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Various disasters have recently occurred in Korea because of weather changes caused by climate change, and the scale of the damage is also increasing. In terms of the weather phenomena and their socioeconomic impacts, weather-related disasters cause the most damage. Therefore, this study suggests a method of calculating rainfall thresholds to predict the impact of heavy rains. To calculate rainfall thresholds on the basis of a multimethod approach, this study divided Korea into a 1 km × 1 km grid and further split it into four categories: standard watershed, urban, river, and inundation trace maps. This study verified the results of the rainfall thresholds in the standard basin and city center by referring to the relevant data on the rainy season in summer 2020 and the Typhoon Haishen in September. Verification results showed that the flooding that occurred in the grid actually caused the urban flooding in Busan in July 2020. Moreover, the calculation on the grid that caused flooding in Gangneung, which was hit by Typhoon Haishen in September, reflected the actual damage. When used in impact forecasting, the proposed method of calculating rainfall thresholds and predicting rainfall information is expected to be able to provide data on the impact of heavy rains and facilitate rainfall forecasting.

In this study, water utilization status and water saving awareness investigation were analyzed through a survey in Gwangju Metropolitan City. Consequently, it was observed that most water is wasted when showering and doing laundry. Therefore, it is necessary to supply water-saving washing machines and dishwashers along with water-saving devices. A total of 64% of the respondents conserve water in their daily lives, and the reasons are worries about the future and economic reasons. Water saving is not practiced because it is unfamiliar or uncomfortable. Therefore, methods are necessary to save water without inconvenience in daily lives. It is judged that the results of this study can be used to establish strategies for water demand management.

In this study, the camera angle of a UAV (Unmanned Aerial Vehicle) was adjusted to take aerial photographs, and 2D and 3D models were constructed to evaluate the quantitative impact. The study area was Waryong Bridge, located in Dalseong-gun, Daegu Metropolitan City. The camera angles of the UAV were 90°, 75°, and 60°; DSM, orthophoto, and the 3D model were analyzed. As a result of the analysis of DSM and orthophoto, images were 1.05 times in 75° and 1.10 times in 60° compared to 90°, and matching was 1.09 times in 75° and 1.60 times in 60° compared to 90°. The point cloud for building 3D models increased analysis points to 1.17 times for 75° and 1.47 times for 60° compared to 90°. However, the area of an orthophoto of 1 pixel increased by 1.10 times for 75° and 1.34 times for 60° compared to 90°, resulting in a decrease in resolution. As the camera angle of the UAV decreases, the overlapping ratio of aerial photographs increases and the structure of wide areas can be implemented. However, since a large difference occurs in the precision of the 3D model, a shooting plan according to the purpose should be established.

Recently, Flood damage in river is mainly occurring in medium and small streams. In case of national river or large scale local rivers, disaster management such as river improvements were established. Whereas, In case of medium and small stream, disaster management for flood damage is insufficient. Among medium and small streams of the streams passing urban areas if flood damage occur, the focus of management is required to large scale damage of human and infrastructure. In this study, it proposed selection criteria of medium and small streams that flood damage is recently increased and medium and small streams that passes through the urban area that classification criteria of urban basin proposes using impervious area.

Hydraulic Structure are inevitably set up and operated in the river that flow characteristics are complex. When designing the water surface elevation and velocity by using 1-D Hydraulic Model, it will not be able to reflect the characteristics of Lateral Eddy and Superelevation due to centrifugal force. This study compared with result of 1-D Hydraulic Model and Hydraulic Model Experiments, Through the model experiment of Sloping Drop Structure installed on Curved-Channel. Hydraulic Model was constructed to baekseok bridge and Shinchun Bridge about 210 m interval located in Uijeongbu, Gyeonggi-do. Result of Hydraulic Modeling observed data and 1-D Hydraulic Modeling date are compared to design flood 100 year and 20 year. Result of experiments are depth ovserved data 35~48% low then 1-D Hydraulic Modeling date and velocity ovserved data 135~167% large then 1-D Hydraulic Modeling date. Research reaults expect to basic information for Curved-Channel Characteristics on Sloping Drop Structure.

In this study, occurrence characteristics of storm event throughout Korea were analyzed as essential information on designing storage facilities or LID for climate change adaptation measures. The comprehensive storm characteristics such as storm event duration, storm event volume, IETD(interevent time definition) for independent storm separation etc., are more important for designing storage facilities or LID than traditional Intensity-Duration-Frequency relationship. The harmonic average characteristics on typical storm events said storm event duration 24 hours and storm event volume 140 mm as a national average. In this analysis, IETD was considered as 10 hours. These results will be helpful to set up baseline of climate change analysis for disaster mitigation.

The entropy parameter of Chiu velocity distribution was examined with the natural river flow characteristics. The previous reserchs focused on maximum point velocity estimation in order to improve the application of Chiu velocity distribution in natural river. However, the improvement of maximum point velocity observation does not ensured more accurate discharge estimation. This study reviewed the variability of the entropy parameter of Chiu equation. The entropy parameter has the relationship with water surface slope as a hydraulic characteristic factor. The decrease of water surface slope due to backwater effect showed the decrease of entropy parameter by experiments.

In this study, rainfall, temperature and population data at 59 cities over the Korean peninsula are spatially analyzed for the assesment of hazard and exposure of the regional disaster management. The EOF (empirical orthogonal function) analysis for spatial distributions of rainfall and temperature is applied. Youngdong region in Gangwon province was the most hazardous area when considering rainfall and temperature. However, the exposure factor, population is relatively greater in the metropolitan cities including Seoul. In order to assess the factors causing floods, the annual maximum rainfall depth series and the annual maximum storm event series are also analyzed using the EOF analysis. The annual maximum rainfall series include 1 hour as the short duration and 24 hour as the long duration. The short duration maximum rainfall depth occurs at Jiri mountain region and it was analyzed as the reason for that phenomenon that the big intensity of the annual maximum storm event is focused around this area. The long duration maximum rainfall depth occurs at the northern area of Gyeonggi province, Yongdong region in Gangwon province and the region near the South sea. It is associated with this phenomenon that the duration characteristics of storm events have the strongest persistence at these areas.