Добірка наукової літератури з теми "Damming susceptibility"

A 4.9-m-thick lake sequence, formed due to the landslide damming of a stream in the semiarid Garhwal Himalaya, was studied to understand past monsoonal variations in the region. The Optically Stimulated Luminescence (OSL) chronology indicates that the lake existed between ~ 12 and ~ 7 ka ago. Chronologically constrained trends of sand percent, organic phosphorus (OP), apatite inorganic phosphorus (AIP) and parameters of environmental magnetism were measured in the paleolake profile. Measured proxies indicate that the Indian summer monsoon ameliorated in the early Holocene after 12 ka cooling, and it appears that all the proxies from the lake have captured this globally recognized early Holocene warming. Four phases of wet conditions (intensified monsoon) are recognized at ~ 11.5 ka, ~ 11–10.5 ka, ~ 10–9 ka and ~ 8–7 ka with maximum uncertainties of ~ 1000 years. The wet phases are characterized by high magnetic susceptibility, increased OP and reduced AIP. In an attempt to understand the primary forcing of the sharp fluctuations in monsoonal activity in the region, we show that changes in magnetic susceptibility match variations of residual atmospheric δ14C, suggesting a role for solar variability as an explanation of climatic variability.

The present Research was carried out in Kishenganga River Where damming of River Was done forgeneration of 330 MW hydroelectricity. Since the damming of river will have impact on aquatic life of theriver. In this research an attempt was made to investigate the impact of hydroelectric dam on Susceptibilityand vulnerability of Brooder population of different fish species of the river.

Abstract: Anthropogenic environmental changes are the main cause of species extinction during the Holocene. Species have been exposed to major source of threats, such as habitat loss and fragmentation, pollution, introduced species, and harvesting, many of which are derived from specific anthropogenic activities, such as urbanization, agriculture, and damming (i.e. fine-scale threats). However, the importance of these threats on the species conservation status in a given region depends on the type of impacts they are exposed to and the susceptibility of species to these impacts. In this study, we used a database of threatened Brazilian freshwater fish species to test whether the major source of threats and the specific anthropogenic impacts to species vary across hydrographic regions and taxonomic groups. Our results showed that habitat loss is a ubiquitous major threat jeopardizing the conservation status of the Brazilian fish species. However, different fine-scale threats mediate this process across hydrographic regions and taxonomic groups. The combination of impacts from agriculture, deforestation, and urbanization affects most of the threatened species in the basins of the Northeast, South, and Southeast, including the species of the most threatened order, the Cyprinodontiformes. Damming is the main human activity affecting threatened species of Siluriformes, Characiformes, Gymnotiformes, and Cichliformes, especially in northern basins (Amazon and Tocantins-Araguaia). Therefore, we found that specific fine-scale threats influencing threatened species vary across hydrographic regions and taxonomic groups, probably due to geographic variability in the incidence of human activities and differential niche requirements and vulnerability of species to these activities.

Landslide dams result from the complex interaction, not yet totally understood, between river and slope dynamics. The study of past landslide dams and their consequences has acquired a significant relevance for forecasting and preventing their induced hydraulic risk on lives and property. The main aim of this thesis was the study of the landslide dam phenomenon and design a useful and easy tools to assess the damming risk with spatial planning purpose. The research started from the geomorphologic investigation of the Italian landslide dams and setting up an archive, updating previous studies on the same topic in smaller areas (Pirocchi, 1991; Ermini, 2000; Pacino, 2002), and integrating it through a careful literature review and cartographic and aerial photos interpretation. The collected data represents the wider example of systematic inventory in Italy, with almost three hundreds of cases selected from the Alps to the Southern Apennines, in Sicily. The research includes landslide dams occurred along the Cordillera Blanca mountain range, in Peru, to study the same phenomenon in a very different geographical, climatic and tectonic settings. A morphological analysis of the collected data was performed to identify morphometric parameters that best define the formation process of a blockage. This analysis confirmed the validity of schematizations already developed by previous authors and new morphometric indexes, useful for forecasting and planning purposes, were proposed. In particular, encouraging result came from the formulation of the Morphological Obstruction Index (MOI) that allowed to perform a reliable analysis of dam formation and provided a good estimator to forecast a landslide blocking a river, from a geomorphic analysis. In order to prevent part of the damages and suffer lower consequences related to landslide dam occurrence, an useful and practical tool was proposed, to predict which areas have a higher damming susceptibility and where preventive measures should be focused. Therefore a simple GIS methodology, useful as a forecasting and planning tool, was developed. This easy methodology, used on the Arno River basin, was able to assess with few data the damming predisposition, connected to existing landslides, and the probability of obstruction, by new landslides along a river network.