The frequency of flooding is increasing due to heavy rainfall caused by climate change and urbanization. In order to prevent flood damage in low-lying areas, systematic measures are needed for urban watersheds. The underground infrastructure of Shinwol was built to sustained heavy rains that occur more than once every 30 years, which has prevent flooding in the area. Additional construction of underground infrastructure facilities is planned in various areas including Seoul and Busan. Overseas countries have installed numerous underground infrastructure facilities for the purpose of preventing flood damage and improving water quality in urban areas, and have verified their social and economic effects. However, since there are still few cases of introduction in Korea, additional research is needed in various fields such as design, construction, operation, and management. In addition, in order to secure the feasibility and economic feasibility of the business, a multipurpose utilization plan must be developed to enhance the value of water resources and underground infrastructure facilities. In order to maximize the flood prevention effect, which is the original purpose, systematic and stable design and operation technology must be secured. The Ministry of Environment was promoted the ‘Technology development for optimizing planning, operation, and maintenance of urban flood control facilities’ project starting in 2024 to secure core technologies for Korea’s customized underground infrastructure. The project aims to develop flood control facility technologies that can protect citizens safety and property from urban flooding. In this paper, investigated the current status of underground infrastructure facilities introduced from overseas for the purpose of responding to urban flooding and examined the improvement effects through introduction.

In the membrane process, it is important to improve water treatment efficiency to ensure water quality and minimize membrane fouling. In this study, a pilot study of membrane process using reservoir water was conducted for a long time to secure high flux operation technology capable of responding to influent turbidity changes. The raw water and DAF(Dissolved Air Flotation) treated water were used for influent water of membrane to analyze the effect of water quality on the TMP (Trans Membrane Pressure) and to optimize the membrane operation. When the membrane flux were operated at 70 LMH and 80 LMH under stable water quality conditions with an inlet turbidity of 10 NTU or less, the TMP increase rates were 0.28 and 0.24 kPa/d, respectively, with minor difference. When the membrane with high flux of 80 LMH was operated for a long time under inlet turbidity of 10 NTU or more, the TMP increase rate showed the maximum of 43.5 kPa/d. However, when the CEB(Chemically Enhanced Backwash) cycle was changed from 7 to 1 day, it was confirmed that the TMP increase rate was stable to 0.23 kPa/d. As a result of applying pre-treatment process(DAF) on unstability water quality conditions, it was confirmed that the TMP rise rates differed by 0.17 and 0.64 kPa/d according to the optimization of the coagulant injection. When combined with coagulation pretreatment, it was thought that the balance with the membrane process was more important than the emphasis on efficiency of the pretreatment process. It was considered that stable TMP can be maintained by optimizing the cleaning conditions when the stable or unstable water quality even in the high flux operation on membrane process.