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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Evaluating Geomorphic Change in Little Creek Using Repeated Cross-Sectional and Longitudinal Profile Surveys

Perkins, Drew Allen 01 March 2012 (has links)
Six geomorphic study reaches were established in 2002 along a forested mountain stream (gradients range from 0.02 to 0.05) on Cal Poly's Swanton Pacific Ranch in Santa Cruz County, California. These study reaches are a component of paired and nested watershed studies in the approximately 500 hectare Little Creek watershed. The overall goal of this study was to monitor water quality and channel conditions before, during, and after a selective harvest of redwood. A selective harvest occurred in the North Fork of Little Creek in Summer 2008. In August 2009, approximately 90% of the Little Creek Watershed was burned in the Lockheed Fire. Channel change was evaluated by measuring ground profiles using traditional survey methods. Cross section and longitudinal profiles are surveyed annually every summer in the six study reaches. Change is assessed through evaluation of cross sections and longitudinal profiles, analysis of bed elevation and cross-sectional area change data, and analysis of residual pool characteristics and longitudinal profile variability. Changes in the channel during this time have been relatively small and are typically associated with movement or introduction of coarse woody debris to the stream channel. However, during the study period no large stream flow events occurred (return interval at the closest USGS gauging station does not exceed 5 years). Historically, large debris flow events have occurred in this watershed, with well documented events in 1955 and 1998. The survey data is an important tool for understanding change detection in channel characteristics before and after harvesting, and following fire disturbance.
2

Odezva vybraných řek Českého masivu na litologické a tektonické podmínky / Response of selected rivers of the Bohemian Massif to lithological and structural conditions

Flašar, Jan January 2012 (has links)
Three groups of streams were selected in the area of the Bohemian Massif: the Berounka river with its source streams; the Vltava river with its tributaries the Malše and the Lužnice; the Labe river with its tributaries the Cidlina, the Bystřice and the Javorka. The lithological and tectonical influences to several parameters of the streams were studied. These parameters include: stream gradient, orientation of the stream and sinuosity of the stream. Data were obtained from digital elevation models, aerial photographs, topographical and geological maps. The longitudinal profiles of the streams (in the combination with geological cross-sections), the SL indexes and the gradient/sinuosity graphs were created on the basis of the obtained data. These tools were used for evaluation of the influence of lithology and the tectonics to the streams. The evolution of the streams and the stream-groups was evaluated and compared as well. A strong influence of lithology on the stream gradient was found on most of the analysed streams. The tectonic situation, on the contrary, had strong influence on the orientation of the streams, especially in the resistant rocks. Also, there were selected areas, where was a higher probability of quaternary vertical movements influencing the streams (mountainous areas of the Novohradské...
3

Geomorfologické projevy neotektonické aktivity podél úpatního zlomu pohoří Cordillera Blanca, Peru / Geomorphological evidence of neotectonic activity along Cordillera Blanca fault zone, Peru

Masák, Ondřej January 2012 (has links)
Southwest base of Cordillera Blanca mts. in South American Ands belongs to the most tectonically active fault zones. The core of this thesis was making of a detailed geomorphological map based on remote sensing satellite images for the purpose of analysis of direct and indirect manifestations of neotectonics. The greatest emphasis was placed on morphological manifestations of tectonics movements which are fault scarps facets and vertical fault steps deforming other shapes of relief - e.g. lateral moraines, dejection cones. Vertical steps reach from a few meters to tens of meters (max. 60 m) according to the age of influenced landform. Evaluation of measurements from deformometr from locality Pitec shows main trends of movements - moderate rise of massif, slow opening of fault plane and negligible left-lateral slip. Calculation of mountain-front sinuosity index, whose values were found relatively low, confirms high tectonic activity of fault zone. Analysis of longitudinal stream profiles hasn't showed presence of knick-points in the place of crossing with fault zone. Non-continuous process of lifting movements, whose interval is estimated at 1ka to 3ka (while the very last 2ka has been in relative tectonic calm), could be a possible explanation. Deep erosion of water streams wiped the tectonics...

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