An environmental geomorphologic approach to site selection for hazardous wastes

Geomorphological features are essential parts of the environment and they represent an important conditioning factor for the development and distribution of certain biological assemblages, as well as for a variety of human activities. However, environmental geomorphology usually receives very limited or no attention at all in the process of environmental impact assessment (EIA). Nevertheless, the site selection process for hazardous wastes in environmental impact studies for individual projects plays an essential role. In order to determine the most suitable site in a region for municipal/hazardous wastes, several criteria are used, including geology, groundwater condition, climate, and land use. The present work describes a methodology taking advantage of environmental geomorphological features, and reducing these criteria in the site selection procedure in land disposal of waste; in addition, a case study is presented to demonstrate the applicability of the proposed methodology. The validity of the adopted site screening method is explained. This methodology comprises the use of a single geomorphological map to locate suitable landfilling sites for hazardous waste, instead of using separate maps for geological features, climatic features (temperature, precipitation, and speed and direction of the prevailing wind), slope and erosion. Furthermore, the present study is compared with a previous study performed in the GAP region, where the use of land resources is crucial for agricultural and water management purposes. The application of the described selection process and the verified method in this region shows that the adopted method and detailed criteria are valid.     

Elastic wave velocity monitoring as an emerging technique for rainfall-induced landslide prediction

Landslides are recurring phenomena causing damages to private property, public facilities, and human lives. The need for an affordable instrumentation that can be used to provide an early warning of slope instability to enable the evacuation of vulnerable people, and timely repair and maintenance of critical infrastructure is self-evident. A new emerging technique that correlates soil moisture changes and deformations in slope surface by means of elastic wave propagation in soil was developed. This approach quantifies elastic wave propagation as wave velocity. To verify its applicability, a series of fixed and varied slope model tests, as well as a large scale model test, were conducted. Analysis of the results has established that the elastic wave velocity continuously decreases in response of moisture content and deformation, and there was a distinct surge in the decrease rate of wave velocity with failure initiation, soil deformation was thus envisaged to have more significant effect on elastic wave velocity than water content. It is proposed that a warning be issued at switch of wave velocity decrease rate. Based on these observations, expected operation of the elastic wave velocity monitoring system for landslide prediction in the field application is presented. Consequently, we conclude that the elastic wave velocity monitoring technique has the potential to contribute to landslide prediction.     

Structurally controlled landslides in saprolitic soils in Hong Kong

A number of large slope failures which have occurred in Hong Kong have highlighted the important influence that discontinuities in saprolitic soils can have on slope stability. Conventional stability analyses normally adopted for such soils, which assume failure through intact materials of uniform shear strength, are not appropriate if discontinuity-controlled failures can be postulated. Stress history and present-day weathering effects should also be taken into consideration in the assessment of the long-term stability of slopes in weathered rocks in tropical and subtropical regions. © Rapid Science Ltd. 1998     

Dynamic behaviour of a cable-stayed bridge

The dynamic response of a cable-stayed bridge to seismic, wind and simulated traffic loads is discussed. The analysis procedure which is used considers non-linear behaviour of the cables, caused by the variation in sag with tensile force, and non-linear behaviour of the bending members, caused by the interaction of axial and bending deformations. It is concluded that the non-linearity of the structure must be considered in determining the stiffness of the structure in the dead load deformed state. A linear dynamic analysis, however, starting from the dead load deformed state will give results within normally required design accuracy.     

Characterization of the groundwater flow system in the hillside and coastal aquifers of the Mersin-Tarsus region (Turkey)

In the region between Mersin and Tarsus cities, located along the Mediterranean Sea coast in southern Turkey, the demand for groundwater has increased dramatically as the available surface water supplies have already been developed. Fundamental information is required to characterize the existing groundwater system in this area in order to establish a sustainable groundwater-use policy. For this purpose, hydrochemical and environmental isotopic data were collected and integrated with available geological and hydrogeological information to develop a conceptual model of the system. Results, backed up mainly by depleted stable isotope composition and infinitesimal tritium content, suggest that most of the groundwater along the coastal zone is supplied by the neighboring mountain belt while local precipitation has also contributes to aquifer recharge. The validation of the conceptual perspective by a steady-state numerical groundwater flow model reveals that about 90% of the recharge to the aquifer system is supplied by the deep flow of karstic groundwater fed from the Taurus Mountains. Monitoring of changes in the recharge regime of the mountain sector seems to be critical in establishing future groundwater use policies.     

Dust-acoustic solitary and rogue waves in a Thomas-Fermi degenerate dusty plasma

The formation and propagation of dust-acoustic (DA) solitary and rogue waves are studied in a non-relativistic degenerate Thomas-Fermi thermal dusty plasma incorporating transverse velocity perturbation effects. The electrons and ions are described by the Thomas-Fermi density distributions, whereas the dust grains are taken as dynamic and classical. By using the reductive perturbation technique, the cylindrical Kadomtsev-Petviashvili (CKP) equation is derived, which is then transformed into a Korteweg-deVries (KdV) equation by using appropriate variable transformations. The latter admits a solitary wave solution. However, when the carrier waves frequency is much smaller than the dust plasma frequency, the DA waves evolve into the nonlinear modulation instability, generating modulated wave packets in the form of Rogue waves. For the study of DA-rogue waves, the KdV equation is transformed into a self-focusing nonlinear Schrödinger equation. The variation of dust temperature and the electron density affects the nonlinearity and dispersion coefficients which suppress the amplitudes of the DA solitary and rogue waves. The present results aim to describe the nonlinear electrostatic excitations in astrophysical degenerate dense plasma.