Assessment of Flood Potential and Vulnerability in Landsubsidence Area
|關鍵字:||不確定性分析;地層下陷;淹水潛勢;脆弱度評估;uncertainty;landsubsidence;flooding potential;vulnerability assessment|
Landsubsidence has become worse in southwest coastal areas of Taiwan; in which, Yunlin is one of the most severe subsidence county in Taiwan. Recently, the center of subsidence cone has gradually migrated inland. Under the global climate change, the subsidence not only increases the vulnerability of disaster, but also threatens more area with flood disasters. For allocating reasonable resources on improvement work, reducing the vulnerability, and decreasing flood disaster losses, therefore investigating the level of vulnerability in disaster areas is necessary. The study area is located in the Northern Yunlin Country. First, the observation data of rainfall and sea levels were collected. Data from Northern Yunlin coastal rainfall stations and Mailiau station are adopted for frequency analysis. Latin Hypercube sampling (LHS) method is later applied to produce samples of rainfall and sea level, which are treated as the external forcing and boundary condition of SOBEK 1D model. The simulation results are used to evaluate the distributions of channel peak water level, and to investigate the effect of rainfall and sea levels to channel water levels. To understand the relationship between the subsidence and flooding potential, we use the subsidence data by kriging method for spatial interpolation, creating contour maps of the subsidence. Combining the created contour map with the Northern Yunlin digital elevation model, we may produce a new digital elevation model. Levee protection levels based on 25 years channel water level probabilistic distribution are taken into account for evaluating the inundation area by SOBEK 1D2D model, taking account several flood return periods with different digital elevation model. The vulnerability index is added to simulation results, and used to evaluate the vulnerability for each town within the study area.
|Appears in Collections:||Thesis|