정성희 Jung Song Hie , 김아름 Kim Areum , 설재원 Seol Jaewon , 임봉순 Lim Bong Soon , 이창석 Lee Chang Seok

DOI:10.15681/KSWE.2018.34.5.447 Vol.34(No.5) 447-461, 2018

To realize river restoration that ecological characteristics of the river are reflected, we classified the river into four reaches of valley stream, upstream, midstream, and downstream based on substrate as well as riverbed gradient obtained from the relationship between distance from the river mouth, and above sea level. Considering that the rivers of Korea have been dominated by various and intense artificial interferences over a lengthy period, we determined cross sectional range of the river based on the geological map and clarified transformation degree by reach. Vegetation profile diagram was prepared by depicting horizontal range and vertical stratification of major vegetation appearing in a belt transect of 10 m breadth installed between weirs constructed in both sides of the river. Restoration models by river reach were prepared based on breadth of waterway, bare ground, herb, shrub, and tree dominated vegetation zones on vegetation profiles wherein a flooding regime was reflected. Species composition information collected from vegetation established in each zone was systematized to use for restoring each reach ecologically. Further, background that longitudinal reaches and horizontal zones were divided, was discussed by comparing with case studies in foreign countries. In addition, necessity of ecological restoration of the river was discussed based on degree of integrity of Korean rivers, ecological significance of riparian vegetation, and importance of reference information for ecological restoration of the river.

Integrity, Reference information, Riparian zone, River reach, River restoration

함상인 Sang In Ham , 이정환 Jeong Hwan Lee , 김대영 Dae Young Kim , 하돈우 Don Woo Ha , 김윤수 Yoon Soo Kim , 정강영 Kang-young Jung , 이영재 Yeong Jae Lee , 김경현 Gyeong Hyeon Kim , 김영석 Young Suk Kim

DOI:10.15681/KSWE.2018.34.5.462 Vol.34(No.5) 462-469, 2018

There are differences in method and cycle of flow rate survey depending on purpose of the operating department. To verify and use results of flow data according to the purpose, flow data of the directly measured and tele monitoring system were compared to verify validity. Flow measurement in the Ministry of Environment is aimed at setting up a standard flow of target water quality for water quality management and securing flow data of low and normal water level seasons for water quality evaluation. In this study, correlation analysis result (R²) of same time zone data by direct measurement and tele monitoring system (TMS) at Seombon D point, a unit watershed of Seomjin river, for six years ('10 ~ '15) according to implementation of Total Daily Maximum Load (TDML) was wading 0.716, boating 0.962 and on bridge 0.943, and effectiveness of measurement method was verified by characteristics of flow duration as a season of dry and low-water; normal and high water are appropriate for wading, boating, and on bridge respectively. Results revealed it is reasonable to use directly measured results using the wading and boating method for low water level and dry seasons, and TMS data for rainy seasons. It can be used important data for future policy decisions.

Correlation, Flow measurement method, Flow duration, Same time zone data, TDML

공동수 Dongsoo Kong , 민정기 Jeong-ki Min , 변명섭 Myeongseop Byeon , 박혜경 Hae Kyung Park , 천세억 Se-uk Cheon

DOI:10.15681/KSWE.2018.34.5.470 Vol.34(No.5) 470-486, 2018

This study is to investigate the allochthonous load and water quality of a typical river-reservoir, Paldang during spring (March ~ May) of 17 years (2001 ~ 2017). Phosphorus loading from point sources seems to have been reduced by 74 % in the 2010s. As a result, trophic state of the Paldang reservoir, eutrophic during the 2000s, has returned to the lmesotrophic state. Along with decrease in phosphorus concentration, standing crops of algae (Chl.a) decreased, and concentration of biodegradable organic material decreased to the past level. Concentration of total suspended solids has decreased, and it is due to the decrease of phytoplankton standing crops since the mid-2000s. As transparency increased, it is estimated that euphotic area increased by 22 % and euphotic capacity expanded by 27 %. In the river/transition zone of Paldang, concentration of organic matter increases slightly due to algal growth, but concentration of all water quality items decreases in the lacustrine zone. Although algal growth rate revealed positive correlation with concentration of phosphorus, it was insignificant. Algal growth appeared to be dependent on renewal of phosphorus by flow, than either flow rate or phosphorus concentration. The empirical model including inflow phytoplankton concentration fit well with observed values, and indicates the Paldang reservoir is greatly influenced by allochthonous loads.

Eutrophication, Material Budget, Paldang, River-reservoir, Water quality

김수현 Kim Suhyun , 김정선 Kim Jungsun , 강임석 Kang Limseok

DOI:10.15681/KSWE.2018.34.5.487 Vol.34(No.5) 487-493, 2018

Urban stormwater runoff is the one of the most extensive causes of deterioration of water quality in streams in urban areas. Especially, in the Suyeong River watershed, non-point sources from urban-residential areas are the most common cause of water pollution. Also, it has been ascertained that BOD and COD as indexes of organic matter, have limitation on management of Suyeong River’s water quality. In this study, changes of organic matter properties of Suyeong River from inflow of non-point source during rainfall were investigated. Fractions of organic matters were analyzed using water samples collected at two sites (Suyeong River and Oncheon Stream) during a rain event. Variations of dissolved organic carbon (DOC) concentration by rainfall were similar to flow rate change in the river. Distribution of organic matter fraction according to change of rain duration revealed that while hydrophilic component increased at initial rainfall, the hydrophobic component was similar to change in dissolved organic carbon (DOC) concentration. Also, the relative proportion of hydrophilic components in organic matter in river water increased, due to rainfall. Results of biodegradation of organic matters revealed that decomposition rate of organic matters during rainfall was higher than that of during a non-rainfall event.

Biodegradation DOC, Organic matter, Rainfall, Suyeong River

김호섭 Ho-sub Kima , 박윤희 Yun-hee Park , 김용삼 Yong-sam Kim , 김상용 Sang-yong Kim

DOI:10.15681/KSWE.2018.34.5.494 Vol.34(No.5) 494-502, 2018

The purpose of this study was to understand distribution characteristics of organic matters through concentration of BOD₅, COD_Mn and TOC in 31 streams in Han River region, and to establish the relationship among organic matter concentration, and discharge load and flow rate. Concentration of BOD₅ and TOC in 22 streams were above IV grade except 9, and the average 80.9 % of total organic matter (by TOC) accounted for dissolved organic type. Correlation among organic matter parameters were higher (r2 > 0.78) and the relationship between TOC and COD_Mn concentration was higher than BOD₅. Ratio of biodegradable organic matter/total organic matter in the 31 streams was estimated at 41.4 % with BOD₅ oxidation rate, and 78.0 % with BOD₅/COD_Mn concentration ratio. Ratio of NBOD/BOD₅ concentration in four sites with BOD₅/COD_Mn concentration ratio exceeding 1 ranged from 54.5 % ~ 79.3 %. Among 979 flow rate data measured at 31 streams, 87 % of measured data was below 0.1 cms and increased water pollution under low flow conditions. Correlation between BOD₅ concentration and BOD₅ discharge load in the watershed was low, and it was revealed that several streams have more BOD₅ delivery load than BOD₅ discharge load. Results suggest that many biodegradable forms of organic matter are being introduced into the stream from pollutant sources in the watershed.

Biodegradable organic matter, BOD₅ oxidation rate, Delivery load, Discharge load, Flow rate

류희성 Hui-seong Ryu , 신라영 Ra-young Shin , 서경애 Kyung-ae Seo , 이정호 Jung-ho Lee , 김경현 Kyunghyun Kim

DOI:10.15681/KSWE.2018.34.5.503 Vol.34(No.5) 503-513, 2018

Freshwater cyanobacterial genus Dolichospermum is one of the most commonly spotted types of phytoplankton, whereas a limited number of studies on morphology of Dolichospermum spp. have been performed in South Korea. The purpose of this study is to investigate the succession pattern of cyanobacteria after weir construction, as well as morphological characteristics of Dolichospermum spp. from natural samples collected in the weir regions of Nakdong River. A total of 31 cyanobacterial taxa observed in this study were classified as belonging to 15 genera, 5 families, and 3 orders. Among them, morphological characteristics in the four species were classified into genus Dolichospermum, for most of the planktic former members of the genus Anabaena, were observed through light microscopy. Water bloom frequently occurred in the middle region of Nakdong River, the maximum number of cyanobacterial species appeared in the lower region of Nakdong River. The appearance of order Chrooccocales was only observed during summer when population density of Microcystis aeruginosa reached an annual peak. In contrast, filamentous cyanobacteria was observed throughout the whole year, even if when water temperature was lower than 5 °C. It implied that the low-temperature-adapted filamentous cyanobacteria can grow in a range of water temperatures. Coil diameter of D. crassum from natural samples was 75 ~ 140 μm (ave. = 91.3 μm; n = 94), slightly larger than those reported by previous studies. Dolichospemum smithii (Komàrek) Wacklin et al. 2009, was described for the first time in Nakdong River.

Cyanobacteria, Genus Anabaena, Taxonomy, Water-bloom

공동수 Dongsoo Kong , 민정기 Jeong-ki Min , 노성유 Seong-yoo Noh

DOI:10.15681/KSWE.2018.34.5.514 Vol.34(No.5) 514-536, 2018

GPI (Group Pollution Index) using 29 indicator groups of Korean benthic macroinvertebrates was proposed in 1992, a higher category taxa-level index developed for rapid field assessment of organic water pollution. This study was performed to revise the assessment scheme of GPI based on taxonomic performance and ecological information accumulated since 1992. The original GPI was renamed SBMI (Simple Benthic Macroinvertebrates Index), and SBMI was based on saprobic valency of 26 indicator groups composed of higher category taxa (mainly family ~ phylum) excluding some genus or species-level taxa. SBMI revealed highly significant correlation with concentration of 5-day biochemical oxygen demand (BOD₅) (correlation coefficient r = 0.78, n = 569 sites), total suspended solids (r = 0.69), and total phosphorus (r = 0.77). Also, SBMI revealed strong correlation with Shannon-Weaver's species diversity (r = -0.85), Margalef's species richness (r = -0.85), and McNaughton's dominance (r = 0.83). Determination coefficient of SBMI to concentration of water quality items and values of community indices such as species diversity was 3 ~ 8 % and approximately 11 ~ 14 % higher than that of GPI, respectively. Correlation between SBMI and water quality factors or community indices such as species diversity did not reveal much difference compared to that of species-level indices, such as BMI (Benthic Macroinvertebrates Index) and ESB (Ecological Score of Benthic Macroinvertebrates). SMBI is a simple-qualitative index with higher category taxa easily identified, and is applicable for rapid field assessment of water environment impairment.

Benthic macroinvertebrates, Biological assessment, Indicator, Rapid bioassessment, Saprobic index

이서로 Seoro Lee , 박상덕 Sang Deog Park , 신승숙 Seung Sook Shin , 김기성 Ki-sung Kim , 김종건 Jonggun Kim , 임경재 Kyoung Jae Lim

DOI:10.15681/KSWE.2018.34.5.537 Vol.34(No.5) 537-547, 2018

Sediment discharge by rainfall runoff affects water quality in rivers such as turbid water, eutrophication. In order to solve various problems caused by soil loss, it is important to establish a sediment management plan for watersheds and rivers in advance. However, there is a lack of sediment data available for estimating sediment discharge in ungauged basins.. Thus, reasonable research is very important to evaluate and predict the sediment discharge quantitatively. In this study, cluster analysis was conducted to classify gauged watersheds into hydrologically homogeneous groups based on the watershed characteristics. Also, this study suggests a method to efficiently predict the sediment discharge for ungauged basins by developing and evaluating the SDR equations based on the PA-SDR module. As the result, the SDR equations for the classified watersheds were derived to predict the most reasonable sediment discharge of ungauged basins with 0.24 % ~ 10.89 % errors. It was found that the optimal parameters for the gauged basins reflect well characteristic of sediment movement. SDR equations proposed in this study will be available for estimating sediment discharge on ungauged basins. Also it is possible to utilize establishing the appropriate sediment management plan for integrated management of watershed and river in Korea.

Cluster analysis sediment management, Sediment delivery ratio, Sediment discharge, Ungauged basin