The purpose of this study was to document groundwater quality in Chungcheongnam-do. Samples were taken from Taean, Dangjin, Seocheon, Boryeong, Seosan, and Nonsan areas, and 48 water quality variables were analyzed in relation to applicable standards, including the amounts of naturally occurring radioactive materials(U and Rn). The results from testing 179 locations indicated that 128 were suitable and 51 were of unacceptable quality, in terms of drinking water quality standards. The nonconformity rate for nitrate nitrogen was 47.0%, while that for total coliforms was 24.2%. Heavy metals-such as Pb, Hg, Cd, and Cr-were detected in low concentrations at all points. Analysis of naturally occurring radioactive materials showed that U concentrations were within the water quality standard (0.03 mg/L) at all points. Rn concentrations were low in NW regions such as Taean, Dangjin, Seocheon, and Boryeong, where Proterozoic sedimentary rocks were distributed, but its concentrations in the Seosan and Nonsan areas, where granite rocks were widely distributed, required closer investigation, and it was found that the alternative maximum contaminant level (148 Bq/L) was exceeded in granite soils which originated from the Mesozoic Era.

This study observed topographic changes resulting from installed groynes at straight and meander experimental test-beds (Shihwa wetland). Bed and edge changes were induced more with installation of groynes than without. In comparison of the installation angle of groynes, erosion was found in the case of 45° to the stream flow while deposition in the case of 135°. In the case of the installation shape of groynes, various topographic changes were found more with those of double bar type than those of one bar type. After that we applied them to a field test-bed (Geumdang Valley) to conduct a comparative analysis. We observed results of topographic change and biodiversity after more than one year from the installation of groynes at the field test area based on test-bed results. In the real stream, which minimized manmade elements, more forms of bed and edge of stream could be created only with the installation of groynes similar to the results of the test-bed. We observed that various topographic changes could form kinds of habitats of fishes and benthic invertebrates.

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