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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-22 1:22 |
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Conference: Bucharest University Faculty of Physics 2013 Meeting
Section: Atmosphere and Earth Science; Environment Protection
Title:
Multiple hazards – flood and landslides modelling. Principle presentation
Authors:
Mary-Jeanne Adler, Zenaida Chitu
Affiliation:
National Institute of Hydrology and Water Management, Bucharest, Romania
E-mail
mj.adler@hidro.ro
Keywords:
multidazard estimation, flood and land slides modelling and mapping
Abstract:
Three branches of applied science contribute to the knowledge base for the identification of areas susceptible to debris-flow initiation and other forms of geohydrological instability: geology, hydrology, and hydraulics Geology is here used in the broad sense and includes topography, geomorphology, pedology, and geomechanics. In the context it deals prevalently with the study of soil and sediment characteristics, as well as the estimation of movable volumes and their spatial distribution.Hydrology studies the movement of water, initially as rain, then as flows within the soil, along the ground surface, and within stream channels. Water flows plays a major role in hillslope stability and, as a consequence, they are essential in determining the conditions that trigger debris-flows and sediment transport.Hazard classification begins with a preliminary investigation. In the context of fluvial and torrential phenomena, this should focus on determining the probability of instability conditions arising in a certain area.Forecasting landslide and debris-flow initiation means locating, temporally (when?) and spatially (where?), the downhill movements of masses of earth. The forecast must also include a quantification of the earth/sediment that may be moved (how much?). Current knowledge of the processes that interact to give rise to instabilities, as well as the natural heterogeneity of the systems involved, mean that these questions can only be partially answered at this time.The methods used to define the instability hazard are based on mathematical models (and on the equations of conservation of mass and momentum, even though at times these are present in very conceptual form), which can be distinguished in:
• distributed models with simplified hydrology (usually assuming simplified, stationary subsurface flows) and concentrated parameters (which require ex post calibration): these are traditional rainfall-runoff models that have been expanded to consider the sediment contribution. This type of analysis is normally used in the most common case studies;
• detailed models (physically based distributed models with non-stationary infiltrations and filtrations) with distributed parameters, which can usually be measured directly (ex-ante), and surface runoff models, which can include integration on a two-dimensional grid: these models are more complex and therefore, in those cases where they are deemed necessary, consultation of a more specific treatise is recommended.
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