Assessment of large wood budget in two different rivers located in Alpine and Andean environment
| Autor: | Tonon, Alessia |
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| Rok vydání: | 2017 |
| Předmět: |
Settore AGR/08 - Idraulica Agraria e Sistemazioni Idraulico-Forestali
AGR/08 Idraulica agraria e sistemazioni idraulico-forestali large wood/legname wood budget/bilancio di legname transport/trasporto recruitment/reclutamento bank erosion/erosione spondale volcanic eruption/eruzioni vulcaniche Piave River/fiume Piave Blanco River/fiume Blanco Italy/Italia Chile/Cile |
| Popis: | In forested river basins, Large Wood (LW) is a key component responsible for the geomorphological and ecological aspect of fluvial systems but, at the same time, is a source of hazard for sensitive places. Given its dual role, the analysis and quantification of LW in rivers, as well as understanding its mobilization and deposition, are crucial steps in order to ensure an appropriate management of riverine areas. This study attempts to increase knowledge in the main LW-related processes, such as the lateral recruitment from bank erosion, fluvial transport and the presence of buried LW, assessing the LW budget in two rivers. The study was conducted in two different fluvial environments. A 3.7 km-long reach was selected along the middle course of the Italian Piave River, a human impacted gravel-bed river typified by wandering and island-braided morphologies. In addition, three 80 m-long reaches were selected along the lower course of the Chilean Blanco River, a natural river with a morphology that drastically changed because of a recent volcanic eruption. The three considered items of the budget were analyzed by field activities conducted during the three years of the PhD. The lateral recruitment of LW was analyzed only in the Piave River for an over-bankfull flood (RI~7yr) by measuring, positioning and tagging all standing trees (D≥ 0.1m) within a 20 m buffer wide along the floodplain banks and island perimeters. A similar methodology was used to investigate, in both rivers, the fluvial transport of LW by considering all woody elements (D≥0.1m and L≥1m) within the active channel. In this way, during post-event surveys it was possible to identify the input (deposition) and output (mobilization) elements. Because the sediments from the volcanic eruption caused the burial of several standing trees and LW, the presence of buried LW was explored only in the Blanco River by Ground Penetrating Radar (GPR) testing. In the Piave River, the LW budget was assessed for very low floods (RI |
| Databáze: | OpenAIRE |
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