Chapter 5 Spatial and temporal variability of water resources in the Polish Tatra Mountains Mirosław Żelazny1, Łukasz Pęksa2, Anna Bojarczuk1, Joanna Paulina Siwek1, Monika Sajdak1, Janusz Siwek1, Agnieszka Rajwa-Kuligiewicz1, Marta Pufelska1, Joanna Pociask-Karteczka1 1 Institute of Geography and Spatial Management, Jagiellonian University in Krakw, Poland, miroslaw.zelazny@uj.edu.pl 2Tatra Mountains National Park, Poland Abstract: Increasing human impact on the Tatra Mountains water resources exerted by local residents, tourists, and ski lobby prompted the Tatra National Park to install a modern monitoring network launched in 2008 (42 digital water gauges). The Tatra Mountains streams are characterized by a simple hydrologic regime with one flood season lasting from April to July. Up to 75% of the annual river run-off outflows from the Tatra Mountains catchments in the summer half-year season (May–October). The contribution of base flow is between 30% and 55% and it tends to be the highest in catchments with a relatively high carbonate rock content as well as in catchments with substantial thickness of fluvioglacial cover and moraine cover. The highest spring discharge is attributed to vaucluse springs (Chochołowskie, Goryczkowe, Lodowe Źródło, Olczyskie, Bystrej) which have recharge area beyond the topographic catchments. Two hydrographic regions have been identified in the Tatra National Park dependent on geology complex, which determines water circulation patterns as well as groundwater and surface water: the Tatra Mountains region (I) and flysch region (II). The Tatra Mountains region consists of three subregions: crystalline subregion (Ia), high mountain, karst, limestone, dolomite sub­region (Ib), and dolomite, shale, middle mountain subregion (Ic). Keywords: vaucluse springs, runoff, streams, hydrological regions Hydrological network The first water level gauges in streams in the Polish Tatra Mountains were operating in the 1960s (Białka, Cicha Woda) and 1970s (Poroniec, Potok Kościeliski, Czarny Dunajec). These gauges were installed by the national service i.e. the Institute of Meteorology and Water Resources. Subsequently, the scientific group led by Prof. Danuta Małecka from the University of Warsaw (Małecka 1984) has operated a network of gauges supervised by the Tatra National Park (TNP) to 1999. TNP staff have been monitoring water levels at 29 gauges ever since. The number of water level mea­surements varies seasonally from 4 to 15 per month. Human impact exerted by local residents and tourists on the Tatra Mountains water resources prompted TNP to install a modern monitoring network for both groundwater and surface water as part of its standard water monitoring work. This new network launched in 2008 includes 42 digital water gauges that measure water levels and temperatures at least once per hour (Fig. 5.1). An additional 11 monitoring sites were acti­vated in 2013 that gauge physical and chemical chara­cteristics of water in two river catchments: Bystra and Sucha Woda (Żelazny et al. 2013–2016). The results are viewable online. Furthermore, hydrologic monito­ring is performed in the Kościeliski Potok catchment, which is affected by deforestation caused by very strong, gusty winds and the bark beetle. This program has been in effect since 2014 and focused on the effect of deforestation on catchment water resources. In ad­dition to providing research material, these types of monitoring efforts help assess development projects in and around TNP, as well as assist in determining limits of water resources exploitation (Pęksa 2010, 2013; Pociask-Karteczka, Ed. 2013). River runoff regime The Tatra Mountains streams are characterized by a simple hydrologic regime with one flood season, with the exception of Poroniec stream. Flood season occurs from April to July. Summer half-year runoff volume (May–October) is between 60% and 75% of the total annual river runoff. The highest discharge is recorded in May and June, especially when snow­melt is accompanied by rainfall that helps accelerate the melting of snow. High discharge in the snowmelt season lasts long enough in many catchments that it becomes superimposed upon the higher summer dis­charge period, especially in July when it is caused by rainfall (Łajczak 1996; Pociask-Karteczka et al. 2010, 2018; Żelazny et al. 2015d, 2016). The low discharge period (passive period) usually lasts from August to March and sometimes is inter­rupted by somewhat higher discharge in autumn (Żelazny et al. 2016). The passive period is characte­rized by a partial stoppage in water circulation due to the accumulation of water in the snow cover (Łajczak 1996). The most variable discharge over the annual cycle is found in small streams in the crystalline part of the Tatra Mountains: Waksmundzki Potok, Rybi Potok, Roztoka, and Dolinczański Potok, as well as in larger streams such as Kościeliski Potok and Chochołowski Potok (Fig. 5.2). The streams above are characterized by extremely low runoff in autumn and winter – caused by lack of precipitation and a very low groundwater sup­ply due to poor groundwater aquifers in the crystalline rocks. The least variable discharge over the annual cyc-le is noted in streams within the sedimentary part of the Tatra Mountains within Low-Tatric and High-Tatric Units (Lejowy Potok, Małołącki Potok, Miętusi Potok, and Filipczański Potok streams), as well as in streams recharged by vaucluse springs (Bystra, Olczyski Potok, Sucha Woda). The discharge in these streams remains quite high even in autumn and winter. The higher the discharge of the spring, the greater the impact on the stream. This pattern may be observed in the Olczyski Potok stream where the stream regime and spring re­gime are virtually identical. However, water intakes for household use in Zakopane in the downstream section leads to large variability in discharge downstream of water intakes (Fig. 5.2; Żelazny et al. 2015d, 2016). Springs1 The mean density of springs in the Polish Tatra Moun­tains is 4.8 springs•km–2 and this value has been stable since the 1950s (Ziemońska 1966, Żelazny 2012). The density of spring reaches locally even 16 springs•km–2, as in the Morskie Oko lake catchment (Pociask-Karte­czka, Bochenek 2014). Most springs (85.2%) has a very low discharge – less than 1.0 dm3•s–1 (Photo. 5.1). The share of high discharge springs over 10 dm3•s–1 is very small at 1.5%, with five being vaucluse springs with discharge at more than 100 dm3•s–1. Vaucluse springs play the most significant role in the formation of water resources in the the Tatra Mountains. The dis­charge of five vaucluse springs is 1760 dm3•s–1, i.e. 65% of discharge of all springs in the Polish Tatra Moun- Research was carried out in the project N 30508132-2824 “Factors determining spatial variability and dynamics of wa-ter chemical composition in the Tatra National Park” fun­ded by the Ministry and Higher Education, carried out from 2007 to 2010 (supervised by Mirosław Żelazny). tains, which equals 2726 dm3•s–1 (Fig. 5.3). This is the equivalent of a specific runoff of 12.9 dm3•s–1•km–2 (i.e. 406 mm). The highest spring discharge is noted in the Bystra catchment – this equals 767 dm3•s–1. This is 28.1% of the total runoff of all springs in the Tatra Moun­tains (Figs. 5.4, 5.5). A higher spring discharge and a little lower share of spring water resources are not­ed in the following stream catchments: Chochołowski Potok (respectively 631.6 dm3•s–1 and 23.17%), Koście­liski Potok (respectively 503.4 dm3•s-1 and 18.47%), and Olczyski Potok (respectively 311.7 dm3•s–1 and 11.43%). The lowest discharge and lowest share of to-tal spring water resources are noted in the following stream catchments: Strążyski Potok, Potok ku Dziurze, and Spadowiec (respectively 12.8 dm3•s–1 and 0.47%), Małałołącki Potok, Potok za Bramką, Suchy Żleb (respectively 16.4 dm3•s-1 and 0.60%), Filipka (respec­tively 19.9 dm3•s-1 and 0.73%, Żelazny 2012). Fig. 5.4. Total spring discharge in the Tatra Mountains catchments (Żelazny 2012, modified). The largest spring water resources expressed as to-tal specific runoff of all springs occur in the follow­ing catchments: Olczyski Potok (67.9 dm3•s–1•km–2), somewhat smaller in Bystra (42.2 dm3•s–1•km–2), and many times smaller in the following catchments: Chochołowski Potok (18.3 dm3•s–1•km–2) and Kościel­iski Potok (13.6 dm3•s–1•km–2; Fig. 5.6). Specific runoff noted in the catchments built of sedimentary rocks (16.9 dm3•s–1•km–2) is almost four times higher than Fig. 5.6. Specific discharge of springs in the Tatra Moun­tains stream catchments (Żelazny 2012, modified). that in areas formed of crystalline rocks (4.9 dm3•s–1• •km–2; Fig. 5.7, Żelazny 2012). The largest spring water resources are in the area be-low 1200 m a.s.l., where the total spring runoff reaches at 2227 dm3•s–1, which equals 81.7% of all water resour- ces in the Polish Tatra Mountains (Fig. 5.8). There are three altitudinal belts with very high spring discharge rates: 950–1000 m a.s.l., 1050–1100 m a.s.l. and 1150– –1200 m a.s.l. The first belt features 61 springs deli- vering 972 dm3•s–1 (35.7% of the water resources of the Polish Tatra Mountains, Fig. 5.9). This belt includes two large vaucluse springs in the Tatra Mountains, Wywierzysko Chochołowskie, which yields 503 dm3•s–1 as well as Lodowe Źródło, which yields 313 dm3•s–1. The belt from 1050 and 1100 m a.s.l. features 86 springs with a total discharge of 336.8 dm3•s–1 (12.4% of the water resources of the Polish Tatra Mountains). This belt also includes the large vaucluse spring i.e. Wywierzysko Olczyskie (286 dm3•s–1). Discharge of Fig. 5.7. Specific discharge of springs in the Tatra Moun­tains valleys versus local geology (Żelazny 2012, modified). Fig. 5.8. Total spring discharge in selected altitudinal belts Fig. 5.9. Share of total spring discharge in total water re-in the Tatra Mountains (Żelazny 2012, modified). sources in selected altitudinal belts in the Tatra Mountains (Żelazny 2012, modified). 86 springs in the third belt equals 721.5 dm3•s–1 i.e. 26.5% of the total discharge of all springs in the Po­lish Tatra Mountains. This zone includes two vaucluse springs: Wywierzysko Goryczkowe (445 dm3•s–1) and Wywierzysko Bystrej Dolne (213 dm3•s–1), both in the Bystra catchment (Żelazny 2012). Water temperature regime Surface water and groundwater of the Tatra Moun­tains exhibit a great variability of thermal regimes, which results from the presence of streams, vaucluse springs influence as well as lakes (Żelazny et al. 2015b). Maximum water temperature in lakes and streams oc­cur frequently in August due to low water levels com­bined with increased atmospheric heating. In the case of vaucluse springs, maximum water temperatures are recorded in September. The highest stream water temperature (> 15°C) is observed in the Filipczański, Roztoka and Rybi. The average water temperature of streams is similar (4.9 ± 1.1°C). Minimum water tem­perature in streams occur frequently during the winter season, from December to March. In lakes, minima of water temperature usually occur between November and May. The highest minimum temperature are ob­served in karst springs and streams discharged by karst springs such as Bystra and Olczyski Potok (Żelazny et al. 2018). Water temperature time series are characterized by the presence of several cycles such as daily, weekly, 8–30 days, half-yearly, and annual, which appear in seven different patterns. The Tatra Mountains lakes display a pattern with 8–30 days, half-yearly and an­nual cycles (Fig. 5.10). Vaucluse springs are characte­rized by two patterns with a) exclusively low-frequency components in the form of annual cycle, and b) less frequently both, annual and half-year cycles (Fig. 5.10). Vaucluse springs are characterized by relatively low and stable water temperature over the year. Small tem­perature amplitudes or even their lack indicate deep water circulation. One such example is the Lodowe Źródło vaucluse spring with an average water tem­perature of 4°C and annual water temperature ampli­tude never exceeding 1°C. Streams represent four patterns with different com­plexity. Most often they are characterized by the lack of half-year cycle and the presence of daily and annual cy­cles (Fig. 5.10). The thermal regime of streams depends Fig. 5.11. Time series of water temperature in Chochołowski Potok stream (both upstream and downstream of water influx from the Wywierzysko Chochołowskie vaucluse springs) and Wywierzysko Chochołowskie vaucluse spring from January 2014 to September 2015 (Żelazny et al. 2018). on cold water supply from snowmelt and groundwater. The latter diminish amplitudes of water temperature fluctuations and dampen daily cycles of water tem­perature. The dampening of daily cycle occurs espe­cially in stream courses located directly below the in-flow of karstic groundwater and gradually disappears with the distance from the karst water inflow. More­over, vaucluse springs influence the energy budget of gaining streams (e.g. Chochołowski Potok, Kościeliski Potok, Bystra, Olczyski Potok and Sucha Woda) by cooling the stream water in summer and warming it in winter. The impact of groundwater on stream wa-ter temperature is clearly visible when comparing time series obtained from the Chochołowski Potok and the Chochołowskie vaucluse spring (Fig. 5.11). The daily cycle occurring in water temperature time series is associated with air temperature, which in mountain conditions depends on the elevation above sea level. The annual cycle of water temperature is the most common and results from the seasonal changes in the temperate climate zone. The semi-annual cycle is associated with the presence of ice cover in lakes, which in fact, has significantly shortened over the last century. The 8–32 day cycle may be related to short peri­ods of summer stratification that are preceded by equal­ly short periods of spring turnover (Żelazny et al. 2018). Surface water resources in The Tatra Mountains National Park in 2012 – 2014 Mean annual river runoff for 16 streams in the Ta­tra Mountains in the period 2012 – 2014 is 7.75 m3·s–1, which is the equivalent of 244.1 mln m3 of water, while mean low discharge equals 2.026 m3·s-1, which is the equivalent of 63.8 mln m3 of water (Tab. 5.1, Żelazny et al. 2013, 2014). High specific runoff (> 50 dm3•s–1•km–2) occurs in catchments built of the High-Tatric units (crystalline part) including the catchments of the following streams: Pyszniański Potok (64.1 dm3•s–1•km–2), Rybi Potok (60.4 dm3•s–1•km–2), Wyżni Chochołowski Potok (55.7 dm3•s–1•km–2), Dolinczański Potok (54.7 dm3•s–1•km–2), and Goryczkowy Potok (51.8 dm3•s–1•km–2, Fig. 5.12). Specific runoff is lower in some of these catchments due to local geomorphologic and hydrogeologic con­ditions, as in the case of the following streams: Roztoka (42.5 dm3•s–1•km–2), Jarząbczy Potok (39.6 dm3•s–1•km–2), Waksmundzki Potok (39.0 dm3•s–1•km–2). Discharge in Jarząbczy Potok stream is reduced by water intake ge- nerated by a hydroelectric plant located near the tour­ist lodge in the Chochołowski Potok catchment. A ri- ver beds of the Roztoka and Waksmundzki Potok “lose” water, which is why it is reasonable to presume that the total water resources of these catchments are much larger. The analysis of water conditions appears that runoff in the crystalline part of the Tatra Moun- Table 5.1. Water resources characteristisc in the Polish Tatra Mountains in 2012 – 2014 (Żelazny et al. 2013, 2014, 2016). The Tatra Mountains Characteristic (179.5 km 2) mean low s-1] Runoff [m 3 • 7.75 2.03 –1 •–2] Specific runoff [dm 3 • s km 43.2 11.3 Runoff index [mm] 1360 356 Volume [milion m 3] 244.1 63.8 tains is strongly divided into two parts: (1) Western Tatra Mountains, (2) High (eastern) Tatra Mountains. The western part is characterized by higher speci­fic runoff (53.4 dm3•s–1•km–2) than the eastern part (48.4dm3•s–1•km–2). However, the High Tatra Moun­tains are characterized by a larger total amount of wa-ter resources than the Western Tatra Mountains due to their larger surface area (29.2 km2 and 16 km2, respec­tively, Tab. 5.2; Żelazny 2015e). Table 5.2. Stream water resources characteristisc in the High-Tatras units of the Tatra Mountains in 2012–2014 (Żelazny et al. 2013, 2014, 2016). Characteristic High Tatra Mountains (29.2 km2) West Tatra Mountains (16 km2) mean low mean low Specific runoff [dm3•s–1•km–2] 48.4 9.4 53.4 11.0 Runoff index [mm] 1524 297 1681 245 Volume [milion m3] 44.5 8.6 26.9 5.5 The Tatra Mountains built of Sub-Tatric Units are characterized by lower water resources and this in­cludes catchments such as those of the following streams: Małołącki Potok (18.6 dm3•s–1•km–2), Filip­czański Potok (23.9 dm3•s–1•km–2), Biały (26.1 dm3•s–1• •km–2), Lejowy Potok (27.7 dm3•s-1•km-2), Strążyski Po­tok (29.1 dm3•s-1•km-2), Sucha Woda (20.4 dm3•s–1•km–2), Poroniec (43.7 dm3•s–1•km–2, Fig. 5.12). On the other hand, very high resources are found in catchments with large vaucluse springs having recharge area be­yond the topographic catchments, as shown by Małec­ka (1993). Examples of catchments of high specific runoff include the following: – Olczyski Potok (92.9 dm3•s–1•km–2 ) – recharge area in the Pańszczyca catchment (crystalline part), – Bystra (75.1 dm3•s–1•km–2) – recharge area in the Su­cha Woda catchment (crystalline part), – Kościeliski Potok (57.1 dm3•s–1•km–2) – recharge area in the Czerwone Wierchy massif (sedimentary part), – Potok u Lisów (86.1 dm3•s–1•km–2), – Potok spod Wołoszyna (73.7 dm3•s–1•km–2). Hydrology of the Bystra stream catchment The Bystra stream is a tributary of Zakopianka – a right-hand tributary of Białka flowing towards the Dunajec river – the right-hand tributary of the Vis­tula river. The Bystra stream catchment is located on the border between the Western and the High Ta­tra Mountains (Photo. 5.2). The highest point of the area is the Kondracka Kopa (2004 m a.s.l.). The water level gauge is located at the elevation of 955 m a.s.l. The average slope is 26.8°. The Bystra stream catchment is characterized by a particularly complex geological and tectonic structure. The northern part of the catch­ment is built of sedimentary rocks of the Sub-Tatric Units, which include dolomite, limestone, and shale (Bac-Moszaszwili et al. 1979, Piotrowska et al. 2015). The southern part is built of crystalline rocks and is divided into western and eastern parts. The western part (with Kondratowa Hala clearing) has no perma­nent watercourses, small number of springs of low discharge reaching 0.5 dm3•s–1. The eastern part (with the Goryczkowy Potok stream) features relatively high discharge springs reaching 10.0 dm3•s–1 and a perma­nent watercourse that disappears in a ponor in the area of the Hala Goryczkowa clearing (Fig. 5.13). The south­ern and middle parts of the catchment were strongly transformed by glaciers, which led to the formation of glacier cirques and thick moraine formations (Kli­maszewski 1988). Moreover, there are numerous karst phenomena such as ponors, caves, and vaucluse springs in the middle part of the catchment (Barczyk 2008; Dąbrowski, Głazek 1968; Małecka 1997; Wit-Jóźwik, Ziemońska 1960a; Wrzosek 1933). Research on the wa-ter balance in the Tatra Mountains has shown that the runoff-rainfall ratio for the Bystra catchment is 1.04, 55 Fig. 5.12. Water resources expressed in specific runoff in the Polish Tatra Mountains in 2013 (Barczyk 2008; Dąbrowski, Głazek 1968; Gromadzka et al. 2015; Łajczak 1996; Małecka 1984; Pęksa 2010; Żelazny 2012; Żelazny et al. 2013, 2014, 2016; modified). which means that river runoff exceeds atmospheric precipitation (Małecka 1993, 1996). As it was men­tioned before, the Bystra catchment is the second catchment, following the Olczyski Potok catchment, in terms of water resources in the Tatra Mountains. Its middle part includes one of the largest springs in Poland – Wywierzysko Goryczkowe vaucluse spring – with a discharge of about 700 dm3·s–1 (Małecka 1997). The recharge area of Wywierzysko Goryczkowe vau­cluse spring is located beyond its topographic catch­ment – in the Sucha Woda catchment as shown in the 1960s by Dąbrowski and Głazek (1968) who used the dye-tracing technique. The east slopes of the Giewont massif feature two vaucluse springs: Wywierzysko Bystrej Dolne and Wy­wierzysko Bystrej Górne (Photo. 5.3). The Wywierzysko Bystrej Górne vaucluse spring is an intermittent and virtually disappears in the winter, while the Wywierzy-sko Bystrej Dolne vaucluse spring is permanent (Bar­czyk 2008, Małecka 1997; Wit, Ziemońska 1960a, b). The total discharge of both springs is 321 dm3·s–1. According to Małecka (1997) and Barczyk (2008), the most likely recharge area of both springs is the Giewont massif and perhaps the eastern parts of the Czerwone Wierchy massif. However contemporary hydrochemical research has shown that the most like­ly recharge area is located in the Sucha Kondracka and Sucha Kondratowa subcatchments, because the total dissolved solids were not enough higher if the recharge area were located on the Giewont massif (Gromadzka et al. 2015). A third vaucluse spring appears south of the Wywierzysko Bystrej Górne vaucluse spring fol­lowing heavy precipitation every dozen years or so. Anthropogenic pressure to use water in Bystra catchment for artificial snowing is significant, which makes it important to identify the amount of water re­sources available during wintertime low flow periods. Detailed studies of this problem have been conduc­ted since 2013 and especial hydrographic network was established there. The highest, crystalline part of the Bystra catchment is drained by two streams: Potok Za­kosy (5.5 dm3·s–1) and the stream at the Goryczkowa Rówień (1.9 dm3·s–1). The two streams then merge to form Goryczkowy Potok stream (Fig. 5.14), although its discharge is much smaller than that expected from the sum of the discharge values for the two contribut­ing streams: 2.3 dm3·s–1. This is explained by the dis­appearance of water from Goryczkowy Potok stream into thick moraine formations and ponors. A complete disappearance of water in Goryczkowy Potok stream in fact was observed already in the 1950s in the down-stream section of the catchment. More recent research has shown that water loss in the channel occurs in an upper section of the catchment – higher than what had been described by Wit and Ziemońska (1960a, b). Discharge of the Bystra stream increases abruptly in the middle part of the catchment due inflow of water from the Wywierzysko Bystrej Górne, Wywierzysko Bystrej Dolne, and Goryczkowe Wywierzysko vaucluse springs and reaches 996 dm3·s–1 (2010-2014). This is the equivalent of a specific runoff of 126.4 dm3·s–1·km–2, which gives it most likely the largest specific runoff in Poland (Tables 5.3, 5.4). There have been observed a regular increase of the Bystra stream discharge in May in the period 2010– –2015. The most regular pattern of minimum dis­charge has been observed in the winter time – Janu­ary or February (Fig. 5.15). The longest low discharge period in 2010–2014 lasted from September 2011 to March 2012 (Fig. 5.16). However, the lowest discharge (244 dm3·s–1) was noted during the year 2014 winter Table 5.3. Characteristics of the discharge of the Bystra stream below the vaucluse springs (Goryczkowe, Bystrej Górne, Bystrej Dolne) in the period 2010–2014 (Żelazny et al. 2015a). Year Discharge Q [dm3·s–1] Qmean Qmin Qmax Q25% Q50% Q75% Q10% Q90% 2010 1119 291 3781 650 858 1448 469 2170 2011 803 291 2433 469 653 1088 379 1511 2012 875 335 2472 423 778 990 423 1774 2013 1049 423 2956 614 842 1314 514 1954 2014 1136 244 5982 469 911 1663 379 2105 Mean 996 317 3525 525 808 1301 433 1903 Table 5.4. Characteristics of specific runoff of the Bystra stream catchment below the vaucluse springs (Goryczkowe, Bystrej Górne, Bystrej Dolne) in the period 2010–2014 (Żelazny et al. 2015a). Year Specific runoff q [dm3·s–1·km–2] qmean qmin qmax q25% q50% q75% q10% q90% 2010 142.0 36.9 479.8 82.5 108.9 183.8 59.5 275.4 2011 101.9 36.9 308.8 59.5 82.9 138.1 48.1 191.8 2012 111.0 42.5 313.7 53.7 98.7 125.6 53.7 225.1 2013 133.1 53.7 375.1 77.9 106.9 166.8 65.2 248.0 2014 144.2 31.0 759.1 59.5 115.6 211.0 48.1 267.1 Mean 126.4 40.2 447.3 66.6 102.6 165.1 54.9 241.5 low flow period (specific discharge equivalent is 31 dm3•s–1•km–2; Tables 5.3, 5.4). The human impact in the Bystra stream catchment increases downstream. As a result, discharge of the Bystra stream declines significantly (by even 96%, Fig. 5.14). A regular daily cycle of water use may be observed – less water is used at night leading to higher discharge at night time, and more water is used in daytime, especially around noon and in the after­noon hours (Fig. 5.17). The discharge of the Bystra stream increases to 71 dm3·s–1 in Kuźnice where it runs in a stone-laden channel (while the discharge of the Bystra stream rechaes 278 dm3·s–1 in the upper course). There are also three spring water intakes at Kuźnice in the lower part of the Bystra catchment (Gonciska, Jedle, and Kórnickie). The Bystra stream divides in Kuźnice down of the dam build of grani­tic rocks: Bystra flows down in a stony channel and another creek – known in Zakopane as Foluszowy Potok – flows partly in a moraine material and stony channel. Hydrologic regions Two hydrographic regions have been identified in Ta­tra National Park based on local geology, which de­termines water circulation patterns as well as ground­water and surface water supply levels in the Park (Fig. 5.18): – the Tatra Mountains region (I), – flysch region (II). The Tatra Mountains region consists of three sub­regions (Ziemońska 1966, Siwek et al. 2015, Żelazny et al. 2015b): – crystalline subregion (Ia), – high mountain, karst, limestone, dolomite region (Ib), – dolomite, shale, middle mountain region (Ic). Crystalline subregion (Ia) is characterized by shal­low water circulation and high water retention across the valley bottom in moraine formations and glacial lakes. Due to its high elevation above sea level, the region receives the highest amounts of precipitation, mostly in the form of snow. High mountain, karst, limestone, dolomite region (Ib), with developed karst system allows for substantial water retention and mi­gration of groundwater as well as the occurrence of large groundwater aquifers. The significant discre­pancy in size of the hydrogeological and topograph­ical catchment is very common characteristic for vaucluse karst springs located in this region. Ponors, dry river channels, periodic and intermittent streams are typical here. The region at the lowest altitude, is the dolomite and shale region (Ic), which is characte­rized by shallow water circulation, a well-developed Fig. 5.15. Mean monthly discharge of Bystra downstream of the vaucluse springs in the period 2010 – 2014 (Żelazny et al. 2015a, modified). Fig. 5.16. Daily discharge of Bystra downstream of the vaucluse springs in the period 2010 – 2014 (Żelazny et al. 2015a). Fig. 5.17. Diurnal changes in discharge of Bystra stream at Kuźnice gauging station from December 2014 to January 2015 (Żelazny et al. 2015a). river network, and a presence of numerous springs of low discharge. The flysch region (II) is located across the Tatra Mountains foreland, and is primarily formed of sand­stone and shale. It is a hydro-geologically distinct en­vironment, but recharge areas of flysch formations also include parts of the Tatra Mountains region. One of the key parameters indicating water re­sources level is the contribution of base flow in river runoff. Catchments characterized by a high base flow tend to be particularly valuable for water use purpo­ses, as they are less sensitive to seasonal changes in hydro-meteorological conditions. The contribution of base flow in the Tatra Mountains river runoff is between 30% and 55% and it tends to be the highest in catchments with a relatively high carbonate rock content (subregion Ib) as well as in catchments with substantial thickness of fluvioglacial cover and mo­raine cover including gravel and sand (Żelazny et al. 2015c).