Rep. Heo Jong-sik: "Restoration of Incheon Seunggi Stream Has Greater Flood Reduction Effect Than Retention Facilities"

Rep. Heo's Office Releases Research on 'Flood Impact Assessment of Chronic Flood Zones in Michuhol-gu'
Drainage Capacity Deficiency in Juan-dong Area Pipes Accounts for 52%...Causing Frequent Flooding in Low-Lying Areas
Similar Results from Incheon City Study... "Flooding Difficult to Resolve Even with Stormwater Retention Facilities"

As a result of flood simulation for the Juandong area in Michuhol-gu, Incheon, a region prone to frequent flooding, it was found that restoring the sewer system into a river form (Seunggi Stream Waterway Connection Project) has a greater flood reduction effect than installing stormwater detention facilities.

On the 29th, Heo Jong-sik, a member of the Democratic Party of Korea representing Dong-gu and Michuhol-gu Gap in Incheon, announced that this was confirmed through the policy research project "Flood Impact Assessment of Frequent Flooding Areas in Michuhol-gu, Incheon."

This study was conducted to evaluate the flood response capability of the sewer system near Yongil Intersection to Seunggi Intersection in Juandong, an area that has suffered damage from frequent flooding for decades, and to prepare flood reduction measures. Heo’s office commissioned KE Consulting, a specialized institution in water resources, after consulting with the Korea Environment Corporation.

The drainage basin area of the target watershed was set at 3.33㎢, with a total sewer pipe length of 106.87 km, and the standard was based on Incheon City's disaster prevention performance goal of a maximum rainfall of 90mm per hour.

First, the analysis of the sewer system revealed that 52.4% of the total sewer pipes (55.98 km out of 106.87 km) have insufficient flow capacity. This has been cited as a major reason for flooding occurring in the low-lying Seunggi Intersection area from the early 1990s to the present.

Democratic Party of Korea Representative Heo Jong-sik

To completely resolve flooding, it is necessary to improve flow capacity by upgrading the existing aging sewer pipes. This study applied two projects as flood prevention alternatives?▲(Option 1) stormwater detention facilities ▲(Option 2) restoration of Seunggi Stream waterway?and verified through simulation how much flooding could be reduced.

Under current conditions, if rainfall reaches the Incheon City disaster prevention performance goal of 90mm per hour, the flooded area was analyzed to be 0.47㎢, accounting for 14.1% of the total area (3.33㎢), with an average flood depth of 31 cm.

Regarding Option 1, if two stormwater detention facilities in the Juandong district (capacity: 9,000㎥ in Juan 2-dong and 21,000㎥ in Juan 4-dong) are completed, the flooded area is expected to be 0.42㎢ (flood ratio 12.6%) and the average flood depth 27 cm. The detention facilities, which are being promoted with a budget of 37 billion KRW from national, city, and district funds and targeted for completion by the end of 2025, showed minimal flood reduction effects.

On the other hand, if Option 2, the restoration of Seunggi Stream waterway, is implemented, the flooded area would be reduced to 0.24㎢, approximately twice the reduction effect compared to the stormwater detention facilities. The average flood depth would also decrease to 20 cm, about 1.6 times lower. This assumes converting the sewer box under the approximately 2 km section of Inju-daero (from Yongil Intersection to Seunggi Intersection) into an open channel with a width of 14 m.

This proves that improving flow capacity in the Yongil Intersection to Seunggi Intersection section through the Seunggi Stream restoration project has a greater flood reduction effect than installing stormwater detention facilities.

Heo’s office stated that this flood simulation study showed results similar to the simulation included in the "Seunggi Stream Waterway Connection Project Planning and Feasibility Study," which Incheon City plans to complete in August.

When applying a 50-year frequency rainfall (approximately 89.8 mm per hour), Incheon City predicted the current conditions would result in ▲flooded area of 132,425㎡, maximum flood depth of 64 cm ▲317 buildings expected to be damaged by flooding. After installing stormwater detention facilities, the predictions were ▲flooded area of 103,475㎡, maximum flood depth of 57 cm ▲262 buildings expected to be damaged.

It was confirmed that stormwater detention facilities alone are insufficient to fundamentally resolve flooding damage in the Juandong area.

Heo said, "This study confirmed the limitations of solving the frequent flooding problem with stormwater detention facilities in the Juan district, so active efforts should be made to restore Seunggi Stream. Restoring underground sewer facilities into a river form as part of sewer capacity expansion and maintenance projects can secure a large flow cross-sectional area to prevent flood damage, and Seunggi Stream is expected to have positive effects as a landmark of the old city by creating parks and cultural spaces and mitigating urban heat island effects."

This content was produced with the assistance of AI translation services.