Soil Bioengineering Techniques Research Articles

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.

Degradação de geotêxteis de <i>Typha latifolia</i> Linn utilizados em técnicas de bioengenharia de solos

O uso das fibras da taboa (Typha latifolia Linn), para confecção de geotêxteis, tem sido trabalhada, buscando a estabilização de taludes de rios ou encostas, e assim criando um ambiente ecologicamente favorável para a recuperação da vegetação e a ancoragem do solo. O objetivo deste trabalho foi avaliar a resistência e durabilidade de geotêxteis fabricados com fibras da taboa submetidos ao envelhecimento acelerado em laboratório e degradação dessas fibras em campo. A confecção dos geotêxteis foi realizada com diferentes nós em fibras que passaram previamente por processos de secagem distintos. Para a realização dos testes em laboratório, foi construído aparato que permitiu submeter os corpos de prova ao envelhecimento precoce, buscando simulação das condições ambientais, isto é, as fibras foram expostas à radiação UVB seguida de condensação, utilizando-se também um resfriador mecânico para equalização da temperatura. Os ensaios de resistência à tração seguiram diretrizes observadas nas normas ISO 10319 (1996) e ISO 12236 (1998). Os ensaios de campo foram conduzidos por disposição de amostras em um talude da margem direita do rio São Francisco no município de Amparo do São Francisco-SE, 10°08'20.7"S 36°54'47.0"W, Nordeste do Brazil, com área de 20m2, submetidas às condições climáticas locais, para posterior avaliação da sua degradação. Uma vez que os materiais não apresentam homogeneidade na sua fabricação, ocorreram resultados não uniformes quando submetidos à degradação. Isso pode explicar o fato de serem observados aumentos inesperados nos valores de tensão e deformação. O geotêxteis de taboa apresentou resultados de tensão de ruptura e deformação que sinaliza positivamente para o seu uso comercial, confirmando, assim, as suas potencialidades para uso como parte das técnicas de bioengenharia de solos.

The beaver’s menu: species and spatial selection of a European beaver population and implications for riverbank bioengineering

Riparian ecosystems are of utmost importance for many key ecosystem services, such as nutrient filtering or flood and erosion control. Restoring degraded riverbanks using soil bioengineering techniques initiates secondary succession improving both protection from erosion and riparian ecological functions. These techniques often rely on the settlement of Salicaceae and sometimes Tamaricaceae species that can be strongly impacted by beaver browsing. During the last decade European beaver (Castor fiber) populations have largely grown in France and can thus impact restored riverbanks, leading practitioners to adapt their management strategy. We conducted a study to assess the feeding preference of C. fiber and their browsing spatial pattern in semi natural riverbanks in the French Alps (Isere, France) by measuring browsing impacts along a transect. Our results indicate selective browsing occurrences at two nested spatial scales: firstly, beavers create large preferentially browsed patches (~ 8 m diameter) secondly, at a finer scale within these patches, they demonstrate a selective browsing between plant species. Among the species used in soil bioengineering, Myricaria germanica showed the lower browsing selectivity with only 2.5% of browsing probability while Salix eleagnos and Salix purpurea (10%) and Populus nigra, Salix daphnoides and Salix alba (20%) showed significant higher selectivity by beaver. Our results suggest that within the beaver presence area soil bioengineering techniques should consider adjusting both the composition and the spatial pattern of plant species settlement to mitigate the impacts of beaver on restored riverbanks.

Macrophytes communities associated to soil bioengineering techniques for erosion control in riverbanks

The objective of this study was to evaluate the temporal and spatial richness of aquatic macrophyte settlement in a right bank of the Sao Francisco river, northeastern Brazil. The botanical material was collected and assembled exsiccate from April 2014 to September 2015, totaling four samplings at the points identified as: Vegetated Slope (A); Vegetated Riprap (B); Eroded Slope (C), Cribwall (D); Vetiver Grass Contour Line (E). It was identified 66 species distributed in 23 families. The Vegetated Slope in the rainfall period presented higher species richness and diversity. The soil bioengineering techniques at points B, D and E presented a stable river bank, thus creating a favorable environment for a larger settlement of macrophytes.

Quantitative evaluation of soil anti-erodibility in riverbank slope remediated with nature-based soil bioengineering in Liaohe River, Northeast China

Soil bioengineering techniques are considered as the cost-effective, nature-friendly, self-repairing and sustainable technique to deal with erosion problems on slopes and enhance riverbank stability, especially for shallow-seated landslides. Research on soil anti-erodibility and stability is one of the keys to understand mechanism of riverbank soil erosion. Three different types of nature-based bioengineering measures were conducted in Liaohe River Protected area and soil erodibility was evaluated in comparison with natural riverbank after four years. On the basis of soil intrinsic properties, 14 index parameters were selected to evaluate soil anti-erodibility, at the same time, soil shear strength and root dry weight were also used to assess soil stability. Results showed that nature-based bioengineering measures apparently increased riverbank stability by improving soil anti-erodibility and shear strength. Additionally, soil shear strength analysis was in agreement with soil anti-erodibility results, indicating riverbank slope soil stability in descending order were FT (Fiber roll + live stakes slope protection technique) > NT (Nonwoven fabric + live stakes slope protection technique) > CT (Condensed live stakes slope protection technique) > CK (natural riverbank). Furthermore, soil silt and silty clay, aggregate status, organic matter, root system and soil cohesion are the main factors controlling soil erodibility.

The use of soil bioengineering to overcome erosion problems in a pipeline river crossing in South America

Exposed pipelines are susceptible to geotechnical–hydraulic phenomena and to a high-risk level of failures caused by scouring or erosive processes in the river bed and river banks. Currently, in the prevention, maintenance, or remediation of river crossings, traditional engineering techniques are generally applied, which often leads to insufficient solutions concerning technical, financial, and environmental issues. The soil bioengineering methods, using vegetation in combination with inert materials for soil stabilization and protection against erosion, can be an alternative, a complementary tool, or even a substitute for traditional engineering practice. In this context, this work aims to present one case study of an exposed pipeline in which were used some soil bioengineering approaches to prevent natural erosion processes at pipeline river crossings. Compared to conventional methods, the soil bioengineering techniques used in the presented case study have proved to be advantageous in economic, environmental, and aesthetic aspects.

New tools and approaches to promote soil and water bioengineering in the Mediterranean

Soil loss and erosion is a major environmental problem in the Mediterranean. Soil and water bioengineering uses plants and/or parts of plants along with inert material to create solutions to fulfill soil conservation objectives combined with an ecological rehabilitation approach. The ECOMED project developed novel approaches and tools to specialize the soil and water bioengineering sector within the Mediterranean. The first activity was the Sector Needs Analysis were the responses to an online questionnaire of 110 stakeholders from the region were analyzed. The main conclusion was the need to specialize the soil and water bioengineering sector in the Mediterranean. In addition, 21 soil and water bioengineering case studies in the Mediterranean were reviewed. Many works of this type are implemented in the region, but have flaws because of the lack of training material, design routines, protocols, specific to the region. The second activity developed New Design Routines and Protocols. Specifically, three protocols, one template and one plant database were developed for the region. Finally, in the Training Material activity, six educational modules along with a handbook (that contained modules, protocols, template and case studies) were developed. Overall the ECOMED project generated new and novel material and tools that were lacking in the region to enhance the specialization process of the soil and water bioengineering sector. These should increase the adoption of soil and water bioengineering techniques with better trained and new professionals as well as improve the work performance of these interventions.

Seeding Dynamics from a Local Seed Mixture on a Bioengineered Riverbank Protection Structure.

Restoration of riverbanks through soil bioengineering techniques allows managers to combine riverbank stability and riparian ecosystem functioning. This restoration often involves the sowing of a seed mixture, which helps develop herbaceous vegetation. This development and sufficient vegetation cover are essential for protection against erosion and for hosting biodiversity, two of the main goals of riverbank bioengineering. Restoration aims at recreating ecosystems closer to an undisturbed state; choosing seed mixtures of local provenance is therefore encouraged. In this study, we investigated the local seed mixture sown on bioengineered riverbanks and the conditions influencing the first steps of plant development, so as to delineate the setting favoring restoration. We focused on the composition of the seed mixture and germination capacity as well as the effect of sowing density and soil quality on vegetation cover and diversity. We tested four sowing densities: 5, 10, 15, and 30 g.m-1. The seed mixture presented considerable diversity and germination rates were heterogeneous. Sowing density had a positive impact on vegetation cover and diversity, and high cover up to 100% was rapidly reached. Soil quality did not affect vegetation diversity but had a significant effect on vegetation cover, with the nutrient content, notably nitrogen, most probably involved.

Community-based landslide risk reduction: a review of a Red Cross soil bioengineering for resilience program in Honduras

Effective long-term participation of communities in disaster risk reduction measures in landslide-prone areas continues to be a challenge. This study aims to evaluate the extent to which community-based soil-bioengineering techniques allow for effective mitigation of shallow landslide events given technical, environmental, economic and socio-cultural sustainability criteria. The Red Cross has been implementing community-based disaster risk reduction programs aimed at increasing resilience at the community level in Honduras since 2005. Since 2010, 230 landslide hazard sites have been stabilized using soil-bioengineering measures (the use of living plant material to provide certain engineering functions) based on a carefully and systematically developed partnership with local communities. In 2018, an assessment of 73 sites established between 2010 and 2014 showed that (1) 83% of the sites were adequately maintained and (2) 69% of the sites fulfilled the function of soil stabilization. A cost–benefit analysis was conducted for two sites and indicated a cost–benefit ratio of 4.5 and 6 respectively. Some of the key factors for these high success rates include the fact that bioengineering is a locally adapted, easily implemented, cost-effective technology that offers landowners multiple benefits by increasing food security and creating income-generation opportunities. The Red Cross has recognized the importance of empowering communities by building self-confidence so that they can ultimately take responsibility for their own future. The creation of well-functioning local emergency committees has proven highly effective in achieving this goal. When adequately trained, these committees are able to support the replication and maintenance of disaster-risk reduction measures at the community-level in the long term. This case study supports the hypothesis that carefully designed participatory approaches are essential for achieving sustainable, long-term transformative change and risk reduction.

Soil bioengineering techniques enhance riparian habitat quality and multi-taxonomic diversity in the foothills of the Alps and Jura Mountains

Riparian zones have disproportional ecological importance relative to their size. For decades, the functionality of riparian zones has been altered, with detrimental consequences on biodiversity. Recently, riparian zone restoration has become a major issue. When channel mobility cannot be restored and when erosion control is of primary concern, soil bioengineering techniques are often viewed as a compromise solution. We studied 37 riverbanks, from civil engineering to soil bioengineering, plus natural willow stands, in the foothills of the Alps and Jura Mountains. Using a principal component analysis, we first studied whether terrestrial and aquatic habitat variables varied among riverbank stabilization structures and bank stabilization age and built a synthetic index of riparian habitat quality reflecting the multivariate similarity of riverbank sites. Then, using a modelling approach, we tested whether multi-taxonomic diversity responded to changes in habitat quality and to broad-scale environmental variables (i.e., climate, hydrology and land cover). Soil bioengineering techniques, especially willow fascines and to lower extend vegetated crib wall, enhanced riparian habitat quality by allowing for a greater richness and density of pioneer tree species but also for a larger cover of high quality aquatic micro-habitats. This increase in riparian habitat quality induced an increase in both terrestrial and aquatic species diversity, highlighting the added-value of soil bioengineering techniques to restore riparian biodiversity. This may confirm that stabilization structures made of willow fascines are better suited than stabilization structures made of artificial substrata to support riparian species. Also, beyond the positive effect of soil bioengineering techniques for riparian biodiversity, we found that climatic, hydrological and land cover variables strongly influenced diversity patterns. Thus, multi-taxonomic diversity decreased along larger rivers and in landscapes dominated by urban areas. This may indicate that the full added value of soil bioengineering techniques for biodiversity will only become apparent if more attention is paid to mitigating the negative impact of human activities in the vicinity of riparian zones and if larger scale environmental parameters are taken into account as early as possible in restoration project. Therefore, we strongly recommend that riverbank restoration projects, based on the active introduction of native pioneer tree species, should be planned at the catchment scale.

KARAKTERISTIK DAN PERSEPSI PETANI TERHADAP INOVASI TEKNIK SOIL BIOENGINEERING UNTUK MITIGASI LONGSOR DI KABUPATEN BANJARNEGARA JAWA TENGAH (Characteristics and farmers’perception to Soil Bioengineering technique for mitigation of landslide at Banjarnegara Regency, Central Java )

Soil Bioengineering technique is a soil and water conservation technology innovation for landslide mitigation. The success of technological innovation is influenced by the perception and characteristic of the user community. This study aimed to determine the characteristics of farmers as potential users and their perceptions that were measured based on an assessment of characteristics of technology innovation. This study used a qualitative approach combined with the support of qualitative data quantification. Data collected consist of primary data and secondary data. Primary data include the characteristics of respondents and their perceptions of Soil Bioengineering innovation in the form of assessment variables consisting of certain indicators which are then measured using a Likert scale. The characteristics of farmers prospective users of Soil Bioengineering techniques are: 1) productive age, 2) lack of education (junior high school), 3) narrow land ownership (0.1 to 0.3 hectares), 4) the commodity planted is salak, 5) experience as farming (16 - 20 years) and, 6) medium/ middle income levels (3- 4.9 million rupiah per month). Farmer's perceptions are generally positive to Soil Bioengineering. Positive perception techniques if it was measured based on: 1) relative advantage, 2) compatibility, 3) simplicity, 4) trialability and 5) observability.

Eco-morphological characteristics of fern species for slope conservation

Degradation of slopes due to shallow landslide and the subsequent erosional processes are a big challenge on the application of soil bioengineering techniques; that is the use of plants as main structural components of a slope protection and conservation system. An optimal application of soil bioengineering techniques should include not only the technical factor of plants as structural components but also the ecology of species and the plant adaptations to disturbances, which is crucial if a longterm successful slope restoration system is intended. Ferns are a dominant understory vegetation species in the forest of Japan, but its characteristics and influences on the recovery of shallow landslide scars have not been fully studied yet. This study aims to find out the ecological characteristics of fern species through the calculation of ecological indicators and the quantification of the morphological features of specimens growing on disturbed and non-disturbed forest slopes in Japan. Gleichenia japonica was found as the vegetation species with biggest ecological indicators on both slopes. The analysis of morphological characteristics of the specimens growing on both sites showed that the development of the specimens is focused in below-ground characteristics. The pull-out force of Gleichenia japonica root system as an indicator of ecological adaptation to a constraint environment and morphological characteristics quality is influenced by height and root length according to the principal component analysis. The eco-morphological characteristics of species can be used as an indicator of an optimal element in soil bioengineering establishment for slope conservation proposes. The long and fibrous root system could be placed on forest roads, steep or small slopes where space limitation is an issue for the establishment of bigger species and if the slope conditions allow it, it can control soil losses due to rainfall and provide stability.

Cutting diameter on early growth performance of purple willow (Salix purpurea L.)

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.

AVALIAÇÃO DA PROPAGAÇÃO VEGETATIVA DE ESPÉCIES UTILIZADAS NA ESTABILIZAÇÃO DE OBRAS DE TERRA COM TÉCNICAS DE ENGENHARIA NATURAL

As técnicas de Engenharia Natural correspondem a um conjunto de ações que utilizam materiais de construção vivos, como plantas e estacas vivas, bem como materiais inertes, como elementos estruturais em construções bastante simples, com vistas à recuperação ecológica e à estabilização dos solos. Os materiais inertes utilizados, na dependência dos objetivos e da disponibilidade local, são basicamente estruturas metálicas, geotêxteis, madeira, pedras ou mesmo concreto. Esses, além de conferirem estabilidade imediata ao solo, oferecem proteção e suporte ao posterior desenvolvimento da vegetação. A parte vegetativa complementa, ou mesmo, gradativa e integralmente, substitui as funções estabilizadoras dos componentes inertes. No entanto, a execução dos trabalhos só pode ser realizada com sucesso quando as características técnicas da vegetação são conhecidas e, assim, corretamente aproveitadas. Esta pesquisa é o resultado de uma sequência de experimentos realizados com o objetivo de identificar, entre espécies de habitat ripário, aquelas com capacidade de propagação e desenvolvimento vegetativo. Uma grande parte dos modelos de intervenção utilizados pela Engenharia Natural vale-se exclusivamente dessa forma de propagação. Entre os muitos fatores potencialmente influentes no desenvolvimento vegetativo tais como sobrevivência, ritmo de enraizamento e de brotação, velocidade de crescimento de raízes e brotos deve-se também ressaltar a importância da época de coleta e plantio do material vegetal. Este estudo, utilizando-se de canteiros experimentais construídos em épocas distintas do ano, busca obter essas informações por meio da avaliação da sobrevivência e do desenvolvimento da parte aérea e radicular de estacas de seis espécies potenciais facilmente encontradas ao longo das margens fluviais dos rios do Sul do Brasil. As espécies testadas são: Calliandra brevipes, Phyllanthus sellowianus, Pouteria salicifolia, Salix humboldtiana, Salix x rubens e Sebastiania schottiana. Os resultados experimentais indicam a possibilidade de utilização de algumas dessas espécies. Calliandra brevipes, Sebastiania schottiana e Pouteria salicifolia apresentaram desenvolvimento inferior ao Phyllanthus sellowianus, Salix humboldtiana e Salix x rubens. Evidenciou-se que a época de plantio é menos importante em espécies de enraizamento rápido, como Phyllanthus sellowianus, Salix humboldtiana e Salix x rubens, mas pode ser decisiva em espécies com enraizamento mais lento, como Sebastiania schottiana, influenciando inclusive a sobrevivência da espécie.

4th International Conference on soil bio- and eco-engineering (SBEE2016) ‘The Use of Vegetation to Improve Slope Stability’

This editorial describes a 10-paper special issue that arises from the 4th International Conference on Soil Bio- and Eco-Engineering (SBEE2016) ‘The Use of Vegetation to Improve Slope Stability’ held at the University of Sydney, Australia, in July 2016. The conference focused on current topics and progress in slope stability research and the successful application of soil bio-engineering and eco-engineering techniques to stabilizing slopes in a variety of climatic and geomorphic settings. The papers are divided into the following categories: vegetation and slope stability (1 paper); root-soil interactions (5 papers); slope stability modelling (2 papers); eco-engineering and land restoration (2 papers). Most of the papers present case studies documenting bio- and eco-engineering techniques, site-specific investigations or innovative slope stability modelling approaches and two papers are aimed at standardizing data collection and sustainability assessment practices within the discipline. Case studies are presented by scientific researchers, practitioners, geotechnical and civil engineers, biologists, ecologists, geomorphologists, and foresters from North America, Europe, South-East Asia, Australia, and New Zealand.

Development of an environmental life cycle assessment model for soil bioengineering constructions

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 engineering solutions which take into consideration not only technical issues but also ecological and aesthetic values. In this context, soil bioengineering constructions are gaining importance because the utilisation of living plants as construction material for conventional protective structures represents a preferred alternative. Different soil bioengineering techniques are used as stand-alone solutions or as complementary to conventional hydraulic and civil engineering solutions. Although the field of soil bioengineering has a long historical tradition, there is no assessment scheme that analyses energy consumption nor carbon footprint throughout the entire life cycle of soil bioengineering constructions. The following paper focuses on assessing three different soil bioengineering construction types. Through the use of an environmental life cycle assessment model, we show the possibilities and deficiencies of this method in the field of soil bioengineering. The analysis concentrates on the product stage and the construction phase. The results reveal that the hotspots of energy consumption for soil bioengineering constructions are the operating machines.

A proposal for assessing the success of soil bioengineering work by analysing vegetation: results of two case studies in the Italian Alps

The evaluation of the success of soil bioengineering work is an issue still poorly addressed by the scientific community. Nevertheless, soil bioengineering techniques are increasingly used worldwide when mitigating the impact on the environment and the landscape is one, but not the only, goal of intervention. A tool to measure the success of soil bioengineering work, with reference to landslide stabilization, is presented in this paper: the index of ecological success (IES). The IES is based on the phytosociological analysis of vegetation and widens the potential applications of the ecological index of maturity (EIM), recently formulated by Giupponi et al. (Restor Ecol 23:635–644, 2015) to assess the degree of disturbance affecting a plant community. The IES compares the EIM values of the vegetation of an area affected by soil stabilization work with those of the expected vegetation at a precise time after completion of soil stabilization work, providing values ranging between 0 (maximum failure) and 1 (complete success). The IES was applied in two study areas located on two mountain slopes of the Southern Alps (Italy) which, as a result of landslides, were subject to soil bioengineering work aimed at slope stabilization. The results of these first two applications confirm the efficacy of the IES in evaluating the success of soil bioengineering work in mountain areas and bode well as to its future application.

Residual life and degradation assessment of wood elements used in soil bioengineering structures for slope protection

Soil bioengineering techniques to repair slope failures and increase slope stability are often used, when possible, as alternatives to traditional structures in order to mitigate environmental impact without compromising effectiveness. However, such techniques use live plants and entrust most of their structural resistance to wood members whose mechanical characteristics diminish with time. To date, the decay of mechanical characteristics of wood elements employed in soil bioengineering techniques and lifetime predictions has been little explored. Such information is also important for durability forecasting. In this paper we present the results of experimental analyses carried out to evaluate the degradation of mechanical properties of untreated timber elements which were collected from single and double live cribwalls or check-dams built about ten years ago in the Vesuvius National Park (Naples, Southern Italy). To help interpret the behavior of a complex material such as wood, a novelty of this study lies not only in combining ultrasonic and sclerometric nondestructive testing (NDT) methods so as to reduce measurement errors, but also in framing the outcomes from mechanical tests within the biological analysis of fungi detected on the timbers. Exploratory statistical analyses reveal that there exist hardly any correlations between moisture contents in the timber elements and both transversal and longitudinal ultrasonic velocities, although some clustering provides insights into the results obtained. Comparisons between results using data measured on “old” and “new” timber elements enable some evaluations of residual safety factor assessment to be carried out.