In recent decades, extreme storm events due to climate change have frequently occurred worldwide, a few of which have even occurred consecutively; we class such rainfall events as mega events. That is to say, if the inter-arrival time between rainfall events with a 100-year frequency is less than the IETD (Inter-Event Time Definition), the event can be considered a mega event. Therefore, the aim of this study was to implement flood inundation analysis using the hypothetical mega event from two consecutively occurring events of 100-year frequency, and select the optimal shelters using a developed method for minimizing casualties from floods. The Gyeongan stream basin, which is a tributary of the Namhan River in Korea, was selected as the study area. This study calculates mega flood discharge using the SSARR (Stream Synthesis and Reservoir Regulation) model, and conducts a flood inundation analysis of mega floods via the level pool method and the HEC-GeoRAS model. An inundation map was constructed, and the inundated area was classified into three zones and five administrative districts. Sixteen shelters were selected as candidates based on the criteria of the local government safety management plans and the Guidelines for Establishing the Disaster Relief Plan of 2013. To evaluate the candidates for evacuation in each district, we selected seven evaluation indicators from the shelter criteria of several countries, and calculated the weights of the indicators using the Analytic Hierarchy Process (AHP) method. As a result, four optimal shelters were selected in the study area. The results of the study can be used as the basic information for analyzing mega natural disaster events and inundation, and for establishing evacuation shelters, which are one of the non-structural flood protection measures.
Abstract. Concurrent floods in multiple locations pose systemic risks to the interconnected economy in East Asia via supply chain disruptions. Despite these significant economic impacts, understanding of the interconnection between rainfall patterns in the region is still currently limited. Here, we analyzed the spatial dependence of the rainfall patterns of 24 megacities in the region using complex analysis theory and discussed the technique's applicability. Each city and rainfall similarity were represented by a node and a link, respectively. Vital-node identification and clustering analysis were conducted using adjacency information entropy and multiresolution community detection. The results of vital-node identification analysis show that high-ranking nodes are cities that are located near main vapor providers in East Asia. Using multiresolution community detection, the groups were clustered to reflect the spatial characteristics of the climate. In addition, the climate links between each group were identified using cross-mutual information considering the delay time for each group. We found a strong bond between Northeast China and the southern Indochinese Peninsula and verified that the links between each group originated from the summer climate characteristics of East Asia. The results of the study show that complex network analysis could be a valuable method for analyzing the spatial relationships between climate factors.
<p>Due to climate change, rainfall occurs at a higher frequency than the design frequency, and flood damage has occurred in excess of the river design standard. Currently, river management in general is gray infrastructure such as embankments and weirs for irrigation and flood control. However, the river management plan through the gray infrastructure emits carbon dioxide, increasing the occurrence of extreme weather due to climate change and intensifying flood damage, causing a vicious cycle to repeat. Therefore, since the river management method by gray infrastructure cannot be adopted as a sustainable solution, the concept of Nature-based Solutions(NbS), which seeks to solve environmental and social problems through ecosystem services, is attracting attention recently. Therefore, in this study, the flood reduction effect of river management using NbS was quantitatively analyzed for the Hwang River, which is directly downstream of Hapcheon Dam. In addition, using the climate change scenarios of the IPCC 6th Assessment Report, the study tried to confirm the ability to respond to climate change through NbS. We used SSP5-8.5(Shared Socioeconomic Pathways5-8.5) and SSP2-4.5 scenarios for future precipitation, and the design flood discharge was calculated through HEC-HMS. Floodplain excavation and dyke relocation, which are included in the NbS, were applied to the flood risk area of the Huang River. As a result of analyzing the flood level of the river through the unsteady flow analysis of HEC-RAS, it was possible to confirm the effect of reducing the flood level by 5 to 7 cm for each scenario at the confluence of the Nakdong River. The results of this study can be expected to be sufficiently utilized as a basis for use as a management plan through NbS rather than the river management with grey infrastructure.</p>
Airlines provide one of the most popular and important transportation services for passengers. While the importance of the airline industry is rising, flight cancellations are also increasing due to abnormal weather factors, such as rainfall and wind speed. Although previous studies on cancellations due to weather factors considered both aircraft and weather factors concurrently, the complex network studies only treated the aircraft factor with a single-layer network. Therefore, the aim of this study was to apply a multilayer complex network (MCN) method that incorporated three different factors, namely, aircraft, rainfall, and wind speed, to investigate aircraft cancellations at 14 airports in the Republic of Korea. The results showed that rainfall had a greater impact on aircraft cancellations compared with wind speed. To find out the most important node in the cancellation, we applied centrality analysis based on information entropy. According to the centrality analysis, Jeju Airport was identified as the most influential node since it has a high demand for aircraft. Also, we showed that characteristics and factors of aircraft cancellation should be appropriately defined by links in the MCN. Furthermore, we verified the applicability of the MCN method in the fields of aviation and meteorology. It is expected that the suggested methodology in this study can help to understand aircraft cancellation due to weather factors.
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