The study of sediment budget and processes at watershed scale.
Date Issued
2014
Date
2014
Author(s)
Lin, Yi-Bei
Abstract
The sediment budget is a common tool to quantify sediment balance in a watershed, including processes. Previous researches mainly applied data-driven or case studies in specific area. As a result, we always only obtain a limited scope or understanding for the sediment budget phenomena in a watershed. In this study, firstly I investigate the different sediment processes within a watershed and make effort to reasonably model them under the different conditions. By using the conceptual model built in this study, sediment supply and outflow can be simulated. This study treats rainfall as a major trigger in sediment budget. Easy to be understood, it dominates occurrences of landslides, transportation of sediment in rivers, and other major process of watershed sedimentation, especially for typhoon or extreme storm events. To discuss the model parameters, this study applies both deterministic and stochastic framework to analyze the watershed sedimentation. By this way, we can have a more comprehensive investigation in this topic.
This study applies the proposed model framework to real cases in Taiwan, inclduing three subbasins in the Kaoping river basin. These subbasins are Laonong river basin, Cishan river basin and Ailiao river basin. We found that the river sediment budget are significantly correlated with the event of rainfalls. For instance, the extreme rainfall event of Typhoon Morakot triggers landslides with mass of 4,300 million cubic meter in the Kaoping basin. But most of the sediment might still stay on the hillslope instead of moving to rivers. For a moderate event such as the Typhoon Sinlaku, the watershed actually could produce less sediment than it transport out. We suggest the general trend of sedimentation can be concluded, but various uncertainties in different process may strongly dominate the phenomena of sediment budget in a watershed.
Subjects
泥砂收支
概念模型
颱風事件
高屏溪流域
莫拉克颱風
Type
thesis
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