Maine Stormwater Conference

LID in South Korea

Hosted by NE IECA
Tuesday, November 17

Presentations from the 2015 Conference are available here. 

The Northeast Chapter of IECA is pleased to host this track on Low Impact Development in South Korea. IECA is an international organization and has recently increased its scope to include stormwater management in addition to erosion control issues at their conferences.

The Korean LID track highlights both research and implementation of Low Impact Development concepts to address water quality and runoff volumes in South Korea.  Even though we are on opposite sides of the globe, the research is transferrable to us in the Northeast.

South Korea enjoys a similar climate to New England. In fact, the 2018 Winter Olympics will be held in PyeongChang, South Korea. Their cities are highly urbanized, and they have developed many unique applications of rainwater harvesting. Implementing practices in fun and unique ways  has increased community acceptance of LID.

Please join NE IECA as we learn more about the exciting work happening in South Korea!

8:30 – 10:00  Session IV 

8:30 – 8:52
Development of Management System for Addressing Stormwater in South Korea
Jongsoo CHOI, Jungmin LEE

The study on Effect Analysis: Runoff Reduction and Water Cycle Improvement according to LID planning of
Site 1 & 2 of Eco Delta City as preset commercial area with the total area of 265,010 m2 have two cases. First
case, the LID facility plan has uniformly distributed planter box in the whole drainage area. Second case, has
distributed planter box in nearby drainage outlet area. As a result of the research, uniformly distributed
LID plan has an advantage on hydrologic cycle improvement but nearby drainage outlet case is better than
uniformly distributed case in view of peak discharges reduction

8:52 – 9:14
Investigation and Analysis of Public Perceptions for the Comprehensive Application of Low Impact Development in Korea
Seok-Hwa LIM, Mi-Hong LEE, Kyoung-Hak HYUN

A necessary survey for determining future policy directions for increasing the effectiveness and expanding the wholesome application of Low Impact Development (LID) in Korea was conducted.  One hundred twenty experts from relevant fields with good knowledge of LID were selected for this survey.  Descriptive statistical analyses were conducted on the survey data, using SPSS v12.0 by dividing the data according to age, level of education, major field of study, affiliation and research career group.  The analysis showed that more than 76% of the respondents knew the concept of LID.   About 52% of the respondents had general knowledge of LID legislation, most respondents perceived that the role of central and local government is important and 85% of the respondents stated that there needs to be a department in charge of LID. 

On questions regarding the effects of LID, about 78% answered that LID had greater positive effects, while about 67% perceived that it can sufficiently replace the existing rainwater management philosophy in Korea.

9:14 – 9:36
Korean LID/GI Research and Verification Facility at Pusan National University
Hyunsuk SHIN

In recent years, there are lots of LID techniques developed to restore the natural phenomenon in various fields. For all these reasons, a facility of verifying LID techniques is needed to analyze how the factors are effective in case of practical application. It is to standardize methods of LID verification by developing and designing some verification instruments. The objective of this study is to construct ‘National GI&LID Verification Research Center’ with indoor and outdoor experiments with the support of MOLIT (Ministry of Land, Infrastructure, and Transport, Korea Government). The research center on the 20,000 m2 is being constructed in Pusan National University, 2nd campus, Yangsan, which is to verify and determine design of various parameters of LID technologies. The center, which is consisted of five sections techniques of parking lot, construction area(for indoor experiment), industrial area, ecology of the wetland, and Road extent, is scheduled to be completed on September next year(2015). There are objectively three areas: LID testing and experiment space, LID education and research center, LID outside test-bed site. Especially, LID outside test-bed site is made of five zones which are architectural LID zone, road permeable pavement LID zone, Parking lot LID zone, industrial testing LID zone, and bioretention LID zone. The zones are completely useful for testing a diversity of LID factors including ecological wetland learning area, green-roof, ecological student rest spaces, convergence rain garden area, and environmental friendly plant area. Also, one of the important things to verify LID factors is to design and build the LID-verification equipment as rainfall simulator, widely open channel, and test-bed for observing water quality. The center will be definitely useful and possible to test and verify quantitatively LID effectiveness from various point of view.

9:36 – 10:00
The verification method used to model LID/GI system effectiveness at the Korean LID/GI Research Facility
Youngsu JANG, Mieun KIM, Sungje YE, Chilho NAM, Hyunsuk SHIN

Climate change and urbanization have affected a variety of factors of water resources, such as an increase of peak discharge, decrease of lag time, etc. In view of these aspects, the LID (Low Impact Development) technology has been highlighted as one of the adjustable control measures to mimic predevelopment hydrologic conditions. In recent years there were a lot of LID techniques developed to restore the natural phenomenon in various fields, but we don’t know how the factors of LID techniques are effective in the case of practical application. Therefore, this study developed the LID Hydrological Efficiency Simulator, LID Small-Scale Multi-Proposed Simulator and LID Movable Rainfall Simulator etc. at the national GI&LID technology facility and center in South Korea. These simulators could verify the efficiency of LID technologies through experiments of rainfall simulation for GI&LID technologies such as porous pavement, porous asphalt, bioretention and planter box. They could also verify the runoff reduction and the nonpoint pollutant control of each GI&LID technology.

10:30 – 12:00  Session V 

10:30 – 10:52
Challenges in Seoul Metropolitan for Restoring Urban Water Cycle 
Jungmin LEE, Jongsoo CHOI, Kyunam JIN, Yunsang LEE

The increased impermeable surfaces such as buildings and roads due to urbanization has dramatically altered the earth’s natural hydrology.  This has had the effect of reducing the space for rainwater retention and infiltration which is necessary to minimize the adverse effects of urbanization.  Moreover, it also causes serious urban problems such as urban flooding, groundwater depletion, degradation of water quality, and heat island impacts.  All populated cities of the world are suffering with these problems and the City of Seoul (capital of Korea) is no exception.  Currently, the percentage of impervious areas in Seoul is 47%, which is an increase of 39% when compared to 1962 where the impervious percentage was only 8%.  Due to enormous increase in the impermeable areas, there are some serious threats of urban flooding in the city.  In 2010 and 2011, the attractive Gwanghwamun area of Seoul had been flooded by torrential rains.  In October 2013, Seoul was declared a “Healthy Water Cycle City” to implement strategies to adapt to climate change and overcome these adverse effects of urbanization.  Since the last year, the Seoul city has experienced a severe drought and heatwave.  Currently, the City of Seoul is pursuing the systematic implementation of administrative, maintenance, and construction of Green Stormwater Infrastructures to mimic the water cycle system that existed in 1962.  The city is facing the challenge of infiltrating, storing and reusing 620 mm of rainfall, which is equivalent to 40% of the annual precipitation by the 2050 year.  Through this paper, we will share the policies for restoring urban water cycle that were promoted by the Seoul Metropolitan Government and provide a place for cooperation

Analyzing the changes to the Hydrologic Cycle with the implementation of LID Techniques in Korea 
Jungmin LEE, Jongsoo CHOI, Kyunam JIN, Yunsang LEE 

The climate change and global warming has been a world-wide issue. Also, the green growth has been a widely adopted strategy for national and regional development.

Nowadays, the hydrologic cycle in urban catchment has been changed due to the expansion of impervious area by rapid urban development.  The discharges of urban streams during dry season are depleted because the hydrologic cycle in the watershed has been destroyed due to the expansion of the impermeable area, climate change, and so forth. Depletion of stream flow may bring out severe water quality problems.

To solve these problems, Low Impact Development (LID) methods have been used to restore the natural hydrology of predevelopment sites using site design techniques such as infiltration, evaporation, and retention.

At present, the development in rainwater management approach is still insufficient due to the numerous adverse effects of urbanization. Storm water management is being developed to restore the natural state of water cycle undergoing several processes which were hindered such as infiltration and evapotranspiration. Low Impact Development (LID) was established in order to reduce the negative effects of urbanization to our environment.

These developments can be used to respond to the effects of climate change such as heat island phenomenon.  The effect of the development of new town in the district plan with application of LID facilities were studied and reported. Typically, LID facilities were applied in small scale development and were rarely used in large-scale development.

Although, not many case studies were done assessing the effects of large-scale development projects with LID application to the natural water cycle. This study was conducted to simulate the urban hydrologic cycle simulation in Pyeongtaek and Asan Test-Bed in Korea.

This study may be used in urban hydrologic cycle simulation and established of an urban  water management plan in the future. This study generated a model using the recently updated SWMM5 which determined the hydrologic cycle simulation after installation of LID facilities.

11:14 – 11:36
Performance Evaluation of Permeable Pavement Systems in Korea
Jaehun AHN, Hyangseon JUNG, Hyunsuk SHIN

LID is growing fast as a viable concept for planning and designing cities and facilities to effectively manage stromwater; Korea is no exception over this global trend. Permeable pavement is one of promising LID techniques as it targets at the most widely spread infrastructure in urban area. Permeable pavement systems, however, should have structural integrity of soil and pavement systems under infiltration, and perform against clogging. As traditional, impermeable pavements developed assuming no infiltration of stromwater to pavement and soil materials, the structural integrity and clogging of permeable pavement systems are still relatively new issues to deal with in application of permeable pavement LID systems. In Korea GI & LID research center, a collection of facilities is being built to experimentally evaluate structural and hydrologic performance of permeable pavement systems. The presentation addresses the items for performance evaluation and testing, and the progress in establishing them.

11:36 – 12:00
Analysis of Runoff Reduction and Hydrologic Cycle utilizing LID concepts
Jongpyo PARK, Lee KYOUNGDO, HyunSuk SHIN

Eco‐Delta City is a large new urban development project carried out by K‐water (Korea Water Resources Corporation) to create a waterfront city space. The total area of the City is 11,885,000 m2. The project started in 2012 and should be completed in 2018. LID (Low Impact Development) techniques will be applied to the entire area of Eco‐Delta City. 

The study on Effect Analysis: Two cases for Runoff Reduction and Water Cycle Improvement according to LID planning for Site 1 & 2 of Eco Delta City as a preset commercial area with the total area of 265,010 m2. In the first case, the LID facility plan uniformly distributed a planter box in the whole drainage area. In the second case, the LID facility plan distributed a planter box in a nearby drainage outlet area. Target Rainfall for rainfall‐runoff reduction analysis is a 5 to 10 to 30 year return period, with a duration of one(1) hour of rainfall at the Busan weather station. 

SWMM‐LID simulation results on Runoff reduction present the case that a uniformly distributed planter box can reduce peak discharge runoff by 6.9 to 8.1% compared to a non‐LID application. The peak discharge reduction rate when a planter box case was installed to the nearby drainage outlet was 10.0%. 

The hydrologic cycle effect of LID analyzes the rate of evaporation, infiltration, and surface runoff using hourly precipitation and monthly evaporation data from 2003‐2014. The Results of the infiltration rate have increased according to LID facility installation. The uniformly distributed planter box case improved the infiltration rate by 9.1% compared to a non‐LID application. The installed planter box case to a nearby drainage outlet is 8.1%. 

The peak runoff discharge reduction rate of a uniformly distributed planter box is less than 1.4 to 1.9%, while the installation of a planter box in a nearby drainage outlet had improved to 1% of the hydrologic infiltration rate. 

As a result of the research, the uniformly distributed LID plan has an advantage on hydrologic cycle improvement. However, the nearby drainage outlet case is better than the uniformly distributed case in terms of peak discharge reduction.

2:30 – 4:00  Session VI

2:30 – 2:52
Development of LID Facility Decision Support System using Multiple Attribute Decision Making (MADM) Method
Lee KYOUNGDO, Jongpyo PARK, Jongsoo CHOI, Jungmin LEE

The reduction facilities for non‐point pollution vary from a detention pond, storage tank, artificial wetland, permeable pavement, Infiltration basin, Infiltration trench, vegetative filter strips, vegetation swale, bio retention, tree box filter for runoff reduction, hydrologic cycle improvement, and nonpoint pollutant removal. To plan and choose reduction facilities for non‐point pollution 15 factors (basin characteristics, rainfall‐runoff, water quality, maintenance, etc.) need to be considered. Comparing evaluations and various decision‐making variables require technical knowledge. For these reasons, nonspecialists or policy makers will have difficulty in terms of decision making for the “best” choice on the type of reduction facilities for non‐point pollution. 

The purpose of this study is to help the decision makers to choose the “best” and the easiest reduction facilities for non-point pollution. LID DSS TOOL BOX: Facility (Ver. 1.0) was developed for decision support, a natural type of reduction facilities for non‐point pollution. The TOOL BOX is a Web‐based Site and it is possible to link the information management system (NPS‐LID) of reduction facilities for non‐point pollution. 

This study utilized the AHP (Analytic Hierarchy Process) for reasonable decision making of various natural type reduction facilities for non‐point pollution. The AHP is essentially the formalization of complex problems using a hierarchical structure. The parameter categories of decision making include basin characteristics, Rainfall‐runoff management, water quality management, maintenance control, etc. 

2:52 – 3:14
Effects of Calcium Chloride on Plant Growth in LID Vegetated Roadside Low Impact Development Facilities in Korea
Eun-Yeob LEE, Kyoung-Hak HYUN

The purpose of this study was to provide information on the management and application of calcium chloride and its effect on roadside plant cover, as well as the capacity of the plant to absorb calcium chloride. The experimental group was composed of a control group ratio of calcium chloride concentrations at 0.5%, 1.0%, and 3.0% in 500 grams of soil. Plant materials consisted of 10 species of plants suitable for vegetation based on LID roadside facilities. The growth of Sedum middendorffianum MAX, Pachysandra terminalis, Iris ensata var. spontanea were poor compared to the growth of calcium chloride treatment, with the exception of the control group at more than 1.0%. These plants are very sensitive to calcium chloride.

Liriope platyphylla Wang et Tang, Phragmites communis TRIN, Pennisetum alopecuroides (L.) Spreng, Euonymus japonica were able to grow and survive at the ratio of 3.0%. These plants can possibly absorb salts in moisture applications and survive in roadside LID systems.

3:14 – 3:36
FEM Analysis of the Effect of Roadside Infiltration Swales on Structural Stability of the Road System
Jong-Suk JUNG, Jin-Woo SONG, Kyoung-Hak HYUN

The effect of rainwater infiltration on roads depending on whether infiltration swales had been installed on the sides of roads was analyzed using FEM. Five conditions were analyzed with consideration to the precipitation and rainfall duration time. Case #3, in which 100 mm of rainfall was recorded for 12 hours, had the quickest time for attaining the maximum water content at 20 hours, while Case #5, in which the 100 mm rainfall was recorded for 24 hours, was the slowest with 48 hours for attaining the maximum water content. The time for which the water content was maintained above 40%, the initial water content recovery time, and the area of water content changed above 40% were maximized in Cases #3 and #4, in which both precipitation conditions corresponded to more than 100 mm/day for 12 – 24 hours. 

Installing infiltration swales have minimal impact on the road, even if they are installed into planting belts or L-shaped gutters, because the infiltration swale is designed for an inflow rainfall of 5 mm and anything exceeding that will overflow. It was determined that problems may arise according to weather conditions if rainfall continuously flows into the infiltration swale for 12 – 14 hours when the rainfall is more than 100 mm per day. 

Road structure analysis was conducted by using KENPAVE and by reflecting the water content change value of FEM to the material property per road layer. The value of allowable load repetitions was 1.185E+06, and it was 1.133E+06 when the elastic modulus of the subgrade after rain was applied. While the allowable load repetitions were relatively lower after a rainfall, it showed a minute difference of about 4.38%. Hence, the present study finds that while the water content in the lower sections of the subgrade of the road pavement layer does change because of inflow through the infiltration swale when the rain intensity is weak, its effect on the actual allowable load repetitions is insignificant.

3:36 – 4:00
Evaluation of the Economic Benefits of Low Impact Development Techniques on Stormwater Management
Mieun KIM, Hyunsuk SHIN

The application of low impact development (LID) techniques preserves the predevelopment hydrology in a site and maximizes the reduction of impervious areas to minimize the effects of urbanization. LID also aims to decentralize stormwater management approaches that attempt to manage stormwater at the source and to have drainage system from various directions. Some LID techniques, such as an infiltration trench, vegetative swale, pervious pavement, etc., are only used at a pilot project level in the Republic of Korea. This study includes the comparison of the effects of stormwater management and economic efficiency between conventional development and LID methods for Songsan Green City in the Republic of Korea. The results showed that the utilization of a LID method was superior as compared with the utilization of a conventional method in terms of the effects of stormwater management and could subsequently reduce the construction cost.

To view speaker bios click here.