TY - CHAP A1 - Brück, Yasemine A1 - Schulte-Overberg, Philipp A1 - Pohle, Ina A1 - Hinz, Christoph ED - Schütze, Niels ED - Müller, Uwe ED - Schwarze, Robert ED - Wöhling, Thomas ED - Grundmann, Jens T1 - Ökohydrologische Systeme im Wandel: NDVI von Tagebaufolgelandschaften T2 - M³ - Messen, Modellieren, Managen in Hydrologie und Wasserressourcenbewirtschaftung. Beiträge zum Tag der Hydrologie am 22./23. März 2018 an der Technischen Universität Dresden N2 - Tagebau(folge)landschaften bieten gute Möglichkeiten den Wandel ökohydrologische Systeme aufgrund veränderter Umweltbedingungen zu untersuchen: Im Zuge des Tagebaubetriebs wird die Vegetation vollständig entfernt, nach dem Tagebau wächst die Vegetation entweder durch aktive Rekultivierung oder natürliche Sukzession wieder auf. Von Interesse ist, ob und wie bzw. wie schnell sich die Tagebauflächen von der Störung erholen und ähnliche Bedingungen wie vor dem Tagebau bzw. auf ungestörten Flächen herrschen. Klimatische, geomorphologische und ökologische Gegebenheiten sowie die Rekultivierungsstrategie spielen eine große Rolle in der Phase der Rehabilitation und bestimmen die Rate der Wiederbesiedlung mit Pflanzen bzw. deren Wachstum. Der NDVI (normalisierter differenzierter Vegetationsindex) bietet die Möglichkeit generelle Muster der Vegetation quantitativ zu detektieren, um die Regenerationsrate der Vegetation für verschiedene Klima- und Ökoregionen abzuschätzen. Wir analysierten den MODIS Terra NDVI (achttägliche Werte) für Tagebaulandschaften verschiedener Klimate (äquatoriale, trockene, warm gemäßigte und Schnee-Klimate nach Köppen-Geiger) im Zeitraum 2001 bis 2015. Es wurden Kohletagebaue betrachtet, da diese gut definierte Chronosequenzen der Störung erzeugen. Bei der Analyse der NDVI-Zeitreihen sollten Charakteristiken der Rehabilitationsphase erfasst werden. Um die räumliche Heterogenität der Zellen (ca. 250 x 250 m²) der Tagebaulandschaft abzubilden, wurde je Tagebau eine hierarchische Clusteranalyse durchgeführt. Die einzelnen Zeitreihen der Cluster wurden mit einer Methode zur Detektion von Bruchpunkten und zur Zeitreihenzerlegung auf Konsistenz bezüglich Eigenschaften der Zeitreihen (Beginn des Tagebaus, Ende des Tagebaus/Beginn der Rehabilitation, Rate der Rehabilitation) untersucht. Die Clusteranalyse führt zu einer Einordnung der Zellen in vom Tagebau nicht direkt beeinflusste Flächen, aktiven Tagebau und in der Rehabilitation befindliche Fläche verschiedenen Alters bzw. rehabilitierte Flächen. Das Zeitfenster der Entfernung der Vegetation kann im NDVI-Signal identifiziert werden, es zeigt sich meist in einer abrupten Änderung des NDVI. Die Rehabilitationsphase hingegen verläuft graduell und kann mehrere Jahre bis Jahrzehnte andauern. Die Zeitreihenzerlegung zeigt auf, dass in der Rehabilitationsphase der Trend dominiert, während mit Voranschreiten der Rehabilitation die Saisonalität im NDVI-Signal vorherrschend wird. Durch die ermittelte Rate der Rehabilitation können die Flächen innerhalb eines Tagebaus miteinander verglichen werden. Die mittlere Rehabilitationsrate der Tagebaue kann in Zusammenhang mit den vorherrschenden hydroklimatischen Bedingungen der Klimazonen und mit Rekultivierungsstrategien gebracht werden. Zudem ist auch eine Betrachtung hydrometeorologischer Größen zur Erkennung von kurzzeitigen Veränderungen des Pflanzenwachstums im NDVI-Signal möglich. Y1 - 2018 UR - https://tu-dresden.de/bu/umwelt/hydro/ihm/hydrologie/ressourcen/dateien/tdh2018/TdH_2018_Abstractband.pdf SP - S. 113 PB - Technische Universität CY - Dresden ER - TY - CHAP A1 - Caviedes-Voullieme, Daniel A1 - Andezhath Mohanan, Anju A1 - Brück, Yasemine A1 - Zaplata, Markus Klemens A1 - Hinz, Christoph ED - Schütze, Niels ED - Müller, Uwe ED - Schwarze, Robert ED - Wöhling, Thomas ED - Grundmann, Jens T1 - Effect of surface water redistribution on vegetation encroachment in the constructed Hühnerwasser catchment T2 - M³ - Messen, Modellieren, Managen in Hydrologie und Wasserressourcenbewirtschaftung. Beiträge zum Tag der Hydrologie am 22./23. März 2018 an der Technischen Universität Dresden N2 - The artificial Hühnerwasser catchment has experienced a significant and monitored evolution since 2005, changing from a post-mining landscape to an almost fully vegetated ecosystem. The early stages showed a fast rate of ecohydrological evolution with changing dominating processes and feedbacks. The evolution of rill vegetation encroachment is one of such complex co-evolving processes. We hypothesise that rill vegetation encroachment is driven by the evolution of the hydrologic/hydraulic regime of the rill network, which in turn affects the regime, potentially creating a stabilising positive feedback. We further hypothesise that rill vegetation occurs later than hillslope vegetation, and follows a particular establishment and encroachment timeline in response to the changing hydrological/hydraulic regimes. That is, the early runoff-dominated regime results in higher flows, velocities, transport and erosion capacity, thus favouring seed flushing and seedling uprooting. On the other hand, as the system transitions from a runoffdominated into an infiltration- and ET-dominated system, flow, velocity, transport and erosion capacity in the rill network are reduced, making seed establishment in the rills more likely. We explore these hypothesis with two complementary approaches: an analysis of the spatiotemporal distribution of vegetation and a process-based numerical modelling study. Firstly, we assess aerial photography of rill vegetation encroachment between 2007 and 2012 in terms of several vegetation types to derive temporal indicators of encroachment. The analysis reveals that in the initial stages, a rill network developed in the hillslope. Shortly after vegetation first established on hillslopes, the rill network became progressively vegetated. Different pioneering species established heterogeneously, at different times and encroached into the rills at different rates. However, despite the volume of data, it is difficult to assess which are the governing and limiting processes which respectively drive and constrain how and at which rate vegetation encroaches into the rills. In consequence, a pilot modelling study to identify the relative relevance of rill network geometry, bare soil infiltration, hillslope vegetation heterogeneity and intra-storm variability on the hydraulic response of the rill network and its possible impact on encroachment. The overall results suggest that vegetation encroachment may be controlled by the rill network hydraulic regime, but such regime is the result of a complex superposition of responses of all the aforementioned factors, of which rill geometry appears to be a dominant one. Furthermore, the simulations showed that vegetation spatial heterogeneity has an impact on the hydraulic regime coupled to the presence of temporal rainfall variability. Altogether, these results show that the governing coevolving ecohydrological processes are interacting and are strongly affected by spatial and temporal heterogeneities. Y1 - 2018 UR - https://tu-dresden.de/bu/umwelt/hydro/ihm/hydrologie/ressourcen/dateien/tdh2018/TdH_2018_Abstractband.pdf SP - S. 91 PB - Technische Universität CY - Dresden ER - TY - CHAP A1 - Brück, Yasemine A1 - Andezhath Mohanan, Anju A1 - Caviedes-Voullième, Daniel A1 - Hinz, Christoph A1 - Zaplata, Markus Klemens T1 - Spatio-temporal development of rill vegetation in the Hühnerwasser Catchment T2 - European Geosciences Union, General Assembly 2018, Vienna, Austria N2 - The artificial catchment “Hühnerwasser” was built in a post-mining landscape, as a field experiment to observe and monitor early-development ecosystems at hillslope scale. Early on, rain-induced rill and channels formation was observed, followed by vegetation growth in between rills, and later on inside the rills. In this work, we aim to describe the temporal evolution of the spatial distribution of rill vegetation. In general terms, we hypothesize four different encroachment patterns might occur: (1) The vegetation spreads from the top of the rills downstream. The underlying hypothesis would be a higher establishment probability due to a lower velocity of surface runoff and therefore less transport probability compared to downstream rill segments. (2) The vegetation starts growing downstream and moves upwards. In this case we can hypothesize that the spatial distribution of the vegetation is dominated by water availability, which is higher or more stable downstream. (3) The vegetation encroaches from the sides into the rills, meaning that inter-rill vegetation governs vegetation encroachment inside the rills. (4) If no patterns are detected it might mean that the encroachment process depends strongly on very local conditions, or perhaps that the underlying assumption of an initially homogeneous seed distribution is false. To investigate the rills formation and rill vegetation encroachment processes, rills and vegetation patches inside these rills were identified and digitized from aerial photographs of the catchment from 2007 to 2012. Different vegetation types were identified based on the colour and texture of the patches. The geometrical properties of the rill segments and vegetation patches were used to define how the different vegetation types have distributed in space and how this distribution has changed over time. Rill mapping reveals a large increase of rill area from 2007 to 2008 and only a small rise from 2008 to 2009. Starting in 2010 dense vegetation prevents a precise mapping of the rills in the aerial photographs, so we assume that there is no change in rill area from 2009 to 2012. In 2007 vegetation covered only 1.4% of the rill area. There is only a small increase of this area in 2008 compared to the later years. In 2012 more than 50% of the rill area is covered by plants. Ten different vegetation types have been identified in the aerial photographs, starting with two types in 2007. By 2012 nine types are spotted in the rills of the catchment. Some of these vegetation types show an encroachment from up- to downstream (e.g. Tussilago farfara), some from down- to upstream like Phragmites australis, whose creeping rhizomes can also promote such spreading. Others reveal no patterns. To better assess and identify the underlying processes leading to these encroachment processes shown by the different vegetation types further data analysis –e.g. comparison with ground based vegetation mapping– and process-based hydrological modelling is necessary to fully explain these observations and assessing additional competition effects, which may be at play. Y1 - 2018 UR - https://meetingorganizer.copernicus.org/EGU2018/EGU2018-13391.pdf N1 - EGU2018-13391 PB - European Geophysical Society CY - Katlenburg-Lindau ER - TY - CHAP A1 - Caviedes-Voullième, Daniel A1 - Andezhath Mohanan, Anju A1 - Brück, Yasemine A1 - Hinz, Christoph T1 - Rill hydrodynamics and its impact on rill vegetation encroachment: a modelling study of the constructed Hühnerwasser catchment T2 - European Geosciences Union, General Assembly 2018, Vienna, Austria N2 - The Hühnerwasser catchment is a monitored, early-development constructed catchment within the Lower Lausatia post-mining landscape in Germany. Observations have shown that a sequence of landscape-forming processes occurred, including the initial vegetation establishment stages, which are the main interest of this study. In the initial stages of geomorphic development a surface drainage network of rills was formed as vegetation started to appear on the hillslopes and subsequently inside the rill network. Observations and analysis of the rill vegetation establishment suggest that different vegetation types encroach into the rill network at different times, rates and form different directions. We hypothesize that these encroachment processes may respond to the runoff properties of the catchment at such time: velocity distribution in the rills might play a significant role in flushing seeds in high-velocity reaches of the rill network, thus favouring the appearance of vegetation in low-velocity regions. Consequently, the goal of this study is to assess the magnitudes and spatiotemporal behaviour of velocity in the rill network, to assess its possible impact on seed flushing and rill vegetation encroachment. One rill subcatchment of Hühnerwasser was selected to perform an explorative study of rill hydrodynamics and their impact on vegetation establishment. Two vegetation states were simulated: bare hillslopes and vegetated hillslopes. The vegetated cover polygons were obtained from digitized aerial photography, and stochastically dissagregated 10-minute resolution precipitation data were used, selecting events with early, middle and late peak storm intensities. A 2D explicit finite volume scheme solving the Zero-Inertia approximation to the shallow water equations was used to simulate surface flow in the subcatchment. The preliminary modelling results suggest that that there is no clear overall velocity gradient in the downstream direction along the rills. In fact, velocity in the rills may increase or decrease along the rill following local topography and rill geometry. Consequently, no global trend for the probability of seeds being transported can be established. The results also shows that varying rainfall intensity and rainfall intrastorm distribution –in the absence of hillslope vegetation– does not affect the rill locations of maximum velocities, but mostly affect the magnitude of velocity. In the presence of hillslope vegetation –and thus heterogeneous infiltration conditions in the hillslopes– the spatial distribution of velocity is strongly affected, and can be in fact governed not by topography or rill geometry, but by the spatial heterogeneity of infiltration capacity. Furthermore, the time at which maximum discharge and velocities occur may not match that of maximum intensity. That is, emerging temporal dynamics arise due to the introduction of spatial heterogeneity, which also manifests in the fact that outflow from the subcatchment exhibits a intensity-thresholded behaviour. Y1 - 2018 UR - https://meetingorganizer.copernicus.org/EGU2018/EGU2018-13392.pdf N1 - EGU2018-13392 PB - European Geophysical Society CY - Katlenburg-Lindau ER - TY - CHAP A1 - Brück, Yasemine A1 - Schulte-Overberg, Philipp A1 - Pohle, Ina A1 - Hinz, Christoph T1 - NDVI (Normalized Difference Vegetation Index) signatures of transient ecohydrological systems: The case of post-mining landscapes T2 - European Geosciences Union, General Assembly 2017, Vienna, Austria N2 - Assessing ecohydrological systems that undergo state transitions due to environmental change is becoming increasingly important. One system that can be used to study severe disturbances are post-mining landscapes as they usually are associated with complete removal of vegetation and afterwards subsequent ecosystem restoration or spontaneous rehabilitation in line with natural succession. Within this context it is of interest, whether and how (fast) the land cover in these areas returns to conditions comparable to those in the undisturbed surrounding or those prior mining. Many aspects of mine site rehabilitation depend on climatic, geomorphic and ecological settings, which determine at which rate vegetation may be reestablished. In order to identify general patterns of vegetation establishment, we propose to use NDVI (Normalized Difference Vegetation Index) time series for mine affected land to estimate rate of recovery across climate regions and ecoregions. In this study we analysed the MODIS Terra Satellite 8 day-composite NDVI for areas influenced by surface mining in different climates from 2001 to 2015. The locations have been chosen based on their extent and the data availability of mining and rehabilitation activities. We selected coal extraction as a case study as strip mining generates well-defined chronosequences of disturbance. The selected mining areas are located in equatorial, arid, warm temperate or snow climates with different precipitation and temperature conditions according to the Köppen-Geiger classification. We analysed the NDVI time series regarding significant characteristics of the re-vegetation phase. We applied hierarchical cluster analysis to capture the spatial heterogeneity between different pixels (ca. 250 * 250 m2 each) in and around each open cast mine. We disentangled seasonality, trend and residual components in the NDVI time series by Seasonal and Trend decomposition using LOESS. As expected the time of the removal of vegetation can be clearly identified from the NDVI time series and provides the starting point of disturbance. The cluster analysis allowed us to distinguish between the non-mining land, the mine and the restored land of different ages. Based on these clusters, the time series decomposition revealed the dominance of the trend of increasing NDVI in areas undergoing the restoration process as well as the prevailing seasonality of the oldest restored sites. The determined phase of a dominant trend component, lasting until the NDVI is in the range of the surrounding landscape or the pre-mining conditions, is in the scale of a decade. The impacts of different hydroclimatic regimes and different rehabilitation strategies on long term NDVI development are currently being investigated. Furthermore, coherence analysis will be applied to quantify short term influences of hydrometeorological variables on vegetation development. Y1 - 2017 UR - http://meetingorganizer.copernicus.org/EGU2017/EGU2017-5353.pdf N1 - EGU2017-5353 PB - European Geophysical Society CY - Katlenburg-Lindau ER - TY - CHAP A1 - Maurer, Thomas A1 - Brück, Yasemine A1 - Hinz, Christoph A1 - Gerke, Horst H. T1 - Modeling 3D soil and sediment distributions for assessing catchment structure and hydrological feedbacks T2 - European Geosciences Union, General Assembly 2015, Vienna, Austria, 13 April - 17 May 2015 Y1 - 2015 UR - http://meetingorganizer.copernicus.org/EGU2015/EGU2015-12519.pdf N1 - EGU2015-12519 PB - European Geophysical Society CY - Katlenburg-Lindau ER - TY - CHAP A1 - Brück, Yasemine A1 - Pohle, Ina A1 - Keuler, Klaus A1 - Schaller, Eberhard A1 - Hinz, Christoph T1 - Do mining lakes in the Lusatian Lignite mining region (Eastern Germany) affect regional precipitation patterns? T2 - European Geosciences Union, General Assembly 2016, Vienna, Austria N2 - Due to the flooding of former open-pit mines, Europe’s largest artificial lake district is created in Eastern Germany. Between 1990 and 2006 more than 80 km² of new lakes have already been formed. These large-scale land cover changes may impact regional meteorological characteristics, therefore it is of interest, whether effects of the mining lakes can already be observed. We especially focus on whether the evaporation from the mining pit lakes leads to a higher precipitation on their lee side. To detect changes in the precipitation patterns, we analysed daily precipitation data (1980-2014) of 25 stations in an area of 10 000 km² widely around the lake district. Under the assumption that the influences of the lakes should be detectable either directly as trends in the observed data or as a deviation from a general measure for precipitation we combined statistical tests and principal component analysis (PCA). We applied pre-whitening Mann-Kendall tests to detect precipitation trends and Mann-Whitney tests to detect differences between split samples (before and after the flooding of most of the lakes). The PCA was applied based on the correlation matrix of daily precipitation at the different stations. As the daily precipitation can sufficiently be explained by the first five principal components, the recombination of these five principal components was used as a general measure of precipitation in the region. By regression trees (random forests) a relation between the eigenvectors of the first five principal components and physiogeographic characteristics of the stations (e.g. altitude) was shown. Both the observed data and the deviations between the measurements and the recombination of the first five principal components showed divergent trends with high spatial variability and also interannual variability, but a pattern consistent with the lee side of the lake could not be detected. Therefore, it has been demonstrated that the emerging lakes had no influence on the daily precipitation at the stations considered in this study. This may be explained by the coarse spatial and also temporal resolution of precipitation measurements. Still, the approach presented here can be applied to (i) detect changes in the spatial pattern of climate variables by a combination of statistical tests and PCA and (ii) to analyse the relationships between such changes and physiogeographic characteristics by regression trees. Y1 - 2016 UR - http://meetingorganizer.copernicus.org/EGU2016/EGU2016-7663.pdf N1 - EGU2016-7663 PB - European Geophysical Society CY - Katlenburg-Lindau ER - TY - GEN A1 - Brück, Yasemine A1 - Rojas, Pedro A1 - Caviedes-Voullième, Daniel A1 - Hinz, Christoph T1 - Processing of aerial images to detect vegetation cover and evaluate transient vegetation patch characteristics of Hühnerwasser catchment T2 - European Geosciences Union, General Assembly 2019, Vienna, Austria, 7–12 April 2019 N2 - The artificial catchment “Hühnerwasser” was built in a post-mining landscape, as a field experiment to observe and monitor early-development ecosystems at first catchment scale. As vegetation is a key driver of hydrological catchment behavior, spatial distribution and temporal dynamics of vegetation affects water redistribution from plot to catchment scale. In the context of early ecosystem development, quantifying changes in vegetation structures is an obvious indicator for state transitions. The first years of ecosystem development at the Hühnerwasser catchment showed rapidly increasing complexity of emerging structures associated with rising vegetation cover and increasing number of plant species. This work will focus on characterizing vegetation cover using aerial images aiming to describe spatial structures and how those evolve in time. The early stages are especially of interest. The structure is therefore characterized by the area of the catchment covered by vegetation, the number of vegetation patches, the mean and maximum patch size and a form factor (area of patch divided by its perimeter). Aerial images with a resolution at cm scale were taken once per year from 2007 to 2018. Binary maps are generated by setting thresholds for red, green and blue channels to differentiate between vegetation cover and bare soil. To evaluate the consistency of the binary images of each channel these images were stacked and compared. The performance of the method was tested by using a set of combinations of thresholds and a comparison with manual mapping of vegetation cover at an image subset was made. The blue channel seems to be very sensitive to detect vegetation and a better differentiation of vegetation and dark/wet soil can be achieved by setting the thresholds of the channels in a specific order. The structures derived by the classification into vegetated and bare soil are more important in the early years of ecosystem development. In those years (2007 to 2011) the most changes took place. As time advances vegetation became less patchy and other characteristics need to be implemented to describe the vegetation cover, taking into account different plant functional types. Y1 - 2019 UR - https://meetingorganizer.copernicus.org/EGU2019/EGU2019-14603.pdf CY - Katlenburg-Lindau ER -