00a0Karlovy Vary was to verify whether the\u00a0current natural and artificial sealing layers at the\u00a0bottom of\u00a0the\u00a0Tepl\u00e1 river channel are sufficiently effective in\u00a0preventing uncontrolled discharges of\u00a0thermal water in\u00a0the\u00a0lowest parts of\u00a0the\u00a0valley. The\u00a0quality of\u00a0sealing has always played a\u00a0crucial role in\u00a0the\u00a0trouble-free exploitation of\u00a0the\u00a0V\u0159\u00eddlo spring; therefore, the\u00a0spring sedimentation forming the\u00a0natural sealing layer had to be continuously supplemented with additional artificial sealing elements to prevent undesirable breakthroughs of\u00a0thermal water\u00a0[14]. However, the\u00a0artificial sealing was never completed over the\u00a0entire area of\u00a0the\u00a0Tepl\u00e1 river channel in\u00a0the\u00a0centre of\u00a0the\u00a0discharge zone. This area is thus still affected by numerous leakages of\u00a0thermal water as well as spring gas directly into the\u00a0surface recipient\u00a0[15]. In\u00a0the\u00a0event of\u00a0more significant damage to the\u00a0sealing of\u00a0the\u00a0channel bottom in\u00a0the\u00a0vicinity of\u00a0the\u00a0V\u0159\u00eddlo spring, a\u00a0decrease in\u00a0the\u00a0yield of\u00a0nearby small springs occurs and degassing of\u00a0the\u00a0structural centre takes place. The\u00a0results of\u00a0the\u00a0survey will serve as baseline material for the\u00a0administrators of\u00a0the\u00a0local natural medicinal resources.<\/p>\n

STUDY AREAS<\/h2>\n

Mari\u00e1nsk\u00e9 L\u00e1zn\u011b<\/h3>\n

In\u00a0Mari\u00e1nsk\u00e9 L\u00e1zn\u011b and its surroundings, more than 100\u00a0mineral springs emerge, all of\u00a0which are characterized by high CO\u2082 degassing, low temperatures ranging from approximately 7 to 12 \u00b0C, and relatively low yields from 0.01 to 1\u00a0l\/s. The\u00a0springs differ from one another primarily in\u00a0their highly variable total dissolved solids (TDS), ranging from 0.2 to 12.0 g\/l, as well as in\u00a0their chemical composition [13, 16]. Based on chemical composition, four main\u00a0groups of\u00a0springs can be distinguished, with each group being formed under specific lithological conditions. The\u00a0first group is associated with serpentinites, the\u00a0second with amphibolites, the\u00a0third probably with infiltrated fossil mineralization. The\u00a0fourth is a\u00a0so-called transitional group, in\u00a0which the\u00a0chemistry is influenced by combined lithology, too short a\u00a0contact time with the\u00a0bedrock, or by lithology that does not exhibit a\u00a0clearly defined chemical signature\u00a0[16]. These general findings concerning the\u00a0spring system formed the\u00a0basis for the\u00a0design of\u00a0an appropriate methodology for the\u00a0thermometric survey.<\/p>\n

Karlovy Vary<\/h3>\n

The\u00a0discharges of\u00a0the\u00a0Karlovy Vary thermal waters, with a\u00a0maximum temperature of\u00a073.4 \u00b0C and a\u00a0total dissolved solids of\u00a06.4 g\/l, together with emissions of\u00a0spring gas, are confined to an approximately 1,700\u00a0m long and about 150\u00a0m wide discharge zone within\u00a0granites. The\u00a0total yield of\u00a0the\u00a0spring structure is approximately 33\u00a0l\/s. From the\u00a0perspective of\u00a0the\u00a0distribution of\u00a0thermal water and spring gas yields, the\u00a0centre of\u00a0the\u00a0discharge zone lies close to the\u00a0historical position of\u00a0the\u00a0V\u0159\u00eddlo spring, which accounts for about 95\u00a0% of\u00a0the\u00a0yield of\u00a0all Karlovy Vary springs. All thermal springs in\u00a0Karlovy Vary are chemically identical, with the\u00a0exception of\u00a0the\u00a0Had\u00ed and \u0160t\u011bp\u00e1n\u010din\u00a0springs, which have lower mineralisation. Individual springs differ from one another only in\u00a0temperature and CO\u2082 concentration\u00a0[17]. The\u00a0temperature of\u00a0the\u00a0springs is influenced primarily by the\u00a0ascent velocity of\u00a0the\u00a0thermal water along favourable discontinuities towards the\u00a0surface and, to a\u00a0certain\u00a0extent, also by the\u00a0distance of\u00a0the\u00a0discharge point from the\u00a0centre of\u00a0the\u00a0structure. A\u00a0completely specific phenomenon within\u00a0the\u00a0discharge zone is the\u00a0presence of\u00a0carbonate spring sediments (aragonite shield) with a\u00a0thickness of\u00a0more than 10\u00a0m in\u00a0places [14, 18]. In\u00a0Karlovy Vary, untapped (\u201cwild\u201d) springs (Fig.\u00a02<\/em>) have been known for centuries and have always had a\u00a0significant impact on the\u00a0exploited springs. The\u00a0causes of\u00a0wild springs resulting from failures in\u00a0the\u00a0sealing of\u00a0the\u00a0riverbed are both natural (river erosion, changes in\u00a0pressure within\u00a0the\u00a0structure, etc.) and anthropogenic (construction works, krenotechnical systems; facilities for the\u00a0collection and distribution of\u00a0thermal spring water to hotels, translator\u2019s\u00a0note, etc.)\u00a0[19]. The\u00a0regime of\u00a0the\u00a0Karlovy Vary springs is also influenced, for example, by tidal forces\u00a0[20]. These general insights into the\u00a0structure formed the\u00a0basis for the\u00a0design of\u00a0an appropriate methodology for thermometric mapping of\u00a0wild springs.<\/p>\n\"\"<\/a>\n

Fig. 2. Untapped \u2018\u2018wild\u2019\u2019 springs; a) springs in the old basement of the V\u0159\u00eddlo, b) wild springs in the Tepl\u00e1 riverbed, c) general view under the bridge with visible untapped springs<\/h6>\n

METHODOLOGY<\/h2>\n

For publication purposes, a\u00a0mineral water spring in\u00a0the\u00a0case of\u00a0Mari\u00e1nsk\u00e9 L\u00e1zn\u011b is defined as one exhibiting a\u00a0free CO\u2082 concentration > 1 g\/l, i.e., a\u00a0carbonated mineral spring, and in\u00a0the\u00a0case of\u00a0Karlovy Vary as one with a\u00a0temperature > 20\u202f\u00b0C, i.e., a\u00a0thermal spring. A\u00a0temperature anomaly refers to any thermal irregularity detected by a\u00a0thermal camera. A\u00a0new or \u201cwild\u201d mineral water spring is defined as a\u00a0thermal anomaly where an elevated free CO\u2082 concentration has been detected using the\u00a0H\u00e4rtl shaking apparatus (hereinafter referred to as the\u00a0H\u00e4rtl tube), or where the\u00a0temperature is at least approximately 3\u202f\u00b0C higher than the\u00a0background water temperature.<\/p>\n

 <\/p>\n

Mari\u00e1nsk\u00e9 L\u00e1zn\u011b<\/h3>\n

In\u00a0the\u00a0study area (Fig.\u00a04), watercourses were first identified using the\u00a0Basic Geographic Data Base of\u00a0the\u00a0Czech Republic (ZABAGED). The\u00a0thermometric survey itself took place from January to March 2023, using a\u00a0FLIR C5 TIR camera (USA), capable of\u00a0measuring temperatures from -20\u202f\u00b0C to +400\u202f\u00b0C with a\u00a0capture frequency of\u00a08.7\u202fHz and a\u00a0resolution of\u00a0240 \u00d7 320 pixels in\u00a0its basic mode, i.e., with automatic calibration. The\u00a0sequence of\u00a0activities following the\u00a0identification of\u00a0a\u00a0temperature anomaly of\u00a0unknown character included: marking the\u00a0site with a\u00a0stake, photographic documentation, GPS positioning using a\u00a0mobile phone, measurement of\u00a0conductivity, temperature, and pH using a\u00a0WTW Multi 340i device with a\u00a0TetraCon 325 probe and a\u00a0pH-Electrode SenTix 41, and finally, determination of\u00a0flow rate and free dissolved CO\u2082 concentration using H\u00e4rtl tube. Although all identified temperature anomalies were surveyed, sampling for chemical analysis was carried out only for those anomalies in\u00a0which the\u00a0presence of\u00a0free dissolved CO\u2082 was detected using the\u00a0H\u00e4rtl tube, i.e., at new mineral water springs. The\u00a0most significant new mineral water springs, in\u00a0terms of\u00a0flow rate and CO\u2082 content, were assigned not only an identification number but also names corresponding to nearby springs. For improved spatial accuracy, the\u00a0temperature anomalies were geolocated in\u00a0March\u2013April 2023 using an RTK (Real-Time Kinematic) GPS station. Subsequently, an interpretation was carried out and the\u00a0data were compared with the\u00a0temperatures and electrical conductivities of\u00a0previously recorded mineral springs, taking into account that the\u00a0water temperature in\u00a0exploited mineral water boreholes increases with depth by an average of\u00a01.6\u202f\u00b0C per 100\u202fm (Fig.\u202f3<\/em>), and that some abstraction points have overflow, which further reduces interpretability. All new mineral water springs were monitored regularly until July\u202f2024 to verify that they were not of\u00a0a\u00a0temporary character.<\/p>\n\"\"<\/a>\n

Fig.\u00a03. Change in\u00a0water temperature with depth in\u00a0exploited mineral water boreholes in\u00a0individual spring structures in\u00a0Mari\u00e1nsk\u00e9 L\u00e1zn\u011b (adapted from\u00a0[21])<\/h6>\n

Karlovy Vary<\/h3>\n

The methodology for locating the thermal spring sources was adapted to the smaller areal extent of the area, the higher temperature of the springs, and the higher dilution ratios, as the Tepl\u00e1 river carries approximately 1.5 m\u00b3\/s with a water column of about 0.4 m, which precludes the use of a TIR camera. Point measurements were carried out using a conductometer with a temperature sensor arranged in a defined grid. For measuring temperature and electrical conductivity, a Greisinger (Germany) G 1410 instrument was used, allowing temperature measurements from \u22125.0 to 105.0\u202f\u00b0C with an accuracy of \u00b1 0.3\u202f\u00b0C. The temperature sensor was encased in insulating foam to ensure that it measured only the temperature at the bottom of the Tepl\u00e1 riverbed. Thermal profiling was conducted over an area of approximately 1,300\u202fm\u00b2 on 11 September 2024. For profiling purposes, a regular\u00a0grid was established from Jansk\u00fd most to V\u0159\u00eddeln\u00ed l\u00e1vka, i.e., in\u00a0areas without additional artificial sealing. The\u00a0spacing between measurement points was 5\u202fm, or 2\u202fm and 1\u202fm in\u00a0locations where thermal spring discharges were expected. At points with anomalously high temperatures, the\u00a0exact location of\u00a0the\u00a0thermal spring was manually identified and recorded. Subsequent spatial evaluation was performed using the\u00a0deterministic interpolation method IDW (Inverse Distance Weighting). This methodology was chosen with the\u00a0understanding that a\u00a0potential spring could be located even outside the\u00a0measured points. Thermometry was complemented by flow measurements of\u00a0the\u00a0Tepl\u00e1 river, taken both upstream and downstream of\u00a0the\u00a0area of\u00a0interest using a\u00a0FlowTracker device. These measurements were intended to help balance the\u00a0total discharge of\u00a0the\u00a0wild springs.<\/p>\n

RESULTS<\/h2>\n

Mari\u00e1nsk\u00e9 L\u00e1zn\u011b<\/h3>\n

Using thermometry along 20 km of\u00a0watercourses in\u00a0the\u00a0study area, 14 new mineral water springs were identified, while a\u00a0total of\u00a0131 thermal anomalies were recorded (Fig.\u00a04<\/em>). The\u00a0thermal anomalies most commonly exhibited an elliptical shape, elongated in\u00a0the\u00a0direction of\u00a0surface water flow. In\u00a0the\u00a0case of\u00a0the\u00a0new mineral water discharges, it was often observed that the\u00a0water emerged above the\u00a0stream bed, overflowing the\u00a0edges of\u00a0the\u00a0spring sediments (Fig.\u00a05a<\/em>). The\u00a0new mineral water discharges were distributed unevenly across the\u00a0area; except for one occurrence (P013A Chud\u00e1), their location was restricted to the\u00a0western part of\u00a0the\u00a0area (Fig.\u00a04<\/em>). Thermal anomalies were also detected in\u00a0the\u00a0very centre of\u00a0Mari\u00e1nsk\u00e9 L\u00e1zn\u011b, where an anomaly with a\u00a0temperature of\u00a05\u202f\u00b0C and a\u00a0conductivity of\u00a01,725\u202f\u00b5S\/cm was measured at the\u00a0bottom of\u00a0the\u00a0partially drained Labut\u00ed jez\u00edrko. However, the\u00a0dissolved CO\u2082 content could not be measured using the\u00a0H\u00e4rtl tube, and therefore this trace was not classified as a\u00a0new mineral water spring.<\/p>\n\"\"<\/a>\n

Fig.\u00a04. Thermometric measurements in\u00a0Mari\u00e1nsk\u00e9 L\u00e1zn\u011b<\/h6>\n
1 = P004\/P069 \u017dab\u00ed, 2 = P011, 3 = P013A Chud\u00e1, 4 = P035, 5 = P037D Je\u017e\u010d\u00ed, 6 = P045A,
\n7 = P047 Mraven\u010d\u00ed, 8 = P053 \u0160ne\u010d\u00ed, 9 = P054 S\u00fdkor\u010d\u00ed, 10 = P059B, 11 = P067A, 12 = P071, 13 = P073, 14 = P116 (Source: map: DMR 5G)<\/h6>\n

Thanks to thermometry carried out in\u00a0freezing conditions, it was possible to detect thermal anomalies at absolute temperatures as low as 1.9\u202f\u00b0C (Fig.\u00a05b<\/em>). Many of\u00a0the\u00a0new mineral water discharges were accompanied by iron coatings, emissions of\u00a0gaseous CO\u2082, distinctive organoleptic properties, and resistance to freezing. All 14 new mineral water springs consistently exhibited a\u00a0pH value below 7. For some thermal anomalies, the\u00a0dissolved CO\u2082 content could not be measured due to significant dilution by surface water. For this reason, it cannot be excluded that the\u00a0actual number of\u00a0mineral water springs is higher. Although the\u00a0entire discharge system is generally associated with the\u00a0Mari\u00e1nsk\u00e9 L\u00e1zn\u011b fault zone, the\u00a0influence of\u00a0local tectonics on the\u00a0spatial distribution of\u00a0discharges could not be determined (Fig.\u00a04<\/em>).<\/p>\n\"\"<\/a>\n

Fig.\u00a05. Thermal camera images; a) Luc\u010dina kyselka, b) small springs in\u00a0the\u00a0river floodplain, c) \u017dab\u00ed kyselka springing outside the\u00a0spring catchment<\/h6>\n

Supplementary conductivity measurements of\u00a0the\u00a0thermal anomalies revealed a\u00a0poor correlation with temperature (Fig.\u00a06<\/em>). A\u00a0slightly better correlation is observed when the\u00a0dataset of\u00a0new and existing mineral water discharges is divided into hydrochemical groups. In\u00a0general, however, water temperature is not a\u00a0suitable predictor for estimating conductivity. The\u00a0highest coefficient of\u00a0determination, R\u00b2\u00a0=\u00a00.718, was observed for the\u00a0Na-HCO\u2083 \/ SO\u2084 group, while the\u00a0other groups showed significantly lower determination coefficients (R\u00b2 = 0.315 and 0.386). The\u00a0only group showing a\u00a0decreasing temperature with increasing conductivity was Mg-HCO\u2083 (R\u00b2\u00a0=\u00a00.497); however, this dataset is limited to only four discharges. It was found that higher spring discharge results in\u00a0lower annual water temperature fluctuations.<\/p>\n\"\"<\/a>\n

Fig.\u00a06. Relationship between seepage temperature and conductivity for temperature anomalies and all known seepages (new and existing) divided by hydrochemical groups in\u00a0Mari\u00e1nsk\u00e9 L\u00e1zn\u011b<\/h6>\n

Beyond its original purpose, the\u00a0TIR camera proved to be a\u00a0suitable tool for verifying the\u00a0status of\u00a0mineral water discharge record. Fig.\u00a05c<\/em> shows that \u017dab\u00ed kyselka, a\u00a0newly discovered and provisionally recorded spring, discharges outside the\u00a0collection system. Repeated monitoring of\u00a0the\u00a0new mineral water discharges revealed significant seasonal variations in\u00a0both temperature and flow rate, with the\u00a0lowest temperatures occurring in\u00a0winter and the\u00a0highest in\u00a0summer. In\u00a0contrast, conductivity and pH values remain\u00a0almost stable. Out of\u00a0the\u00a014 new mineral water springs, 11 were sampled for chemical analysis, and the\u00a0results will be used for the\u00a0future revision of\u00a0protection zones within\u00a0the\u00a0Slavkovsk\u00fd les PLA.<\/p>\n

Karlovy Vary<\/h3>\n

The\u00a0thermometric survey, supplemented by conductometry of\u00a0the\u00a0Tepl\u00e1 riverbed around the\u00a0V\u0159\u00eddeln\u00ed Collonade, revealed the\u00a0presence of\u00a014 wild discharges of\u00a0thermal mineral water over an area of\u00a01,300\u202fm\u00b2. In\u00a0terms of\u00a0spatial distribution, the\u00a0wild discharges are concentrated along the\u00a0right bank of\u00a0the\u00a0Tepl\u00e1 riverbed, with the\u00a0highest density at the\u00a0level of\u00a0the\u00a0Wolker Spa House. Only four discharges were identified in\u00a0the\u00a0centre of\u00a0the\u00a0flow or outside the\u00a0Wolker Spa House section. The\u00a0fact that wild discharges are predominantly found along the\u00a0right bank of\u00a0the\u00a0Tepl\u00e1 opposite the\u00a0Wolker Spa House aligns with the\u00a0historical and current intake points of\u00a0the\u00a0V\u0159\u00eddlo (BJ 35\u201337, 70), which have always been located on the\u00a0right bank. The\u00a0highest concentration of\u00a0wild mineral springs is located near the\u00a0bases of\u00a0the\u00a0inclined spring boreholes BJ\u202f35, BJ\u202f36, and BJ\u202f70. A\u00a0wild mineral water spring was also found above the\u00a0fourth spring borehole, BJ\u202f37, although its temperature reaches only 23.3\u202f\u00b0C. Even though it was not possible to completely prevent contact between surface water and the\u00a0temperature\/conductivity probe, the\u00a0highest recorded temperature of\u00a0a\u00a0wild spring was 71.3\u202f\u00b0C, and the\u00a0highest measured conductivity was 7,470\u202f\u00b5S\/cm\u00a0\u2013 values almost identical to those of\u00a0the\u00a0V\u0159\u00eddlo spring. Beyond the\u00a0original scope, six main\u00a0sites of\u00a0gaseous CO\u2082 escape through the\u00a0Tepl\u00e1\u2019s\u00a0water column were visually identified.<\/p>\n

\"\"<\/a><\/h6>\n
Fig.\u00a07. Thermometric measurements in\u00a0Karlovy Vary<\/h6>\n

Due to the\u00a0well-known long-term variations in\u00a0the\u00a0discharge of\u00a0the\u00a0structure and pressure changes at the\u00a0regulating wells, it has been estimated that wild discharges currently flow into the\u00a0Tepl\u00e1 riverbed with a\u00a0total flow rate of\u00a0approximately 2 to 3\u202fl\/s, including an unknown amount of\u00a0gaseous CO\u2082. The\u00a0total flow of\u00a0the\u00a0wild springs was also tentatively assessed using a\u00a0FlowTracker device, but due to its \u00b1 10\u202f% accuracy, the\u00a0measurements did not yield the\u00a0expected results.<\/p>\n

Analysis of\u00a0the\u00a0data revealed a\u00a0correlation between water conductivity in\u00a0the\u00a0defined network and temperature, with a\u00a0coefficient of\u00a0determination R\u00b2\u00a0= 0.585. Although the\u00a0coefficient is very similar for the\u00a0already recorded springs (R\u00b2 = 0.520), the\u00a0distribution of\u00a0values is entirely different. The\u00a0Had\u00ed spring is the\u00a0only recorded spring with a\u00a0distinctly different conductivity. It is the\u00a0most distant discharge from the\u00a0centre of\u00a0the\u00a0structure, has the\u00a0highest concentration of\u00a0dissolved CO\u2082, and is also the\u00a0coldest (Fig.\u00a08<\/em>). Therefore, it can be excluded from the\u00a0dataset. By analogy with wild mineral water springs, it can be concluded that water temperature is not a\u00a0reliable precursor for determining conductivity, because if dilution by the\u00a0Tepl\u00e1 is prevented, the\u00a0conductivity for all new wild springs would be the\u00a0same, i.e., \u00b1 7,300\u202f\u00b5S\/cm, while the\u00a0water temperature would vary depending on the\u00a0discharge rate of\u00a0the\u00a0thermal water.<\/p>\n\"\"<\/a>\n

Fig.\u00a08. Relationship between point measurements of\u00a0water temperature at the\u00a0bottom of\u00a0the\u00a0Tepl\u00e1 riverbed and recorded springs on conductivity<\/h6>\n

DISCUSSION<\/h2>\n

The\u00a0methodology for the\u00a0thermometric survey must reflect the\u00a0required nature of\u00a0the\u00a0survey results. The\u00a0data collection typology in\u00a0Mari\u00e1nsk\u00e9 L\u00e1zn\u011b was adapted to the\u00a0considerable spatial extent of\u00a0the\u00a0area, whereas in\u00a0Karlovy Vary it was adjusted to the\u00a0high temperature gradient between surface and thermal waters. Both methodologies proved to be highly effective and each led to the\u00a0successful identification of\u00a0mineral water springs.<\/p>\n

The\u00a0results of\u00a0the\u00a0survey have practical implications at both sites. In\u00a0Mari\u00e1nsk\u00e9 L\u00e1zn\u011b, they are particularly relevant for the\u00a0Nature Conservation Agency of\u00a0the\u00a0Slavkovsk\u00fd les PLA, which seeks to adopt an objective approach to protecting even the\u00a0less significant mineral water discharge structures. In\u00a0Karlovy Vary, the\u00a0findings are important for the\u00a0administrators of\u00a0natural medicinal resources (Administration of\u00a0Natural Medicinal Resources and Colonnades), who are implementing the\u00a0results in\u00a0a\u00a0sealing works project near the\u00a0V\u0159\u00eddeln\u00ed Colonnade. The\u00a0high total discharge of\u00a0the\u00a0wild springs into the\u00a0Tepl\u00e1 river may be linked to the\u00a0recent reconstruction of\u00a0part of\u00a0the\u00a0V\u0159\u00eddeln\u00ed Colonnade between 2019 and 2023, which, due to pressure changes, reactivated the\u00a0wild springs.<\/p>\n

Although thermometric measurements, whether using a TIR camera or a temperature probe, proved to be a highly effective tool for locating water discharges and measuring the CO\u2082 content of mineral water springs, it should be noted that it was not possible to perform H\u00e4rtl tube measurements on all\u00a0the\u00a0identified thermal anomalies in\u00a0Mari\u00e1nsk\u00e9 L\u00e1zn\u011b due to the\u00a0impossibility of\u00a0isolating surrounding watercourses. Therefore, the\u00a0total number of\u00a0new mineral water springs within\u00a0the\u00a0set of\u00a0131 thermal anomalies may be higher, which is why all thermal anomalies are included in\u00a0the\u00a0study results. The\u00a0discrepancy between the\u00a0number of\u00a0detected thermal anomalies and the\u00a0number of\u00a0confirmed mineral springs is primarily due to the\u00a0fact that discharges of\u00a0ordinary water are far more frequent, even under the\u00a0conditions in\u00a0Mari\u00e1nsk\u00e9 L\u00e1zn\u011b. Even though mineral water discharges are generally warmer during frosty conditions, the\u00a0methodology was followed consistently: all anomalies exceeding the\u00a0background temperature by approximately 3\u202f\u00b0C were marked. Discharges that were not detected may have been diluted by surface water, which complicates their identification. In\u00a0Karlovy Vary, a\u00a0limiting factor was the\u00a0measurement grid with intervals of\u00a01 to 5\u202fm, which undoubtedly led to some discharges not being identified because they fell between measurement points. Continuous temperature measurement was not a\u00a0viable solution, as the\u00a0sensor\u2019s\u00a0response time was insufficiently fast. At the\u00a0same time, despite efforts to minimise other interfering factors, it should be emphasised that in\u00a0Mari\u00e1nsk\u00e9 L\u00e1zn\u011b it was not possible to maintain\u00a0completely consistent meteorological conditions, such as daily temperature cycles, thaws, etc., throughout the\u00a0entire duration of\u00a0the\u00a0thermometric survey.<\/p>\n

Comparison of\u00a0the\u00a0new measurement results with data from the\u00a01980s, both in\u00a0Mari\u00e1nsk\u00e9 L\u00e1zn\u011b and Karlovy Vary, shows that modern technologies can significantly increase the\u00a0success of\u00a0surveys. While the\u00a0authors of\u00a0the\u00a0study conducted between 1984 and 1988 in\u00a0the\u00a0wider Mari\u00e1nsk\u00e9 L\u00e1zn\u011b area reached rather inconclusive results, springs were successfully located in\u00a0the\u00a0survey carried out in\u00a02023\u20132024. The\u00a0earlier thermometric survey was conducted without the\u00a0use of\u00a0a\u00a0TIR camera, which would have sped up, improved the\u00a0accuracy of, and reduced the\u00a0cost of\u00a0data collection. The\u00a01980 survey in\u00a0Karlovy Vary was more of\u00a0a\u00a0reconnaissance in\u00a0nature, so the\u00a0authors\u2019 conclusions were purely qualitative, for example, leaks of\u00a0thermal water were found along the\u00a0casing perimeters of\u00a0the\u00a0wells in\u00a0the\u00a0riverbed.<\/p>\n

Quantification of\u00a0discharge could not be achieved from either the\u00a0thermometric data or the\u00a0supplementary conductometric data. It should be noted that in\u00a0Mari\u00e1nsk\u00e9 L\u00e1zn\u011b the\u00a0mineral water springs exhibit highly variable conductivity but nearly uniform temperature, whereas in\u00a0Karlovy Vary the\u00a0springs have almost identical conductivity but differing temperatures. Furthermore, while in\u00a0Karlovy Vary only the\u00a0temperature of\u00a0the\u00a0mineral water increases with depth of\u00a0abstraction, in\u00a0Mari\u00e1nsk\u00e9 L\u00e1zn\u011b it is primarily the\u00a0conductivity that increases, as confirmed, for example, in\u00a0the\u00a0Ferdinand spring structure\u00a0[16]. The\u00a0fact that the\u00a0springs in\u00a0Mari\u00e1nsk\u00e9 L\u00e1zn\u011b have similar temperatures could facilitate the\u00a0quantification of\u00a0discharge; however, this would require ideal conditions, as mentioned in\u00a0the\u00a0introduction. Subsequently, in\u00a0the\u00a0case of\u00a0parallel conductivity measurements, it would even be possible to calculate the\u00a0conductivity of\u00a0a\u00a0spring using a\u00a0mixing equation. Within\u00a0the\u00a0study, the\u00a0relationship between conductivity and temperature was tested, but the\u00a0results are inconclusive. Correlating conservative conductivity with non-conservative temperature presents considerable challenges, even though, in\u00a0the\u00a0context of\u00a0this study, the\u00a0two parameters are not independent, as evidenced by the\u00a0data from the\u00a0recorded springs (Fig.\u00a06<\/em>). In\u00a0Karlovy Vary, the\u00a0unknown temperature of\u00a0the\u00a0spring as it emerges into the\u00a0channel is additionally problematic. This is caused by the\u00a0varying rate of\u00a0thermal water discharge to the\u00a0surface, partly by the\u00a0distance from the\u00a0centre of\u00a0the\u00a0discharge zone, and consequently the\u00a0depth of\u00a0capture. For this reason, in\u00a0the\u00a0case of\u00a0recorded smaller springs (e.g., Skaln\u00ed, Ml\u00fdnsk\u00fd, Sadov\u00fd), the\u00a0temperature of\u00a0the\u00a0springs has previously increased, as a\u00a0preferential pathway was created, shortening the\u00a0residence time within\u00a0the\u00a0rock matrix\u00a0[17].<\/p>\n

CONCLUSION<\/h2>\n

The\u00a0research focused on the\u00a0use of\u00a0thermometry as an effective tool for locating mineral water discharges. However, this method cannot be regarded as self-sufficient for the\u00a0identification of\u00a0mineral springs and should be complemented, for example, by measurements of\u00a0free CO\u2082 or electrical conductivity. Thermometry was applied at two contrasting sites: Mari\u00e1nsk\u00e9 L\u00e1zn\u011b, characterised by cold springs, and Karlovy Vary, with thermal springs. In\u00a0Mari\u00e1nsk\u00e9 L\u00e1zn\u011b, the\u00a0use of\u00a0a\u00a0TIR camera enabled the\u00a0identification of\u00a014 new, low-yield mineral water discharges. It can be concluded that thermometry alone is not sufficient to unambiguously determine the\u00a0presence of\u00a0emerging non-thermal, gas-rich springs (< 20 \u00b0C). On the\u00a0other hand, when combined with measurements using a\u00a0H\u00e4rtl tube, a\u00a0conductometer, and a\u00a0pH meter, it represents the\u00a0most effective and also the\u00a0least costly method for locating even low-yield discharges of\u00a0gas-rich mineral waters. It should be noted that thermometry is naturally applicable also to the\u00a0detection of\u00a0non-mineral groundwater outflows. The\u00a0results will be submitted to the\u00a0administration of\u00a0the\u00a0Slavkovsk\u00fd les PLA for the\u00a0purposes of\u00a0registration and improved protection of\u00a0mineral waters in\u00a0the\u00a0area.<\/p>\n

For the\u00a0survey in\u00a0the\u00a0channel of\u00a0the\u00a0Tepl\u00e1 in\u00a0Karlovy Vary, a\u00a0point-based measurement method using a\u00a0conductometer with an integrated temperature sensor arranged in\u00a0a\u00a0regular grid was selected. The\u00a0thermometric analysis demonstrated the\u00a0presence of\u00a014 wild discharges of\u00a0thermal water in\u00a0the\u00a0channel of\u00a0the\u00a0Tepl\u00e1 over an area of\u00a01,300\u00a0m\u00b2, reaching temperatures of\u00a0up to 71.3 \u00b0C and conductivities of\u00a0up to 7,470 \u00b5S\/cm. The\u00a0total yield of\u00a0the\u00a0wild discharges in\u00a0the\u00a0area of\u00a0interest was estimated at approximately 2\u20133\u00a0l\/s. The\u00a0thermometric results constitute a\u00a0key basis for the\u00a0planned remediation works in\u00a0the\u00a0Tepl\u00e1 riverbed. Repeating the\u00a0measurements after the\u00a0remediation has been carried out can be considered desirable in\u00a0order to verify its effectiveness.<\/p>\n

Thermometry is suitable for rapid mapping of\u00a0interaction zones between groundwater and surface water, particularly due to its non-invasive nature. The\u00a0effectiveness of\u00a0the\u00a0method depends on optimal timing of\u00a0the\u00a0measurements (diurnal and seasonal periodicity) and on the\u00a0magnitude of\u00a0the\u00a0temperature difference (\u2206T) between groundwater and surface water. Quantitative interpretation of\u00a0thermal anomalies in\u00a0terms of\u00a0discharge is complicated, as temperature is a\u00a0non-conservative tracer. Quantification therefore requires calibration for the\u00a0specific site and conditions. The\u00a0research confirmed that, despite the\u00a0general limitations regarding quantification, thermometry is well suited for the\u00a0qualitative assessment of\u00a0concealed springs. Application in\u00a0the\u00a0field of\u00a0mineral waters, as demonstrated by both parts of\u00a0the\u00a0study, is highly effective, but requires careful consideration of\u00a0local conditions when selecting the\u00a0appropriate methodology. In\u00a0the\u00a0future, further increases can be expected in\u00a0the\u00a0sensitivity and refresh rate of\u00a0TIR sensors, their affordability, and the\u00a0availability of\u00a0additional sensors (including hyperspectral sensors). Simultaneously, improvements are anticipated in\u00a0atmospheric correction algorithms, emissivity measurements, and the\u00a0use of\u00a0artificial intelligence and machine learning, as well as in\u00a0the\u00a0fusion of\u00a0these data with remote sensing data, particularly from drones. This will lead to simplification of\u00a0spatio-temporal monitoring and enable broader application in\u00a0hydrology and hydrogeology.<\/p>\n

Acknowledgement<\/h3>\n

The\u00a0research carried out within\u00a0the\u00a0project Spa Research Centre is funded from the\u00a0Just Transition Fund (JTF) through project No. CZ.10.\u00a001.\u00a001\/00\/22_001\/0000261.<\/em><\/p>\n

The\u00a0Czech version of\u00a0this article was peer-reviewed, the\u00a0English version was translated from the\u00a0Czech original by Environmental Translation Ltd.<\/p>\n","protected":false},"excerpt":{"rendered":"

Thermometry is a non-invasive technique suitable for detecting hidden mineral water springs. Its applicability was evaluated in two contrasting hydrogeological settings: Mari\u00e1nsk\u00e9 L\u00e1zn\u011b, characterized by cold, CO\u2082-rich mineral springs, and Karlovy Vary, dominated by thermal springs.<\/p>\n","protected":false},"author":8,"featured_media":37794,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[86],"tags":[4005,4025,4004,4024],"coauthors":[3994,3995,3996,3586,3997,3998],"class_list":["post-37796","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-hydraulics-hydrology-and-hydrogeology","tag-karlovy-vary","tag-mapping-of-mineral-springs","tag-marianske-lazne","tag-thermometry"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/posts\/37796","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/users\/8"}],"replies":[{"embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/comments?post=37796"}],"version-history":[{"count":9,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/posts\/37796\/revisions"}],"predecessor-version":[{"id":38044,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/posts\/37796\/revisions\/38044"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/media\/37794"}],"wp:attachment":[{"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/media?parent=37796"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/categories?post=37796"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/tags?post=37796"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/coauthors?post=37796"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}