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Recently, applications of soil and water bioengineering constructions using living plants and supplementary materials have become increasingly popular. Besides technical effects, soil and water bioengineering has the advantage of additionally taking into consideration ecological values and the values of landscape aesthetics. When implementing soil and water bioengineering structures, suitable plants must be selected, and the structures must be given a dimension taking into account potential impact loads. A consideration of energy flows and the potential negative impact of construction in terms of energy and greenhouse gas balance has been neglected until now. The current study closes this gap of knowledge by introducing a method for detecting the possible negative effects of installing soil and water bioengineering measures. For this purpose, an environmental life cycle assessment model has been applied. The impact categories global warming potential and cumulative energy demand are used in this paper to describe the type of impacts which a bioengineering construction site causes. Additionally, the water bioengineering measure is contrasted with a conventional civil engineering structure. The results determine that the bioengineering alternative performs slightly better, in terms of energy demand and global warming potential, than the conventional measure. The most relevant factor is shown to be the impact of the running machines at the water bioengineering construction site. Finally, an integral ecological assessment model for applications of soil and water bioengineering structures should point out the potential negative effects caused during installation and, furthermore, integrate the assessment of potential positive effects due to the development of living plants in the use stage of the structures.

This study emerged from a research project that aimed to develop a Life Cycle Assessment (LCA) model for torrent control structures. This publication constitutes the last part of model development and shows the LCA results of the examined structure types considering the entire life cycle. These LCA results will be used in a further step to close the environmental knowledge gap within the area of sustainability assessment. The sustainability assessment of buildings is already widespread and standardised in Green Building Rating Systems (GBRSs), which use LCA benchmarks for the rating of environmental indicators. The development of GBRSs for infrastructure is somewhat younger than the developements in the building sector and the existing systems do not yet provide LCA benchmarks for the environmental rating of the structures. The study shows how to derive benchmarks from the LCA results and thus gives a quantitative basis for a future rating of environmental indicators of torrent control structures. The methodological basics for the LCA of torrent control structures were created by screening LCAs of several construction projects. From these construction projects, different structure types could be identified and classified. Functional units were developed, which can be assigned to the structure types. Uncertainties arise because these structure types are not always built in the same way. It can be distinguished between five uncertainties. Uncertainties of material dataset modeling, variable material use and machine use have been identified. Furthermore, the variable material use influences the emissions of transport. The transport in turn demonstrates uncertainties in the transport distances. Last but not least, there are variable service life times that dictate the replacement cycles of the structures. LCA benchmarks can be derived by the elevation of the various uncertainty distributions and its application in a Monte Carlo simulation. By applying the method described above, it was possible to develop LCA benchmarks for different types of torrent control structures. These benchmarks show the range of LCA results for these structures. Furthermore, a sensitivity and uncertainty contribution analysis was carried out to investigate dependencies. By determining the range of LCA results, an estimate of environmental impacts in early planning stages becomes possible. Furthermore, this allows decision-making in early planning stages and throughout the entire life cycle of the structures, taking into account environmental impacts. A further development of the benchmarks requires the analysis of additional structures to increase the accuracy and to reduce parameter uncertainties.

In the last decades, soil bioengineering has gained considerable popularity worldwide, especially in hillslope, riverbank, and earth embankment stabilisation works. The use of plants as a building material transfers the plant multifunctionality within engineering structures and meets the demand rising from society for more environmental-friendly approaches to structure design. In addition, soil bioengineering approach complies with public policies, such as EU strategies concerning the green infrastructures, the circular economy and the green deal, as well as the global framework defined by the Global Goals for Sustainable Development. Despite the widespread use of soil bioengineering techniques and their adherence to the new directions of public policies, however, quantitative and temporal aspects of soil bioengineering approach are not fully considered. Construction criteria typical of civil engineering approaches, such as safety, serviceability and duration, need to be evaluated and fulfilled by bioengineering measures in an analog way as for technical construction, with the additional effort to consider spatial and temporal variability of their properties. In particular, it must be considered at the same time the dynamic temporal development of vegetation (especially the dynamic of root reinforcement) and the decrease in strength of some additive construction material (e.g. wood decay). A comprehensive design scheme, comparable with the one for conventional engineering structures, is still lacking. In this paper, knowledge and tools aiming to address the above issues, are reviewed, with particular reference to points associated with the structural stability of soil bioengineering structures for shallow landslide stabilisation. The paper: - provides the background to the traditional engineering design for slope stabilisation, and the normative state of the art of geotechnical and construction design, as well as the residual risk of slope stabilisation; - considers the temporal issues associated with the vegetation and the effect of soil bioengineering structures on the stability of natural, man-made, and anthropogenically influenced slopes; - develops a decision framework for soil bioengineering applications that explicitly considers quantitative and temporal aspects of soil bioengineering approach, highlighting critical parameters governing the design with vegetation against shallow slope instability; - critically debates the issues of the quantifiability of vegetated slopes and the use of permanent and temporary inert material.

The present work describes a transferability analysis for soil and water bioengineering techniques as an instrument for sustainable erosion control in Central and South America based on an empirical data base from the last decades. In total, 31 case studies in Mexico, Nicaragua, Guatemala, Colombia, Ecuador and Brazil generated a database from an area where soil and water bioengineering techniques are not commonly used. The Transferability Analysis is structured in seven steps: (1) Objectives of the procedure, (2) Impacts of the measure, (3) Identification of up-scaling/down-scaling needs (4) Identification of the main phases and its components, (5) Identification of the level of importance of the components, (6) Assessment of the components in the context of the Take-Up Site and (7) Conclusions. For the assessment of soil and water bioengineering via the Transferability Analysis, in step 4 the following main phases have been identified from the data base: (a) Planning Phase, (b) Construction Phase, (c) Use Phase, as well as (d) End of Life Phase of a construction. Within these categories, 14 components have been defined: (a) know-how of soil and water bioengineering techniques, local climate conditions, botany, hydraulics, pedology, (b) materials, qualified labor, equipment and mechanical instruments, economic resources, (c) monitoring, efficiency, sustainability, maintenance, (d) replicability. The following assessment of the components allowed to determine key barriers, as well as key support factors for the transfer of soil and water bioengineering. As a result, barriers appeared to be the components qualified labor, equipment/mechanical instruments, hydraulics, know-how in soil and water bioengineering and pedology. Neither barriers, nor supporting key factors resulted to be the components local climate conditions, economic resources and efficiency. Supporting key factors for the transfer were materials, monitoring, sustainability, maintenance and replicability. The most important key factor of success was assessed to be botany, as various plant species with important characteristics for soil and water bioengineering are available in Central and South America, able to compensate the constraints through barriers in certain cases.

Considering the high abundance of knotweeds along river courses, the expected increase of invasion and the consequent negative impacts on riparian ecosystems, there is a high demand for innovative approaches and management strategies. While a primary aim of weed management is to reduce the population of an invasive plant species, the goal of the pre-sented nature-based engineering solution (NABES) is to reinstall native riparian forests and to restore ecosystem functioning. The concept of NABES is to support the implemented species by frequent removal of the knotweed shoots until the native vegetation represses the knotweeds by root competition and shadow pressure. In order to be able to develop adaptive knotweed management strategies, knowledge concerning sea-sonal biomass development and the most effective maintenance intervals must be improved. Additionally, greater understanding of the interaction between invasive and native species is essential. In the present study, the effectiveness of a willow brush mattress (a frequent technique for controlling riverbank erosion) in combination with adapted management strategies was tested on a Fallopia japonica-dominated brook embankment. Due to its high ecological amplitude and excellent soil bioengineering properties the species S. purpurea was used. In the upper part of the embankment, F. japonica shoot production was by far the strongest, while it was low in the sections next to the water. The strongest biomass production was observed in the months April and May. Even though the temporal interval between shoot removal was increased, shoot production decreased strongly and nearly ceased in August. Branches of S. purpurea with contact to the water of the brook showed good development. In contrast to F. japonica, which suffered a rapid decrease in biomass production after the third survey, the coverage ratio of S. purpurea decreased gradually over the vegetation period.

Cuttings are a common soil and water bioengineering technique used for slope stabilization and erosion control along rivers. Above- and belowground growth of cuttings, especially immediately after installation, have a strong impact on the protective performance. To assess the effects of diameter on the early growth performance of purple willow (Salix purpurea L.), freshly harvested (nondormant) cuttings of different diameters (5 to 24 mm) were planted as part of an outdoor raised-bed experiment from March to October of 2010. The aim of this study was to investigate the growth performance of purple willow cuttings and to gain deeper insight into the plant9s development during the first growth stage (six months). After two months of growth, 99% of the cuttings sprouted, and the diameter had no statistically significant impact on the sprouting performance of the cuttings. During the first four months, aboveground biomass production (Mag) was 5.7 and 4.4 (after two and four months, respectively) times higher than belowground biomass (Mbg). However, after six months, Mag and Mbg were balanced. The diameter of the cuttings had a significant impact on biomass development at all of the time steps. The cuttings of the diameter class C (15 to 19 mm) produced the most Mag and Mbg, with 33% and 34% of total Mag and Mbg of all diameter classes after six months. Four months after planting, at least 80%, and after six months at least 90%, of the Mbg was allocated in the lowermost third of the cuttings. The observations showed high Mag production for the entire period; Mbg production was relatively low during the first four months, which resulted in a diminished protective function of the roots until this specific point of development.

The Austrian Federal Railways (ÖBB) are operating about 4800 kilometers of railway track in all regions of Austria. Most parts of this infrastructure are exposed to various natural hazards like landslides, debris flows, rockfalls, floodings and avalanches but also extreme weather events like strong winds or extreme heat can disrupt railway traffic. The frequency of their occurrence is changing due to recent climate change.We use over 2000 events from 1990 to 2018 and a principal component approach to create an event space which lets us combine events and meteorological data on a fine spatial grid. This is necessary to detect characteristic climate-indices (CIs) in temporal series of meteorological parameters, like temperature or precipitation, that have negative effects on railway operation or trigger natural hazards that do so. The results are evaluated using various multivariate statistic methods to quantify the quality of the found CIs.After these steps we can estimate the frequency of CI occurrence in near (2036-2065) and remote future (2071-2100) by analyzing ensembles of downscaled GCM projections for different climate scenarios. The result are hazard-development-corridors that are a relative measure for the number of predicted hazard events during the two periods of time along the considered railway tracks.

Due to the growing stock of torrent control structures and decreasing investments, the protection level can be reduced in the long term. Therefore, the focus of the future investments has been shif...

Soil and Water Bioengineers using plants for civil engineering purposes are faced with challenges to determine the interrelation of dynamic and architectural properties of riparian trees. This study aims to improve the characterization of young riparian trees (Salix purpurea L.) in the framework of such an eco-engineering approach. Dimensioning the mechanical effects of a complex multilevel system in a temporal and spatial context is a key issue understanding the plant-fluid interaction. We investigated the natural frequency (fn), the damping ratio (ζ) and the architectural properties of three 4 year old purple willow specimens. From a tree architectural point of view, we found a clear distinction of the specimens in terms of the distribution of the projected area along the tree height, and for the slenderness ratio over the axes orders. The foliage of the specimens had a significant impact on the damping ratio depending on the tree architecture. A high slenderness ratio across the tree axes increased the flexibility of the branching system, and reduced the share of the foliage impact on the damping ratio. In comparison, a low slenderness ratio led to a stiffer tree structure, and therefore the damping ratio, due to the aerodynamic drag of the leaves, had received a higher share of the total damping ratio. Linking tree architectural analysis with its dynamic properties proved to be helpful in advancing the physical characterization of complex riparian trees.

A module-based Green Infrastructure (GI) and Ecosystem Service (ES) approach, adapted to the specific requirements and conditions for railway line-side vegetation management, is presented in this paper. The multi-functionality of line-side vegetation is addressed by an integration of the GI and ES concepts. The use of widely available geo-data enables its applicability, both in terms of large-scale and other infrastructure networks. In this way it can serve as a feature for emphasizing the creation of a productive, attractive and cost effective landscape resource. A methodological approach for the Ecosystem Service Demand Assessment (ESDA) of GI line-side elements was developed and applied at a study site. An ESDA was performed concerning “Structural landscape diversity” and “Water and climate regulation”. The results represent the composition of landscape types, the demand for structural landscape features, the distribution of GI line-side elements and hotspots of land consumption. Additionally, potential capacity of GI line-side vegetation to provide ecosystem services was addressed. Maps created provide basic information for the railway operator to consider ecosystem service demand in construction and maintenance works. In this way, the presented GIS approach can support decision-making-sovereignty in implementing holistic line-side vegetation management strategies. The use of high resolution geo-data proved to provide a good basis for the accurate mapping of GI line-side elements. The study has confirmed that high resolution geo-data and GIS technologies have great potentials regarding spatial data provision and as analytical frameworks for line-side vegetation management.

The purpose of this article is to find a suitable life cycle assessment (LCA) method to quantify the most important environmental burdens caused by construction processes of torrent control structures. To find these environmental burdens, 17 construction projects of the “Austrian Service for Torrent and Avalanche Control” (WLV) were analyzed using the “cradle to gate with options” LCA methodology (CEN, 2013). This article explains an LCA methodology for the product stage and the construction process of torrent control structures following existing standards. The iterative approach of LCA methodology (ISO, 2006a) was used to record all important processes of the system and to supplement missing information. The LCA methodology has been developed from existing standards of the construction and product sector. Since the production of some construction materials takes place locally, the generic data, for Austria, was adapted. Wood inherent biogenic carbon and primary energy, used as raw material, are treated as materials inherent properties (CEN, 2014). The contribution of the various processes was reproduced by hotspot. Hotspots of the different stages are related to the construction materials used. The emissions and primary energy inputs in the product stage are clearly dominated by concrete and steel. If these two materials are used sparingly, the focus is on machine application and transportation. Depending on the selected scenarios, the smallest share of emissions, in relation to the total result of product and construction stage emitted by transport, is 3% and the maximum share is 69%. The greatest environmental impacts in the construction stage are caused by excavation work and transportation on-site. With an average of 4% in the construction stage, the transport of workers to the construction site cannot be neglected as is done in the building sector. The conclusion of this study is that existing LCA models can be adapted to protective structures. In contrast to conventional buildings, the construction process and transportation are much more important and cannot be neglected. Shifting the hotspots to these processes requires specific calculation rules for that particular field. There is still a need for research to find a suitable functional unit and to develop a methodology for the use and end of life stage of these structures.

In recent times, a trend towards more climate-friendly and sustainable strategies and techniques in the field of civil engineering has arisen. For this reason, there is a high demand for engineerin...

The greening of shotcrete walls represents a major challenge due to the extreme environmental conditions for plants and its technical implementation aiming to establish a sustainable vegetation layer. The objective of the study was to assess the performance of an innovative ‘Green Wall’ system (double-layered, integrated irrigation, filled with excavation material, application on vertical inclination) with respect to its microclimatic characteristics. The measurement campaign was conducted from June 2015 to September 2016 in Plon (Steinach am Brenner, Tyrol, Austria). Microclimatic parameters (air temperature, air humidity, short-wave radiation, substrate temperature and wall surface temperature) were investigated by sensors installed in different layers of the greenery system, as well as in a control area (bare concrete wall). Results indicated a pronounced insulation effect of the ‘Green Wall’ system during summer and wintertime. Analyses in July 2015 (30% vegetation cover) and July 2016 (100% vegetation cover) indicated that reductions of temperature fluctuations were predominately attributable to the substrate layers of the greenery system and less to the vegetation cover. Furthermore, reductions of albedo (reflectivity) and heat stress were achieved. In conclusion, the ‘Green Wall’ system is a promising technique with positive effects regarding temperature and radiation as well as human thermal sensation and therefore recommendable for use also in urban areas. In rural areas it helps to optimize landscape aesthetics, as even vertical slopes can be greened.

River morphology, field study. Riparian vegetation, field study. Stream water temperature, oberservations and predictions. Near stream microclimate, oberservations and predictions. Fish species and assemblages, sampling. Benthic invertebrate abundance and diversity, sampling. Initially only stream water observations, predictions of the river Pinka and corresponding input data for extreme heat wave events used in Trimmel et al. (2016b) are available for download. Other parts of the data set may be included later after they have been published.

Vorliegende transdisziplinare Studie untersuchte im Rahmen des ACRP Projektes BIO_CLIC die Wirkung der Ufervegetation auf das Wassertemperaturregime sowie die Interaktionen mit aquatischen Organismen von kleinen und mittelgrosen Flussen am Beispiel von Lafnitz und Pinka. Ziel ist es, relevante Zusammenhange zu analysieren und darzustellen, um daraus Managementmasnahmen und Anpassungsstrategien entwickeln zu konnen. Die beiden Flusse befinden sich im Sudosten Osterreichs, einer Region, die nach derzeitigem Wissensstand mit relativ starken Auswirkungen des Klimawandels zu rechnen hat. Es ist davon auszugehen, dass der Klimawandel die Wassertemperaturen nicht nur steigen lasst, sondern dass auch haufiger Hitzeperioden auftreten konnen. Im Zuge der vorliegenden Arbeit wurden die thermischen Habitate sowie die Ufervegetation erfasst und die longitudinale Verbreitung von Fischen sowie der benthischen Evertebraten-Fauna (gewasserbodenbewohnende wirbellose Lebensgemeinschaft) analysiert. Dabei stellt die Lafnitz, vor allem im Mittellauf, ein weitgehend naturnahes Gewasser dar, wahrend die Pinka starke anthropogene Beeintrachtigungen aufweist. Eine Synthese von Wassertemperatur und Ufervegetation mit der Fisch- und wirbellosen benthischen Fauna, in Form von „Fact Sheets“, zeigt sehr grose Unterschiede an sechs verschiedenen „Hot Spots“ und unterstreicht die Bedeutung abiotischer gewassertypspezifischer Parameter fur aquatische Lebensgemeinschaften. Die globale Erwarmung zeigt heute bereits Auswirkungen auf Fliesgewassersysteme und wird in Zukunft diese Okosysteme und ihre Leistungen noch starker beeinflussen. In naturnahen Flussabschnitten mit geringen menschlichen Belastungen betragt der Wassertemperaturunterschied zwischen den biozonotischen Zonen im Sommer zwischen 2 °C und 3 °C und ist somit oft ein trennender Faktor zwischen den Zonen. Hohere Wassertemperaturen zwingen die Zonosen zu Anpassungen oder zur Abwanderung in Abschnitte, wo geeignete Habitate vorhanden sind. Ein Anstieg der Wassertemperatur um 2 °C fuhrt daher zu einer Verschiebung der Artenzusammensetzung. Die Ufervegetation ist fur die aquatische Okologie unserer Fliesgewasser wichtig und hat durch die zukunftig zu erwartenden Auswirkungen des Klimawandels auf das thermische Regime eine besondere Bedeutung. Sie kann durch ihre beschattende Wirkung, besonders in Hitzephasen, die Erwarmung der Wassertemperatur um bis 2 °C verringern. Die Synthese unterstreicht, dass fur nachhaltige Flussrevitalisierungen, die Berucksichtigung der gewassertypspezifischen Ufervegetation sowie eine entsprechende aquatische Habitatausstattung unumganglich ist.

Railway networks are linear landscape elements that are mostly accompanied by adjacent lineside vegetation. In order to maintain safe railway operation, lineside vegetation must be continuously monitored and maintained. A large-scale assessment approach to identify safety-relevant woody vegetation structures along a railway corridor is presented in this paper. Based on accurate surface and terrain data, precise models of the lineside vegetation and the railway corridor were created for a study site. A proximity analysis was performed to assess elements of woody vegetation that are tall enough and close enough to strike the railway infrastructure in the case of failure. Information about the vegetation type and the geometric position of identified safety-relevant vegetation is provided in hazard classes. Falling curves of safety-relevant vegetation were calculated to indicate areas where trees pose a potential risk to the railway track. Analysis of datasets from 2012 and 2017 shows a dynamic development of safety-relevant vegetation along the railway corridor between the two studied years. A vegetation risk index (VRI) was calculated for the study site. Both sections of high presence and sections where safety-relevant vegetation is completely absent could be identified. The study has confirmed that airborne remote sensing technologies have great potential to provide data for large-scale lineside vegetation assessments. Through a combination of airborne laser scanning data and high resolution orthophotos, safety-relevant vegetation could be mapped successfully. The presented approach can support tree care management and contribute to maintaining safe and functional lineside vegetation.

One of the principal purposes of soil bioengineering is the application of vegetation layers from a civil engineering point of view. Living plants are used to reinforce slopes and to control erosion. For a standardised implementation, it is essential to quantify the effectiveness and to assess technical parameters for such bioengineering systems. The objective of this study is to investigate the flexibility of stems and branches of different riparian species of the area of Southern Brazil suitable for soil bioengineering (Phyllanthus sellowianus Müll. Arg., Sebastiania schottiana (Müll. Arg.) Müll. Arg., Salix humboldtiana Willd., and Salix×rubens Schrank). Fifty specimens (green stem samples) were collected in the surroundings of Santa Maria, state of Rio Grande do Sul, Brazil, and subjected to static bending tests. Their overall deformation behaviour (elastic and plastic) is of crucial importance for bioengineering systems. Thus, additional to the state of the art of material parameters, a new parameter is introduced: the "angle of flexibility". This parameter describes the elastic and plastic deformation behaviour of a plant under load in a more engineering practival experience. The results show that the species of Phyllanthus sellowianus is the most flexible species, followed by Sebastiania schottiana, Salix humboldtiana and Salix×rubens.

This paper investigates the structural properties of four common riparian tree species and their reconfiguration under hydrodynamic loading in a towing tank in foliated and defoliated conditions. 3D tree models were generated by digitizing twenty 0.8–3.3 m tall specimens at branch level. Branch diameters and lengths were measured in order to calculate the one-sided stem area and stem volume over the plant height. The novelty of the investigations originated from the characterization of the reconfiguration which was achieved by combining the contracted width, the deflected height, and the underwater projected area in order to determine the porosity at different velocities. The results showed that the basal diameter could be used to predict the entire total one-sided stem area, although this method was not capable of reproducing the observed non-linear vertical distributions. The flow-induced width contraction contributed significantly to the reduction of the rectangular cross-sectional area occupied by the plant. The porosity of the foliated trees increased at the lower velocities, and then decreased at the higher velocities. Overall, detailed spatial–structural analyses of woody vegetation provided valuable information about plant behaviour under load, and thus are helpful for improving the determination of the physically based parameters of complex vegetative elements which is highly relevant for environmental modelling in order to fill the gap of knowledge concerning the hydrodynamic and aerodynamic flow around trees.

It is important to select the appropriate plants for soil bioengineering by taking their development and the root anchorage into consideration. The aims of the study were to evaluate the survival rate and anchorage capability of five species planted as cuttings and to further investigate the interrelationship of pull out force and plant morphology. Above 90% of Salix matsudana cv. Umbraculifera , Populus canadensis Moench , Salix alba var.Tristis and Salix purpurea cuttings survived. Less than 30% of Amorpha fruticosa L. survived. The highest number of roots had developed in the 30–40 cm stem section in the deepest layer of soil. A total of 77 cuttings were vertically pulled out and the morphological characteristics of their root structure were measured. Cuttings of S. matsudana cv. Umbraculifera showed the greatest uprooting resistance (1214.8 N), followed by A. fruticosa L. (1043.9 N), P. canadensis Moench (879.7 N), S. purpurea (802.9 N) and S. alba var. Tristis (765.2 N). Uprooting resistance was effected mostly by the roots than by the shoot profiles. The pull out resistance force ( F max ) has shown the best relationships with multiple morphological parameters as total number of roots combined with root dry mass ( P The species with the highest capability suitable for purposes of soil bioengineering should be S. matsudana cv. Umbraculifera , P. canadensis Moench , S. purpurea and S. alba var. Tristis . A. fruticosa L. is not suitable for being used in soil bioengineering techniques due to its low level of survival rate.

Soil bioengineering has been applied more and more in different regions of Brazil in recent years. The study in hand presents the installation of “new” riparian forest based on soil bioengineering techniques. This riverbank restoration work was implemented in the year 2010 and two onsite vegetation surveys, one shortly after the construction, and one in 2013. Besides that, the structures of reinforcement work, and its effectiveness were evaluated. By means of the vegetation survey, the applied species were examined for their ability to establish the riverbank in an environmentally sustainable way. Most notably, the species Calliandra brevipes Benth. (Fabaceae, Mimosoideae), Phyllanthus sellowianus Muller Arg. (Euphorbiaceae), Salix humboldtiana Willd. (Salicaceae), Bauhinia forficate Link (Leguminosae), Inga marginata Willd. (Mimosoideae) and Ateleia glazioveana Baill. (Leguminosae, Papilionoideae) showed a good growth development. The proportion of spontaneous vegetation increased significantly, with Pennisetum purpureum Schumach. becoming a dominating species. Resulting from that, the intervention can be assessed as functional and safe, but the strong increase of spontaneous vegetation is undesirable due to less flood resistance. The vegetated riprap could be the best to meet the expectations of the construction elements. Partly, the anchored willows showed as well a good growth development whereas the species used for the hedge brush layer could not develop as expected in large parts of the construction.

Riparian vegetation strongly influences the solar radiation input, especially into small- to medium-sized rivers. Solar radiation is one of the main impact factors concerning the river water temperature regime. Effects of different vegetation management strategies on incident solar radiation are to a large extent unknown. In this study, the stream vegetation model Shade-a-lator 6.2 is calibrated using experimental investigations. The Shade-a-lator 6.2 model is adapted for simulations of the influence of willow coppice riparian vegetation on incident solar radiation on rivers since they are characteristic species of riparian plant associations. The main objective is the simulation of riparian vegetation management scenarios based on the calibrated Shade-a-lator 6.2. Results show that plant configuration effectively influences the energy input into the river system. The Shade-a-lator 6.2 is a helpful instrument to take into account different riparian management strategies. Simulations showed that the largest solar radiation reduction occurred for an Austrian (Vienna) west to east orientated river with 10 m width at the time of highest sun elevation when the vegetation was homogeneously distributed along the whole river stretch, starting right next to the river, with a minimum vegetation height of 15 m and a minimum width of 2 m. Based on these conditions, a reduction of approximately 85% of global irradiance was obtained.

Stream water temperature limits the growth and survival of aquatic organisms; whereby riparian shading plays a key role in inhibiting river warming. This study explains the effects of riparian shading on summer water temperatures at a pre-alpine Austrian river, during heatwave and non-heatwave periods at low flow conditions. A vegetation-shading index was introduced for the quantification of riparian vegetation effects on water temperature. For maximum water temperatures, a downstream warming of 3.9 °C was observed in unshaded areas, followed by a downstream cooling of 3.5 °C in shaded reaches. Water temperature directly responded to air temperature and cloudiness. For an air temperature change of 2 °C we modelled a water temperature change of 1.3 °C for unshaded reaches, but lower changes for intensively shaded reaches. Similar daily variations at shaded reaches were up to 4 °C lower than unshaded ones. This study gives clear evidence that for a medium-sized pre-alpine river, restoration practices should consider that discontinuity of riparian vegetation should be less than 6000 m; with more than 40% dense vegetation in order to minimize water temperature increases due to unshaded conditions.

Soil bioengineering techniques use plants as construction material for civil and hydraulic engineering purposes such as reinforcement of slopes and erosion control of embankments. The interactions of plants and stress from natural processes have to be quantified to assess such soil bioengineering systems from an engineering point of view. The objective of this study is to investigate the flexural behaviour of stems and branches of four riparian species of the Southern Brazilian region, suitable for soil bioengineering purposes ( Phyllanthus sellowianus Mull. Arg., Sebastiania schottiana (Mull. Arg.) Mull. Arg., Salix humboldtiana Willd. and Salix × rubens Schrank). 50 green stems of each species were collected in the surroundings of Santa Maria city (29°35′S, 53°32′W), state of Rio Grande do Sul, Brazil, and subjected to static bending tests. Specimens were tested with their bark, immediately after harvesting. The setup of the bending tests was based on the DIN standard ( DIN 52186 ) for 3-point bending tests. Measurements were carried out to obtain characteristic stress × strain diagrams for each stems. The following data analyse resulted in characteristic parameters to describe the overall deformation behaviour (elastic – MOE and plastic – MOR). An additional parameter according to Denardi (2007) was introduced: the “angle of inflection”. This parameter describes the elastic and plastic deformation behaviour of a plant under load from an engineering point of view. Results showed that P. sellowianus and S. schottiana are very appropriate for the protection of river banks according to the criteria of stem flexural behaviour, rupture strength, angle of inflection, growth rate and plant size. P. sellowianus is the most flexible species, followed by S. schottiana , S. humboldtiana and Salix × rubens . Therefore riparian forest stands of S. humboldtiana and Salix × rubens need more frequent maintenance in order to keep flexibility.

Using a three-dimensional finite volume code with standard k-Iµ turbulence closure the hydraulic impact of willow stands (Salix alba and Salix fragilis) on the velocity distribution was modelled. The additional hydraulic resistance of the willow stands was modelled separately to the bed resistance using a drag force term that was introduced into the Navier–Stokes equations. Two flood events of varying magnitude and stages of plant development were simulated using this approach. The river comprises an asymmetric compound channel with vegetated floodplain of reach length 170 m. The willow development has been monitored annually and this information was used to define the density of the willow stands (average number per m2) and its variation as a function of stand height. During both flood events the willow stands were submerged and in pronation. The willow stands were modelled in bending as well as in their undisturbed vertical state. Modelling the willow stands as vertical or in bending was found to have a major impact on the computed velocity profiles. The impact of using a drag-force approach based on a non-uniform projected area distribution was found to be greater when the plants are modelled vertically than when the plants are modelled in high degrees of bending. In field studies involving flexible plants without leaves, the determination of the drag coefficient is of less importance compared to the need to quantify the degree by which plants are in pronation.

Recent approaches in two and three‐dimensional numerical models have used a drag force term in the momentum equations to model the stem drag imposed by plants which project through a significant amount of the water depth. This approach reduces the ability to subsume under‐represented processes and data uncertainties in the calibration process which are inherent in roughness closures using a bed friction term such as the Mannings n. This paper examines the data uncertainties when applying the drag force approach to flow through natural plants by an a priori determination of the projected area of the plants as a function of height and explores the implications of this relationship on the computed velocity profile. Using eight individual trees of species Salix fragilis, geometric parameters including diameter and volume were measured and the projected area as a function of tree height was determined. Velocity measurements were conducted in the Wienfluss river in Austria and the relationship of drag ...

This paper investigates the response of full-scale submerged riparian vegetation to hydrodynamic loading, using data from towing tank experiments of high resolution and accuracy. Drag force and physical property data are presented for 21 foliated and defoliated trees, including specimens of Alnus glutinosa, Populus nigra and Salix alba. The force–velocity data and contribution of foliage to the total drag are first discussed, highlighting the non-classical drag force behaviour of flexible vegetation. A theoretical model, based on the vegetative Cauchy number, is proposed from dimensional consideration to account for the bending and reconfiguration of the trees under flow action. The model links measurable vegetation properties, such as volume, height and flexural rigidity, to the force–velocity response. This allows the otherwise complex drag force of flexible vegetation to be predicted with greater accuracy than compared with a rigid cylinder approximation.

Soil bioengineering is an appropriate approach to deal with erosion problems and shallow seated landslides especially in developing countries such as Nepal. This technique is a cost-effective solution using locally available materials and low-cost labour. Furthermore, this approach allows the involvement of the local population in the management and maintenance aspects. As an example for prevention of soil erosion and increased slope stability by means of vegetation, a landslide in the Middle Mountains of Nepal was selected for an innovative approach of rescheduling the implementation of soil bioengineering stabilisation works into the dry, winter season, testing plants for their suitability and using cut bamboo (Bambusa nutans G. C. Wall.) for the construction of vegetated crib walls. This paper deals with investigation, design, construction and monitoring over a period of 32 months. Soil bioengineering solutions for erosion control and shallow slope instabilities in the Middle Mountains proved to be highly successful and all plants, in particular Salix tetrasperma Roxb. and Alnus nepalensis Don., seemed to be suitable for winter plantation.