This study analyzes the change in the peak flow rate and discharge capacity of a sewage network with LID facilities using the rainfall runoff hydrological model SWMM. The demonstration complex has an area of 35,151 m2 and include the seven elements of LID facilities: a porous pavement, tree box filter, planter box, bio retention, infiltration trench, rain barrel, and an infiltration rain catch basin. The results of analysis using the SWMM show that the peak flow rate per watershed decreased by 9.07% on average and 7.46% within the target site. According to the result observed for discharge capacity within sewerage network, the branch sewer improved by an allowance of 13.22% for a 10-year return frequency and main sewer improved by an allowance of 9.69% for a 30-year return frequency.

Locally concentrated heavy rainfall has led to an increase in the occurrence of flood damage. This is especially so in the urban areas, which are relatively more vulnerable to flood damage due to the high population and property density. In Seoul, which has 25 administrative districts, heavy rainfall triggered flood-related damage in 2010, 2011, and 2018. However, the flood characteristics of each district were different due to difference in flood impact factors such as topography, weather, and disaster prevention measures. The flood vulnerability of each district should be assessed based on local characteristics to reduce flood damage. This study collected and calculated 15 characteristic data points that can explain the climate exposure, sensitivity, and adaptive capacity of each district using the entropy weight method. Thereafter, the flood vulnerability of each district was calculated based on climate exposure, sensitivity, and adaptive capacity, using the Euclidean method. The results showed that the northern and western areas in Seoul are highly vulnerable due to high climate exposure, sensitivity, and low adaptive capacity. In contrast, the other parts of Seoul had low vulnerability due to high sensitivity, low climate exposure, and high adaptive capacity. These results will contribute to the establishment of a flood damage reduction plan that reflects local characteristics.

No abstract

In urban areas, the damage caused by locally concentrated heavy rainfall has recently increased due to the congestion of population and assets, high impervious ratio, and increased utilization of underground space. The extent and types of damage differ depending on the characteristics of the area. Therefore, the vulnerability to and impact of floods should be assessed according to local characteristics, and flood mitigation alternatives should be developed accordingly. In this study, the urban areas of the Han river basin were classified by flood vulnerability and damage characteristics, and the relationship between flood vulnerability and flood damage was analyzed using historical flood damage data. First, the municipalities of the Han River basin were divided into urban and non-urban areas by multivariate statistical analysis using urban factors. Next, climate exposure, sensitivity, and adaptability were used to asses flood vulnerability for 56 local governments classified as urban areas. As a result of statistical analysis, they were divided into four clusters: regions with high flood vulnerability for all factors, regions with high flood sensitivity and low adaptability, regions with low sensitivity and high adaptability, and regions with low flood vulnerability for all factors. Finally, flood damage reduction measures were suggested according to the flood damage characteristics of each cluster.

With exacerbating climate change, the current reservoir storage capacity in South Korea is insufficient to meet the future scheduled water demand. No study has yet evaluated the effects of applying the water supply adjustment standard (Standard) and activating the reservoir emergency storage in response to extreme drought. The main objective is to assess the effects of applying Standard and activating emergency storage in meeting the water demand under extreme drought at six multipurpose reservoirs (Andong, Gimcheon-Buhang, Gunwi, Hapcheon, Imha, and Milyang) in the Nakdong River Basin, South Korea. We built a reservoir simulation model (HEC-ResSim), determined the extreme drought scenarios, and emergency storage capacity. We evaluated three reservoir operation cases (general operation, regular Standard, and revised Standard) from 2011 to 2100. The results show that applying the Standard and activating the emergency storage are effective in meeting the future water demand during extreme drought. In conclusion, we need to secure 110 million cubic meters (MCM) (Hapcheon reservoir) and 8 MCM (Gunwi reservoir) of water to reduce the number of days in the emergency stage. This research serves as a fundamental study that can help establish Standard and emergency storage activation criteria for other multipurpose reservoirs in preparation for extreme drought.