Soil Bioengineering Techniques Research Articles

Resistance of the fiber-derived geotextile from Typha domingensis submitted to field degradation

Geotextiles made from plant fibers creates a suitable environment for plant growth as part of soil bioengineering techniques. The faster decomposition of plant fiber geotextiles compared to synthetic ones demands the use of composites that enhance their waterproofing and extend their durability in the environment. The objective of this work was to evaluate the resistance of a geotextile made with Thypha domingensis to degradation caused by climatic variables. Tensile strength tests were conducted in the laboratory in order to evaluate the degradation of geotextiles treated with single and double layers of waterproofing resin. Based on Scanning Electron Microscopy (SEM) images, it was verified that applying double layer of waterproofing resin delays the fibers degradation up to 120 days of exposure to the effects of climatic variables other than temperature. The maximum resistance losses due to the geotextile's exposure to degradation were statistically significant for all three treatments: control-without waterproofing resin, with one layer resin, and with two layers resin. Therefore, waterproofing resin, provides a long-term protective solution for geotextiles made from cattail fibers.

Knowledge influences perceptions and values of nature-based solutions: The example of soil and water bioengineering techniques applied to urban rivers

Soil and water bioengineering (SWBE) is a nature-based solution (NBS) that can be used to stabilize riverbanks with living vegetation. Aside to protecting property and people, SWBE provides benefits for human well-being and biodiversity. Its use remains modest in cities, where the presumed benefits are important in a context of biodiversity crisis and warming. Negative public perceptions have been identified as one barrier to the dissemination of NBS. This article studies how environmental expertise influences perceptions and values associated with SWBE, and how the possible differences in perceptions and values induced by knowledge contribute to hindering or promoting the dissemination of these solutions. We carried out an original interdisciplinary study based on a sociological survey and ecological field measurements to characterize: (1) the perceived value that actors associate with several riverbanks equipped with different protection structures (green, hybrid, or gray) according to their level of expertise in the aquatic environment; (2) the interactions between these perceived values and the ecological values measured by restoration ecologists; and (3) the perceived benefits and drawbacks of SBWE techniques. Our results show that the ecological and social benefits provided by NBS are recognized by all, whatever their level of knowledge. Despite this consensus, we observed different hierarchies of value associated with bank protection structures among the surveyed actors, depending on their level of environmental expertise (some prioritising ecological values, others relational values), and these could hinder the dissemination of NBS. The most tangible obstacle to the dissemination of NBS in urban areas relates to the risk perceptions of lay people, who experience a higher sense of vulnerability than they do with traditional gray solutions.

Herbaceous angiosperms, pteridophytes and shrubs cocktail for rapid ground cover for soil and water bioengineering in the Caribbean

Among the Nature-based Solutions currently spreading worldwide, soil and water bioengineering techniques, are used to stabilize hill slopes, earth embankment, and riverbanks. They consist in the use of living plants, sometimes coupled with dead materials, to control erosion and restore ecosystems.These approaches remain to be adapted to Neotropics and particularly to the Caribbean Islands biodiversity hotspot. The success of soil and water bioengineering designs depends on the selection of suitable native plant species and considering the hydrodynamic and geotechnical processes. In the Caribbean, data are available concerning woody species but are still lacking for the other constitutive components of riparian plant communities. The objective of this study was to identify the riparian forest understory species best suited for use in SWBE at their establishment phase. In a three-month ex situ experiment, we measured the survival rate, biomass production and root growth of propagules (cuttings and bulbils) of eleven native Caribbean species (5 herbs, 4 pteridophytes, 2 shrubs) occurring naturally in a variety of riparian environments. All the herb and shrub species studied displayed growth vigour adequate for a successful inclusion in soil and water bioengineering techniques. Among herbs, Commelina diffusa, Hymenachne amplexicaulis and Sphagneticola trilobata performed the best. Gynerium sagittatum and Dieffenbachia seguine, despite their slower growth and root development, remain suitable. Regarding the two shrubs, Ludwigia octovalvis gave better results than Clidemia hirta. Among the pteridophytes, Adiantum latifolium, Thelypteris reticulata and particularly Lycopodium cernuum appeared poorly suited to soil and water bioengineering. Acrostichum danaeifolium was the best-performing pteridophyte. These first experimental results focusing on the propagation and establishment of native herbs, pteridophytes and shrubs, allowed to identify a diversity of species of interest as cuttings for soil and water bioengineering and practical clues for their use in the Neotropics.

Probabilistic Analyses of Root-Reinforced Slopes Using Monte Carlo Simulation

Among measures that are used to prevent the triggering of shallow landslides and for erosion control, root reinforcement has spread out widely as its contribution to environmental sustainability is high. Although in recent years reliability-based design (RBD) has been applied increasingly to the assessment of slope stability to address the shortcomings of the deterministic approach (which does not consider geotechnical uncertainties explicitly), there is still a lack in the application of this method to root reinforcement. Plants are characterised by high inherent uncertainty, making it necessary to investigate the level of reliability of these soil-bioengineering techniques. In this context, to determine whether or not root-reinforced slopes designed according to Eurocodes (that is, by applying their statistical partial factors), and providing satisfactory factors of safety, may lead to a probability of failure that is, in contrast, unacceptable, the Authors carried out several probabilistic analyses by using Monte Carlo simulation (MCS). MCS was applied to the simplified Bishop Method modified to bear pseudo-static forces representing earthquake loading in mind. To take into account the mechanical effect provided by roots, an apparent root cohesion was added to the Mohr–Coulomb failure criterion. Results showed that not every slope configuration that satisfies the safety criterion has acceptable levels of reliability, and this evidence is caused by the high variability of the design parameters.

Selecting Native Species for Soil and Water Bioengineering Techniques: Alternative to Restore Areas in Brumadinho, MG, Brazil

Selecting Native Species for Soil and Water Bioengineering Techniques: Alternative to Restore Areas in Brumadinho, MG, Brazil

Soil bioengineering techniques for Mediterranean coastal dune restoration using autochthonous vegetation species

Coastal dunes are extremely fragile and threatened ecotones, which play a key environmental role in terms of functional connection between terrestrial and marine ecosystems. To counteract the hydrogeological vulnerability in coastal risk areas, reliance can be made on soil bioengineering techniques, consisting of planting native species in combination with natural inert materials. These interventions involve the use of typical Mediterranean plant species, which are fundamental for increasing soil surface protection as well as for their ecologic function in coastal dune consolidation. Monitoring studies on plant growth parameters are useful to assess the suitability of the different species to be used in soil bioengineering works. Hence, this study aimed to (i) identify some Mediterranean herbaceous and shrubby plant species to be used in coastal interventions, (ii) evaluate different plant propagation methods and short-term growth parameters, and (iii) provide useful insights into field management strategies before and after transplanting.Juniperus phoenicea L., Juniperus macrocarpa Sm., Pistacia lentiscus L., Tamarix africana Poir. and Tamarix gallica L. were the selected shrubs species while Ammophila arenaria (L.) Link, Sporobolus pungens (Schreb.) Kunth., Agropyron junceum (L.) P. Beauv., Eryngium maritimum L., Calystegia soldanella (L.) R. Br., and Pancratium maritimum L. were the selected herbaceous species. As to shrubs, seeds and cuttings proved the best propagation methods with an efficiency of up to 90%. Agamic propagation methods, on the other hand, were the most efficient (80–90%) for the herbaceous species. After transplantation, all the species showed an adaptation period to the new climatic and edaphic conditions. In particular, Pistacia lentiscus L. was found withered with the presence of some radical shoots.

Performance assessment of a soil and water bioengineering work on the basis of the flora development and its associated ecosystem processes

The Atlantic Forest of Brazil is one of the world's 25 biodiversity hotspots, but floodplains in this region are continuously converted into agricultural or urban areas, and riverine ecosystems are affected by anthropogenic interventions. Soil and water bioengineering techniques are a component of ecological engineering that can provide nature-based solutions as an alternative or as complementary measures to conventional hydraulic or civil engineering approaches. However, there is a lack of post-evaluation of interventions and there are still great difficulties in identifying valid evaluation criteria and measurement variables, especially in countries like Brazil where soil and water bioengineering measures have only been implemented in the last decade. Another limitation to the widespread application of the techniques is the lack of knowledge about their technical performance, their impact on ecological processes and the evolution of the species used. This study aims to investigate the development of species, evaluate the technical performance of the intervention and assess the ecological benefits and processes of one of the first soil and water bioengineering riparian restoration interventions in Brazil, which was carried out in 2010 on the Pardinho river. Parameters on bank stability, development of species used in different construction techniques and its ecological benefits and ecological processes (plant species and soil fauna richness and diversity, ecological group and recruitment species, invasive species, soil organic matter and soil temperature) were collected over a period of ten years. The study proved that soil and water bioengineering works can both stabilise and control erosion, and at the same time initiate ecological processes on degraded riverbanks. The active introduction of native species has promoted vegetation succession, increased the biodiversity of both plants and soil fauna on the site and improved the site conditions. The establishment of native vegetation led to sediment and organic material deposition, which changed the local ecological conditions (e.g., soil properties, light, flow conditions) and thus facilitated rapid establishment of other plants and re-established interactions between plants and soil fauna groups. This study provides a monitoring approach which examines the technical performance of the measures and species used, as well as their impact on the ecological process over time, which is essential for establishing soil and water bioengineering techniques as the standard in the field of river engineering in Brazil. Furthermore, the results obtained will help in planning and designing future works in the field of soil and water bioengineering in Brazil, adding to the knowledge of the techniques and species to be selected, as well as supporting the evaluation of the success of interventions.

Evaluating the suitability of neotropical trees and shrubs for soil and water bioengineering: Survival and growth of cuttings from ten Caribbean species

Soil and water bioengineering techniques are now increasingly adopted worldwide for controlling riverbank erosion but have not yet been implemented in the Caribbean Islands biodiversity hotspot. The selection of suitable native plant species is critical for successful soil bioengineering designs on riverbanks, but few data are available regarding Caribbean species. This study aimed to characterize the performance and biotechnical traits of native Caribbean species potentially compatible with soil and water bioengineering. In a six-month shadehouse experiment, we measured the survival rate, biomass production and root growth of cuttings of ten native Caribbean shrub and tree species occurring naturally in a variety of riparian environments. All species appeared suitable for soil and water bioengineering but differed as to the specific bioengineering techniques they seemed particularly suited for, depending on their respective survival rates, growth performances and root system structures. Five tree species, Citharexylum spinosum, Cedrela odorata, Ficus citrifolia, Chimarrhis cymosa, Homalium racemosum, and three shrubs, Piper dussii, Piper dilatatum and Phyllanthus mimosoides, exhibited survival, growth and root characteristics compatible with a broad range of techniques, whereas Tabebuia heterophylla and Cordia sulcata may only be compatible with a few. We also propose using of the DEXi decision-support software for assessing species suitability to a series of widespread soil and water bioengineering techniques. Our results provide practical guidance for the integration of native species in soil and water bioengineering in the Caribbean and the Neotropics at large.

Evaluation of the root system of Vetiver grass (Chrysopogon zizanioides L. Roberty) using different sampling methods

BackgroundVetiver grass (Chrysopogon zizanioides L. Roberty) is one of the most studied and applied species in soil bioengineering techniques all over the world, but there are technical information related to its root system deserving a better comprehension provided by different methodologies’. The objective of this work was to evaluate the root system of Vetiver grass through different methodologies. The trench method evaluated 50 images in 10 × 10 cm squares in its vertical face. The volumetric ring method uses a metallic ring with a volume of 50 cm3 (diameter ≅ 4.6 cm and height ≅ 3.0 cm) to collect samples in the same trench’s vertical face. A hand auger hole method worked with soil samples and roots removed from the surface up to 0.50 m depth. The monolith method comprises a 0.50 m wide, 0.50 m long, and 1 m deep monolith. A spatial correlation between root volume and root area was observed in the kriging maps by the volumetric ring method.ResultsThe root area values for both the volumetric ring method and the hand auger hole method were similar, up to 0.10 to 0.20 m. On the analyzed variables, the root area showed the best correlation coefficient among the root methods, especially those that use the limited spatial distribution by its sampling collection, such as the volumetric ring method and the hand auger hole method (r = 0.526, p < 0.05).ConclusionsThe studied methods can be separated in different groups, such as those that provide more detailed information on the behavior and distribution of the root system, like trench and monolith methods and the methods that better describe the morphological characteristics of the features, like the volumetric ring method. Both require greater spatial coverage, and therefore have greater precision.

The Conservation and Restoration of Riparian Forests along Caribbean Riverbanks Using Legume Trees

In the actual context of global change and biodiversity depletion, soil bioengineering represents an important tool for riparian ecosystem restoration and species conservation. Various techniques have already been implemented, but their adaptation still must be carried out in Caribbean Islands biodiversity hotspots, where suitable species remains unknown. Nitrogen-fixing legumes are particularly relevant for ecological restoration and the diversity of native Caribbean legume trees is promising in the search for suitable species for soil bioengineering. We hypothesized that Caribbean legume tree species present a growth performance and set of biotechnical traits compatible with their use in soil bioengineering. We selected five native legume trees, adapted to riparian environments, in different ecosystems (swamp forest, evergreen seasonal forest, rainforest) based on their ecology, resistance to disturbance and seed production characteristics. We measured root traits relevant for soil bioengineering on nursery grown 3-month-old seedlings. Despite their differences in sensitivity to herbivory and in growth strategies, the selected species have a high potential for use in soil bioengineering, with high seed production, high germination rates—from 88 to 100%—, and 100% survival rates, and are therefore compatible with large scale plant material production. We provided practical guidance tools for their integration into soil bioengineering techniques.

Nature-based solutions (NbS): A management paradigm shift in practitioners’ perspectives on riverbank soil bioengineering

Nature-based Solutions (NbS) are promoted as practical and theoretical solutions that simultaneously provide human well-being and biodiversity benefits. One example is soil bioengineering using construction techniques based on living vegetation, and is frequently used for riverbank stabilization, flood protection, and erosion control. Compared with civil engineering, NbS offer many advantages such as cost reduction, limited impact on the environment, and production of ecosystem services. However, their use is still marginal for riverbank control, especially in urban areas. In this paper, we focus on soil bioengineering techniques for riverbank protection in an urban context from the practitioners’ perspective. We question to what extent NbS require a shift in management paradigm. We used qualitative methods to interview 17 practitioners working in the Rhone Alps basin (France). Our results reveal that switching from civil engineering to soil bioengineering is not only a technical change, but also requires a shift from a “predict and control” paradigm to an “adaptive management” paradigm because of three major reasons. First, soil bioengineering techniques require redefinition of the performance of engineering structures with the inclusion of ecological and social dimensions. Second, the adoption of soil bioengineering techniques requires that practitioners, elected people and inhabitants reconsider risk sharing and acceptance. Third, the techniques require practitioners to adopt a new posture, with new soft skills (humility and daring) and a new collective organization (collective feedback). Finally, we identify three levers for a broader use of such techniques: (i) systematic assessment of the ecological, economical, and social benefits of such techniques; (ii) improving risk acceptance and sharing; (iii) fostering of social learning among practitioners through collective or technical feedback.

Ecological challenges* for the use of soil and water bioengineering techniques in river and coastal engineering projects

A major challenge for the modern river and coastal management is a holistic design approach in order to integrate flood and erosion protection combined with ecological restoration. Nowadays, a lot of EU regulations request nature-based engineering solutions such as soil and water bioengineering techniques (SWBE). In contrast to conventional ‘hard’ civil engineering structures, the idea of SWBE structures is the use of biological components in the engineering structure to not just consider a technical function, but also ecological and aesthetic values. While SWBE techniques are applied worldwide and well established as an engineering discipline, there is a high demand on the further development specifically in terms of ecology.The use of plants in river engineering projects requires the right choice of species depending on the techniques used and the environmental conditions. Furthermore, a right harvest, storage and implementation of the plants is significant. Their use also requires the quantification of the hydraulic and sedimentological impact of riparian vegetation on the one hand and on the other hand to know the impact of SWBE structures on the aquatic and terrestrial habitats. Different ecological, vegetational and phytosociological criterias are available and discussed in terms of assessment of SWBE structures. All these criteria can be helpful to develop a framework supporting stakeholders to define objectives, design, implementation work and to assess the post-construction lifetime phase, which is most relevant for SWBE structures. From a wider point of view, when looking at the multitaxonomic diversity in both terrestrial and aquatic habitats, it has been shown that SWBE techniques could enhance global riparian habitat quality by allowing a greater richness and density of pioneer tree species. The use of phytosociology has become more important for the application of SWBE structures as nature-based vegetation composition. Specific challenges arise for river managers and practitioners with invasive alien species and climate change forcing us to redefine what is meant by ‘non-native’ species. Therefore, using a local and historical phytosociological typology to define the reference to be achieved could become increasingly misleading. By analyzing the ecological value of SWBE structures, another aspect must be considered from an ecological point of view. The possible negative impacts on ecosystems caused by SWBE measures, during the period of construction (e.g., emissions, energy consumption, intervention in nature) should be taken into consideration. A popular methodology to provide the possibility of achieving a better understanding of environmental burdens and to assess the potential environmental impact of products or services is environmental life cycle assessment (LCA). We are faced with the problems of climate change which means that we have to optimize our civil engineering (including SWBE) construction activities in terms of positive effects, for example urban heat islands or carbon storage and also any potential negative effects, for example emission of greenhouse gases or energy demand.We must critically examine our model of the SWBE approach, the application of SWBE techniques does not automatically mean an ecological improvement. SWBE systems are dynamic and always different, depending on their field of application. A harmonization of strategies and goals needs to be developed in order to support coherent measures aimed at improving the ecological status of river bodies, coastal areas and at the same time, guaranteeing hydraulic safety and adequate protection of human activities from hydromorphological hazards (flooding, floodplain erosion, failure of river and coastal-related infrastructures).

Improvement of the Plantation Success in a Crib Wall in a Mediterranean Hydro-Meteorological Risks Scenario—Practical Results

Due to the clime change scenario, severe hydro-meteorological phenomena are having a high impact on the ecosystems of the earth. Some strategies based on the use of natural communities associated with geomorphological changes that restore the natural landscape are gaining success due the resistance and resilience against damages. All of these strategies are known as nature-based solutions (NBS). Soil and water bioengineering techniques are one of the most appreciated tools to reach effectiveness for slope stabilization. They are based on the capacity of some plants to consolidate the soil with his rooting system in special conditions (high slope, flooding impact). Slope stabilization solutions with soil and water bioengineering techniques need to be adapted to this new scenario. Crib wall is one of the most complete soil and water bioengineering technique for structural slope stabilization. It is based on a wooden box full of live plants that in the future will grow and gain stability at the same time that wood decays. The crib wall box is full of soil, and the front area is traditionally stabilized with some branches of fascines to let plants grow, maintaining the structure. Fascines are made of branches of riparian species with the capacity for vegetative propagation. Their diameter can change due to the humidity variation, so the stiffness of the system is at risk against severe hydro-meteorological phenomena. This study aims to assess that the introduction of HDCL in crib walls improves planting success and makes them more resistant to adverse weather events in Mediterranean areas. Four experiments were performed in controlled and natural conditions with this proposal. The results show that the use of natural fibers instead of branch fascine helps to maintain the humidity conditions and increase the resistance capacity. High-density coir logs (HDCL) are not affected by volume changes for humidity conditions. HDCL maintains the plant’s humidity conditions longer and makes plants grow faster, bigger and increase their survival. This method of Crib wall construction increases the associated biodiversity. The most important results are that the use of HDCL in crib walls has an effect on the growth of planted shrub, the development of roots, the colonization of native vegetation and ultimately, the resistance of the structure to the floods. The results also show that crib walls are a good technique for the stabilization of slopes with considerable gradients and high hydraulic impacts. HDCL can reduce the water stress of plantations, and they can be a good system to retain runoff and provide it to the plants. Finally, the HDCL allows the revegetation of a crib wall 30% faster than with branch fascine.

Temporal efficiencies of soil bioengineering techniques to mitigate geo-hydrological risks

Natural hazards such as landslides, soil erosion and floods are increasingly affecting many regions of the world in relation to ongoing climate change and the abandonment of rural areas. In the last decades, the need to mitigate such phenomena and preserve natural resources, including landscapes, has motivated a number of local and national authorities to promote the use of soil bioengineering techniques. Consequently, these techniques have been increasingly used with variable success rates. This study analysed the efficiencies of different bioengineering structures to mitigate geo-hydrological risks by examining the interventions installed between 2007 and 2013 in the Avellino Province southern Italy. To this end, a specific project consistency analysis and functionality classification were carried out and the causes of inefficiencies were identified. The analysis showed that after a few years, only a small number of the installed bioengineering structures were fully functional and efficient. Overall, the installed structures were generally affected by maintenance issues and in many cases they suffered from design and execution issues, inducing a generally lower degree of efficiency, with most of them classified as ‘not very efficient’. The conclusions of this work are that i) the long-term efficiency of a bioengineering structure is related to its correct design, installation, and maintenance; ii) the design of a bioengineering structure should account for the geological, geotechnical and hydrological characteristics of the area of interest, and iii) maintenance must not affect the short-term efficiency of a structure, but may affect the long-term efficiency.

Soil bioengineering in northeastern Brazil: An Overview

This article presents an overview of the application of soil bioengineering techniques, also modeled as natural engineering, in the state of Sergipe, northeastern Brazil, showing the importance of integrating living and inert elements to protect river banks from erosion. The employed techniques are different, ranging from the characterization of susceptibility to erosion to the use of biotechniques, considering knowledge in the areas of agronomic engineering, forestry engineering, civil engineering, biology, pedology, geology, geomorphology and geotechnics. It is an approach that uses techniques and methodologies in a multidisciplinary way, seeking to maximize synergies (for example, natural engineering techniques to combine inert materials in ways that help plants to develop increasingly efficient systems). This approach also considers maintenance-cost optimization in the conduction of the works, using different materials, differing from traditional engineering, which uses predominantly inert materials. The research work carried out in different locations sought the availability of local materials such as rocks, geotextiles made from fibers from the native flora or even available on the market, in addition to the use of native species to recovery of the banks or slopes, according to the ecological conditions of the northeastern Brazil. Size and technological and ecological reach were also considered, in addition to different biotechnical aesthetic objectives adapted to different situations.

Design and temporal issues in Soil Bioengineering structures for the stabilisation of shallow soil movements

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.

Does soil bioengineering benefits aquatic biodiversity? An empirical study of the relative influence of local and regional drivers on benthic macroinvertebrate assemblages

Riverine ecosystems form a dendritic network in which landscape and catchment-scale properties influence freshwater community structure. Placed in a restoration framework, this suggests that regional drivers can overrule the benefit of measures aiming at improving local habitat quality. Disentangling the relative influence of local and regional drivers on freshwater communities is thus crucial for ecosystem management and restoration. Along riverbanks, soil bioengineering is often used to both control erosion and improve ecological conditions. Soil bioengineering techniques aim at copying naturally functioning riverbank models and can thus be viewed as riparian ecosystem restoration. Nevertheless, these techniques are mostly designed at the local scale and are implemented in a broad range of rivers. This implies large variations in regional drivers, which may greatly influence the response of freshwater communities to restoration efforts. We studied 37 riverbanks, from civil engineering to soil bioengineering, plus natural willow stands, in the foothills of the Alps and Jura Mountains, and assessed the relative influence of local (terrestrial and aquatic habitat conditions) and regional (water quality, hydrological context and land cover composition) drivers on benthic macroinvertebrate assemblages. Using multivariate GLM and structural equation modelling, we investigated variations in the taxonomic and functional composition and in the diversity of native, exotic, shredder and scraper taxa to both set of drivers. Our results showed that soil bioengineering improved local habitat conditions, with an increase in the vegetation density and in the aquatic habitat quality. These changes directly influenced functional composition but indirectly diversity patterns. Instead, we found that native and shredder species richness increased between civil engineered and soil bioengineered structures, suggesting a positive effect of vegetated riverbanks on other local abiotic factors (i.e. shade, water temperature, organic matter supply). Our results also showed that macroinvertebrates were more influenced by regional than by local drivers. Thus, the hydrological context best explained the composition of taxa feeding habits and variation in taxa diversity, with larger abundance and richness of scrapers and shredders in small headwater streams. Land cover ranked second in explaining variation in functional composition. Also, the diversity of natives, scrapers and shredders increased as the proportion of predominantly urban landscapes decreased. Finally, the abundance of scraper and native species increased with water quality, while the richness of exotic species decreased. Overall, these results highlight the hierarchical structure of local and regional drivers on freshwater communities. Along river networks, catchment-scale properties and landscape attributes are major drivers of macroinvertebrate assemblages. Soil bioengineering improves habitat quality and as such appears to be a good compromise solution to control erosion and support freshwater communities, even though this nature-based solution cannot solve anthropogenic pressures at larger scales. To improve the efficiency of restoration efforts, integrated approaches accounting for both local and regional drivers remains a priority.

Sediment input from the São Francisco River bank, Northeast Brazil, under low discharge period

The objective of this study was to evaluate the input of suspended sediment from the slope toe in the São Francisco River channel, in Northeast Brazil, under different soil bioengineering techniques. Sediments were collected in the years of 2013, 2014 and 2015, in five transects crossing the river channel. Sediment input in the sampling points was higher in the year of 2013, i.e., the year of the highest river discharge. Sediment supply to the river channel for a period of 3 years (2013, 2014 and 2015), was evaluated at 20, 40 and 60% depth, along five different transects (P1= riverbank, P2= beginning of the thalweg, P3= middle of the thalweg, P4= end of the thalweg, and P5 = margin of the side sandybar), oriented by the presence or absence of erosion control techniques (treatments) such as: 1-Natural Vegetated Slope; 2-Vegetated Riprap; 3-Eroded Slope; 4-Live Cribwall and 5-Vetiver grass Contour Line. Sediments input was different in all evaluated transects, and the one identified as Eroded Slope at 20% depth presented the lowest amount of suspended sediment load. There was a decrease in the total amount of suspended sediment in the evaluated periods, probably due to the progressive decrease in the river discharge, and the protection provided by the soil bioengineering techniques.

Rejuvenated Prominence: Reclaiming the Landscape of Extraction Based on Hydro-topographic Network

As an ongoing project, Rejuvenated Prominence aims to explore operative and hydro-topographic strategies for the overburdened layer landscape of Mae Moh Mine in Lampang Province, Thailand. The 135 km² mine is located inside Mae Moh Basin, the headwater of Wang River. Since 1969, over 500 million tons of lignite have been extracted, while the remaining reserve of 224 million tons will last for the next 29 years. To recover ecosystems and maintain sustainable development of surrounding communities, the Electricity Generating Authority of Thailand developed post-mining alternatives from 2020 to 2049. As a part of this research, Rejuvenated Prominence focuses on the 32 km² overburden dump, where rectangular surfaces completely replaced with complex natural terrains, to thoroughly decode the nature’s structure, function and change. Time-based strategies in accordance with the Mine Master Plan deploy hydro-topographic operations combining soil-bioengineering techniques to activate topographic agents and reclaim the land. Re-engineered geomorphic structures would be initiated to moderate rapid runoff, mitigate mass wasting, disperse soil moisture and replenish the topsoil. This dump would be transformed into an operative landscape with complex hydro-topographic networks and reconnected as a part of the projected headwater landscape over time—to realize the resilience of Mae Moh Basin.

Soil and Water Bioengineering Applications in Central and South America: A Transferability Analysis

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.