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Integrated Risk Assessment of Hydrologically-Driven Landslides

Final Report Summary - HYDRODRIL (Integrated Risk Assessment of Hydrologically-Driven Landslides)

HYDRODRIL (Integrated Risk Assessment of Hydrologically-Driven Landslides) is a project supported by IRSES Programme within the framework of Marie Curie ITN (Initial Training Networks) aiming to provide high quality training to a group of young researchers, contributing to the development of a new generation of multidisciplinary researchers able to work in the challenging field of advanced computational and physical modeling of landslides and debris flows. The partnership of this multidisciplinary exchange programme has brought together the researchers from the European Union, Asia and Central America. The scientific goal of HYDRODRIL is to investigate and evaluate the risk and nature of hydrologically-driven landslides, therefore contributing to better understanding of the relationship between small-scale deformations in soil/rock structures, the failure mechanisms induced by these deformations and the following large-scale dynamic behaviour, as well as detailed risk assessment. Major entities of HYDRODRIL was the extensive monitoring at Huangtupo-landslide in the Three-Gorges region (Hubei province, China), the corresponding experiments on a small-scale model in centrifuge tests and multiscale modeling approach of landslides by numerical simulations. The multidisciplinary research group, consisting of experts in their respective fields have covered the geotechnical, geological, geophysical and geographical issues. The participating institutions of this project are:
• Universität für Bodenkultur (BOKU) , Vienna, Austria
• University of Nottingham (UNOTT), Nottingham, UK
• China University of Geosciences (CUG), Wuhan, China
• Indian Institute of Technology (IIT), Kharagpur, India
• Universidad Nacional Autonoma de Mexico (UNAM), Mexico

BOKU is the coordinator of this project. The main objective of HYDRODRIL exchange programme is to create a strong multidisciplinary network of researchers based both in the European Research Area (Austria and United Kingdom) and in the countries of emerging economies, i.e. China, India and Mexico.

The scientific objectives of HYDRODRIL are:
• To address the urgent need of understanding and forecasting of triggering mechanisms of landslides and establish coherent strategies for disasters prevention and mitigation.
• To investigate and evaluate the risk and nature of hydrologically-driven landslides and have better understanding of mechanisms governing hydrologically-driven landslides
The main topics of the research project are:
• Influence of precipitation on unsaturated slopes
• Water infiltration in soil
• Propagation of water and raising of water table in slopes
• Water influence on the reduction of strength of soil
• Water influence on the factor of safety of slopes
• Assessing the risk for people and infrastructure
• Measuring changes in soil strength by means of geophysical investigations
• Protection and mitigation measures for slopes
• Understanding of water flow during drainage
• Provision of information and risk assessment with GIS.

Project achievements and key events:
The project was divided into five scientific work packages which were led by each partner. A summary of achievements is given below.
WP1: Monitoring of hydrologically-driven landslides (Leader: CUG, China)
The informational system for monitoring and early-warning of landslides induced by hydrological effect has been established on the basis of the field testing site of Huangtupo Landslide in Badong. The measured parameters are used for different analysis of the landslides and for the forecasting model of landslides. Several papers have been published.

WP2: Triggering mechanisms of hydrologically-driven landslides (Leader, UNOTT, UK)
Landslide behaviour depends on the in-situ conditions during failure initialisation. A major destabilizing effect of slopes plays the water content. However, field observation and reliable field data recording is barely feasible. Therefore, the triggering of landslides has been simulated in intensively instrumented experiments at a small scale under the increased gravity field of a geotechnical centrifuge. Several experiments have been conducted at BOKU. A PhD thesis will be submitted under this topic and some papers are ready for publication.

WP3: Multiscale modeling of landslides (Leader, BOKU)
The core scientific objective of WP3 is the numerical simulation of hydrologically-driven slope failures by continuum and discontinuum approaches. The multiscale and multiphase approach provides deep insight into the process of hydrologically-driven slope failure from initiation to the post bifurcation regime. A number of numerical models have been developed at BOKU considering different situations of slopes. An integrated slope model which considers also the hydrogeological and mechanical effects of the plants is ready to use. Some papers have already been published and a PhD thesis will also be submitted under this topic.

WP4: GIS based risk assessment (Leader, UNAM)
There is a lack of the integration of different approaches to assess and map slope risk in one complete system. The lack of investigations concerning the systematic comparison of landslide models at different cartographic scales, resolution of digital elevation models, and sampling strategies not only compromises the reliability of the models, but also leads to the misuse of the models. In this project the development of an integrated system was proposed. This project has achieved some success in this regard. Some papers have been already published which describes the different approaches to assess the risk potential of landslides.

WP5: Mitigation measures
The purpose of landslide mitigation is to minimize the potential occurrence of the phenomenon by means of various structures and interventions which are generally subdivided into: geometric methods (in which the geometry of the hillside is changed), hydrogeological methods (in which the groundwater level is lowered or the water content of the material is reduced), chemical and mechanical methods (which attempt either to increase the shear strength of the soil or to anchor the unstable soil mass to the stable substratum). Not all the above delineated methods are pertinent and thus effective in the case of hydrologically induced landslides; our concern is therefore mainly about drainage of the percolated water. Some papers have already published on different methods of mitigation measures.