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Impacts hydromorphologiques et sédimentaires du décloisonnement de l'Yerres : identification, quantification, spatialisation / Effects of small dam lowering on fluvial geomorphology in the Yerres River, France : processes identification, quantification and mappingMichler, Luc 16 November 2018 (has links)
Le bassin-versant de l’Yerres (1030 km²) est localisé au sud-est de l’agglomération parisienne et s’étend sur le plateau de Brie au relief très modéré. Ses caractéristiques physiographiques et sa situation géographique confèrent au lit de l’Yerres une très faible pente (0,009 %), entravée par une forte segmentation longitudinale (0,5 ouvrage/km). Cette dernière est ancienne (moulins hydrauliques) ou plus récente (barrages mobiles) et s’est généralement accompagnée d’une chenalisation du lit. Les perturbations engendrées par ces ouvrages et les modifications morphologiques du lit ont provoqué une altération considérable de la dynamique fluviale et de la diversité morphologique du cours d’eau. Dans ce contexte d’un cours d’eau de faible énergie (< 10 W/m²) fortement artificialisé, notre recherche s’est attachée à évaluer l’efficience de l’effacement de trois barrages à clapets mobiles (h < 3 m) sur la restauration hydromorphologique du lit. À cet effet, des suivis topographique et sédimentologique à haute résolution spatio-temporelle ont été mis en œuvre entre 2015 et 2017 afin d’appréhender les réajustements du système fluvial à partir de l’évolution des caractéristiques morphologiques et granulométriques de son lit. Ils ont dévoilé un remblaiement alluvial se produisant principalement sous la forme de banquettes latérales de vases, à l’exception du site d’Ozouer (le plus en amont). Sur ce dernier le remblaiement alluvial sableux est plus généralisé. À la suite des abaissements hivernaux, celui-ci a fait l’objet des changements morphologiques les plus prononcés, caractérisés par une érosion marquée du fond du lit de la retenue et un faible alluvionnement en aval. Les réajustements morphologiques restent toutefois modérés compte tenu des débits exceptionnellement forts sur la période de suivi et semblent par ailleurs être subordonnés à la présence de substrats sableux. Ainsi, si les abaissements améliorent indubitablement les conditions hydro-éco-morphologiques (i.e. la diversité des faciès d’écoulement), la restauration physique du lit fortement dégradé de l’Yerres se limite au rétablissement du transport du matériel de fond sableux. / The Yerres catchment (1030 km²) is located at the southeast border of the Paris conurbation and spreads on the low relief Brie Plateau. Topographical characteristics and geographical location provide the Yerres River with a very low gradient (0,009 %) and a high longitudinal partitioning (0,5 dam/km). Cross-structures are either ancient (medieval watermills) or more recent (mobile dams) and often associated with river channelling. Dam perturbation on sediment fluxes and bed morphological modifications have led to a significant degradation of the river fluvial dynamic and morphological diversity. In this context of a much artificialized low-energy river (< 10 W/m²), we aimed at assessing the efficiency of three mobile dam (h < 3 m) lowering on bed hydromorphological restoration. For that purpose, high spatial and temporal resolution monitoring of bed topography and sediment-size were carried out between 2015 and 2017, in order to document fluvial system adjustment to dam lowering through morphological and grain-size change. Before dam lowering, fine sediment had mainly deposited in channel margins forming mud banks, except for Ozouer impoundment (the more upstream study site). For the latter, sand sedimentation had been extended to the whole channel width. After dam lowering, it also experienced the more pronounced morphological change, characterised by significant bed erosion upstream and little bed aggradation downstream. However, morphological response to dam lowering remained moderate given the high discharges over the monitoring period. Channel adjustments also appeared to be linked to sand-bed. Thus, while dam lowering undoubtedly improve hydro-eco-morphological conditions (i.e. flow facies diversity), physical restoration of the highly degraded Yerres riverbed is restricted to the sand bed material transport restoration.
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Impact of flow energy distribution on the ecological status of rivers / Tėkmės energijos pasiskirstymo poveikis upelių ekologinei būkleiGegužis, Ramūnas 18 December 2013 (has links)
The aim of the study - to investigate interaction regularities of water flow energy distribution and stream beds during the naturalization process, to identify morphometric changes in the beds of streams and to assess the impact of these factors on the ecological status of rivers. To achieving this aim, 6 specific tasks were identified: 1 Designing geostatistical models of hydromorphological characteristics of regulated and natural river beds based on the field research results; 2 Identifying morphometric characteristics of river beds based on geostatistical models; 3 Determining regularities of the flow energy distribution and its interaction with the stream bed; 4 Determining the abundance and composition of grass and woody vegetation in the investigated sections of streams; 5 Determining the diversity, composition and abundance of macrozoobenthos and fish species; 6 Identifying the impact of flow energy distribution and stream bed interaction on the ecological status of rivers. / Darbo tikslas – ištirti vandens tėkmės energijos pasiskirstymo ir upelių vagų sąveikos dėsningumus, vykstant natūralizacijos procesams, nustatyti morfometrinius pokyčius upelių vagose lemiančius veiksnius ir įvertinti jų poveikį upių ekologinei būklei. Darbo tikslui pasiekti buvo sprendžiami 6 uždaviniai: 1) taikant natūrinių tyrimų rezultatus, sudaryti geostatistinius reguliuotų ir natūralių vagų hidromorfologinių charakteristikų modelius; 2) pasinaudojus gautais modeliais, nustatyti morfometrines vagų charakteristikas; 3) pasinaudojus gautais modeliais, išsiaiškinti tėkmės energijos pasiskirstymo ir jos sąveikos su upelių vaga dėsningumus; 4) ištirti žolinės ir sumedėjusios augalijos gausą ir jos sudėtį tiriamų upelių atkarpose; 5) nustatyti makrozoobentoso ir juo besimaitinančių žuvų rūšinę įvairovę, sudėtį ir gausą; 6) išsiaiškinti tėkmės energijos pasiskirstymo ir upelių vagų sąveikos įtaką upių ekologinei būklei.
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Gradients of time and complexity : understanding how riparian and instream ecosystems recover after stream restorationHasselquist, Eliza Maher January 2015 (has links)
Why evaluations of the ecological outcomes of stream and river restoration have largely reported inconclusive or negative results has been the subject of much debate over the last decade or more. Understanding the reasons behind the lack of positive results is important for bettering future restoration efforts and setting realistic expectations for restoration outcomes. This thesis explores possible explanations for why researchers have failed to find clear and predictable biotic responses to stream restoration: recovery time has been too short, that restoration of habitat complexity is not clearly linked to instream biodiversity, that one monitored organism group is not representative of the entire community, that restoration effort was not intense enough to restore the potential habitat complexity of a system, and that reach-scale restoration done in the presence of catchment-scale degradation obscures restoration results. The overarching goal of this thesis is to study the holistic effect of reach-scale restoration of historic reach-scale simplification, due to timber floating in northern Swedish streams, thus avoiding the added pressure of catchment-scale degradation typically found at most restoration sites (e.g., non-point-source pollution and impervious cover). Using this model system, I was able to show that it took 25 years for riparian plant species richness at restored sites to increase above that of channelized sites. Furthermore, it was clear that restoration of these streams caused a large and rapid change in N-processing in the riparian zone and this alteration persists for at least 25 years. Additionally, multiple metrics of geomorphic complexity were needed to explain some of the more subtle responses of organism groups. Macroinvertebrates, diatoms, and macrophytes did not respond concordantly and cannot serve as surrogates or indicators for each other. I found that older best practice methods of restoration rarely restored the large-scale features needed to bring the sites up to their potential complexity because these elements were destroyed or removed from the system. Advanced restoration techniques used in more recent restorations added big boulders and instream wood and increased complexity to a level that elicited a biological response. By combining surveys of multiple metrics of structure, diversity of multiple organism groups, and process in this thesis I was able to get a holistic view of the effects of restoration of streams after timber floating. We now know that it takes at least 25 years for riparian plants and N-cycling to recover, we understand that multiple metrics of geomorphic complexity should be measured to be able to explain biotic responses, and that restored complexity should better match the potential complexity of the site in order to elicit a biological response. Finally, we know that multiple organism groups need to be assessed when evaluating the response of biodiversity to restoration.
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Monitoring plůdkových společenstev ve vybraných tocích na Moravě / Monitoring of 0+ juvenile fish communities in selected Moravian riversGEBAUER, Radek January 2014 (has links)
Monitoring of 0+ juvenile fish communities was realized in years 2012 and 2013 in 39 localities in 25 selected Moravian rivers. It was realized in collaboration with Povodí Moravy SOE research workers. The aim of this diploma thesis was to conduct a survey of 0+ juvenile fish communities and evaluate basic attributes of these ichthyocenosis (species richness, biodiversity, equitability, abundance and domiance). Secondary aim was the evalutation od hydromorphological conditions and water quality based on data provided by Povodí Moravy SOE. This monitoring was realized using the mobile FEG 1500 electrofishing device. The electrofishing crew moved upstream using continuous fishing strategy. Each locality was selected by highly experienced research workers of Povodí Moravy SOE. Caught fish were determined immediately and carefully retruned to the stream. In total there was present 28 0+ juvenile fish species. The most frequent was chub (Leuciscus cephalus, 23 localities), gudgeon (Gobio gobio, 19 localities) and roach (Rutilus rutilus, 19 localities). In 13 localities occured the fish fry of barbel (Barbus barbus) wich is positive surprise due to its sensitivity to water pollution. In contrast the massive presence of round goby (Neogobius melanostomus) in some localities was an unpleasant finding. 4 localities were without fish fry. This survey has observed increasing trend of biodiversity depending on improving of hydromorphological status while the abundance showed almost no diference. Saprobic index of 0+ juvenilie fish community increased with deteriorating of water quality which could mean that the fish fry is relatively reliable indicator of water quality. The results of this diploma thesis could be used in documenting of Moravian streams and in comparisson with another monitorings in these localities.
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Specifika hydroekologického monitoringu na malých vodních tocích a jeho vylepšení / Specifics of the hydromorphological monitoring on small water courses and its improvementBeneš, Jakub January 2017 (has links)
This thesis deals with hydroecological monitoring of watercourses. The HEM – Hydroecological monitoring is part of evaluation of status of watercourses, which is a requirement of the European Water Framework Directive. The content of this thesis is firstly to find out the status monitoring of hydromorphological quality of watercourses in the Czech Republic and a subsequent survey of methodology HEM. The aim of this thesis is comparison with the older methodologies and ways to improve the practical implementation of monitoring on smaller waterways. Measurement and knowledge will be applied to Troubsko creek.
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Ekologija i konzervaciona vrednost vodene vegetacije šljunkara u plavnom području reke Drine / Ecology and conservation value of aquatic vegetation of gravel pit lakes in the Drina RiverfloodplainDamnjanovic Bojan 03 December 2019 (has links)
<p>Sa jedne strane se eksploatacija šljunka navodi kao značajan ugrožavajući faktor sa velikim negativnim uticajem na vodena staništa i biodiverzitet, dok same šljunkare mogu predstavljati vredne refugijume akavtičnog biodiverziteta. Osnovni cilj disertacije je određivanje najznačajnijih i relevantnih hidromorfoloških parametara koji utiču na strukturiranje makrofitskih zajednica u šljunkarama duž plavnog područja reke Drine i određivanje korelacije između izdvojenih parametara i kvantitativnih indeksa makrofita.Istraživanje je vršeno u toku letnjih meseci 2015, 2016, 2017 i 2018. godine na 18 šljunkara (60 istraživačkih vegetacijskih sektora) u okviru tri eksploataciona polja u Crnoj Bari, Badovincima i Lipničkom Šoru i na četiri prirodna fluvijalna jezera (13 istraživačkih vegetacijskih sektora) u plavnom području reke Drine. Makrofitska vegetacija je konstatovana na svih 18 istraţivanih šljunkara, prikupljenih na tri eksploataciona polja (Badovinci, Crna Bara i<br />Lipniĉki Šor). Zabeležena je 31 biljna vrsta. Kao najučestalije, sa najvećom apsolutnom pokrovnošću izdvojile su se vrste: <em> Potamogeton nodosus</em> Poiret, <em>Ceratophyllum demersum L subsp. demersum, Myriophyllum spicatum L,Najas marina L i Chara globularis Thuill </em> Na četiri prirodna fluvijalna jezera zabeleženo je 13 vrsta. Vrste <em>Vallisneria spiralis L, Elodea canadensis Michx, Callitriche palustris L, Potamogeton natans L i Nuphar lutea (L) </em> Sm izdvojile su se kao konstantne i dominantne. Vrednosti svih kvantitativnih indeksa makrofita,<br />značajno su veće za šljunkare u poređenju sa prirodnim fluvijalnim jezerima na nivouLEAFPACS sektora. Na istraživanim šljunkarama, analizom klasterovanja je<br />izdvojeno 13 vegetacijskih grupa (VG): VG1<em> Ceratophyllum demersum</em>, VG2 <em>Ceratophyllum demersum - Valisneria spiralis</em>, VG3 <em>Chara contraria,</em> VG4 <em>Chara</em> <em>globularis,</em> VG5 <em>Elodea canadensis,</em> VG6 <em>Elodea nuttallii</em>, VG7 <em>Najas marina</em>, VG8 <em>Najas minor,</em> VG9 <em>Nitellopsis obtusa</em>, VG10 <em> Nuphar lutea</em>, VG11 <em>Potamogeton nodosus</em>, VG12 <em> Potamogeton natans </em> i VG13 <em>Potamogeton pectinatus</em>. Na prirodnim fluvijalnim jezerima konstatovane su četiri vegetacijske grupe: VG5 <em> Elodea canadensis</em>, VG10 <em>Nuphar lutea,</em> VG12<em> Potamogeton natans </em> i VG14 <em>Typha latifolia</em>. Na osnovu izmerenih fizičko-hemijskih parametara,kvalitet vode u većini šljunkara odgovara II klasi kvaliteta, na osnovu čega se mogu okarakterisati kao vodna tela sa dobrim i boljim ekološkim potencijalom. Sve šljunkare i fluvijalna jezera se klasifikuju kao visoko alkalna. Kvalitet vode u prirodnim fluvijalnim jezerima odgovara III – IV klasi kvaliteta voda, pri čemu se mogu okarakterisati kao vodna tela sa slabim do umerenim ekološkim statusom. Značajno veće<br />vrednosti ukupnih suspendovanih materija, hemijske i biološke potrošnje kiseonika, ukupnog organskog kiseonika i nitrata zabeležene su na prirodnim fluvijalnim jezerima u poređenju sa šljunkarama. Izmerene vrednosti fizičko-hemijskih parametara ukazuju na mezotrofni karakter lokaliteta u Badovincima i mezo-eutrofni karakter lokaliteta u Lipničkom Šoru, dok se šljunkare na teritoriji Crne Bare mogu okarakterisati kao eutrofna jezera.Vrednosti LHMS (modifikacionog) skora za šljunkare kretale su se u rasponu od 9 – 15, dok su vrednosti LHQA skora (stanišnog diverziteta) bile u rasponu izmeĊu 33 – 44. Sliĉne vrednosti za LHQA skor su izraĉunate i za prirodna fluvijalna jezera (36 – 49). MeĊutim, vrednosti<br />LHMS skora za prirodna fluvijalna jezera su znaĉajno veće u odnosu na vrednosti LHMS skora za šljunkare. Ovi podaci ukazuju na manje prisustvo antropogenog pritiska na šljunkarama u poređenju sa prirodnim fluvijalnim jezerima uistraţivanom podruĉju. Fizičko -hemijski i hidromorfološki parametri zajedno su objasnili 57.07 % od ukupne varijanse vegetacijskih podataka, sa 16.57 % deljenog efekta. Fizičkohemijski parametri kvaliteta vode objasnili su 17.02 % varijabilnosti u strukturi makrofitske vegetacije. Kao najsignifikantniji parametri<br />izdvojili su se: saturacija vode kiseonikom,ukupni organski ugljenik, površinski aktivne materije, temperatura, elektroprovodljivost, pH i ukpni alkalitet. Hidromorfološki parametri su objasnili 23.48 % varijabilnosti u strukturi makrofitske vegetacije. Kao najsignifikantnije varijable, izdvojile su se: struktura vegetacije u priobalnoj zoni, diverzitet prirodnih tipova staništa priobalne zone, prirodnost obale, diverzitet prirodnog supstrata litorala,masimalna dubina šljunkara, površina šljunkara,indeks relativne dubine, udaljenost šljunkara od glavnog reĉnog toka i starost šljunkara. Hidrološki parametri su objasnili 8.38 % varijabilnosti u strukturi makrofitske vegetacije. Kao najsignifikantnije varijable, izdvojile su se broj plavnih talasa u vegetacionoj sezoni tokom godine u kojoj je vršeno uzorkovanje vegetacije i broj plavnih talasa u prolećnom periodu za sve četiri godine. Ovi rezultati potvrđuju direktni destruktivni uticaj plavnih talasa na vodenu vegetaciju u vegetacionoj sezoni, kao i indirektni uticaj prolećnih poplava, usled uticaja na trofički status vode. Sumarno, šljunkare u plavnom području reke Drine predstavljaju optimalno stanište za razvoj retke i ugroţene makrofitske flore. Od ukupnog broja zabeleženih vrsta makrofita, 30 % se kategoriše kao zaštićeno ili ugroženo na nacionalnom nivou. Značajno veće vrednosti konzervacionih indeksa ustanovljene su za šljunkare u poređenju sa prirodnim fluvijalnim jezerima, što ukazuje na njihov visok ekološki potencijal. Ustanovljen je visok diverzitet prioritetnih tipova akvatiĉnih staništa prema Pravilniku o kriterijumima za izdvajanje tipova staništa, o tipovima staništa, osetljivim, ugroženim, retkim i za zaštitu prioritetnim tipovima staništa i o merama zaštite za njihovo očuvanje, Aneksu I, Direktive Evropske unije ozaštiti prirodnih staništa i divlje flore i faune (Natura 2000), Rezoluciji br. 4 Konvencije o očuvanju evropske divlje flore i faune i prirodnih staništa (EMERALD) i Evropskoj crvenoj listi staništa. Vrednosti izdvojenih atributa šljunkara mogli bi se iskoristiti u procesu ranog planiranja i projektovanja eksploatacionih polja u plavnom području reke Drine i na drugim, sličnim lokalitetima. Generalna preporuka je da se dva tipa šljunkara kreiraju u okviru jednog eksploatacionog polja. Prvi tip, odnosno šljunkare koje bi podržavale pionirsku vegetaciju pršljenčica trebale bi da budu locirane na razdaljini do 100 m od glavnog rečnog toka, površine do 1000 m 2 i da imaju vrednost indeksa relativne dubine > 5 %. Drugi tip šljunkara koje bi podržavale vegetaciju karakterističnu za nizijska fluvijalna jezera trebale bi da budu locirane na razdaljani od oko 300 m od glavnog rečnog toka, dubine 3 – 4 m (najmanje 2 m), površine između 10000 i 20000 m <sup>2 </sup>(najmanje 4000 m<sup> 2</sup> ), različitih vrednosti indeksa relativne dubine, ali ne preko 5 %. Sva eksploataciona polja bi trebalo isplanirati i isprojektovati kako bi se minimizirao uticaj na priobalnu i obalnu zonu. Pridržavanjem datih smernica povećao bi se diverzitet i kvalitet staništa, kao i konzervacioni potencijal šljunkara. Kreiranjem šljunkara na naĉin kao što je predloženo u ovoj disertaciji omogućila bi se spontana rekultivacija eksploatacionih polja,odnosno remedijacija u cilju poboljšanja kvaliteta vode i renaturalizacija staništa, čime bi se znatno smanjili, ili u potpunosti eliminisali, troškovi tehničke rekultivacije terena.</p> / <p>Gravel pit lakes in the river floodplains represent a kind of ecological paradox. Gravel exploitation was recognised as important factor significantlyaffecting aquatic habitats and biodiversity. On the other hand, gravel pit lakes are valuable biodiversity refugiums, potentially supporting rarae species and habitats. The aim of this dissertation was to determine the most significant and relevant hydromorphological parameters in structuring macrophyte assemblages in gravel pit lakes along the Drina River floodplain and to determine the correlation between selected parameters and macrophyte quantitative indices. The research was carried out at the 18 gravel pit lakes (60 survey sectors) in Crna Bara, Badovinci and Lipnicki Sor and four natural fluvial lakes (13 survey sectors), in the Drina River floodplain during the summer months of 2015, 2016, 2017 and 2018.Macrophyte vegetation was recorded in all 18 gravel pit lakes, in total supporting 31 taxa. The most abundant species, with highest tot al cover value were <em>Potamogeton</em> <em>nodosus,Ceratophyllum </em> demersum subsp. demersum,<em> Myriophyllum spicatum, </em> <em>Najas marina </em> and<em> Chara globularis</em>. Fluvial lakes supported 13 macrophyte taxa with <em> Vallisneria spiralis, Elodea canadensis, Callitriche palustris,Potamogeton </em> <em>natans </em> and <em> Nuphar lutea</em> as constant and dominant species. The values of all macrophyte quantitative indices found to be significantly higher in the gravel pit lakes compared to the fluvial ones. The cluster analysis revealed 14 aquatic vegetation groups (VG). At 16 out of 18 gravel pit lakes 13 vegetation groups were revealed: VG1<em>Ceratophyllum demersum</em>, VG2 <em>Ceratophyllum demersum- Valisneria spiralis</em>, VG3 <em> Chara contraria</em>, VG4 <em>Chara globularis</em>, VG5 <em> Elodea canadensis,</em> VG6 <em> Elodea nuttallii,</em> VG7 <em>Najas marina, </em> VG8 <em> Najas minor,</em> VG9 <em>Nitellopsis obtusa</em>, VG10 <em>Nuphar lutea,</em> VG11 <em>Potamogeton nodosus</em>, VG12 <em>Potamogeton natans,</em> VG13 <em> Potamogeton pectinatus</em>), Natural fluvial lakes supported 4 vegetation groups: VG5 <em>Elodea canadensis</em>, VG10 <em>Nuphar lutea</em>, VG12 <em>Potamogeton natans </em> and VG14 <em> Typha latifolia</em>. All gravel pit lakes can be characterized as water bodies with good to maximal ecological potential, while all the fluvial ones can be characterized as water bidies with poor to moderate ecological status. The values of total suspended supstances, chemical and biological oxygen demand, total organic carbon and nitrates were significantly higher in the natural fluvial lakes compared to the gravel pit ones. Measured level of physico-chemical parameters indicating mesotrophic character of gravel pit lakes in Badovinci and mesoeutrophic in Lipnicki Sor, while all the gravel pits in Crna Bara could be characterized as eutrophic. Similar range values were calculated for LHQA for gravel pit and fluvial lakes (36 – 49). However, natural lakes showed significantly higher values for LHMS score. The above mentioned, indicates higher anthropogenic pressures on natural fluvial lakes compared to gravel pit ones. Physico-chemical and hydromorphological parameters together explained about 57 % of the total variance of macrophyte assemblages with 16.57 % of the shared effect. After accounting for the effects of physico-chemical parameters (17.02 %), hydromorphological variables explained around 23 % of the total variance. The most significant water quality variables were: oxygen saturation, total organic carbon, surfactants, ,electroconductivity, pH and total alkalinity. The The most significant hydromorphology variables for structuring macrophyte assemblages were: riparian vegetation structural complexity, diversity of natural landcover types in riparianzone, shore structural habitat diversity, diversity of natural littoral zone, maximal lake depth, lake surface area, relative depth ratio, lake distance from r iver main channel and lake age.Hydrologycal parameters were explained 8.38 % of variance in structuring macrophyte assemblages. The most significant hydrology variables were the number of floods in vegetation season in first year when vegetation was sampled, and the number of spring floods in all four research years. These results confirm the direct destructive influence of summer floods on aquatic vegetation, as well as the indirect impact of spring floods, due to the impact on trophic status of water. Gravel pit lakes in te Drina River floodplain represent an optimal habitat for rare and threatened macrophyte flora. Of the total macrophyte species recorded, 30 % were categorized as protected or threatened. At least one strictly protected, protected or threatened species was recorded in each gravel pit lake. Significantly higher values of conservation indices (C and Csp score) found to be significantly higher in the gravel pit lakes compared to the fluvial ones. High habitat diversity and conservation value of the sites have been recorded according to the National Rulebook, Annex I of Habitats Directive (NATURA 2000), Resolution no. 4 of the Bern Convention (EMERALD) and the European Red List of Habitats. Values of selected lake attributes can be used for early-design phases of future gravel extraction in the Drina River floodplain area, and in other similar sites. Therefore, general recommendations are that two gravel pit types should be excavated within the single extraction area in order to support pioneering charophyte vegetation and vegetation of typical eutrophic lowland floodplain lakes as well. The first hydromorphological lake type, suitable for stonewort species, should be excavated up to 100 m from river main channel, saving a surface area up to 1000 m 2 and a relative depth ratio > 5 %. The second gravel pit type should be located about 300 m from river main channel, with preferable maximal depth inrange 3–4 m (at least 2 m depth), and a lake surface area between 10000 m 2 and 20000 m 2 (at least 4000 m 2 ). Relative depth ratio may vary, but should be less than 5 %. Generally, all sites should be designed with the minimal impact to the riparian and shore zones. These proposed measures would considerably increase lake habitat diversity and their conservation potential. Creating gravel pit lakes as proposed in this dissertation would allow spontaneous recultivation of exploitation fields, remediation in order to improve water quality and renaturalization of habitats, which will significantly reduce, or completely eliminate, the costs of terrain technical recultivation.</p>
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Hydromorfologický průzkum a identifikace referenčních stavů řeky Jizery / Hydromorphological survey and identification of reference status of the Jizera RiverTomšová, Zuzana January 2015 (has links)
Long-term and intensive human use of watercourses has led to their considerable degradation. Recently, there has been an effort to improve the ecological status of aquatic ecosystems, based on studies of hydromorphological characteristics of natural watercourses and identification of reference conditions. The aim of this thesis was the hydromorphological survey and an identification of reference conditions of the Jizera River. The selection of sites suitable for identification of reference status was based on pre-set criteria determined on remote sensing data, which eliminated significant anthropogenic impacts on the channel and floodplain. The survey using River Habitat Survey (Environmental Agency, 2003), Hydroecological Monitoring (Langhammer et al., 2014) and REFCON (Šmerousová a Matoušková, 2014a) methods was conducted in selected sites. Sites where hydromorphological conditions correspond with very good class, according to Hydroecological Monitoring, were used for identification of the type-specific reference conditions. Physico-chemical characteristics according to ČSN 757221 (1998) and Rosendorf et al. (2011) and the biological quality element macroinvertebrates according to Opatřilová et al. (2011) were also evaluated. Physico-chemical characteristics reached class I - II (ČSN, 1998) and...
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Riparian vegetation patterns according to hydrogeomorphological factors at different spatial and temporal scales in Mediterranean riversGarófano Gómez, Virginia 03 June 2013 (has links)
Los corredores riparios en ambientes semiáridos mediterráneos son ecosistemas de gran biodiversidad y
complejidad. En ellos confluyen una gran variedad de perturbaciones naturales capaces de crear un mosaico
espacial y temporal con pocos paralelos en otros ecosistemas. Sin embargo, a pesar de su valor, los ecosistemas
riparios están amenazados debido a los altos niveles de intervención humana. La construcción de presas (y la
consecuente manipulación del caudal) está considerada como la perturbación humana más importante que se
cierne sobre ellos. Esta tesis ha tenido como objetivo analizar el ecosistema ripario, abarcando diferentes escalas
espaciales y temporales, y centrándose en los factores que influyen en la distribución, estructura, composición,
calidad y dinámica de su vegetación, tanto en tramos naturales como hidrológicamente alterados de ríos
mediterráneos, concretamente de la Demarcación Hidrográfica del Júcar (Este de España).
Para lograr este objetivo, se han hecho los siguientes aportes a la investigación: A) Determinar los patrones de
distribución de especies leñosas riparias en el gradiente transversal de la ribera y definir grupos de especies con
respuesta similar a las condiciones físicas del hábitat; B) Comparar la respuesta de dichas especies en tramos
naturales y alterados hidrológicamente; C) Definir curvas de respuesta y gremios hidrológicos de especies en
tramos con régimen natural; D) Establecer los principales factores que determinan la calidad del hábitat ripario y
fluvial y los patrones longitudinales de la composición florística, así como de las características del hábitat fluvial
en un segmento hidrológicamente alterado; E) Describir los cambios espacio-temporales en la estructura y
complejidad de la vegetación, y los cambios temporales en el régimen de caudales del corredor ripario de un
tramo hidrológicamente alterado.
Los objetivos anteriores fueron abordados con diferentes metodologías que implicaron la combinación de
diversas fuentes de información y un esfuerzo importante en la toma de datos en varios lugares de estudio de los
ríos Cabriel, Mijares y Serpis. Para cumplir con los objetivos A y B, se llevaron a cabo un muestreo de suelos y
un muestreo georreferenciado de vegetación a través de transectos transversales al cauce en dos tramos naturales
y tres regulados. Los datos fueron analizados con estadística robusta y multivariante. Para cumplir el objetivo C,
el muestreo georreferenciado anterior (junto con un muestreo dendrocronológico) fue acoplado con un modelo
hidráulico en los dos tramos naturales, con el fin de obtener la serie temporal de cotas del agua a la que habían
estado expuestas cada una de las plantas durante su vida. La respuesta de las especies y su posible agregación en
gremios hidrológicos fue comparada mediante estadística robusta en relación a la duración de la inundación,
duración de la inundación durante el período de crecimiento, duración continua de la inundación, frecuencia de
inundación y elevación de la planta respecto al caudal base. Para lograr el objetivo D, toda la sección regulada del
río Serpis (desde la presa Beniarrés - hasta la desembocadura; 40 km) se dividió en segmentos. En cada uno de
ellos se llevó a cabo un inventario de flora y se aplicaron índices hidromorfológicos. Los segmentos fueron
agrupados de acuerdo a su composición florística y características del hábitat fluvial utilizando diferentes técnicas
de estadística multivariante. Finalmente se discutieron los factores principales que controlan los patrones
espaciales de la composición florística, las características del hábitat fluvial, la calidad del hábitat ribereño y la
heterogeneidad del hábitat fluvial. Para alcanzar el objetivo E, se combinaron series históricas de caudales y su
manipulación humana con imágenes aéreas históricas (reveladoras de cambios en la cubierta vegetal) y
observaciones de campo de la distribución de edades de la vegetación y morfología del corredor ripario del río
Mijares en los últimos 60 años. De esta información, se extrajeron métricas del paisaje e índices hidrológicos para
identificar y resumir los cambios espacio-temporales en la estructura de la ribera y en el régimen de caudales.
El estudio a escala transversal nos ayudó a comprender en cada uno de los tramos la zonación de las especies
leñosas riparias en función de la morfología y características del suelo, revelando que la alteración del caudal
puede influir en la modificación de los patrones posicionales de las especies. Se definieron tres gremios
hidrológicos: ¿altamente tolerante a la inundación¿, ¿tolerante intermedio¿ y ¿de transición entre ripario y
terrestre¿. El estudio a escala longitudinal sugirió que la respuesta de la vegetación a un cambio hidrológico es
altamente dependiente de la geomorfología local. Se constató que los factores principales que determinan los
patrones hidromorfológicos y florísticos son un régimen de caudales artificial y altamente variable (identificado
en los segmentos con peor calidad del hábitat ripario y fluvial), la presencia de estructuras laterales en el cauce y
las características geomorfológicas. Como efectos importantes de la regulación del caudal a largo plazo, el estudio
a escala espacio-temporal reveló un aumento en la cobertura y densidad de la vegetación leñosa, una deriva en la
composición de especies y una disminución en las áreas de sedimento desnudo (esencial para el reclutamiento de
las especies riparias pioneras), junto con una reducción sincrónica en la complejidad de la ribera. Estos cambios
estarían relacionados con la disminución de la magnitud y variabilidad de los caudales en las últimas seis décadas.
Solo una mejor comprensión de los procesos ecohidrológicos y de las implicaciones de la alteración hidrológica
sobre los ecosistemas riparios mediterráneos podrá apoyar la integración eficaz de estos sistemas en las
decisiones de gestión del agua. / Garófano Gómez, V. (2013). Riparian vegetation patterns according to hydrogeomorphological factors at different spatial and temporal scales in Mediterranean rivers [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/29395 / TESIS
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Analyse par bilan ligneux de la dynamique des bois morts à multiples échelles spatiales et temporelles dans une rivière semi-alluviale de région froide / Analysis of the dynamics of large wood in river by a multi-scale large wood budget approach in a semi-alluvial river of cold regionsBoivin, Maxime 09 June 2016 (has links)
Cette thèse constitue une analyse de la dynamique du bois mort en rivière par une approche de bilan ligneux multi-scalaire dans une rivière semi-alluviale de région froide: la rivière Saint-Jean, Gaspé. L’étude de la variabilité spatiale et temporelle de la dynamique du bois mort a été réalisée grâce à une approche méthodologique combinant quatre années de terrain et par l’analyse de documents historiques. Les rivières de la péninsule gaspésienne produisent et transportent annuellement de grandes quantités de bois mort. Cette production provient à la fois de la puissance spécifique élevée des cours d’eau et de berges composées de sédiments peu cohésifs et comportant une ripisylve arborescente généralement dense. Jusqu’en 2015, le delta de la rivière Saint-Jean comportait plusieurs embâcles de bois de très grandes tailles. Ces embâcles se mettent en place depuis les années 1960, ils représentent une opportunité unique de quantifier et d’appliquer un budget ligneux pour cerner les variables clefs liées à la dynamique du bois mort à multiples échelles spatiales et temporelles.Nos résultats montrent que la quasi-totalité des bois morts en rivière est produite par la migration latérale et par l’influence de la morphologie. Au niveau des accumulations dans le corridor fluvial, deux zones accumulent la majorité des bois et ces premiers résultats montrent une mobilité importante qui peut varier fortement d'une année à l'autre. Au niveau de la mobilité, l’analyse d’imagerie vidéo de trois évènements différents ont montré que l’intensité (nombre de bois par minute) du transport de bois pouvait être jusqu’à dix fois supérieures durant un évènement avec débâcle mécanique glacielle, comparativement à un évènement hydroclimatique en eau libre.Finalement, nous avons réalisé une analyse par bilans ligneux et une analyse de la trajectoire éco-hydrophormologique sur une période de plus de 50 ans. Nous avons quantifié chaque composante (intrant, accumulée et sortie) d'un budget ligneux à multiples échelles spatio-temporelles. Autant à l’échelle interannuelle, qu’à l’échelle décennale, la dynamique du bois mort comporte des périodes où l’entrée de bois, le stockage et la mobilité diffèrent selon les contextes éco-hydromorphologiques. La trajectoire éco-hydromorphologiques suggère une augmentation de la dynamique fluviale en raison d'un changement significatif dans l'hydrologie conduisant à une plus grande production et mobilité des bois morts et par l'augmentation des volumes accumulés dans le corridor de la RSJ depuis 2004. / This thesis is an analysis of the dynamics of large wood in river by a multi-scale large wood budget approach in a semi-alluvial river of cold regions: the Saint-Jean River, Gaspé. The study of the spatial and temporal variability of the dynamics of large wood was carried out through a methodological approach combining four years of field and by analyzing historical documents. The rivers of the Gaspé Peninsula produce annually and carry large amounts of large wood. This production comes from the high specific power of rivers and by banks composed of noncohesive sediment and having a generally dense riparian forest tree. Until 2015, the Delta of the Saint-Jean River had several very large jams. These jams are put in place since the 1960s, they represent a unique opportunity to quantify and apply a wood budget and to identify key variables related to the dynamics of large wood at multiple spatial and temporal scales.Our results show that almost all large wood in river is produced by lateral migration and by the influence of the morphology. For the accumulations in the river corridor, two areas accumulate the majority of wood and these first results show a significant mobility, which can fluctuate substantially from year to year. In terms of mobility, video analysis of three different events showed that the intensity of the transport (number of large wood per minute) can be higher to ten times during an event with mechanical ice-breakup, compared to an open water.hydroclimatic event.Finally, we conducted an analysis by large wood budget and analysis of eco-hydromorphological trajectory over more than 50 years. We quantified each component (input, output and accumulated) of a large wood budget at multiple spatial and temporal scales. At the interannual scale or decadal, scale, the dynamics of large wood have periods when the input, storage and mobility of large wood differ according to eco-hydromorphological contexts. The eco-hydromorphological trajectory suggests an increase in river dynamics due to a significant change in the hydrology, resulting in higher production and mobility of large wood and increased in volumes accumulated in the corridor of the Saint-Jean River since the last decade.
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