Saemangeum Estuarine System (Republic of Korea): Before and After Reclamation

  • Nial MooresEmail author
Living reference work entry


Saemangeum is the name coined in the 1980s to promote a controversial 40,100 ha reclamation project on the west coast of the Republic of Korea (ROK). The project entails the construction of a 33.9 km long outer seawall (accredited as the world’s longest man-made barrier) to impound two free-flowing estuaries in order to create 29,000 ha of land and a reclamation reservoir. In their natural state, these estuaries supported approximately 330,000–570,000 shorebirds annually and the livelihoods of 20,000–30,000 fishers and shell-fishers. Following seawall closure in 2006, there was a catastrophic decline in shorebirds supported by the site, and research found no evidence that the majority of affected birds were able to relocate to other sites in the ROK. Rather, substantial declines have been recorded at the population level in some shorebird species. Local fisheries have also been lost. Currently, construction on the inner dikes is continuing.


Korea Reclamation Impacts Shorebirds Fisheries Declines 


Saemangeum (alternative spelling, Saemangum) is a name originally coined in the 1980s to describe and promote a 40,100 ha reclamation project on the west coast of the Republic of Korea (ROK). The project entails the construction of 33.9 km long seawall (accredited as the world’s longest man-made barrier) to impound two free-flowing estuaries (combined, the Saemangeum Estuarine System or SES). Inner dikes and walls (presently under construction) would then enable the conversion of approximately 29,000 ha of estuarine tidal flat (estimated at lowest low tide) and 11,000 ha of subtidal sea shallows into dry land and freshwater reservoirs.

The reclamation plan was developed initially in the 1980s, and construction of the outer seawall was started in 1991. Following several court cases and growing civil opposition, the last remaining gaps in the seawall were completed in April 2006. Outer seawall strengthening continued into 2008, and inner sea-dike construction started in ~2009 and was still ongoing in 2015.

The Saemangeum reclamation was the largest single coastal reclamation project in the world in the 1990s and early 2000s. It was the focus of sustained civil society opposition within the ROK especially from the late 1990s until seawall closure in 2006. Opposition focused initially on the predicted social and economic impacts on local fisheries and fishing communities and concerns over pollution. Following the ROK’s accession to the Ramsar Convention in 1997 and because of the international importance of the SES in its natural or near-natural state to migratory waterbirds, the reclamation project was also the first major infrastructure project in the ROK and in the Yellow Sea Eco-region to attract sustained international concern, including reference in Ramsar Resolution IX.15 (2005). During the same period, the reclamation was actively promoted by central and provincial government. Most advertising since the mid-2000s has emphasized the reclamation’s potential importance to the national economy (with designation of the area as a special economic zone) and its alleged environmental sustainability (Birds Korea 2010; Moores 2012).


The Saemangeum reclamation (approximately 35°30 – 35° 50′ N and 125° 40 – 126° 45′ E) entails the impoundment of the Mangyeung (alternative spelling, Mangyeong) and Dongjin Estuaries and adjacent intertidal flats and subtidal shallows. Historically, both estuaries and the neighboring Geum Estuary formed the central part of a more or less contiguous subregion of intertidal wetland along the west coast of the ROK that extended c. 175 km from Cheonsu Bay in the north to Hampyeong Bay in the south (Moores 2012). Following on from piecemeal reclamation projects that increased in scale during the first half of the twentieth century, the whole subregion was identified as fit for reclamation by central government in 1984 in a pre-feasibility study for the 1984–2001 National Master Plan (Long et al. 1988). The area initially targeted for Saemangeum (a word incorporating part of the names of both the Mangyeung and Geum Rivers, with the additional connotation in Korean of “new big treasure”) was increased between the late 1980s and the start of seawall construction in 1991 to include the outer estuarine tidal flats too. As constructed, the seawall (now with a national trunk road and a series of pocket parks running along its length) connects offshore islands and an earlier reclamation project and runs to a total length of 33.9 km. There are two sluice gates to allow tidal exchange totaling 540 m in length.

Reclamation Project Rationale

In line with the National Master Plan for Land Use and extant legislation within the Public Waters Reclamation Act (1962), the reclamation was initially proposed to create additional land and a water supply for rice agriculture. However, by 1990, the reclamation project was described as being primarily for the development of the port city of Gunsan for future trade with China (Birds Korea 2010). By 2001, agriculture was publicly given up as the primary land use and the Special Act to Promote the Saemangeum Reclamation was passed in December 2007 to legalize other development (Kim 2011). From 2010 the area was promoted as “Ariul, the Water City of Asia” with several proposed artificial islands and industrial complexes and 5,950 ha reserved as “ecological and environmental lots” (Birds Korea 2010). However, by 2012, as in 2015, less than 1000 ha of tidal flat remained seaward of the outer seawall; almost all intertidal wetland landward of the outer seawall had become desiccated or submerged; and there was no conservation plan for the migratory shorebirds supported by the site (Moores 2012).

Physical Geography and Human Use Pre-seawall Closure

The SES was comprised of two free-flowing estuaries, divided by the Simpo headland (see Fig. 1), and was contained within seawalls constructed as part of earlier reclamation projects. In its natural and near-natural state, the SES had semidiurnal tides with a tidal range of 1.2–7.2 m. On higher spring tides, a tidal bore (+/− 1 m) moved up the Mangyeung River, and the whole system was temporarily inundated. During neap and low tide, extensive salt marshes (dominated by Suaeda japonica) were exposed, in addition to unvegetated tidal flat which extended 3 km north–south and up to 10 km west–east in some areas. Upstream from Simpo, most tidal flat areas were steep sided, muddy, or mud-sand mix, while most outer tidal flats were sandy with a very gentle slope.
Fig. 1

The SSMP Study Region in May 1989 (Left) before construction started on the Saemangeum seawall and in late 2005/early 2006 (Right), showing SSMP count sites (NASA images, reproduced with permission in Moores 2012)

Although high levels of pollutants were found within some of the sediments (in Long et al. 1988), the economic livelihoods of an estimated 20,000–30,000 fisherfolk depended on the system for shellfishing or commercial fishing from boats (Birds Korea 2010). The hinterland (through to at least 2010) contained a mix of agriculture (largely rice fields) and rural villages, with many communities economically dependent upon both shellfishing and land-based agriculture.

International Importance to Waterbirds Before Seawall Closure

At least 27 species of waterbird, including 20 species of migratory shorebird were recorded within the SES in Ramsar-defined internationally important concentrations (of either >20,000 individuals or 1 % or more of a biogeographical population) between 1997 and 2003 (Moores 2012). Surveys by the national Ministry of Environment during the same period led to estimates during northward and southward migration, respectively, of 138,000 and 145,000 shorebirds supported by the Mangyeung Estuary and of 178,000 and 112,000 shorebirds supported by the Dongjin Estuary (Yi 2004). Combined, 330,000–573,000 migratory shorebirds were estimated to be supported by the SES each year. The lower estimate is based on the sum of the seasonal site maxima in Barter (2002), and the higher estimate is based on the sum of peak counts of each species at both estuaries in different years between 1997 and 2001 (Yi 2004). The SES was thus the most important known shorebird site in the whole of the Yellow Sea during northward migration and the second most important known site in the Yellow Sea during southward migration (Barter 2002).

History of Opposition

Civil society opposition to the reclamation project, led by environmental NGOs, religious leaders, leading academics, and some local community representatives, intensified during the late 1990s (Kim 2001). This was a period in which wetland conservation issues rose to prominence in the ROK due in part to the nation’s accession to the Ramsar Convention. A ritual walk (the samboilbae) from Saemangeum to Seoul increased national awareness of the likely social and environmental impacts, as did a series of court cases which challenged the project’s legal status (Kim 2011). Internationally, a growing number of environmental organizations expressed their concerns during, and subsequent to, the Ramsar Convention’s 7th Conference of the Contracting Parties (COP7 – 1999). Such concerns intensified following the publication of Barter (2002) and were expressed in Ramsar Resolution IX.15, which formally requested the government of the Republic of Korea to advise the Secretary-General of the current situation concerning the seawall construction and reclamation of the Saemangeum coastal wetlands and the impact of the construction works to date on the internationally important migratory waterbird populations dependent upon these wetlands. No detailed response to this request was provided by the ROK government to the Ramsar Secretariat.

Changes to the SES following Seawall Closure

Remaining gaps in the Saemangeum seawall were closed on 26 April 2006. Tidal movement, with high tides peaking at 7 m in early 2006, was then controlled through sluice gates, with a tidal range of between 0 and 50 cm (maximum 1.3 m) during most subsequent tidal cycles. Low-lying tidal flats became submerged, and higher areas desiccated. Mass shellfish die-offs were first recorded in late April and occurred with each subsequent major influx or release of seawater (Moores 2012).

Saemangeum Shorebird Monitoring Program

As an independent scientific response to Ramsar Resolution IX.15, the ROK-based conservation organization Birds Korea and the specialist Australasian Wader Studies Group partnered to conduct the Saemangeum Shorebird Monitoring Program (SSMP). The SSMP entailed intensive shorebird counting during northward migration in 2006–2008 within both the SES and also at the adjacent Gomso Bay and Geum Estuary (combined with the SES, the “SSMP Study Region”).

The SSMP also included a national shorebird count in the ROK (in May 2008) and was designed to share data with the Monitoring Yellow Sea Migrants in Australia program (in Australia).

Based only on the sum of peak counts, 181,755 shorebirds were recorded within the SES during the SSMP. Between 2006 and 2008, 16 out of the 20 most numerous shorebird species showed declines that totalled >126,000 birds. The largest declines in number were shown by great knot Calidris tenuirostris (>74,000), dunlin Calidris alpina (>37,000), and Mongolian plover Charadrius mongolus (5,327). The largest declines in percentage terms were shown by sanderling Calidris alba (96 %), sharp-tailed sandpiper Calidris acuminata (94 %), and spoon-billed sandpiper Eurynorhynchus pygmeus (91 %). Within the SSMP Study Region as a whole, based on the sum of peak counts, there were almost 264,000 shorebirds in 2006 and 164,261 in 2008. Thus, there was a decline of almost 130,000 shorebirds within the SES and of 100,000 shorebirds within the SSMP Study Region during northward migration between 2006 and 2008. The most affected species included great knot with >92,000 lost from the SES and the two adjacent wetlands. The national survey in May 2008 failed to find evidence of displaced great knot from the SSMP Study Region at other internationally important wetlands nationwide, including all other sites known to be internationally important for the species in the ROK (Moores et al. 2008; Moores 2012). Research in Australia (yet to be published in full) also indicates a decline in numbers and adult survival of great knot and several other shorebird species after seawall closure at Saemangeum (Rogers et al. 2009; Moores 2012). The SSMP therefore became the first research program to detect trans-hemispheric impacts on shorebirds at the population level caused by reclamation on the East Asian-Australasian Flyway.

Further construction and conversion of formerly natural intertidal wetland into dry land and freshwater reservoirs at Saemangeum and other internationally important wetlands in the ROK are predicted to lead to further declines in shorebirds at the site, national, and population level (Moores 2012).

Other Impacts

The Saemangeum reclamation has already caused massive changes to the natural biological and physical conditions previously found within the SES and threatened the extinction of a recently described mollusc (Hong et al. 2007). The loss of tidal exchange and tidal flat area has led to a reduction in fisheries and shellfishing opportunity and resulted in a major loss of local livelihoods (Hahm 2004, Birds Korea 2010). Before seawall closure 50,000–90,000 t of hard clams and 1,000 t of mud octopus were collected annually in the SES (MacKinnon et al. 2012). Although robust data are presently unavailable, yields within the SES are now considered to have fallen close to zero. The reclamation has also affected patterns of erosion and sedimentation outside the outer seawall, including in the Geum Estuary to the north (Suh 2008; Lee 2010) and Gomso Bay 15 km to the south (Lee et al. 2015). Following closure of the Saemangeum seawall, levels of suspended solids and the speed of the tidal current in Gomso Bay both increased. The direction of the tidal current changed, the area dominated by sand increased, and the sedimentation trend changed from accretion to erosion on the lower flats in the outer bay, resulting in reduced habitat for fish and shellfish, decline in water quality, and large-scale degradation of natural habitat (Lee et al. 2015). In addition, most of the sand and gravel required for reclaiming land within the Saemangeum reclamation area, estimated at 700 million cubic meters, will be supplied by dredging seabed 10–20 km off the coast (Ministry of Land, Infrastructure and Transport 2011), likely to cause further degradation to surrounding marine and coastal ecosystems.



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Copyright information

© Springer Science+Business Media Dordrecht 2016

Authors and Affiliations

  1. 1.Birds KoreaBusanRepublic of Korea

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