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<\/a>\nMETHODOLOGY<\/h2>\n
The\u00a0main\u00a0objective of\u00a0this study is to assess and compare the\u00a0impacts of\u00a0sudden environmental disturbances (forest fire and intensive groundwater abstraction) and long-term landscape changes (large-scale drainage and subsequent natural recovery) on the\u00a0hydrochemical status of\u00a0springs and, where applicable, their discharge.<\/p>\n
The\u00a0springs selected for further study were primarily those for which we had documented the\u00a0baseline conditions prior to significant changes. All available archival materials were reviewed and analysed and compared with the\u00a0current conditions.<\/p>\n
In\u00a02026, a\u00a0comprehensive standardised form was completed for all springs investigated. It included not only information on the\u00a0location and extent of\u00a0the\u00a0spring areas and the\u00a0results of\u00a0field measurements of\u00a0water parameters, but also a\u00a0description and basic quantification of\u00a0the\u00a0biological components of\u00a0the\u00a0natural environment.<\/p>\n
At the\u00a0selected springs, discharge and the\u00a0physical and chemical properties of\u00a0the\u00a0water were measured, and water samples were collected for chemical analysis. During repeated visits to the\u00a0springs, their discharge was measured using a\u00a0suitable measuring container, along with water parameters including electrical conductivity, temperature and, where applicable, pH and dissolved oxygen.<\/p>\n
For the\u00a0study, three areas with markedly different hydrogeological characteristics were selected. The\u00a0study area around H\u0159ensko in\u00a0northern Bohemia forms part of\u00a0the\u00a0Czech Cretaceous Basin, with significant deep hydrogeological structures and a\u00a0greater delay in\u00a0the\u00a0response of\u00a0spring discharge to precipitation and is located within\u00a0a\u00a0national park. In\u00a0the\u00a0H\u0159ensko area, eight springs with high discharge at different altitudes were monitored directly as\u00a0part of\u00a0the\u00a0ongoing project. Other springs were inaccessible for monitoring and were therefore assessed using only archival data and supporting materials.<\/p>\n
In\u00a0the\u00a0H\u0159ensko area, the\u00a0impact of\u00a0the\u00a0large-scale wildfire on springs was investigated. This involved comparing our own field measurements and the\u00a0results of\u00a0water analyses with archival sources of\u00a0expert information, as well as data from the\u00a0Raw Water Database and, last but not least, freely available data from the\u00a0Czech Hydrometeorological Institute (CHMI).<\/p>\n
Another selected spring area was the\u00a0A\u0161 region in\u00a0western Bohemia, which is located in\u00a0an\u00a0area of\u00a0crystalline rocks (underlain\u00a0by low-grade metamorphic phyllites and schists), where springs are generally highly dependent on climatic conditions. In\u00a0the\u00a0recent past, major changes in\u00a0agricultural management took place here, affecting the\u00a0springs, and the\u00a0area is also home to specially protected organisms associated with aquatic environments.<\/p>\n
The third study area was the Blanice catchment in the \u0160umava foothills. From a hydrogeological perspective, it lies within the crystalline basement, in an area of highly metamorphosed rocks of the Moldanubian Zone (migmatites,\u00a0granulites, etc.). The\u00a0area is situated at a\u00a0higher altitude than\u00a0the\u00a0two previous areas and is therefore slightly wetter and cooler.<\/p>\n
For comparison of\u00a0water quality at spring areas affected and unaffected by drainage, data from two periods 16\u201320 years apart were obtained. The\u00a0first period covers the\u00a0beginning of\u00a0monitoring between 2005 and 2009. The\u00a0comparison dataset is current, covering 2025\/2026. The\u00a0data include individual spring areas from two study regions: the\u00a0A\u0161 region and the\u00a0Blanice and Zlat\u00fd Stream catchments. The\u00a0following water-quality parameters were selected: conductivity, nitrate, nitrite, ammonium-ion, phosphate and chloride concentrations. For the\u00a0calculation of\u00a0the\u00a0resulting score, indicating an\u00a0improvement or deterioration in\u00a0the\u00a0hydrochemical status of\u00a0the\u00a0spring area, only those parameters for which data from the\u00a0first period were available were used (Tab.\u00a02<\/em>). Where data from multiple seasons were available for a\u00a0given spring area within\u00a0a\u00a0particular period, the\u00a0mean\u00a0values were used. Individual parameters were assigned one or two positive or negative points depending on the\u00a0magnitude of\u00a0the\u00a0improvement or deterioration. Where a\u00a0parameter remained unchanged (or the\u00a0change was negligible), it was assigned zero points. The\u00a0theoretical score could therefore range from \u221212 (significant deterioration in\u00a0all monitored parameters) to\u00a0+12 (significant improvement in\u00a0all monitored parameters).<\/p>\n The\u00a0spring areas investigated were divided into two categories according to whether or not they were affected by drainage. In\u00a0this context, drainage refers both to systematic subsurface drainage systems and to deepened surface ditches conveying water to a\u00a0receiving watercourse. In\u00a0addition to entirely natural spring areas, the\u00a0unaffected category also included spring SP82\/SC05 (U\u00a0panenky Marie), which has been modified as a\u00a0drinking-water spring, but is not affected by drainage in\u00a0any way.<\/span><\/p>\n The\u00a0study area east of\u00a0the\u00a0town of\u00a0H\u0159ensko is in\u00a0the\u00a0\u00dast\u00ed nad Labem Region, within\u00a0Bohemian\u00a0Switzerland National Park.<\/p>\n From a\u00a0hydrological perspective, the\u00a0springs investigated are located in\u00a0the\u00a0Dlouh\u00e1 B\u011bl\u00e1 Stream catchment. The\u00a0stream flows into the\u00a0H\u0159ensk\u00e1 Kamenice from the\u00a0right at H\u0159ensko, just over one kilometre upstream of\u00a0its confluence with the\u00a0Elbe river. The\u00a0Such\u00e1 B\u011bl\u00e1 stream is a\u00a0right-bank tributary of\u00a0the\u00a0Dlouh\u00e1 B\u011bl\u00e1, and its catchment contains five of\u00a0the\u00a0springs investigated. In\u00a0total, eight high-discharge springs were monitored directly as part of\u00a0the\u00a0project. Some other historical springs were inaccessible for direct monitoring, particularly because they are used for groundwater abstraction for public drinking-water supply.<\/p>\n From a hydrogeological perspective, the study area is part of the Czech Cretaceous Basin and lies in the northern part of Hydrogeological Region 4660 \u2013 Lower Kamenice and K\u0159inice Cretaceous Basin and Groundwater Body 46600 \u2013 Lower Kamenice and K\u0159inice Cretaceous Basin [15]. The hydrogeologically significant aquifers in the study area occur in psammitic Cretaceous rocks, particularly sandstones, with intergranular and fracture permeability. The springs studied are associated with the locally most important aquifer (BC), hosted in the sandstones of the Jizera Formation and the upper part of the B\u00edl\u00e1 Hora Formation [16]. The high-discharge springs of interest occur at aquitard layers within the BC aquifer, as described, for example, in more detailed Saxon geological and hydrogeological studies [10].<\/p>\n The\u00a0earliest available study of\u00a0the\u00a0springs [7] provides a\u00a0clear picture of\u00a0their condition more than\u00a0100 years ago. It describes the\u00a0following situation in\u00a01911\u20131912: the\u00a0settlement of\u00a0H\u0159ensko already had a\u00a0public water supply fed by a\u00a0captured spring in\u00a0the\u00a0upper part of\u00a0Malinov\u00fd d\u016fl (the\u00a0Nad Klep\u00e1\u010dem spring; see Fig.\u00a04<\/em>). The\u00a0author classifies it as a\u00a0contact spring emerging at the\u00a0outcrop of\u00a0an\u00a0overlying sandstone layer underlain\u00a0by a\u00a0clay layer.<\/p>\n One of\u00a0the\u00a0highest-discharge springs in\u00a0the\u00a0area was the\u00a0T\u0159i prameny spring area (Pod Prav\u010dickou br\u00e1nou spring), at an\u00a0elevation of\u00a0200 m above sea level. Near the\u00a0junction of\u00a0the\u00a0hiking trail to Prav\u010dick\u00e1 br\u00e1na and the\u00a0Dlouh\u00e1 B\u011bl\u00e1 stream, a\u00a0powerful spring emerged from a\u00a0rocky slope covered with scree, forming a\u00a0small pond inhabited by trout and covered with aquatic vegetation. The\u00a0original three outlets of\u00a0the\u00a0spring area had already been artificially combined. The\u00a0spring discharge was at least 6 L\/s, and the\u00a0water temperature on 6\u00a0March 1912 was 8 \u00b0C. The\u00a0author concludes that it is a\u00a0contact spring emerging at the\u00a0outcrop of\u00a0a\u00a0sandstone layer (Labiatus).<\/p>\n One of\u00a0the\u00a0best-known springs in\u00a0Saxon-Bohemian\u00a0Switzerland was Panensk\u00fd spring (elevation 185 m above sea level), which had already been modified at the\u00a0time, with its banks artificially widened. Clear water emerged from the\u00a0ground at several points, playing over white pebbles at the\u00a0spring outlets. The\u00a0spring discharge was similar to that of\u00a0T\u0159i prameny. On 3\u00a0February 1911, the\u00a0water temperature at the\u00a0strongest outlet of\u00a0Panensk\u00fd spring was measured at 9.05 \u00b0C. From this, the\u00a0author concluded that it was an\u00a0ascending spring, since under normal conditions its temperature would be expected to be only around 7.5 \u00b0C. In\u00a0the\u00a0Such\u00e1 B\u011bl\u00e1 valley, about 200 metres from its confluence with the\u00a0Dlouh\u00e1 B\u011bl\u00e1, a\u00a0spring (Such\u00e1 B\u011bl\u00e1 3) emerged from scree, with a\u00a0discharge of\u00a0around 2 L\/s\u00a0[7].<\/p>\n In\u00a0the\u00a0late 1960s and early 1970s, a\u00a0series of\u00a0hydrogeological investigations were conducted in\u00a0the\u00a0study area, including monitoring of\u00a0some of\u00a0the\u00a0major local springs (e.g. [9] and other studies [21]). Borehole drilling and other hydrogeological work led to the\u00a0establishment of\u00a0the\u00a0extensive H\u0159ensko groundwater abstraction area. Groundwater was, and continues to be, abstracted here from a\u00a0system of\u00a0hydrogeological boreholes in\u00a0the\u00a0Dlouh\u00e1 B\u011bl\u00e1 valley. The\u00a0high-discharge Pod Prav\u010dickou br\u00e1nou (T\u0159i prameny) and Pytl\u016fv springs were subsequently incorporated into the\u00a0system. Since the\u00a0second half of\u00a0the\u00a020th century, the\u00a0H\u0159ensko abstraction area has supplied drinking water to the\u00a0town of\u00a0D\u011b\u010d\u00edn and the\u00a0surrounding area.<\/p>\n Around the\u00a0groundwater abstraction area, seven springs were monitored regularly once a\u00a0week in\u00a0the\u00a0late 1960s and early 1970s (Panensk\u00fd spring, Such\u00e1 B\u011bl\u00e1 1\u20133, Pod Prav\u010dickou br\u00e1nou spring, Pytl\u016fv spring and U\u00a0Cik\u00e1nsk\u00e9ho smrku spring). Their former locations are shown on the\u00a0historical map in\u00a0Fig.\u00a01<\/em>. Panensk\u00fd spring disappeared completely as a\u00a0result of\u00a0groundwater abstraction and was decommissioned in\u00a01974 [20]. The\u00a0monitored springs were gradually removed from the\u00a0monitoring programme. Of\u00a0these, only Such\u00e1 B\u011bl\u00e1 3 continues to be monitored regularly by the\u00a0CHMI.<\/p>\n The\u00a0discharge of\u00a0Such\u00e1 B\u011bl\u00e1 2 spring gradually declined from 3.8 L\/s\u00a0in\u00a01960 until surface discharge ceased completely in\u00a01989. This was most likely due to a\u00a0combination of\u00a0increased groundwater abstraction from the\u00a0H\u0159ensko abstraction area (up to 135 L\/s) and unfavourable climatic conditions [10]. Following a\u00a0reduction in\u00a0groundwater abstraction and the\u00a0end of\u00a0the\u00a0dry period, the\u00a0discharge of\u00a0Such\u00e1 B\u011bl\u00e1 2 spring increased slightly again.<\/span><\/p>\n The\u00a0discharge of\u00a0some other major springs responded similarly to high levels of\u00a0groundwater abstraction and unfavourable climatic conditions. Pod Prav\u010dickou br\u00e1nou spring, which has the\u00a0highest discharge in\u00a0the\u00a0area, had a\u00a0discharge of\u00a0approximately 20 L\/s\u00a0in\u00a0the\u00a0late 1970s and early 1980s, compared with only around 10.6 L\/s\u00a0in\u00a02013. The\u00a0discharge of\u00a0U\u00a0Cik\u00e1nsk\u00e9ho smrku spring generally fluctuated between 0.5 and 3.3 L\/s\u00a0from 1957 to 1982, whereas in\u00a02012\u20132014<\/span> the\u00a0mean\u00a0discharge was only 0.22 L\/s.<\/span><\/p>\n Between 2012 and 2014, springs in\u00a0the\u00a0area were mapped and their discharge measured and assessed as part of\u00a0the\u00a0cross-border GRACE programme [8, 10].<\/span><\/p>\n In\u00a0the\u00a0early 2020s, the\u00a0area was affected by a\u00a0bark beetle outbreak. In\u00a0July\u00a02022, the\u00a0resulting dry woody biomass was consumed by a\u00a0large-scale wildfire covering more than\u00a010 km\u00b2 (e.g. [18]), which, with a\u00a0few exceptions, affected the\u00a0entire study area from the\u00a0built-up area of\u00a0H\u0159ensko to that of\u00a0Mezn\u00e1 village.<\/span><\/p>\n Panensk\u00fd spring has disappeared as a result of groundwater abstraction, and no\u00a0traces of it remain at the site of its former outflow. Nad Klep\u00e1\u010dem spring area in Malinov\u00fd d\u016fl is used as a source of drinking water for the town of H\u0159ensko. The\u00a0main surface outflow from this spring area has disappeared (the spring intake is shown in Fig. 4<\/em>). Groundwater outflows with substantially lower discharge occur within the spring area, but infiltrate back into the rock environment after several tens of metres. After abstraction, the overflow from the main spring is discharged unused through a pipe into the Dlouh\u00e1 B\u011bl\u00e1 stream. Pod Prav\u010dickou br\u00e1nou spring (T\u0159i prameny) and Pytl\u016fv spring are fenced off, covered by chambers and soil, and connected to the public water supply system; consequently, there are no longer any surface groundwater outflows at these sites (Fig. 5<\/em>). U Cik\u00e1nsk\u00e9ho smrku spring still exists in a degraded state (a concrete well ring; see Fig. 6<\/em>) and has a markedly lower discharge than in the last century. The five high-discharge springs monitored in the Such\u00e1 B\u011bl\u00e1 valley flow freely onto the surface without any significant restrictions. The highest-discharge spring, Such\u00e1 B\u011bl\u00e1 3, is regularly monitored by CHMI. Groundwater abstraction from the H\u0159ensko abstraction area has decreased compared with the past and is currently around 80 l\/s [17]. Even several years after the\u00a0fire, much of the area remains covered with charred wood debris. Scorched tree trunks rise towards the sky, with vegetation gradually regenerating between them, particularly through self-seeding birch (Figs. 5<\/em> and 6<\/em>).<\/p>\n <\/p>\n The\u00a0large-scale fire, which burned from 24\u00a0July to 12\u00a0August 2022, affected an\u00a0area of\u00a0more than\u00a010 km\u00b2 around the\u00a0monitored springs east of\u00a0the\u00a0town of\u00a0H\u0159ensko [18]. It was the\u00a0largest forest fire recorded in\u00a0Czechia in\u00a0modern times.<\/p>\n Fires can\u00a0generally affect groundwater, particularly through contamination by substances contained in\u00a0smoke and ash (toxic metals, polycyclic aromatic hydrocarbons, etc.). Infiltration of\u00a0firefighting water and fire-suppressing agents may also play a\u00a0role [19]. In\u00a0this case, water from the\u00a0Elbe river, Lake Milada and other sources was used to extinguish the\u00a0fire.<\/p>\n To assess changes in\u00a0water chemistry, analytical data on abstracted groundwater from the\u00a0Raw Water Database [22] were available for the\u00a0captured springs. The\u00a0database contains data for Nad Klep\u00e1\u010dem spring (a\u00a0drinking-water source for H\u0159ensko) and the\u00a0H\u0159ensko abstraction area, into which the\u00a0high-discharge Pod Prav\u010dickou br\u00e1nou and Pytl\u016fv springs are incorporated. Within\u00a0the\u00a0study area affected by the\u00a0fire, the\u00a0Mezn\u00e1 abstraction area is also monitored in\u00a0this way; it abstracts groundwater from a\u00a0hydrogeological borehole east of\u00a0U\u00a0Cik\u00e1nsk\u00e9ho smrku spring. Results from the\u00a0Mezn\u00e1 abstraction area were therefore also included for comparison in\u00a0the\u00a0assessment of\u00a0the\u00a0effects of\u00a0the\u00a0fire on groundwater (see, for example, the\u00a0graphs in\u00a0Figs. 2a<\/em> and 2b<\/em>).<\/p>\n The\u00a0three groundwater sources mentioned above abstract groundwater with low mineralisation and low pH. Groundwater from these sources was sampled both before the\u00a0fire (analyses from 2019 to spring 2022 were considered) and after the\u00a0fire (analyses from autumn 2022 and 2023).<\/p>\n Nad Klep\u00e1\u010dem captured spring<\/strong><\/span><\/p>\n The\u00a0pH of\u00a0water abstracted from Nad Klep\u00e1\u010dem spring area was around 5.8\u00a0before the\u00a0fire and decreased slightly to 5.7 after the\u00a0fire (Fig.\u00a02a<\/em>). Water conductivity gradually increased slightly between autumn 2019 and spring 2022, reaching 16.7 mS\/m before the\u00a0fire. After the\u00a0fire, it decreased to 15.3 mS\/m before returning to around 16.3 mS\/m in\u00a02023 (Fig.\u00a02b<\/em>).<\/p>\n In\u00a02022, following the\u00a0fire, chloride concentrations increased slightly compared with pre-fire levels (from 4.47 to 5.35 mg\/L), while sulphate concentrations decreased slightly (from 46.7 to 40.7 mg\/L). Nitrate concentrations were identical before and after the\u00a0fire (11.5 mg\/L). Magnesium concentrations fluctuated around 3 mg\/L both before and after the\u00a0fire. Concentrations of\u00a0ammonium ions, nitrites, aluminium and manganese were below the\u00a0analytical detection limit both before and after the\u00a0fire. No Escherichia coli or enterococci were detected either before or after the\u00a0fire.<\/p>\n In autumn 2022, slight increases were recorded in the concentrations of iron (from < 0.02 to 0.07 mg\/L), calcium (from 18.4 to 20.2 mg\/L), the sum of Ca + Mg (from 0.58 to 0.63 mmol\/L), and CODMn (from < 0.5 to 0.71 mg\/L) in water\u00a0abstracted from Nad Klep\u00e1\u010dem spring. However, all these parameters returned to their previous typical levels in\u00a02023.<\/p>\n In\u00a0October 2022, a\u00a0broader range of\u00a0analyses was conducted, confirming the\u00a0absence of\u00a0significant concentrations of\u00a0polycyclic aromatic hydrocarbons (PAHs), nickel, lead, zinc, phosphates, boron, copper, mercury, fluorides, selenium, chromium, cadmium, cyanides and beryllium in\u00a0the\u00a0abstracted water.<\/p>\n When compared with the\u00a0requirements of\u00a0Decree No. 252\/2004 Coll. [20], the\u00a0abstracted water failed to meet the\u00a0same parameters both before and after the\u00a0fire. These included, in\u00a0particular, low pH and low magnesium concentrations, which were attributable to the\u00a0natural background conditions.<\/p>\n Groundwater from the\u00a0H\u0159ensko abstraction area<\/strong><\/span><\/p>\n In\u00a0the\u00a0H\u0159ensko abstraction area, most groundwater is abstracted by pumping from hydrogeological boreholes. In\u00a02022, the\u00a0mean\u00a0abstraction rate from this area was 75.7 L\/s\u00a0[17]. The\u00a0discharge of\u00a0the\u00a0two captured springs (Pod Prav\u010dickou br\u00e1nou and Pytl\u016fv) is not measured but calculated, which our findings indicate is unreliable [8]. Based on expert estimates, spring water accounts for approximately one seventh of\u00a0the\u00a0total volume abstracted. Any contamination of\u00a0the\u00a0springs resulting from the\u00a0fire could therefore be reflected in\u00a0the\u00a0results for the\u00a0mixed abstracted groundwater, but only to a\u00a0limited extent due to substantial dilution by groundwater pumped from the\u00a0boreholes. In\u00a02022, water analyses were conducted both before the\u00a0fire (March and 14\u00a0July) and after the\u00a0fire (September and October 2022).<\/p>\n The\u00a0raw water from the\u00a0H\u0159ensko abstraction area was weakly mineralised and slightly acidic both before and after the\u00a0fire. Comparison of\u00a0the\u00a0values before and after the\u00a0fire showed a\u00a0slight decrease in\u00a0pH (from 6.3 to 6.0), followed by a\u00a0return to the\u00a0initial level (Fig.\u00a02a<\/em>). Similarly, the\u00a0conductivity of\u00a0the\u00a0groundwater decreased after the\u00a0fire and then returned relatively quickly to its previous level (Fig.\u00a02b<\/em>). The\u00a0graphs also show an\u00a0isolated sharp increase in\u00a0both pH and conductivity in\u00a0September 2023 (more than\u00a0a\u00a0year after the\u00a0fire), which, in\u00a0view of\u00a0the\u00a0preceding and subsequent measurements, we interpret as a\u00a0probable measurement or database entry error.<\/p>\n For comparison, conductivity in\u00a0the\u00a0Mezn\u00e1 abstraction area decreased after the\u00a0fire in\u00a0a\u00a0similar manner to that in\u00a0the\u00a0H\u0159ensko abstraction area (Fig.\u00a02b<\/em>). By\u00a0contrast, the\u00a0decrease in\u00a0pH after the\u00a0fire was considerably greater in\u00a0the\u00a0Mezn\u00e1 abstraction area (from 6.6 to 6.0), falling well below the\u00a0minimum limit for drinking water specified in\u00a0Decree No. 252\/2004 Coll. [20].<\/p>\n Both before and after the\u00a0fire, groundwater from the\u00a0H\u0159ensko abstraction area had favourably low concentrations of\u00a0nitrates, nitrites, ammonium ions, phosphates, sulphates, chlorides, iron, manganese, toxic metals and selected bacteria, as well as a\u00a0wide range of\u00a0other parameters analysed.<\/p>\n When compared with the\u00a0requirements of\u00a0Decree No. 252\/2004 Coll. [20], the\u00a0water from the\u00a0H\u0159ensko abstraction area failed to meet the\u00a0same criteria both before and after the\u00a0fire, including pH below the\u00a0specified range and low calcium and magnesium concentrations, all of\u00a0which are of\u00a0natural origin. The\u00a0raw water is treated before being supplied to the\u00a0public water-supply system to ensure compliance with the\u00a0requirements of\u00a0the\u00a0Decree [20]. Water analyses show that the\u00a0fire did not cause any significant changes in\u00a0the\u00a0quality of\u00a0water from the\u00a0H\u0159ensko abstraction area.<\/p>\n Overall, the\u00a0differences in\u00a0the\u00a0quality of\u00a0groundwater from the\u00a0monitored sources incorporating captured springs before and after the\u00a0fire near H\u0159ensko were not significant, although some short-term adverse changes were observed. A\u00a0marked decrease in\u00a0groundwater pH after the\u00a0fire was recorded in\u00a0the\u00a0Mezn\u00e1 abstraction area, which, however, does not abstract water from springs.<\/p>\n Such\u00e1 B\u011bl\u00e1 3 spring<\/strong><\/span><\/p>\n The high-discharge Such\u00e1 B\u011bl\u00e1 3 spring (database number PP0552) has been monitored by CHMI over the long term. The spring has been modified for monitoring purposes, with both its discharge and water quality being monitored. Daily discharge data and the results of chemical and bacteriological analyses, generally conducted once or twice a year, are freely available for the study period (2019\u20132024) from the CHMI hydrological database (https:\/\/hydro.chmi.cz\/hpps).<\/p>\n The\u00a0discharge of\u00a0Such\u00e1 B\u011bl\u00e1 3 spring fluctuated slightly around a\u00a0mean\u00a0value of\u00a04.3 L\/s\u00a0between 2013 and 2024. During some periods, discharge increased to more than\u00a05 L\/s, while at other times it fell to just above 3 L\/s. The\u00a0only period in\u00a0which discharge fell below 3 L\/s\u00a0was during the\u00a0study year 2022 (Fig.\u00a03<\/em>). Marked decreases in\u00a0discharge had already occurred before the\u00a0fire, falling to 2.5 L\/s\u00a0in\u00a0February and subsequently to below 2 L\/s, with the\u00a0annual minimum occurring in\u00a0mid-April. Discharge then gradually increased to an\u00a0annual maximum of\u00a0approximately 4.8 L\/s\u00a0around the\u00a0end of\u00a0June and beginning of\u00a0July, followed by a\u00a0decrease to around 3 L\/s\u00a0in\u00a0mid-July. During the\u00a0fire in\u00a0late July, spring discharge increased from 3.18 L\/s\u00a0to almost 4 L\/s\u00a0before falling to 2.44\u00a0L\/s\u00a0in\u00a0early August, including a\u00a0very marked daily decrease of\u00a0as much as 0.9 L\/s. After the\u00a0fire, discharge increased to the\u00a0usual level of\u00a0around 4\u00a0L\/s\u00a0in\u00a0the\u00a0second half of\u00a0August, before declining to the\u00a0second-lowest annual value in\u00a0November and then returning to usual levels by the\u00a0end of\u00a0December. In\u00a0our opinion, the\u00a0daily discharge data recorded during the\u00a0fire should be interpreted with caution, particularly given the\u00a0possible sensitivity of\u00a0the\u00a0automatic measuring equipment to changes such as trees and branches falling into the\u00a0measuring structure or firefighting activities (e.g. the\u00a0use of\u00a0water). Nevertheless, it is apparent that the\u00a0more pronounced absolute changes in\u00a0spring discharge in\u00a02022 occurred not during the\u00a0fire itself, but in\u00a0the\u00a0periods before and after it.<\/p>\n Water quality was compared primarily using analytical results from October\u00a02021 (well before the\u00a0fire), May 2022 (the\u00a0last analysis before the\u00a0fire), October 2022 (the\u00a0first analysis after the\u00a0fire) and May 2024 (the\u00a0second analysis after the\u00a0fire).<\/p>\n The\u00a0spring water was weakly mineralised and slightly acidic (pH around 6) both before and after the\u00a0fire. Concentrations of\u00a0ammonium ions, nitrites, fluorides, dissolved organic carbon and phosphates, as well as acid neutralising capacity to pH 4.5 and base neutralising capacity to pH 8.3, remained consistently below the\u00a0laboratory detection limits both before and after the\u00a0fire. Similar levels before and after the\u00a0fire were recorded for bicarbonates (around 5 mg\/L), magnesium (approximately 1.7 mg\/L), potassium (around 2.5 mg\/L), sodium (approximately 2.8 mg\/L), carbonates and total hardness (around 0.26\u00a0mval\/L). Slight increases after the\u00a0fire were recorded in\u00a0nitrate concentrations (from 10\u00a0to 11 mg\/L), calcium (from 6.75 to 7.75 and subsequently 8.11 mg\/L), chlorides (to\u00a0above 4 mg\/L) and sulphates (from 17.9 to 18.5 mg\/L). CODMn increased from approximately 0.5 mg\/L before the\u00a0fire to 0.62 mg\/L in\u00a0October after the\u00a0fire, before decreasing to 0.54 mg\/L in\u00a02024.<\/p>\n No analysis of\u00a0metals and other elements is available for the\u00a0period shortly after the\u00a0fire. However, both before the\u00a0fire (October 2021 and May 2022) and in\u00a0May 2024, concentrations of\u00a0antimony, arsenic, boron, chromium, cadmium, cobalt, lithium, manganese, copper, molybdenum, nickel, lead, selenium, vanadium, zinc and iron were below the\u00a0laboratory detection limits after filtration. Similarly, anionic surfactants, the\u00a0pesticides analysed, chlorinated aliphatic hydrocarbons, simple aromatic hydrocarbons, chlorinated benzenes and other substances were below the\u00a0detection limits.<\/p>\n Comparison with the\u00a0drinking-water limits [20] showed no change in\u00a0the\u00a0assessment of\u00a0the\u00a0water quality of\u00a0Such\u00e1 B\u011bl\u00e1 3 spring before and after the\u00a0fire. The\u00a0water failed to meet the\u00a0requirements primarily because of\u00a0its low pH (below the\u00a0specified range), magnesium concentrations below the\u00a0minimum limit, and calcium and magnesium concentrations below the\u00a0recommended ranges. These deviations are of\u00a0natural origin.<\/p>\n Springs monitored in\u00a0the\u00a0Spring Areas project<\/strong><\/span><\/p>\n During fieldwork in\u00a0the\u00a0first half of\u00a02026, water parameters were measured at\u00a0eight major freely accessible springs in\u00a0the\u00a0study area that had been monitored previously. Samples for chemical analysis were collected from six of\u00a0these springs.<\/p>\n Recent analyses of\u00a0groundwater from the\u00a0five springs in\u00a0the\u00a0Such\u00e1 B\u011bl\u00e1 valley showed similar characteristics. The\u00a0pH was slightly acidic, ranging from 5.8 to 6.0, and water conductivity was low (8.7\u201310.0 mS\/m). Concentrations of\u00a0ammonium ions and nitrites were below the\u00a0analytical detection limit (< 0.05 mg\/L), as were concentrations of\u00a0phosphates and total phosphorus (< 0.025 mg\/L) and aluminium (< 0.005 mg\/L). Nitrate concentrations were only around 10 mg\/L, while calcium concentrations were around 8 mg\/L and magnesium around 1.6\u00a0mg\/L. The\u00a0groundwater at Nad Klep\u00e1\u010dem spring originates from a\u00a0higher level of\u00a0the\u00a0sandstone complex. Compared with the\u00a0springs in\u00a0the\u00a0Such\u00e1 B\u011bl\u00e1 valley, water sampled from the\u00a0smaller outlets of\u00a0Nad Klep\u00e1\u010dem spring area had higher conductivity (16.8 mS\/m) and higher calcium and magnesium concentrations, consistent with the\u00a0characteristics described above based on data from [22].<\/p>\n Comparison of\u00a0the\u00a0parameters of\u00a0emerging groundwater measured in\u00a0the\u00a0field using the\u00a0same method (in\u00a0each case, the\u00a0mean\u00a0of\u00a0at least three sets of\u00a0spot measurements taken at different times) in\u00a02012\u20132014 (well before the\u00a0fire) and in\u00a02026 (well after the\u00a0fire) showed the\u00a0following:<\/p>\n Measured discharge remained broadly similar between 2012\u20132014 and 2026 at four springs, including Such\u00e1 B\u011bl\u00e1 3 spring (approximately 3.9 L\/s) and U\u00a0Cik\u00e1nsk\u00e9ho smrku spring (approximately 0.22 L\/s). At two of\u00a0the\u00a0monitored springs, measured discharge decreased markedly, including Such\u00e1 B\u011bl\u00e1 2 spring (from 1.2 to 0.5 L\/s). By contrast, discharge increased markedly at two other monitored springs.<\/p>\n Mean\u00a0measured water conductivity increased slightly compared with 2012\u20132014. For example, at Such\u00e1 B\u011bl\u00e1 2 spring, it increased from a\u00a0mean\u00a0of\u00a07.75\u00a0to 9.0 mS\/m. The\u00a0higher-elevation springs in\u00a0the\u00a0area have higher water conductivity; for example, at U\u00a0Cik\u00e1nsk\u00e9ho smrku spring, the\u00a0mean\u00a0increased from 19.55 to 22.2 mS\/m. The\u00a0slight increase in\u00a0conductivity is probably unrelated to the\u00a0fire; data from more frequently monitored springs (e.g. Nad Klep\u00e1\u010dem) suggest that it is more likely part of\u00a0a\u00a0longer-term trend.<\/p>\n Overall, the\u00a0differences in\u00a0groundwater quality at the\u00a0monitored springs before and after the\u00a0fire were not considered significant.<\/p>\n A\u0161 study area<\/strong><\/span><\/p>\n To compare changes in\u00a0spring areas that are demonstrably occurring and measurable, but do not result from sudden disturbances, we selected two areas for which both older and more recent data are available. The\u00a0first study area, around the\u00a0town of\u00a0A\u0161, is located in\u00a0the\u00a0Cheb District of\u00a0the\u00a0Karlovy Vary Region. The\u00a0older, incomplete dataset available to us comes from spring-area mapping conducted in\u00a02009 as part of\u00a0a\u00a0restoration study commissioned by the\u00a0Nature Conservation Agency of\u00a0the\u00a0Czech Republic [11]. Some of\u00a0these spring areas were monitored again\u00a0under an\u00a0Interreg project in\u00a02020\u20132022. The\u00a0most recent data come from the\u00a0current Technology Agency of\u00a0the\u00a0Czech Republic project Methods for the\u00a0identification and stabilisation of\u00a0existing spring areas and restoration of\u00a0historical spring areas.<\/p>\n From a\u00a0hydrological perspective, the\u00a0springs investigated lie within\u00a0the\u00a0catchments of\u00a0the\u00a0Lu\u017en\u00ed, Pekelsk\u00fd, \u00dajezdsk\u00fd, Rokytnice and Byst\u0159ina streams. These watercourses flow across the\u00a0border into Germany, where, via the\u00a0S\u00fcdliche Regnitz and Schwesnitz, they form part of\u00a0the\u00a0Saale catchment and, ultimately, the\u00a0Elbe river basin.<\/p>\n Hydrogeologically, the\u00a0area forms part of\u00a0the\u00a0crystalline basement of\u00a0the\u00a0Bohemian\u00a0Massif, specifically Hydrogeological Region 6111 \u2013 Crystalline Basement of\u00a0the\u00a0Fichtel Mountains and the\u00a0western part of\u00a0the\u00a0Ore Mountains, and Groundwater Body 61110 of\u00a0the\u00a0same name [15]. The\u00a0area is characterised by fractured-rock aquifers, particularly in\u00a0phyllites and schists, together with intergranular aquifers in\u00a0the\u00a0overlying deposits [12].<\/p>\n Development of the springs in the A\u0161 area<\/strong><\/span><\/p>\n Historically, water management in the A\u0161 area was strongly associated with a dense network of springs and small streams that had been extensively modified by people for centuries. At the beginning of the 18th century, local watercourses powered around 20 mills, while by the end of the 19th century the landscape also contained networks of small retention ponds. In the floodplains of the B\u00edl\u00fd Hal\u0161trov and Rokytnice, farmers constructed sophisticated irrigation and drainage systems. A distinctive chapter in the area\u2019s history began with the expansion of the textile industry in the late 19th century, when local factory owners had special underground water-collection galleries constructed, remains of which can still be found around the villages of Mok\u0159iny, \u0160t\u00edtary and Vern\u00e9\u0159ov [23].<\/p>\n Around 1900, some of\u00a0the\u00a0springs, including those in\u00a0the\u00a0Pekelsk\u00fd stream catchment, were captured to supply drinking water to the\u00a0local population. This occurred mainly on the\u00a0German\u00a0side of\u00a0the\u00a0border, although Pekelsk\u00fd stream, located on the\u00a0Czech side, was also connected to the\u00a0system [12]. Today, this spring is captured in\u00a0a\u00a0concrete chamber with a\u00a0cast-iron cover, with no water emerging at the\u00a0surface (Fig.\u00a07<\/em>); all the\u00a0water is conveyed by pipes to Germany. At the\u00a0border section of\u00a0the\u00a0Pekelsk\u00fd stream, the\u00a0channel contains wetland vegetation but is completely dry in\u00a0the\u00a0spring area, with only isolated areas of\u00a0standing water farther downstream. On the\u00a0German\u00a0side of\u00a0the\u00a0border, springs in\u00a0the\u00a0headwaters of\u00a0the\u00a0Pekelsk\u00fd stream have been fenced off and fitted with chambers with rather more presentable stainless-steel covers. The\u00a0effect on both the\u00a0springs and the\u00a0Pekelsk\u00fd stream is similar, however: capture has eliminated surface discharge from the\u00a0springs, and no water from them now flows into the\u00a0former border stream.<\/p>\n Another major intervention affecting the structure of springs in the study area was land drainage, introduced to increase agricultural yields, particularly on arable land. Subsurface and surface drainage systems in this area date from the 1960s and 1970s [23] (Fig. 8<\/em>). Over the past 30 years in particular, arable land in this submontane area has increasingly been converted to meadows and pastures, and drainage has therefore largely lost its agricultural purpose. The landscape has undergone numerous changes since the drainage systems were constructed and now contains a mosaic of functional and degraded drainage systems [13]. On some level sites in the floodplains of small watercourses, particularly in the Rokytnice catchment, the old drainage systems are now completely non-functional. This has led to natural recovery and the return of these areas to near-natural wetlands or periodically flooded floodplains. At the same time, approximately one third of all spring areas mapped in the A\u0161 area on both sides of the border in 2020\u20132022 occur on land drained by systematic subsurface drainage. These are therefore so-called \u2018secondary spring areas\u2019 formed where blocked or damaged pipes cause drainage water to emerge at the surface (Fig. 9<\/em>). Perhaps surprisingly, these secondary spring areas can perform the same functions in the landscape as natural spring areas, although they may have certain disadvantages by comparison. These can include greater fluctuations in temperature over the course of the year, poorer and more variable water quality, or instability of the spring outlet itself. As blockages and other changes occur within damaged drainage pipes, the point at which water emerges may\u00a0shift from place to place. This has been observed, for example, at the\u00a0long-term monitored secondary spring area U\u00a0stru\u017eky (Luz 67) (Fig.\u00a09<\/em>), where the\u00a0manager of\u00a0the\u00a0Byst\u0159ina \u2013 Lu\u017en\u00ed stream National Nature Monument (Slavkovsk\u00fd les Protected Landscape Area) has confirmed that the\u00a0subsurface drainage system has been blocked for many years. Nevertheless, in\u00a0spring areas with a\u00a0disturbed water regime, even these habitats are important components of\u00a0the\u00a0heterogeneous landscape structure. They provide refugia for temporary macrozoobenthic species and other animals and increase biodiversity within\u00a0the\u00a0study area. Tab.\u00a01<\/em> presents basic information on the\u00a0nine monitored spring areas, including their principal characteristics and relationship to drainage.<\/p>\n By contrast, where parts of\u00a0the\u00a0subsurface drainage systems remain\u00a0functional, they continue to accelerate water runoff, reducing the\u00a0landscape\u2019s\u00a0capacity to retain\u00a0water and causing spring wetlands to dry out. In\u00a0some cases, drainage systems continue to serve a\u00a0useful purpose. For example, they are often retained around major linear infrastructure or infrastructure reconstructed in\u00a0the\u00a0recent past to prevent damage to these structures. In\u00a0protected areas, or in\u00a0catchments immediately adjacent to them, however, nature conservation interests should take precedence [24]. In\u00a0spring areas, the\u00a0quality of\u00a0drinking water and the\u00a0benefits of\u00a0retaining water in\u00a0the\u00a0landscape likewise outweigh the\u00a0benefits of\u00a0maintaining agricultural land on sites that would otherwise be naturally waterlogged. Nevertheless, although the\u00a0removal of\u00a0systematic drainage is desirable in\u00a0many places, it faces numerous administrative and practical obstacles, involves complex property ownership issues, is financially costly and requires not only project planning but also cooperation between several stakeholders.<\/span><\/p>\n In\u00a0the\u00a0forests of\u00a0this area, surface drainage channels were constructed in\u00a0the\u00a0past to drain\u00a0some spring areas and other wetlands locally (Fig.\u00a010<\/span><\/em>). They are most concentrated in\u00a0the\u00a0headwaters of\u00a0the\u00a0Lu\u017en\u00ed stream and in\u00a0the\u00a0Rokytnice catchment above Dol\u00ed\u0161ka pond. These are generally simple excavated ditches leading from small forest spring areas to the\u00a0nearest headwater stream, or sometimes into another ditch, forming a\u00a0more or less functional drainage network. Some ditches carry water throughout the\u00a0year, others only for part of\u00a0the\u00a0year, while some have now dried up completely. Straightened spring-fed channels lined with concrete slabs, such as those in\u00a0the\u00a0spring area of\u00a0the\u00a0\u00dajezdsk\u00fd stream, also contribute to accelerated runoff and reduced infiltration. The\u00a0present-day landscape of\u00a0the\u00a0A\u0161 area is also changing as small historical ponds and pools, often situated in\u00a0or along the\u00a0edges of\u00a0forests, gradually silt up and disappear naturally. These were constructed by the\u00a0original German\u00a0inhabitants of\u00a0the\u00a0area from the\u00a0beginning of\u00a0the\u00a0modern period, but particularly during the\u00a019th century. Interestingly, one reason for constructing these retention ponds was the\u00a0seasonal fluctuation in\u00a0streamflow during the\u00a0summer months, which had already been observed in\u00a0the\u00a0A\u0161 area at that time, and the\u00a0need to maintain\u00a0a\u00a0reliable water supply for mills, sawmills and the\u00a0first ironworks, and later for paper mills and the\u00a0textile industry [23].<\/span><\/p>\n Drainage of agricultural and forest land, whether through subsurface systems or surface drains, rapidly conveys water from spring areas into watercourses. In years with below-average precipitation, this contributes to the drying out of spring wetlands and, subsequently, small watercourses. In years with average or above-average precipitation, by contrast, accelerated runoff can contribute to flash flooding or lead to the formation of gullies and other forms of erosion. Since the designation of small-scale protected areas in the A\u0161 area from the 1990s onwards, numerous restoration projects of varying scales have been conducted and land management practices have improved [14]. The most recent example is the restoration of a straightened and incised\u00a0<\/span>section of\u00a0the\u00a0Lu\u017en\u00ed stream near Pastviny [25]. Most restoration measures, however, have focused solely on watercourses, while spring areas and small headwater channels have been neglected for various reasons.<\/span><\/p>\n Blanice and Zlat\u00fd streams catchment study area<\/strong><\/span><\/p>\n The\u00a0upper catchments of\u00a0the\u00a0Blanice and Zlat\u00fd stream in\u00a0the\u00a0\u0160umava region are important headwater areas. In\u00a0addition to well-known springs and wells that have historically been used by local people, hundreds of\u00a0natural and near-natural spring areas have been mapped here in\u00a0several phases associated with different projects from 2005 to the\u00a0present. From a\u00a0hydrogeological perspective, the\u00a0study area lies within\u00a0Hydrogeological Region 6310 \u2013 Crystalline Basement in\u00a0the\u00a0Upper Vltava and \u00dahlava Catchments, and Groundwater Body 63101 \u2013 Crystalline Basement in\u00a0the\u00a0Upper Vltava and \u00dahlava Catchments [15]. Hydrologically, some of\u00a0these spring areas lie within\u00a0the\u00a0catchments of\u00a0the\u00a0Sp\u00e1leneck\u00fd, Sn\u011b\u017eensk\u00fd and Tet\u0159\u00edv\u010d\u00ed streams and the\u00a0upper Blanice itself, while others lie within\u00a0the\u00a0Lu\u010dn\u00ed and Zlat\u00fd stream catchments. The\u00a0Zlat\u00fd stream is also a\u00a0tributary of\u00a0the\u00a0Blanice downstream of\u00a0Husinec Reservoir.<\/p>\n Development of\u00a0springs in\u00a0the\u00a0Blanice study area<\/strong><\/span><\/p>\n Historically, small watercourses flowing from springs in\u00a0the\u00a0K\u0159i\u0161\u0165anov, Arno\u0161tov and Boletice areas were used for gold panning from as early as the\u00a014th century, as was the\u00a0Blanice itself. Later, under Schwarzenberg administration, timber harvesting expanded considerably in\u00a0the\u00a0catchment. Transporting the\u00a0timber required modifications to the\u00a0hydrographic network, including the\u00a0construction of\u00a0log-driving reservoirs (splash dams), which were used to increase water levels artificially. Most have since disappeared, although some still exist, including Puch\u00e1rensk\u00fd pond. Springtime timber floating continued until the\u00a0beginning of\u00a0the\u00a020th century. As in\u00a0other areas, water was also used to power mills and ironworks.<\/p>\n This area is unique within\u00a0the\u00a0Czech Republic in\u00a0that, although agriculture and forestry were intensified here between 1970 and 1990, accompanied by efforts to drain\u00a0land extensively for agricultural use, it was relatively little affected by drainage schemes [26, 27] (Fig.\u00a011<\/em>). This may have been because the\u00a0area was not targeted until the\u00a0late 1980s. Systematic subsurface drainage systems were constructed, for example, in\u00a0the\u00a0catchments of\u00a0the\u00a0Vy\u0161ensk\u00fd, Zbytinsk\u00fd, Magdalensk\u00fd and Kuka\u010d\u010d\u00ed streams within\u00a0the\u00a0Blanice catchment, and in\u00a0the\u00a0Lu\u010dn\u00ed and Zlat\u00fd stream catchments in\u00a0the\u00a0neighbouring area. Some catchments remain\u00a0unaffected by large-scale drainage, including those of\u00a0the\u00a0Hornosn\u011b\u017eensk\u00fd, Tet\u0159\u00edv\u010d\u00ed and Sp\u00e1leneck\u00fd streams, as well as other small watercourses within\u00a0the\u00a0Boletice Military Training Area (Fig.\u00a012<\/em>). In\u00a0these catchments, therefore, the\u00a0capacity of\u00a0natural spring areas to retain\u00a0water in\u00a0the\u00a0landscape, maintain\u00a0local biodiversity and potentially provide other ecosystem services can\u00a0be readily compared, on a\u00a0larger scale than\u00a0in\u00a0the\u00a0A\u0161 region, with the\u00a0limited functionality of\u00a0secondary spring areas. Although, after 1990, arable land in\u00a0the\u00a0Blanice National Nature Monument and the\u00a0Prameni\u0161t\u011b Blanice National Nature Monument was converted to grassland and extensive management was introduced, significantly improving water quality [28], the\u00a0historical large-scale drainage itself is still regarded as an\u00a0irreversible adverse intervention, with the\u00a0deteriorating drainage systems continuing to have a\u00a0negative impact on the\u00a0landscape water regime.<\/p>\n For comparison, we identified the\u00a0basic characteristics of\u00a014 spring areas in\u00a0the\u00a0Blanice and Zlat\u00fd stream catchments and their relationship to drainage. An\u00a0overview is provided in\u00a0Tab.\u00a01<\/em>.<\/p>\n Comparison of\u00a0water quality in\u00a0natural and restored spring areas in\u00a0the\u00a0A\u0161 and Blanice study areas<\/strong><\/span><\/p>\n The\u00a0comparison of\u00a0changes in\u00a0water quality between natural and drained spring areas revealed several interesting patterns within\u00a0this limited sample. While some natural spring areas showed slight improvements and others slight deterioration, the\u00a0overall mean\u00a0score for all undrained spring areas (0.42 points) indicated that water quality at these outlets was relatively stable. No\u00a0differences were observed between the\u00a0catchments (A\u0161 versus Blanice\/Zlat\u00fd stream). The\u00a0scores for spring areas affected by drainage showed a\u00a0different pattern. No\u00a0deterioration was recorded; water quality at these outlets had either remained unchanged or improved since the\u00a0initial sampling in\u00a02005\u20132009 (mean\u00a0score 2.22 points). Relatively marked improvements in\u00a0two or three parameters were recorded, for example, at three spring areas in\u00a0the\u00a0A\u0161 area. Two of\u00a0these are secondary spring areas formed as a\u00a0result of\u00a0failures in\u00a0drainage systems (Luz 67 \u2013 U\u00a0stru\u017eky and Bys 04 \u2013 U\u00a0hl\u00e1sky), while the\u00a0third is drained by a\u00a0deepened ditch (Luz 23 \u2013 B\u00edl\u00fd v\u00fdv\u011br).<\/p>\n Of\u00a0the\u00a0three impacts investigated, spring capture for public drinking-water supply proved fatal to the\u00a0very existence of\u00a0surface spring outlets. This was the\u00a0case both in\u00a0the\u00a0H\u0159ensko study area (Pod Prav\u010dickou br\u00e1nou spring, Pytl\u016fv spring and the\u00a0main\u00a0outlet of\u00a0Nad Klep\u00e1\u010dem spring) and in\u00a0the\u00a0A\u0161 area (e.g. Pekelsk\u00fd stream spring). Intensive groundwater abstraction near H\u0159ensko also resulted in\u00a0the\u00a0disappearance of\u00a0Panensk\u00fd spring and a\u00a0decline in\u00a0the\u00a0discharge of\u00a0some of\u00a0the\u00a0surrounding springs.<\/p>\n By contrast, the\u00a0large-scale fire around H\u0159ensko did not result in\u00a0significant long-term changes in\u00a0either the\u00a0quantity or chemical composition of\u00a0water from the\u00a0major springs monitored within\u00a0this hydrogeological structure. Some short-term adverse changes were nevertheless observed. A\u00a0marked decrease in\u00a0groundwater pH after the\u00a0fire was recorded in\u00a0the\u00a0Mezn\u00e1 abstraction area, although this area does not abstract water from springs. Following the\u00a0deterioration of\u00a0some groundwater parameters after the\u00a0fire, individual hydrochemical parameters returned to their usual long-term levels within\u00a0several months to one year. The\u00a0forest fire therefore had only a\u00a0minor effect on groundwater quality, unlike some fires at industrial sites [19].<\/p>\n Land drainage and the\u00a0shortening and straightening of\u00a0watercourses in\u00a0the\u00a0A\u0161 area have accelerated runoff from the\u00a0catchments. Together with the\u00a0capture of\u00a0some springs, particularly in\u00a0the\u00a0Pekelsk\u00fd stream area, this causes significant problems during periods of\u00a0drought. Changes in\u00a0the\u00a0landscape water regime, combined with climate change, are resulting in\u00a0more frequent hydrological extremes \u2013 floods and droughts \u2013 which increasingly disrupt the\u00a0normal functioning of\u00a0human\u00a0society and also have a\u00a0major impact on aquatic and water-dependent organisms in\u00a0the\u00a0area. In\u00a0the\u00a0Blanice and Zlat\u00fd stream catchments, the\u00a0smaller extent of\u00a0land drainage means that, although flooding and the\u00a0drying out of\u00a0some surface springs also occur, there are currently no records of\u00a0watercourses drying out.<\/p>\n The comparison of water quality in the spring areas shows that water quality improved in those affected by drainage, particularly in terms of nitrogen compounds. In contrast to sudden disturbances, such as the fire around H\u0159ensko, gradual changes can therefore have a positive effect on water quality in spring areas. The observed improvement was probably largely due to changes in land management between 2005 and 2025 and the gradual natural recovery of areas affected by systematic drainage. All the secondary spring areas investigated are located either within small-scale protected areas or in their immediate vicinity. In the late 1990s and after 2000, most of the formerly intensively managed land in this area was converted to meadows or pastures, including the sites containing the monitored non-forest spring areas. While the effects of intensive management probably persisted during the first sampling period, when concentrations of nitrogen compounds were still elevated, by the second monitoring period these substances were below the detection limit in the secondary spring outlets. A second factor is the natural recovery of drained areas. As unmaintained subsurface drainage systems gradually deteriorate, secondary\u00a0springs increasingly acquire near-natural characteristics, while their water quality improves through natural self-purification processes.<\/p>\n The\u00a0gradual improvement in\u00a0water quality observed at secondary spring areas in\u00a0the\u00a0A\u0161 area and \u0160umava closely corresponds with the\u00a0growing need to protect these small aquatic habitats. Although these spring areas developed secondarily as a\u00a0result of\u00a0failures in\u00a0drainage systems, studies from other countries show that, despite their secondary origin, they can\u00a0provide key ecosystem services [29, 30]. Protecting and supporting these naturally recovering spring outlets is all the\u00a0more important because ongoing climate change is likely to expose springs to increasing anthropogenic pressure from widespread abstraction of\u00a0water resources, potentially leading to further irreversible degradation of\u00a0these sensitive habitats [6]. Assessment of\u00a0water chemistry alone, however, is only a\u00a0first step and one of\u00a0many criteria. A\u00a0comprehensive assessment of\u00a0the\u00a0success of\u00a0natural recovery in\u00a0spring areas must also take into account biological indicators, typically benthic macroinvertebrate and bryophyte communities [31]. Previous research indicates that the\u00a0ecological recovery of\u00a0wetland habitats may not proceed entirely linearly: the\u00a0diversity of\u00a0sensitive communities may temporarily decline or remain\u00a0unchanged immediately after changes in\u00a0habitat conditions before a\u00a0demonstrable increase occurs\u00a0[32\u201334]. For this reason, as part of\u00a0the\u00a0ongoing project No. SQ01010130, the\u00a0hydrochemical data presented here will be further evaluated in\u00a0conjunction with the\u00a0results of\u00a0detailed biological monitoring.<\/p>\n Springs contribute to biodiversity and help maintain\u00a0water availability near the\u00a0surface during dry periods. Their at least partial restoration would therefore be desirable, not only within\u00a0the\u00a0study areas.<\/p>\n For example, in Bohemian Switzerland National Park, where enhancing biodiversity and nature conservation should be a priority, some historical springs\u00a0could be restored at suitable sites. Restoration could make use of\u00a0overflow water from Nad Klep\u00e1\u010dem spring and potentially some of\u00a0the\u00a0water from Pod Prav\u010dickou br\u00e1nou and Pytl\u016fv springs, provided that this water is not essential for the\u00a0public water supply and that the\u00a0work is carried out in\u00a0accordance with the\u00a0enhanced groundwater protection measures applying in\u00a0the\u00a0area. Carefully returning spring water to the\u00a0surface would not only enhance biodiversity but could also reduce the\u00a0risk of\u00a0fire in\u00a0this sensitive area of\u00a0the\u00a0national park. Finally, the\u00a0heavily used hiking trail to Prav\u010dick\u00e1 br\u00e1na, which is currently dusty and runs alongside the\u00a0road, could once again\u00a0become a\u00a0more pleasant environment for both nature and the\u00a0many visitors to the\u00a0area.<\/p>\n Similarly, returning at least some of\u00a0the\u00a0water from Pekelsk\u00fd stream spring in\u00a0the\u00a0A\u0161 area to the\u00a0surface could restore the\u00a0border watercourse, improve natural conditions, enhance biodiversity, and provide some additional protection against fire on land on both sides of\u00a0the\u00a0border.<\/p>\n Springs are important landscape features that enhance local biodiversity and help maintain\u00a0water availability in\u00a0the\u00a0landscape during dry periods. Research into spring areas in\u00a0the\u00a0three study areas showed that the\u00a0most significant intervention is their direct technical capture for drinking-water supply, which results in\u00a0the\u00a0complete loss of\u00a0surface spring outlets. Large-scale land drainage also has a\u00a0significant impact, contributing to the\u00a0drying out of\u00a0small watercourses and wetlands during dry years and accelerating runoff from the\u00a0landscape. By contrast, some sudden disturbances, such as the\u00a0large-scale forest fire in\u00a0the\u00a0national park, have no significant long-term effect on either the\u00a0hydrochemical status or the\u00a0quantity of\u00a0groundwater in\u00a0deeper hydrogeological structures.<\/p>\n Longer-term monitoring confirmed that gradual changes have a\u00a0positive effect on water quality, particularly by reducing concentrations of\u00a0nitrogen compounds. Specifically, these changes include the\u00a0transition to extensive land management and the\u00a0natural recovery of\u00a0areas resulting from the\u00a0deterioration of\u00a0old drainage systems, leading to the\u00a0formation of\u00a0more or less stable secondary spring areas. For future landscape management, the\u00a0sensitive restoration of\u00a0historical springs by returning surplus or overflow water to the\u00a0surface would be desirable, for example in\u00a0Bohemian\u00a0Switzerland National Park and the\u00a0A\u0161 area. This would not only help enhance biodiversity but also provide more effective protection against fire in\u00a0sensitive areas.<\/p>\n The\u00a0work was funded by the\u00a0Technology Agency of\u00a0the\u00a0Czech Republic under the\u00a0Environment for Life 2 Programme, project No. SQ01010130. We would also like to thank the\u00a0Czech Hydrometeorological Institute (CHMI) for making its spring-monitoring data freely available, and the\u00a0Czech Geological Survey (Geofond) for access to its archive.<\/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.<\/span><\/p>\n","protected":false},"excerpt":{"rendered":" This article compares the condition of selected spring areas following sudden major disturbances with their previous condition, while also assessing long-term changes in drained and undrained spring areas. The impacts examined include major changes in groundwater abstraction for drinking-water supply, disturbances resulting from failures of drainage systems, and the effects of a large-scale forest fire. Three areas with contrasting hydrogeological characteristics were selected for the study. The results show that, while the abstraction of spring water for drinking-water supply has a fundamental effect on the very existence of springs, the large-scale forest fire did not significantly affect either the quality or quantity of groundwater. By contrast, gradual changes in agricultural management and the natural recovery of non-functioning drainage systems lead to the formation of secondary spring areas and a gradual improvement in the quality of the emerging water.<\/p>\n","protected":false},"author":8,"featured_media":40645,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":"","_members_access_role":[],"_members_access_error":""},"categories":[94,86,92],"tags":[3138,4246,308,2959,112,873],"coauthors":[331,4233],"class_list":["post-40646","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-current-issue","category-hydraulics-hydrology-and-hydrogeology","category-main","tag-drainage","tag-forest-fire","tag-groundwater","tag-restoration","tag-springs","tag-water-resources"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/posts\/40646","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=40646"}],"version-history":[{"count":13,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/posts\/40646\/revisions"}],"predecessor-version":[{"id":41088,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/posts\/40646\/revisions\/41088"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/media\/40645"}],"wp:attachment":[{"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/media?parent=40646"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/categories?post=40646"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/tags?post=40646"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/coauthors?post=40646"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}Tab. 2. Chemical water-quality parameters in selected spring areas during the two monitoring periods<\/h5>\n
<\/a>\n<\/a>\nRESULTS FOR THE SELECTED SPRING AREAS<\/h2>\n
Study area around H\u0159ensko<\/h3>\n
Evolution of\u00a0the\u00a0springs east of\u00a0H\u0159ensko<\/h3>\n
<\/h3>\n
<\/a><\/h3>\nFig. 1. Historical map showing the locations of springs around H\u0159ensko (source: [21])<\/h6>\n
<\/a>\nFig. 2a. Changes in pH of abstracted groundwater sources near H\u0159ensko before and after the fire (data source: [22])<\/h6>\n
<\/a>\nFig. 2b. Changes in conductivity of water from abstracted groundwater sources near\u00a0H\u0159ensko before and after the fire (data source: [22])<\/h6>\n
Current status of\u00a0springs in\u00a0the\u00a0H\u0159ensko area<\/h3>\n
<\/a>\nFig. 3. Fluctuation in the discharge of the Such\u00e1 B\u011bl\u00e1 3 spring in 2022 (data source: CHMI)<\/h6>\n
<\/a>\nFig. 4. Historical capture structure at Nad Klep\u00e1\u010dem spring near H\u0159ensko; condition in\u00a0February 2026 (photo: P. Eckhardt)<\/h6>\n
<\/a>\nFig. 5. Pod Prav\u010dickou br\u00e1nou spring site near H\u0159ensko, currently with no water emerging at the surface, status in May 2026 (photo: P. Eckhardt)<\/h6>\n
<\/a>\nFig. 6. Concrete well ring at U Cik\u00e1nsk\u00e9ho smrku spring in the H\u0159ensko study area, May\u00a02026 (photo: P. Eckhardt)<\/h6>\n
Potential effects of\u00a0the\u00a0fire on spring water quality<\/h3>\n
Evaluation of\u00a0data from the\u00a0Raw Water Database<\/h3>\n
<\/a>\nFig. 7. No water flows at the surface from the captured Pekelsk\u00fd stream spring near A\u0161, which is enclosed in a chamber (photo: P. Eckhardt)<\/h6>\n
<\/a>\nFig. 8. Historical aerial photograph showing the construction of drainage systems around the village of Pastviny in the A\u0161 area<\/h6>\n
<\/a>\nFig. 9. Luz 67 spring area formed by a drainage-system failure in a pasture; previously fenced off, the secondary spring outlet has since shifted, and the wetland area is now repeatedly damaged by livestock (A\u0161 area)<\/h6>\n
<\/a>\nFig. 10. One of the upper spring outlets of the Lu\u017en\u00ed stream, dry in 2025; drainage channels located 20\u201350 m from the outlet convey water towards the Lu\u017en\u00ed stream, affecting the discharge and overall condition of the spring areas (A\u0161 area)<\/h6>\n
<\/a>\nFig. 11. VMP08 spring area drained by a drainage channel (upper Blanice catchment area)<\/h6>\n
<\/a>\nFig. 12. Natural forest spring area M01A (upper Blanice catchment area)<\/h6>\n
DISCUSSION<\/h2>\n
CONCLUSION<\/h2>\n
Acknowledgements<\/h3>\n