The impact of disturbance on the dynamics of fluvial processes in mountain landscapes Czech Science Foundation GAČR P209/12/0997 2012-14 About the project The project examines the impact of disturbances in mountain landscapes, particularly changes in the structure, extent and health of forest vegetation as a result of different causal processes on the dynamics of fluvial processes. The project analyzes the different types of landscape and forest disturbance, induced by different causal factors, such as the forest vegetation damage by pollution, bark beetle outbreak, wind storms or forest management, or modifications of river network, riverbed and floodplains. The effect of these changes on the dynamics of runoff and fluvial processes is analyzed using detailed monitoring of rainfall-runoff processes and field mapping of changes in morphological characteristics in channels and floodplains. The research is focused on mountain areas, which represent the most sensitive indicator of the impact of environmental changes on the dynamics of fluvial processes, namely the the headwaters of the Sumava and Ore Mountains, and as examples of areas affected by different manifestations of disturbances of forest vegetation and anthropogenic modifcations of streams. Principal investigator Assoc. Prof. Jakub Langhammer 1. Project aim The main aim of the project is to assess the influence of forest disturbance, land cover changes, and artificial river channels changes on discharge dynamics, fluvial system activity, and morphological changes within the valley floor. 2. Research questions
3. Fields of research Analysis of landscape disturbance and stream modifications in montane regions The initial research aim is to analyse the current state of the landscape and to determine the evolutionary dynamics for different forms of disturbance within the montane region. The majority of both rapid and protracted landscape changes are associated with changes in land use and land cover due to anthropogenic activities such as farming, constructing settlements, deforestation, or forest management techniques. One of the most important processes in montane regions is forest disturbance and decay, and this will be the central topic of the proposed research. This can be caused by different factors including industrial air pollution, windstorms, widespread felling, or the spread of bark beetles. The spatial and temporal dynamics of different types of forest disturbance within the study areas will be analysed as this represents one of the key forms of landscape disturbance. The modification of streams in montane regions has a very significant effect on runoff dynamics as well as on the supply of material and fluvial morphology. The artificial modification of streams and riverbeds will be analysed as well as the extent to which the drainage and road networks are important in affecting runoff dynamics during extreme events. Effect of landscape disturbance and stream modifications to the runoff dynamics This will identify the driving forces responsible for these changes and assess the influence of different initial physiographic conditions and differences caused by variation in the magnitude of the rainfall-runoff event. The analysis will focus on different aspects of runoff dynamics. The statistical analysis of time series will be performed in order to identify changes in runoff dynamics within a number of catchments. The types of event will be different as will the antecedent conditions. Using non-linear statistical techniques, the relationships that exist between the detected changes in runoff dynamics and landscape/forest disturbance, stream modification, and the drainage and road networks will be analysed in order to identify the links between the changes, the affecting factors, and their limiting conditions. Hydrological and hydraulic models will be used to simulate the propagation of flood waves in selected stream segments. The effects of stream modification will be tested using different scenarios to that of the initial event. To calibrate the models, precise hydrometric measurements will be taken in the stream channels during different hydrologic conditions using digital measurement devices. The findings of the geostatistical analyses and hydrological and hydraulic modelling will be used to identify critical scenarios of landscape change and stream modification with respect to the course and consequences of flooding. The influence of disturbance and land cover change on fluvial system morphology The final research aim is to analyse how changes in the landscape are reflected in the observable characteristics of the fluvial system, i.e. channels, floodplain, and valley floor. It is particularly during extreme discharge events that such changes occur, as it is then that the fluvial system is most active in reshaping the valley floor. Unfortunately, it is very difficult to directly observe reshaping of the fluvial system morphology during these events as a result of their extreme nature. Nonetheless, it is possible to observe the consequences of these events through the investigation of morphological changes and sedimentary accumulations. The sedimentary record has the advantage of preserving a rather long, generally Holocene, history of fluvial dynamics. Clearly, the research described above requires long-term changes in the valley floor to be observed. This would be impossible to undertake within the framework of a two, three, or four year project. Fortunately, several members of the proposal team have been working in the study area within the framework of several preceding projects. Thus we have collected necessary observations from various time-horizons and created a unique database detailing the consequences of the extreme events during multi-temporal mapping campaigns. 4. Project results Project solution summary Project solution enabled to achieve new findings in the research of landscape disturbance and its effect on the hydrological processess and fluvial dynamics, to apply new technologies of field survey, monitoring and spatial data analysis and to benefit from the interdisciplinary team in the interpretation of processes changing the dynamics of the landscape and of the fluvial processes. In the given key directions of research, the following substantial findings were achieved: Research of the disturbed forest recovery proved that in the spontaneously developing stands, advance regeneration grew very successfully under the protection of dead wood and was sufficient to replace the previous canopy. Moreover, from a comparison with undisturbed stand it is obvious that disturbance in the spruce forest is needed to start the process of its regeneration. Anthropogenic disturbance destroyed a significant part of seedlings and saplings (especially the youngest advance regeneration was eliminated), and artificial reforestation was applied in all plots after salvage logging. Research of snowpack variability and snowmelt rate, based on instrumental monitoring and modeling helped to disclose the role of physiography and forest cover in snowmelt process. Analysis of snowmelt rates in different land cover environments (different types of forests and open area) indicated that the differences in snow accumulation and snowmelt in various types of vegetation are caused mainly by the interception and different amount of solar radiation. The results from study sites proved that the snowmelt in open areas is more than two times faster compared to the forest sites while the snowmelt in clearings, partly protected from solar radiation is only about 50% faster than in the forest. Analysis of the effect of peat bogs on the runoff variability indicated that runoff generation conditions of peatbogs cannot be satisfactorily analyzed by traditional statistical and hydrological approaches. The suitable approach for interpretation of peat bog effects under varying types of events is the application of isotope and hydrochemical tracers. Analysis of long-term trends of mean monthly discharge data Sumava Mts region by proved significant differences between northern and southern slopes of the mountain range. Czech side displayed a significantly increasing trend during early spring and a decreasing trend for late spring and early summer. In opposite, German site indicated significantly increasing trends in early spring and no significantly decreasing trends. Austrian side showed an increasing trend in March but a significant decrease in late spring and early summer. Analysis of climate warming change and forest disturbance effect on runoff indicated that the extent and timing of changes were notable and they can be attributed to the effect of these driving forces. There were identified markeable changes in intra-annual discharge variability and in runoff seasonal distribution with significant shift of peak flows from late spring towards early spring. The turning point of changes correspond to the period of positive difference in annual temperature, detected in observed data since the 1980´s as well as in regional data resulting from the global 20th century climate reanalysis. The runoff variability have in common the point of change of rising values of variability in the period of most extensive forest decay. Analysis of runoff response properties in experimental catchments in relation to their physiography, stage of forest disturbance, and precipitation event characteristics indicated a significant effect of forest cover properties on runoff response. There was not apparent trend in discharge balance; however, there were significant differences in the dynamics of runoff response dynamics and properties to different types of events, namely the storm precipitation, long-term precipitation from regional rains, and droughts. Analysis of paired catchments with contrasting landcover revealed significant differences in daily flow variability between forest and grassland dominated catchments. Runoff was significantly larger in forested catchment, especially in low saturated years, , as well as in cases of high flows. Analysis of past fluvial activity of streams in the study area indicated that the valley floor sedimentary infill is surprisingly shallow (5-10, max. 12 m), notably in the case of Javoří and Roklanský brook where the valley floor width often exceeds 200 - 300 m. The upper part of the valley is predisposed by a significant fault system but there is no incision. The sediment character (coarse material, gentle slopes, and mild valley inclination) indicated strong impact of flood events on the valley floor morphology. Analysis of stream hydromorphology proved significant stream channel changes in the near past. The observed part of Javoří brook remains to be very dynamic till present while the dominating process here is lateral accretion. Stream beds are moved downstream with highly active lateral erosion of the banks. Despite the permanent hith fluvial activity the system of Javoří Brook becomes to be narrower and more stable since 1949 to the present time. This might be result of extensive anthropogenic changes in the past. The river system in currently strictly protected area was subject to channel straightening during the period of intense forest management which was affecting the fluvial dynamics till present. Analyisis of the recent fluvial activity of the montane streams indicated that despite the lack of stream regulations there is high level of spatial concentration of active fluvial processes into isolated zones. The spots of active bank erosion and accumulations are corresponding to the distribution of traces of the past fluvial processes. Results, gained from the coupling of UAV photogrammetry, automated sensor network and hydrodynamic modeling proved that highly dynamic fluvial processes in active zones are triggered already by floods with recurrence periods of 2-5 years. Research results on the recent and past fluvial dynamics are important in integration with the findings on the changing hydroclimatic processes and montane environment. The observed rising frequency of the low magnitude floods, related to the rise of air temperatures and extensive forest disturbance thus have potential to substantially accelerate the processes transforming the stream channels, but spatially concentrated to stream segments with predisposition by given the past processes. The project initiated serveral new international cooperations, aimed in establishing new methods of research and resulting in preparation of joint publications. It applies to following partners and research topics: JRC Ispra - effect of deforestation on soil erosion, Zurich University -snowpack variability, NP Bayerischer Wald - effects of forest disturbance on runoff response, TU Delft - runoff dynamics modeling, and Stockholm University - hydrochemical tracers as indicators of runoff dynamics. From all of the the key directions of research there were prepared papers, published or submitted to relevant international journals in the field with impact factor. The research results were presented at the principal research conferences in the field: Europan Geosciences Union (EGU) 2012, 2013 and 2014 in Vienna, International Associaton of Geomorphology (IAG) 2013, Paris or American Geosciences Union (AGU) 2014, San Francisco. 5. Publications Papers BERNSTEINOVÁ J., BÄSSLER C., ZIMMERMANN L., LANGHAMMER J. & BEUDERT B., 2015: Changes in runoff in two neighbouring catchments in the Bohemian Forest related to climate and land cover changes. Journal of Hydrology and Hydromechanics, 63, 342–352. Borrelli, P., Panagos, P., Langhammer, J., Apostol, B., Schütt, B., 2015. Assessment of the cover changes and the soil loss potential in European forestland: First approach to derive indicators to capture the ecological impacts on soil-related forest ecosystems. Ecol. Indic. 60, 1208–1220. JENÍČEK M., BEITLEROVÁ H., HASA M., KUČEROVÁ D., PEVNÁ H. & PODZIMEK S., 2012: Modelling snow accumulation and snowmelt runoff – present approaches and results. AUC Geographica, 47 (2): 15–24. KAIGLOVÁ J., LANGHAMMER J., JIŘINEC P., JANSKÝ B. & CHALUPOVÁ D., 2015: Numerical simulations of heavily polluted fine-grained sediment remobilization using 1D, 1D+ and 2D channel schematization. Environmental Monitoring and Assessment, 187: 115. KUČEROVÁ D. & JENÍČEK M., 2014: Comparison of selected methods used for the calculation of the snowpack spatial distribution, Bystřice River basin, Czechia. Geografie, 119: 199–217. LANGHAMMER J., MATOUŠKOVÁ M. & KLIMENT Z., 2013: Assessment of spatial and temporal changes of ecological status of streams in Czechia: a geographical approach. Geografie, 118: 309–333. LANGHAMMER J., SU Y. & BERNSTEINOVÁ J., 2015: Runoff response to climate warming and forest disturbance in a mid-mountain basin. Water, 7: 3320–3342. MIŘIJOVSKÝ J. & LANGHAMMER J., 2015: Multitemporal monitoring of the morphodynamics of a mid-mountain stream using UAS photogrammetry. Remote Sensing, 7: 8586–8609. NOVÁKOVÁ M.H. & EDWARDS-JONÁŠOVÁ M., 2015: Restoration of Central-European mountain Norway spruce forest 15 years after natural and anthropogenic disturbance. Forest Ecology and Management, 344: 120–130. SKRČENÁ L., 2013: Analýza fluviálního systému v povodí Roklanského potoka [Analysis of the fluvial system in the Roklanský Potok catchment (with a closer look at VLČEK L., KOCUM J., JANSKÝ B., ŠEFRNA L. & KUČEROVÁ A., 2012: Retenční potenciál a hydrologická bilance horského vrchoviště: případová studie Rokytecké slatě, povodí horní Otavy, jz. Česko., Geografie, 117: 395–41. Theses BAKEŠOVÁ V., 2014: Granulometrická analýza hrubě klastických sedimentů – metody a jejich porovnání. [Comparation of methods of granulometrical analysis of coarse fluvial sediments]. Ms., Bachelor thesis, Faculty of Science, Charles University in Prague, 76 pp. (in Czech). (deposited in the library of Faculty of Science, Charles University in Prague). BEITLEROVÁ H., 2012: Aplikace degree-day modelu akumulace a tání sněhu v povodí Ptačího potoka. [Application of degree-day accumulation and snowmelt model in the Ptačí Potok basin]. Ms., Master thesis, Faculty of Science, Charles University in Prague, 111 pp. (in Czech). (deposited in the library of Faculty of Science, Charles University in Prague). FIALA O., 2012: Změny odtokového režimu v oblasti Šumavy. [Runoff Changes in the Šumava/Bohemian Forest Region]. Ms., Bachelor thesis, Faculty of Science, Charles University in Prague, 100 pp. (in Czech). (deposited in the library of Faculty of Science, Charles University in Prague). FLIEGL O., 2013: Vliv klíčových faktorů dynamiky vývoje sněhové pokrývky v podmínkách Šumavy [Effect of key factors on dynamics of a snow cover evolution in Šumava Mts. Conditions]. Ms., Master thesis, Faculty of Science, Charles University in Prague, 108 pp. (in Czech). (deposited in the library of Faculty of Science, Charles University in Prague). KALKUS J., 2012: Možnosti hodnocení variability odtoku v experimentálních povodích na Šumavě. [Possible assessment of runoff variability at experimental catchments in the Šumava Mountains]. Ms., Bachelor thesis, Faculty of Science, Charles University in Prague, 69 pp. (in Czech). (deposited in the library of Faculty of Science, Charles University in Prague). KODÁDKOVÁ I., 2014: Časová a prostorová variabilita vybraných odtokových epizod v pramenné oblasti Śumavy. [Temporal and spatial variability of selected runoff episodes in the headstream area of the Blanice River]. Ms., Master thesis, Faculty of Science, Charles University in Prague, 100 pp. (in Czech). (deposited in the library of Faculty of Science, Charles University in Prague). KOFROŇOVÁ J., 2014: Význam evapotranspirace v hydrologické bilanci malého povodí.[The role of evapotranspiration in hydrological balance of small catchment]. Ms., Bachelor thesis, Faculty of Science, Charles University in Prague, 47 pp. (in Czech). (deposited in the library of Faculty of Science, Charles University in Prague). LEIPELTOVÁ P., 2014: Definice referenčního stavu horských a podhorských toků jako součást ekomorfologického průzkumu. [Definition of reference conditions of mountain and submountain streams as a part of ecological survey]. Ms., Master thesis, Faculty of Science, Charles University in Prague, 171 pp. (in Czech). (deposited in the library of Faculty of Science, Charles University in Prague). LIHANOVÁ K., 2013: Hodnocení poškození lesních porostů s využitím družicových a lidoarových dat. [Assessments of forest damage using satellite and LIDAR data]. Ms., Master thesis, Faculty of Science, Charles University in Prague, 80 pp. (in Czech). (deposited in the library of Faculty of Science, Charles University in Prague). MACOUNOVÁ K., 2014: Vztah asimilační plochy lesních porostů k intercepci ve vybraných povodích [Relationship of assimilation of forest stands to interception in selected watersheds]. Ms., Bachelor thesis, Faculty of Science, Charles University in Prague, 46 pp. (in Czech). (deposited in the library of Faculty of Science, Charles University in Prague). MATĚJKA O., 2015: Energeticky založený model akumulace a tání sněhu v jehličnatém lese a na otevřené ploše. [An energy-based model accounting for snow accumulation and snowmelt in a coniferous forest and in an open area]. Ms., Master thesis, Faculty of Science, Charles University in Prague, 75 pp. (in Czech). (deposited in the library of Faculty of Science, Charles University in Prague). NEDĚLČEV O., 2015: Vliv intercepce lesního porostu na akumulaci sněhu ve vybraných horských lokalitách v ČR [Effect of canopy interception on snow accumulation at selected alpine localities in the Czech Republic]. Ms., Bachelor thesis, Faculty of Science, Charles University in Prague, 47 pp. (in Czech). (deposited in the library of Faculty of Science, Charles University in Prague). ŠACHOVÁ B., 2013: Vliv klimatické změny na hydrologické sucho v povodí horní Otavy [Climatic change effect on hydrological drought in the Otava River headwaters]. Ms., Master thesis, Faculty of Science, Charles University in Prague, 104 pp. (in Czech). (deposited in the library of Faculty of Science, Charles University in Prague). ŠTYCH P., ŠANDERA J., MALÍKOVÁ L., MARCINKOWSKA-OCHTYRA A., JOROCIŇSKA A. & ZAGAJEWSKI B., 2015: The use of vegetation indices in the evaluation of vegetation phenology based on MERIS data, the Czech Republic case study. AUC Geographica, 50: 101–110. |
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