Loss of tidal flats and the decline of East Asian birds.

Tidal flats and estuaries in the Yellow Sea are arguably one of the most endangered, valuable, and productive habitats in the Yellow Sea ecoregion. Annually they host thousands of migratory Australasian wading birds during the spring and fall including critically endangered Spoon-billed Sandpipers and Nordmann's Greenshank. During the summer they play host to numerous breeding birds including endangered Black-faced Spoobills, Saunder's Gulls, and a diverse array of long-legged waders and shorebirds. During the winter they support numerous species of Arctic and near-Arctic breeders who come to spend the cold months feeding on the rich tidal flats. Besides the obvious value to the avifauna the Republic of Korea's (ROK) Yellow Sea tidal flats and estuaries possess great economic and culture value as they play a critical role in supporting the regions fisheries and fishery cultures.

I am working with Birds Korea to understand the impacts of tidal flat and estuary loss on birds in the Yellow Sea region of the ROK. The first step in this process is to determine how much tidal flat remains. Data deficiencies and lack of publicly available imagery and spatial data make determining the remaining modern tidal flat area problematic and difficult. I am currently using a combination of Google Earth and Daum (www.daum.net) imagery to estimate tidal flat cover in the region in 10 minute x 10 minute grids. I am incorporating this data into Arc-GIS to visually project tidal flat densities along the west coast of the ROK and relate this information to shorebird surveys to identify tidal flats of key conservation concern.

A second goal is to map and estimate the amount of tidal flat and estuary loss over time. Using a combination of historical declassified aerial and Global Land Survey satellite imagery I am estimating changes in coastal land use including reclamation activities. By comparing historical mid-20th and modern early 21st century shoreline data I have documented remarkable changes in coastal shape and land area gain. For example (in the animated map below) in the last 50 years over over 3,500 square km of estuary and tidal flat have been reclaimed. This reshaping of the coastline into a less meandering shape has resulted in a nearly 30% reduction in coastline. Besides quantitatively estimating habitat loss overtime, a major objective of mapping is to present tidal flat and estuary loss to reclamation in a visually stimulating form in order to convey the seriousness of the environmental degradation in the region.


A map depicting the dramatic reshaping of the Republic of Korea's coastline,
through reclamation, over the past 50 years.

A third and final goal will be to incorporate predictive models, based on predetermined rates of habitat loss, on how much tidal flat will remain in the next 10, 20, 50, and 100 years. In addition, this will require the incorporation of global climate change effects of rising seas. Ultimately, I hope to determine which tidal flats and associated bird species should be the focus of conservation priority in the near and distant future.