E3S Web of Conferences 40, 02005 (2018) https://doi.org/10.1051/e3sconf/20184002005 River Flow 2018
Impacts of gravel-bed rivers transformation on fluvial ecosystems and human society: Examples from the Czech flysch Carpathians
Václav Škarpich1,*, Miroslav Kubín2, Tomáš Galia1, Stanislav Ruman1, and Jan Hradecký1 1Department of Physical Geography and Geoecology, Faculty of Science, University of Ostrava, Chittussiho 10, 71000 Ostrava, Czech Republic 2Protected Landscape Area Administration Beskydy, Nádražní 36 756 61 Rožnov pod Radhoštěm, Czech Republic
Abstract. In the last centuries, gravel-bed rivers in developed countries have undergone rapid changes in channel morphology. The most serious problems include channel transformation related to progressive channel narrowing, incision or bed sediment coarsening. The main reasons for transformations were connected to the human interventions, which affected water and sediment fluxes in the basins. This paper summarizes contemporary research activities focused on these negative effects of channel transformations in the Czech flysch Carpathian rivers (the Morávka, the Olše and the Ostravice draining the highest mountainous areas of the Beskydy Mts). As the result of channel transformations, progressive changes in fluvial ecosystem were observed. The initial phytosociological survey demonstrates a higher biodiversity in the floodplain along the preserved multi-thread river channel than along the deeply incised channel in the Morávka River basin. Our observations of aquatic communities demonstrated that the channel transformation connected with incision and coarsening of bed sediments negatively affected fish or lamprey populations in the studied rivers. Regulation, damming and incision of channels caused changes of hydrological regime linked with gradual drying of floodplain. Additionally, a large set of hydraulic structures, bridges or weirs were affected by undercutting and progressive destruction in the Ostravice, Olše and Morávka River basins, which is assigned to increased transport capacity of regulated channels together with decreased sediment supply from mountainous parts.
1. Introduction Gravel-bed rivers are defined as channel reaches with coarse sediment material on bed and banks and typically with large discharge variation, which affects sediment material movement in river network [1, 2]. Their occurrence is characteristic for montane and upland valley and mountain foreland area [3]. During the 20th century, the most serious problems of gravel-bed rivers transformation were widely studied around the globe [4, 5,
* Corresponding author: [email protected]
© The Authors, published by EDP Sciences. This is an open access article distributed under the terms of the Creative Commons Attribution License 4.0 (http://creativecommons.org/licenses/by/4.0/). E3S Web of Conferences 40, 02005 (2018) https://doi.org/10.1051/e3sconf/20184002005 River Flow 2018
he re earche cu ed n he iden i ica i n channe pa ern chan e hich ere acc panied b pr re i e channe narr in ri er bed inci i n r bed edi en c ar enin he ain rea n r he e chan e ere re a ed he edi en e en and i pedi en bu er barrier and b anke edi en e en in he u ia e b ca ed di c nnec i i ie i i ar pa ern channe chan e a a rec rded in he ri er drainin he ech par ch arpa hian hi paper pre en channe ran r a i n in a ider c n e ec e chan e and a er re urce ruc ure nu ber de ri en a eedback e ec ran r a i n he ech arpa hian ri er ha e been iden i ied e decrea in bi di er i de ruc i n i h and a pre habi a and cape dr in r de ruc i n an ade c n ruc i n a eir r brid e
2. Channel transformations and their effect on riverine ecosystems in the Czech Carpathian rivers ran r a i n ri er drainin he ech par arpa hian ere udied in he Ostravice, Morávka [8, 9, 10] and Olše [11] River basins. The contemporary state of rivers in he ech arpa hian ha been par icu ar a ec ed b hu an i pac ar in a he be innin he h cen ur durin he ca ed a achian c ni a i n he un ain u area en i e de re a i n c ear pa ure and and upp he de and r d di rup ed he ri ina a e channe he de re a i n and pr bab e ec i e ce e in en i ied edi en upp he ri er ne rk and ub e uen de e p en u i hread channe reache hich had been de e pin r he end he a acia peri d he chan e in ba in ana e en re a ed he chan e in hu an i e e r he be innin he h cen ur br u h ne a re a i n and hu an ini ia i n de ici in edi en upp r u i hread reache ndu ria de e p en re a ed increa ed de and r ar e a un a er c n ruc i n a e da eir hich cau ed he acce era i n he ab e en i ned pr ce e and he b cka e edi en ran p r n re u channe ere ran r ed r ri ina u i hread ri er pa ern i h in en i e edi en ran p r in e hread ri er pa ern en inci ed in he bedr ck ec channe ran r a i n n ri erine p an ec e a udied in he Morávka River basin [12]. The research was conducted with phytosociological survey of plant species composition from phytosociological relevés in the transversal profiles in he dp ain he ere c nduc ed in he dp ain i h i he in e hread bedr ck inci ed channe and ii he pre er ed u i hread channe he hann n iener and i p n indice bi di er i r he ana i pecie di ribu i n a e a ua ed n he c n e he i p r ance e e a i n re p n e channe dp ain c ndi i n he in en ir n en a ariab e ere e ec ed a re p n e ariab e r he ana i phytosociological relevé distance from the main channel i h in a er and re a i e elevation of a phytosociological relevé from the water level in the channel. The channel e ec n he riparian e e a i n c ndi i n a e a ua ed b u in u i aria e da a ana i de rended c rre p ndence ana i and redundanc ana i he re u h ed ha di eren p an habi a c ndi i n ccur in he inci ed channe reach and in he u i hread channe reach he ana i he hann n iener and i p n indice de n ra ed a ar er arie habi a c ndi i n in he dp ain area a n he u i hread ri er channe ee i u i aria e ana i c n ir ed ha inci i n pr ce e channe cau e a re rapid chan e in he p an c uni c p i i n i h increa in di ance r he ain channe hi u e ha r und a er c ndi i n c u d be a ec ed b he ri er inci i n hr u h he radua re a i e inkin a er e e in he ri er channe – re a i e he dp ain e e
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he re earche cu ed n he iden i ica i n channe pa ern chan e hich ere acc panied b pr re i e channe narr in ri er bed inci i n r bed edi en c ar enin he ain rea n r he e chan e ere re a ed he edi en e en and i pedi en bu er barrier and b anke edi en e en in he u ia e b ca ed di c nnec i i ie i i ar pa ern channe chan e a a rec rded in he ri er drainin he ech par ch arpa hian hi paper pre en channe ran r a i n in a ider c n e ec e chan e and a er re urce ruc ure nu ber de ri en a eedback e ec ran r a i n he ech arpa hian ri er ha e been iden i ied e decrea in bi di er i de ruc i n i h and a pre habi a and cape dr in r de ruc i n an ade c n ruc i n a eir r brid e
2. Channel transformations and their effect on riverine ecosystems in the Czech Carpathian rivers Fig. 1. – hannon iener inde and – Simpson's index of phytosociological relevés in the study area of the Morávka River floodplain (reprinted from [12]). ran r a i n ri er drainin he ech par arpa hian ere udied in he n the last several decades, the flysch ech arpathian rivers showed changes of Ostravice, Morávka [8, 9, 10] and Olše [11] River basins. The contemporary state of rivers hydrological conditions. Originally, they were characterised by high discharge variation, in he ech arpa hian ha been par icu ar a ec ed b hu an i pac ar in a he e.g. for the Ostravice River it was appro imately 1 2,000 between minimal and ma imal be innin he h cen ur durin he ca ed a achian c ni a i n he discharges and for the Morávka River 1:4,000 [15]. Constructions of the Šance (built on the un ain u area en i e de re a i n c ear pa ure and and upp he de and r Ostravice River in years 19 1969), the Morávka (built on the Morávka River in years d di rup ed he ri ina a e channe he de re a i n and pr bab e ec 19 1 1967) valley dams and partially the Morávka Žermanice Canal (in the Morávka River i e ce e in en i ied edi en upp he ri er ne rk and ub e uen basin) which diverts the water flow into the neighbouring Lučina River basin, caused the de e p en u i hread channe reache hich had been de e pin r he end decrease in the fre uency and magnitude of flood discharges see fig. 2 . imilarly, the he a acia peri d he chan e in ba in ana e en re a ed he chan e in analysis of groundwater detected hydrological conditions changes of the floodplain which hu an i e e r he be innin he h cen ur br u h ne a re a i n and hu is gradually drying out in the Morávka River basin (see fig. 2A) [12]. an ini ia i n de ici in edi en upp r u i hread reache ndu ria de e p en re a ed increa ed de and r ar e a un a er c n ruc i n a e da eir hich cau ed he acce era i n he ab e en i ned pr ce e and he b cka e edi en ran p r n re u channe ere ran r ed r ri ina u i hread ri er pa ern i h in en i e edi en ran p r in e hread ri er pa ern en inci ed in he bedr ck ec channe ran r a i n n ri erine p an ec e a udied in he Morávka River basin [12]. The research was conducted with phytosociological survey of plant species composition from phytosociological relevés in the transversal profiles in he dp ain he ere c nduc ed in he dp ain i h i he in e hread bedr ck inci ed channe and ii he pre er ed u i hread channe he hann n iener and i p n indice bi di er i r he ana i pecie di ribu i n a e a ua ed n he c n e he i p r ance e e a i n re p n e channe dp ain c ndi i n he in en ir n en a ariab e ere e ec ed a re p n e ariab e r he ana i Fig. 2. – Ma imum annual groundwater levels in the years 19 –2008 at the O 009 – Nižní phytosociological relevé distance from the main channel i h in a er and re a i e hoty drill well gauging station, cross symbols ma imum annual groundwater levels, solid line elevation of a phytosociological relevé from the water level in the channel. The channel five point running mean, dashed line linear trend – umulative distribution of annual e ec n he riparian e e a i n c ndi i n a e a ua ed b u in u i aria e da a maximum discharge of the Morávka River at the Raškovice gauging station; cross symbols (+) = ana i de rended c rre p ndence ana i and redundanc ana i cumulative distribution of annual ma imum discharge reprinted from [9, 12] data source ech ydrometeorological nstitute . he re u h ed ha di eren p an habi a c ndi i n ccur in he inci ed channe reach and in he u i hread channe reach he ana i he hann n iener and i p n indice de n ra ed a ar er arie habi a c ndi i n in he dp ain area 3. Fish and lamprey communities affected by channel a n he u i hread ri er channe ee i u i aria e ana i c n ir ed ha transformation and related hungry water effect inci i n pr ce e channe cau e a re rapid chan e in he p an c uni c p i i n i h increa in di ance r he ain channe hi u e ha The channel transformations of the gravel bed rivers within ech part of arpathians r und a er c ndi i n c u d be a ec ed b he ri er inci i n hr u h he radua re a i e resulted in changes of flow hydraulics and it brought a new set of boundary conditions for inkin a er e e in he ri er channe – re a i e he dp ain e e erosion, transport and deposition processes [10, 11]. enerally, increased flow velocity in
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transformed channels and hungry ater effect related ith coarsening of bed sediments of the studied rivers affected habitat for fish communities [16]. or example, rook lamprey (Lampetra planeri), uropean bullhead (Cottus gobio) and Alpine bullhead (Cottus poecilopus) belong to protected species and they are listed in the Red ist of threatened species of vertebrates of the C ech Republic [17]. ro n trout (Salmo trutta) represents a typical fish for C ech fresh aters and it is from the fishing industry focus economically important fish. he young larvae of rook lampreys re uire river reaches ith slo running flo and clay sand bed substrate ( ith depth about 0 cm) [1 ]. n contrast, adult rook lampreys (like as ro n trouts) spa n in shallo fast running flo gravel close to the soft sediment bed reaches. he sand bed substrate depth about 25 cm armoured gravels ( ith mean diameter of particle si es from 5 to 20 cm) and flo velocity to 0. m s is typical for bullheads [19]. n fact, complexity of habitats [20], variability of flo velocity of channel reaches [21] and sufficient refugium availability [22] is necessary for natural development of these fish lamprey species. ased on the preliminary results of research, habitats of above mentioned fish and lamprey communities were highly degraded in some channel reaches of the Morávka River (see fig. ). he main reasons for degradation of habitats ere incision and narro ing of river reaches, absence of appropriate finer (clay and sand) bed deposits hich are armouring gravel particles on bed and increased flo velocity in channels. heir number decreased in these reaches. n contrast, numerously and age balanced populations of lamprey and fish species ere observed in river reaches ith multi thread channel pattern ith gravel bed armoured by fine sediments and lo flo velocities.
Fig. 3. A ravels and armouring fine sediments on the channel bed of the stravice River; – Channel bed of into the bedrock incised reach of the Morávka River (Photo: M. Kubín).
4. Man-made river structures affected by erosion processes of Czech Carpathian rivers egative effects of the transformation of gravel bed rivers on human society (hydraulic structures) in C ech flysch Carpathians ere visible in number of localities. specially eir structures were affected by gradual incision and undercutting. In the Morávka River basin, the Vyšní Lhoty weir (at 11.38 r. km) built bet een 195 and 1964 as gradually affected by undercutting and headward erosion. The Vyšní Lhoty weir has important function for society, when it improves water inflow into the adjacent Lučina River basin and Žermanice ater reservoir and helps to decrease flood discharges downstream. The Žermanice water reservoir has important storage and ater supply function for local industry. irstly, a protective drop as made under the eir in 1969, follo ed by a rock chute construction in
4 E3S Web of Conferences 40, 02005 (2018) https://doi.org/10.1051/e3sconf/20184002005 River Flow 2018 transformed channels and hungry ater effect related ith coarsening of bed sediments of 1 to prevent incision and undercutting 1 . In the year , antierosion measures of the studied rivers affected habitat for fish communities [16]. local channel widening have been implemented below the Vyšní Lhoty weir, but or example, rook lamprey (Lampetra planeri), uropean bullhead (Cottus gobio) and problematic management connected with absence of bed sediment for support of close to Alpine bullhead (Cottus poecilopus) belong to protected species and they are listed in the natural processes of gravel bed Morávka River caused total destruction of this antierosive Red ist of threatened species of vertebrates of the C ech Republic [17]. ro n trout measures. s the conse uence, gradual incision of river reach 1 km long below this (Salmo trutta) represents a typical fish for C ech fresh aters and it is from the fishing measure took place during the flood in year 1 3 . Similarly, the Frýdek weir (at 1.25 r. industry focus economically important fish. he young larvae of rook lampreys re uire km) and the Konečný weir (2.31 r. km) built in the lower river reach of the Morávka River river reaches ith slo running flo and clay sand bed substrate ( ith depth about 0 cm) were destroyed by floods from the reasons of headward erosion and undercutting (the first [1 ]. n contrast, adult rook lampreys (like as ro n trouts) spa n in shallo fast running one was destroyed in 1 , the latter in the mid 1 s). lso, their destruction negatively flo gravel close to the soft sediment bed reaches. he sand bed substrate depth about 25 affected originally multi thread river channel pattern, which has been transformed into the cm armoured gravels ( ith mean diameter of particle si es from 5 to 20 cm) and flo single thread channel incised m below the original bed level since the 1 s . velocity to 0. m s is typical for bullheads [19]. n fact, complexity of habitats [20], Problematics of channel incision and its effect on man made structures is not only a domain variability of flo velocity of channel reaches [21] and sufficient refugium availability [22] of weir structures. large number of bridge constructions at crossing of the river channels is necessary for natural development of these fish lamprey species. in the ech flysch arpathians were destroyed or damaged by undercutting. or e ample, ased on the preliminary results of research, habitats of above mentioned fish and some bridges in the stravice River basin were repetively repaired several times (see fig ). lamprey communities were highly degraded in some channel reaches of the Morávka River imilarly, bank stabilisation structures, as typical technical approach for river regulation, (see fig. ). he main reasons for degradation of habitats ere incision and narro ing of are very often damaged by lateral erosion processes. river reaches, absence of appropriate finer (clay and sand) bed deposits hich are armouring gravel particles on bed and increased flo velocity in channels. heir number decreased in these reaches. n contrast, numerously and age balanced populations of lamprey and fish species ere observed in river reaches ith multi thread channel pattern ith gravel bed armoured by fine sediments and lo flo velocities.
Fig. 4. A residue of wooden bridge crossing the Ostravice River in Baška near Frýdek Místek during the floods in 1960 (Source: Povodí Odry State Enterprise Archives); B – ridge affected by incision of the Ostravice River channel in Baška near Frýdek Místek (Photo: V. Škarpich).
5. Conclusions
Intensive research was reali ed to detect how the channel transformation of ech Fig. 3. A ravels and armouring fine sediments on the channel bed of the stravice River; – arpathian rivers affects fluvial ecosystems and human society 8, , 1 , 11, 1 , 1 , 3 . Channel bed of into the bedrock incised reach of the Morávka River (Photo: M. Kubín). The ecosystem services produced by riverine landscape were significantly degraded. The decline in river habitat and reduction in functional floodplain resulted in significant 4. Man-made river structures affected by erosion processes of reductions of associated biodiversity, which include impacts on spatiotemporal heterogeneity, functional processes and species. lso, the transformations of channels Czech Carpathian rivers increased financial re uirements for water treatment, repair of hydraulic structures (weirs, egative effects of the transformation of gravel bed rivers on human society (hydraulic dams) or bridges affected by incision of river channel and undercutting. uture river structures) in C ech flysch Carpathians ere visible in number of localities. specially eir restoration of ech arpathian rivers is necessary to improve the current state. Various structures were affected by gradual incision and undercutting. In the Morávka River basin, legislative measures to stopping of further river systems degradation were established but the Vyšní Lhoty weir (at 11.38 r. km) built bet een 195 and 1964 as gradually affected the one of the biggest problem is the potential for river restoration. It is limited by by undercutting and headward erosion. The Vyšní Lhoty weir has important function for constraints such as need for flood protection of urban areas, need of water for human society, when it improves water inflow into the adjacent Lučina River basin and Žermanice society, density of urbanisation, etc. ater reservoir and helps to decrease flood discharges downstream. The Žermanice water reservoir has important storage and ater supply function for local industry. irstly, a cknowledgement protective drop as made under the eir in 1969, follo ed by a rock chute construction in The study was supported by The Technology Agency of the Czech Republic TAČR: TH02030509 ( 1 1 ): Risks identification and possibility of support of landscape natural functions in
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landscape protected areas influenced by climate change. Thanks are extended to Aneta Krótka, Radek Dušek, Tomáš Gwóźdź, Zdeněk Kašpárek, Matěj Horáček, Veronika Kapustová, Vladimír Šala for their help with fieldwork and data collection.
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