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Numerical issues in computing inundation areas over natural terrains using Savage-Hutter theory 总被引：1，自引：0，他引：1
Bin Yu Keith Dalbey Amy Webb Marcus Bursik Abani Patra E. Bruce Pitman Camil Nichita 《Natural Hazards》2009,50(2):249-267
When characterizing geologic natural hazards, specifically granular flows including pyroclastic flows, debris avalanches and
debris flows, perhaps the most important factor to consider is the area of inundation. One of the key parameters demarcating
the leading edge of inundation is the run-out distance. To define the run-out distance, it is necessary to know when the flow
stops. Numerical experiments are presented for determining a stopping criterion and exploring the suitability of the Savage-Hutter
theory for computing inundation areas of granular flows. The stopping criterion is a function of dimensionless average velocity,
pile aspect ratio and internal and bed friction angle and can be implemented on either a global (entire flow) or local (small
areas of the flow) level. Slumping piles on a horizontal surface, and geophysical flows over complex topography were simulated.
Mountainous areas, such as Colima volcano, Mexico; Casita, Nicaragua; Little Tahoma Peak, USA, and the San Bernardino Mountains,
USA, were used as test regions. These areas have combinations of steep, open slopes and sinuous channels. Because of differences
in topography and physical scaling, slumping piles in the laboratory and geophysical flows in natural terrain must be scaled
differently to determine a reasonable dimensionless relationship for the stopping criterion. 相似文献
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Mapping the Risk of Burning in the Brazilian Amazon with the Use of Logistic Regression and Fuzzy Inference 总被引：1，自引：1，他引：0
Camil Wadih Salame Joaquim Carlos Barbosa Queiroz Gilberto de Miranda Rocha Mario Miguel Amin 《Mathematical Geosciences》2012,44(3):241-256
Through the PRODESDIGITAL Project, the National Institute for Space Research (INPE) has been mapping vegetal coverage in the
Brazilian Legal Amazon using Landsat satellite images. INPE not only identifies deforested areas but also releases a daily
map of burning areas. Burning is frequently used as the cheapest way to deforest, to clear areas for farming and to increase
the soil’s fertility in a short period of time. In many instances, these fires get out of control and end up accidentally
invading areas of forest exploited by the lumber industry, agricultural plantations and pastures. However, the deforestation
and burning area maps alone are insufficient for monitoring and control on a regional scale. It is necessary to know in an
analytical way how actions (deforestation and burnings) that characterize human occupation are occurring in a region. In this
research, two methods are used that allow the inclusion of co-variation in the estimation of variables of interest: logistic
regression, which is a statistical method that considers a categorical or discrete response variable and discrete and/or continuous
co-variation; and fuzzy logic, which makes use of artificial intelligence methods to incorporate into computational models
information based on the knowledge or experience of a specialist. In both methods, the response variable may be related to
the probability of occurrence of the environmental variable under study. 相似文献
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With the proposition for the adoption of Geocentric Reference System for the Americas (SIRGAS) as a terrestrial reference frame for South America, the need for temporal monitoring of station coordinates used in its materialization has become apparent. This would provide a dynamic characterization of the frame. The Brazilian Network for Continuous Monitoring of GPS (RBMC) has collected high accuracy GPS measurements since 1996. The Brazilian Institute of Geography and Statistics (IBGE) maintains this network in collaboration with several universities and organizations. Most of the stations are also part of the SIRGAS network. The RBMC also contributes data to the International Terrestrial Reference System (ITRS) to densify the global frame. Two of the RBMC stations are also part of the International GPS Service (IGS). This paper reports initial results from these stations. To estimate the velocity field defined by these stations, ten IGS stations located on the border of the South American plate and in adjacent plates, along with nine RBMC stations, were used. Observations covering five groups of 15 days each were used. These groups of observations were at epochs 1997.3, 1997.9, 1998.3, 1998.9 and 1999.2. Seven IGS stations were chosen to have their coordinates constrained to those epochs. IGS products (precise ephemeris and clocks) were used to process the daily solutions, which were carried out with Bernese software. Carrier phase double differences were formed using the ionospheric-delay free observable. The troposphere was modeled using a combination of the Saastamoinen model and the Niell mapping function. A tropospheric parameter was estimated every two hours. The results of the daily baseline solutions were combined using the summation of normal equations technique, in which the final coordinates and velocities were estimated. The results were compared with various models, such as the NNR-NUVEL1 and the APKIM8.80. Velocity vectors estimated for the RBMC stations show good agreement with those two models, with rates approximately equal to 2 cm/year. 相似文献
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