Soil bioengineering for risk mitigation and environmental restoration in a humid tropical area

The use of soil bio-engineering techniques in developing countries is a relevant issue for disaster mitigation, environmental restoration and poverty reduction. Research on the autochthonal plants suitable for these kinds of interventions and on the economic efficiency of the interventions is essential for the dissemination of such techniques. The present paper is focused on these two issues as related to the realization of various typologies of soil bioengineering works in the humid tropics of Nicaragua.<br> <br> In the area of Río Blanco, located in the Department of Matagalpa, soil bioengineering installations were built in several sites. The particular structures built were: drainages with live fascine mattress, a live palisade, a vegetated live crib wall for riverbank protection, a vegetative covering made of a metallic net and biotextile coupled with a live palisade made of bamboo. In order to evaluate the suitability of the various plants used in these works, monitoring was performed, one on the live palisade alongside an unpaved road and the other on the live crib wall along a riverbank, by collecting data on survival rate and morphological parameters. Concerning economic efficiency, we proceeded to a financial analysis of the works. Once the unit price was obtained, we converted the amount into EPP Dollars (Equal Purchasing Power) in order to compare the Nicaraguan context with the European one.<br> <br> Among the species used we found that <i>Gliricidia sepium</i> (local common name: Madero negro) and <i>Tabebuia rosea</i> (local common name: Roble macuelizo) are adequate for soil bioengineering measures on slopes, while <i>Erythrina fusca</i> (local common name: Helequeme) resulted in successful behaviour only in the crib wall for riverbank protection.<br> <br> In comparing costs in Nicaragua and in Italy, the unit price reduction for Nicaragua ranges from 1.5 times (for the vegetative covering) to almost 4 times (for the fascine mattress), using the EPP dollar exchange rate.<br> <br> Our conclusions with regard to hydrological-risk mitigating actions performed on a basin scale and through naturalistic (live) interventions are that they are not only socially and technically possible, even in hardship areas (by maximizing the contribution of the local labour force and minimizing the use of mechanical equipment), but also economically sustainable

Shallow landslide susceptibility assessment in a data-poor region of Guatemala (Comitancillo Municipality)

Although landslides are frequent natural phenomena in mountainous regions, the lack of data in emerging countries is a significant issue in the assessment of shallow landslide susceptibility. A key factor in risk-mitigation strategies is the evaluation of deterministic physical models for hazard assessment in these data-poor regions. Given the lack of physical information, input parameters to these data-intensive deterministic models have to be estimated, which has a negative impact on the reliability of the assessment. To address this problem, we examined shallow landslide hazard in Comitancillo municipality, Guatemala. Shallow landslides are here defined as small (less than two or three metre-deep) rotational or translational slides or earth flows. We based our hazard simulation on the stability index mapping model. The model’s input parameters were estimated from a statistical analysis of factors affecting landslides in the municipality obtained from a geodatabase. The outputs from the model were analysed and compared to an inventory of small-scale landslides. The results of the comparison show the effectiveness of the method developed to estimate input parameters for a deterministic model, in regions where physical data related to the assessment of shallow landslide susceptibility is lacking

Experiences of improving water access in rural areas in Guatemala

The GESAAF Department of the UNIFI has been involved in the project “Gestione ambientale e del rischio nel dipartimento di Sololà” in the period 2011-’12 aiming at guaranteeing water access to people leaving in rural areas in the Sololà Department in Guatemala, in collaboration with the two NGOs Movimento Africa ’70 and Oxfam Italia. Appropriate technologies, such as EMAS pump and well drilled with the Baptista- Boliviana technique, have been proposed and utilized for improving water access in areas where lack of water represented a limiting factor for the human development. They can be both considered compatible with local, cultural and economic conditions: in fact locally available materials are used and the tools can be maintained and operationally controlled by the local users. At the end of the project, 52 EMAS pumps have been installed and 19 wells drilled, 33 pumps have been installed in already existing wells tank. Formation activities of local people played an important role: diffusion actions of the methodology started from schools, 20 workers participated to an in class course and more than 100 participated in the field work. Monitoring activities on the 52 installed pumps have been carried out in order to check the performances of the pumps and the knowledge level acquired by the users. After some months of operation, more than 80% of the pumps were correctly functioning and the required maintenance activities have been carried out in collaboration with the local users. In order to analyze the project results, a SWOT analysis (Strengths, Weaknesses, Opportunities, and Threats) has been carried out for developing a strategy able to tackle the weaknesses and threats of the procedure. The application of the SWOT analysis showed to be an useful tool to analyse the current situation coming from the ended project. It has been helpful to gauge how the project performed. The analysis results may be also utilized for exploring strengths and weaknesses of a possible transferring of the methodology to other sites

Terraced Landscapes and Hydrological-Geological Hazards: Innovative Approaches and Future Perspectives

In the last few years, terraced landscapes have been receiving renovated interest all over the world (e [...