Case study: On hydrological function improvement for an endemic plant habitat in Gangcheon wetland, Korea

Abstract

Wetlands are one of the most important ecosystems for the biodiversity of plants and animals. Especially, Gangcheon wetland in NamHan river, Korea is a very valuable one because Aster altaicus var. uchiyamae, which is one of endemic plants is inhabited. However, Gangcheon wetland was impaired by a river improvement project called ‘Four Major Rivers Project’. After the project, Gangcheon wetland restoration work was performed, for the rehabilitation of wetland functions but the habitat of Aster altaicus var. uchiyamae could not be restored. Actually, Aster altaicus var. uchiyamae can grow in a habitat made by mixing of gravel and sand from flood inundation of the river but there was no inundation after the project because of the rise of levee height. Therefore, this study evaluated wetland functions using Hydrogeomorphic(HGM) approach and analyzed flood inundation using HEC-GeoRAS model after the project for diagnosis of the functions and the habitat. Then we proposed a plan to improve the functions of Gangcheon wetland as a habitat for Aster altaicus var. uchiyamae. The reference wetland is Gangcheon wetland before the project and the wetland functions after the project were compared with the reference one. As a result of the function assessment, hydrological, biogeochemical, and plant habitat functions were deteriorated. The study wetland has three zones of A, B, and C for Aster altaicus var. uchiyamae habitats and particularly, hydrologic functions for zone C which is poor as the habitat should be improved. In particular, the habitat of Aster altaicus var. uchiyamae was adversely affected by the decrease in inundation depth and water level of the river. These hydrologic functions should be improved and the levee height be lowered for obtaining more proper habitat of Aster altaicus var. uchiyamae. This suggestion might be helpful for establishment of the habitat of Aster altaicus var. uchiyamae. Also, it could be expected that the overall function of Gangcheon wetland will be improved because biogeochemical and plant habitat functions are rehabilitated by the improved hydrological function.