Ecological Status in Urban Settings
Excessive pavement can have negative impact on human life and the environment. In particular, impermeable pavements using artificial materials in big cities not only affect their climate but also water management, ecology of the soil, and flora and fauna. In Seoul, 46% of the area has less than 0~10% of impervious land while 48% of the land has more than 70%.
Meanwhile, actual vegetation is an indicator of the level of ecological maturity of a city, which plays an essential role in the city’s ecosystem. For instance, higher actual vegetation level can ensure wildlife habitats for various flora and fauna. The status of actual vegetation in Seoul shows that forest accounts for the largest portion (26%) followed by grassland and waters (9%), arable land (5%) and garden tree planting sites (3%). Vegetations that are rare in the city are Manchurian alder/quercus spp (2.6ha), Carpinus laxiflora (1.9ha) and Ailanthus altissima Swingle (3.7ha).
Forest takes up 13% of Seoul’s land and 2% of the herbaceous vegetation area are dominated by naturalized species. This is because most of the herbaceous vegetation is home to naturalized species. Also, constant artificial changes to the urban area result in smaller herbaceous vegetation for species that grow in dry or wetlands.

Changes of Water Quality in Han River
The quality of Han River gradually improved until 1993 thanks to the government support. For instance, the Seoul government increased the number of sewage disposal plant, constructed treatment facilities including night soil treatment and water purifier, and monitored waste water discharge facilities along with Han River Development Project of the 1980s. The trend turned around, however, due to constant winter droughts since 1994 and delayed construction of environmental facilities including a sewage disposal plant in Han River’s upstream area. Also, in places such as Namyangju, Hanam and Guri which are adjacent to upstream of Han River, large apartment complex were constructed, which led to an increase in inflow of domestic sewage to the river. Making matters worse, recreational facilities including accommodations and large restaurants near water protection area were built, degrading the quality of the river to a large extent. Soon, the quality of water hit the trough in 1997 but has since improved again.
The city government played a crucial role in these improvements; for instance, it introduced the ‘Special Measures on Management of Han River System and Paldang Lake as Source of Water Supply’ in 1998, enacted the ‘Act on the Improvement of Water Quality and Support for Residents of the Riverhead of the Han River System’ and in 1999, designated Jamsil Water Source Protection area in 1995 as well as Water Pollutant Buffer Zone in 1999. In addition to the institutional support, the government conducted supervision and monitoring on wastewater discharge facilities.
Yearly changes of BOD (Biochemical Oxygen Demand), a widely used indicator of water pollution, shows that Jamsil had 2.6mg/L of BOD in 1997. However, after special policy on improving water source took place in 1998, the figured has significantly declined to 1.7mg/L in 2004 and 1.4mg/L in 2005. Since 2006 the indicator shows 1.1 ~1.9mg/L (Ib) due to inflow of non point pollutant source during dry season, changes in precipitation and discharge flow of Paldang Dam. BOD in Kayang fell from 5.5mg/L in 1997 to 2.9mg/L in 2005; however various factors including changes in precipitation caused BOD to increase to 2.5~4.5mg/L (III).
Changes in discharge flow of Paldang Dam caused by precipitation affect the quality of Han River to a large extent. Jamsil’s water pollution level compared to monthly discharge flow of the Dam is relatively low from July to October when the flow is high and relatively high from December to May during reduced discharge flow.
 
Water Supply Status
Han River is a source of water for 18 million people living in metropolitan area including Seoul. The quantity of water intake per day is 16.89 million tons on average of which 7.12million tons belong to Seoul and the rest 9.77 million tons go to metropolitan area. Actual intake per day is 7.99 million tons in total and for Seoul it is 3.29 million tons (41.2%) and metropolitan area 4.7 million tons (58.8%). Paldang Lake’s actual intake is 230,000 tons per day accounting for 7.0% of the total, while Jamsil area’s intake is 3.06 million tons a day (93.0%).
Seoul purified 12,500 tons of water per day in 1998 and supplied to 125,000 people. However as of 2013, the number rose to 4.35 million tons and 10.38 million people, that is 34 times and 83 times increase respectively. There were difficulties in managing water supply due to lack of capacity in facilities until 1992, but with increasing number of facilities built since 1998, the problem has been resolved. The amount of water use in Seoul in 2013 was 1.1billion 64 million 635,000 tons in total and 3.19 million tons per day on average. Revenue water ratio of Seoul significantly improved from 72.0% in 2000 to 94.4% in 2013, an unprecedented progress in the world.
Revenue water ratio or RWR refers to the ratio of tap water produced in purification plant charged to consumers. (RWR(%) = supply/ adjustment x100). For example, if 100m3 of tap water is supplied to consumers and 90m3 worth of tap water is charged for revenue, then the RWR is 90%. The increase in RWR saves budgets required to buy raw water, chemicals and power cost, which, in turn, contributes to improving financial status of water management. From 1989 to 2013, RWR increased by 39.2% (from 55.2% in 1989 to 94.4% in 2013), reducing the cost by approximately KRW 4.665 trillion (based on unit cost of sales). Distribution water pipe in Seoul downtown area is 13,791 km long. In order to improve RWR and the water quality in distribution process, 13,192km of the pipe was replaced from 1984 to 2013 and the rest will be completed by 2018. Also, the quantity and time of distribution will be enhanced from 2.42 million tons/ 13.9 hours to 2.48 million tons/15.0 hours by 2030.

Progress and Status
In December 1991, the Act on Natural Environment Conservation was enacted, as an effort to ensure systematic conservation and management can help create a pleasant environment for citizens. In January 1998, an amendment was made to the Natural Environment Conservation Act to allow for city/province ordinance. As a result of the change, the Natural Environment Conservation Ordinance of Seoul was enacted on March 20, 1999. As environment evolved, a need for revision rose. Consequently, some portion of the ordinance was revised on November 5, 2003 and June 16, 2005 and on January 2, 2007 the entire ordinance was revised. Finally, on September 30, 2008, some portion of the ordinance was once again revised according to ‘Creating Well-defined Laws’ project.
 
Natural Environment Conservation Ordinance of Seoul (September 30, 2008)
General Provision
Basic principles for natural environment conservation and usage should be established in order to conserve the environment for the public good and to maintain its sustainability. The market is responsible for establishing and conducting natural environment conservation measures suitable for area conditions such as devising action plan in every 10 years. Finally, the citizen should abide by natural environment conservation policy.
 
Designation and Management of Ecological and Scenery Conservation Area
Areas with rich biodiversity or natural scenery are designated as Ecological and Scenery Conservation Area of Seoul and efficiently managed by dividing them into core and buffer zone according to their ecological characteristics and terrain conditions. Based on observation on ecological changes, management plans suitable for area conditions are established and conducted. Additionally, capture and collection of wildlife or new constructions and changes to form and quality of lands are restricted and dispose of particular toxic substance and waste materials are prohibited. When approving development projects surrounding natural parks, its affects on the scenery as well as conservation plans are reviewed.
 
Wildlife Conservation Endangered or decreasing species will be on the list of Protected
Wildlife Species in Seoul and protection measures will be established and conducted accordingly. While restricting capture and collection of wildlife, areas where protected species inhabits as a group will be designated as wildlife reserve in Seoul and relevant protection measures will be conducted. Any act to damage the reserve will be restricted and if necessary, limited access can be followed for certain period of time. Migratory bird protectorate will be enforced and managed in order to protect the area where they appear most often. Additionally, surveys will be conducted on habitats of wildlife that need to be conserved.
 
Management and Utilization of Natural Environment Information
To ensure efficient management of the nature, environmental survey is conducted in every 10 years. If necessary, detailed and complimentary surveys as well as observations on ecosystem changes will be followed to create ecosystem/environmental maps which are utilized in planning and developing relevant projects. The maps are systematically managed for rational usage of environmental information.
 
Management of Natural Capitals
Areas with high ecological and scenic value that are not parks, tourist complex and recreational forest will be designated as natural relaxation sites to be used for field trips and ecological education. Streams will be maintained and restored without impacting water utilization and flood control. Also, efforts to develop ecological cities will continue by restoring destroyed and disturbed ecosystems within the area.
 

Progress and Status
Through site survey on vegetation and the environment across Seoul from March 1999 ~ March 2001, the city of Seoul identified Biotopes according to their characteristics and categorized them into 5 grades considering their conservation value.
Based on the site survey, Seoul conducted detailed survey on areas with outstanding ecosystems, especially areas with grade 1 biotopes that contain high conservation value with forests, streams and wetlands. A total of 15 sites have been selected through preliminary survey and expert consultation. The selected areas were studied and analyzed on their natural characteristics, organisms’ ability to work as a habitat, rarity, distance from urban areas and history. The result of the study provides basic direction for the city to establish criteria on designating Ecological and Scenery Conservation Area.
The city of Seoul has been designating areas with high conservative value and ecological importance that are rich in biodiversity to prevent them from artificial deterioration and pollution and to systematically conserve and manage them. As a result a total of 17 sites equivalent of 4,807,327m2 of land have been designated as Ecological and Scenery Conservation Area that include Bamseom (1999), Dunchondong( 2000), Tancheon, Bangi-dong, Amsa-dong, Jingwan-dong (2002),Godeok-dong, Cheonggyesan Wonteogol (2004), Heoninlleung (2005), Namsan, Bulamsan Sahmyook University, Changdeokgung Huwon Garden (2006), Bongsan, .Inwangsan (2007) Seongnaecheon downstream,Gwanaksan, Baeksasil Valley (2009).
Also, the icty plans to add a site to the list every other year until 2014 and will continuously expand the list by discovering more ecologically valuable areas.
Management of Ecological and Scenery Conservation Area is conducted by both the city of Seoul and related autonomous districts. Seoul is in charge of setting basic principles and conditions for management which include establishing management plans, observing ecosystem changes, and restoring ecosystems and providing budget support. Meanwhile, autonomous districts conduct site management and purification such as patrol, monitor and protection of sites and removal of harmful wildlife.