An analysis of debris-flow events in the Sardinia Island (Thyrrenian Sea, Italy)

On 6 December 2004, the Villagrande Strisaili area (middle-east Sardinia), was struck by debris flows; 330 mm of rainfall took place within 3 h with an hourly intensity of 120 mm, which is far more above than normal for the study area. In the urban center stony and driftwood deposits accounted for a total volume estimated as 10,000 m³. The event claimed huge amount of infrastructural loss and two human lives. According to the chronicle reports, the area experienced two debris-flow events in the last century. The present paper is the outcome of an intensive study of such debris-flow events including their physical processes and geomorphological effects through both field survey and laboratory analysis.     

A GIS-based Spatial Pattern Analysis Model for eco-region mapping and characterization

Growing concerns about global climate change, biodiversity maintenance, natural resources conservation, and long-term ecosystem sustainability have been responsible for the transformation of traditional single resource management approaches into integrated ecosystem management models. Eco-regions are large ecosystems of regional extent that contain smaller ecosystems of similar response potential and resource production capabilities. They can be used as a geographical framework for organizing and reporting resource information, setting bioecological recovery criteria, extrapolating site-level management, and monitoring global change. The objective of this research is to develop a quantitative, multivariate regionalization model that is capable of delineating eco-regions at multiple levels from remotely sensed information and other environmental and natural resources spatial data. The Spatial Pattern Analysis Model developed in this study uses a region-growing algorithm to generate spatially contiguous regions from primitive polygonal land units. The algorithm merges the most similar pair of neighbouring units at each iteration, based on satisfying certain similarity criteria until all units are grouped into one. This model was utilized to develop an eco-region map of Nebraska with three hierarchical levels. In the mapping process, the STATSGO data set was used to build the primitive map units. Environmental parameters included in the model were multi-temporal AVHRR data, soil rooting depth, organic matter content, available water capacity, and long-term annual averages of water balance and growing degree day totals. Development of the model provides a new and useful approach to eco-region mapping for resource managers and researchers. The method is automated and efficient, reduces the judgement biases and uncertainty of manual analyses, and can be replicated for other regions or for the regionalization of other themes.     

Towards a potential research agenda to guide the implementation of Spatial Data Infrastructures—A case study from India

Recently, Spatial Data Infrastructures (SDIs) has been a rapidly expanding field and broadly assumed to underpin the development of information society and the knowledge economy. In this paper, we argue that the anticipated benefits of SDIs have largely not yet been generally realized in practice due to a lack of a robust theoretical framework as well as insufficient empirical research to guide the implementation efforts. We posit that learnings from the allied discipline of Information Infrastructures, which has matured during the 1990s in response to the proliferation of distributed, complex, and heterogeneous networked systems, can provide a useful theoretical lens to inform the emerging domain of SDIs. We focus on three key concepts identified in the domain of information infrastructure theory, viz. the installed base, reflexive standardization, and cultivation approach to design, to develop a theoretical framework, which is then applied to analyse the ongoing initiative to establish National Spatial Data Infrastructure (NSDI) in India. This analysis helps us to provide the basis to articulate a potential research agenda—for both theory and practice—which, we believe, offers the promise to better conceptualize and implement SDIs, particularly in developing country settings like India.     

Bulk viscous barotropic magnetised string cosmological models

Spatially homogeneous and anisotropic LRSBianchi type-I string cosmological models are studied in the frame work of general relativity when the source for the energy momentum tensor is a bulk viscous fluid containing one dimensional strings embedded in a magnetic field. A barotropic equation of state for the pressure and density is assumed to get determinate solutions of the field equations. The bulk viscous pressure is assumed to be proportional to the energy density. The effects of viscosity and electromagnetic field on the properties of the model are investigated. The role of bulk viscosity and electromagnetic field in getting an inflationary phase and in establishing a string phase in the universe is studied.     

Bianchi type-VIh string cloud cosmological models with bulk viscosity

String cloud cosmological models are studied using spatially homogeneous and anisotropic Bianchi type VI_h metric in the frame work of general relativity. The field equations are solved for massive string cloud in presence of bulk viscosity. A general linear equation of state of the cosmic string tension density with the proper energy density of the universe is considered. The physical and kinematical properties of the models have been discussed in detail and the limits of the anisotropic parameter responsible for different phases of the universe are explored.     

The effects of induced magnetic field on unsteady hydromagnetic flows in a rotating medium

Unsteady flows of a viscous incompressible electrically conducting fluid filling the semi-infinite space in contact with an infinite conducting plate in a rotating medium in the presence of a transverse induced magnetic field are investigated under an arbitrary time-dependent forcing effect on the motion of the plate where the plate and the fluid rotate uniformly as a rigid body. By using the Laplace transform technique, the Greens function of the problem is determined and certain asymptotic expansions of the exact solutions are analyzed. the steady-state oscillatory flow problem is solved, and structure of waves and displacement thickness of the boundary layers are discussed for different cases of some natural parameters in the problem. The results are compared with similar flows in the presence of a constant magnetic field.     

Underground opening damage from earthquakes

A summary of worldwide qualitative data regarding the behavior of underground openings during earthquakes is presented. This information has been collected for 192 reports of underground behavior from 85 earthquakes throughout the world. The data have been assembled into a data base to determine some of the significant factors that may affect underground stability. The parameters of interest are: (1) extent of damage; (2) overburden cover; (3) predominant rock type; (4) form of support (i.e. type of internal liner or opening support); (5) geographic location; and (6) magnitude and epicentral distance of the affecting earthquake. A significant contribution to this study is the development of a correlation between peak ground acceleration at the surface, overburden depth and damage. This relationship will allow for preliminary assessment of stability of new underground structures prior to extensive dynamic analyses. Also, the vulnerability of existing underground facilities may be assessed rapidly on the basis of the qualitative data presented herein.     

Unsteady MHD free-convection flows on a porous plate with time-dependent heating in a rotating medium

The three-dimensional unsteady free-convection flows of a viscous fluid near a porous infinite vertical plate in a rotating medium in the presence of a constant transverse magnetic field are investigated under an arbitrary time-dependent heating of the plate. By using the Laplace transform technique, the Green function of the problem is determined and exact solutions are obtained for special cases of the impulsive and the accelerated heating effect for an arbitrary Prandtl number. The thermal influence on skin friction at the plate and the displacement thickness of the boundary layers are discussed.