• Journal of the Korean Institute of Landscape Architecture
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• v.39 no.2
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• pp.103-112
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• 2011

The purpose of this study is to specify the prior eco-preserve zone by establishing the eco-landscape unit on the stream corridor and evaluating the stream ecosystem in the dam basin. The fundamental ecological data was surveyed and collected through "the ecosystem project on Yongdam multipurpose dam watershed" from 2008 to 2009. The Yongdam Dam Watershed has several streams, Jujacheon, Jeongjacheon and Guryangcheon, of which the area is $930km^2$, stretching to Jinangun, Jangsugun and Mujugun Jellabukdo. In spite of being used for drinking purpose, the dam water quality and ecosystem is threatened by in-watershed pollution produced by development, golf course grounds and sports complex, etc. The landscape unit of stream corridor was zoned across by 250m, 500m, and 750m from the vicinity line of stream, which was decided to the accuracy of mapping and surveying. Types of evaluation are the Stream Corridor Evaluation(SCE) and the Vegetated Area Evaluation(VAE). In the process of SCE, several indices were analysed, fish species diversity, species peculiarity, and stream naturality. Indices for VAE were forest stand map, vegetation protection grade, species diversity and peculiarity for wild bird and mammal life. The importance of the ecological items is categorized into three levels and overlapped for specifying the prior preserve zone. The area at which legally protecting species appeared is categorized as absolute preserve area. This study might be meaningful for proposing the evaluation process of a stream corridor ecosystem, which can synthesize a lot of individual ecological surveys. We hope further research will be actively performed about the ecotope mapping which is based on a individual wildlife territory and habitats and also their relationships.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.6
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• pp.1093-1101
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• 2000

The object of this study was to develop new BNR process using fixed-biofilm which could be applied to retrofit the existing wastewater treatment plant or to introduce as tertiary treatment plant. To achieve complete denitrification from typical raw sewage in Korea, external carbon source must be supplied because $SCOD_{cr}/T-N(NH_4{^+}-N+NOx-N)$of raw sewage was lower than other countries. In this study, the ratio of $SCOD_{cr}/NH_4{^+}-N$ was 2.49 and the influent $NH_4{^+}$-N concentration during the experimental period was varied from 25 to 37 mg/L. To enhance nitrogen removal from the sewage, the two processes using fixed biofilm were adopted as R-Hanoxic/mid.settler/aerobic/anoxic/ aerobic) and R-2(aerobic/mid.settlerlanoxic/anoxic/aerobic), respectively. In the comparison of $NH_4{^+}$-N, T-N effluent quality and T-N removal efficiency in both processes without external carbon source, R-1 process was better than R-2 process for nitrogen removal from raw sewage. With respect to $SCOD_{cr}$/NOx-N ratio and total nitrogen removal in each anoxic reactor of two processes, R-1's was more effective than R-2's for distributing organic matters of raw sewage. In the both processes using fixed biofilm, the amount of required alkalinity to remove unit $NH_4{^+}$-N were 5.18 and 5.76($g{\cdot}CaCO_3/g{\cdot}NH_4{^+}-N_{removed}$), respectively and were lower than activated sludge BNR process(7.14).

• Korean Journal of Environmental Agriculture
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• v.27 no.1
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• pp.35-43
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• 2008

The study was carried out to estimate runoff loads of heavy metals in the valley watershed at the middle of South Korea, during farming season. There were no other pollution sources except agricultural activity. From 27 April 2006 to 31 October 2007, water samples were collected using two methods. The first method was regular sampling wherein water samples were taken every two weeks; and the other method was through regular sampling when water were collected during each rainfall event. Results showed that heavy metals were found in the water from the regular samples, and were highest during May and June. It was presumed that this might have been contributed by farming activities. Heavy metal concentration of the irregular samples was lower than regular samples. The correlation coefficient between each heavy metal of the regular samples were as follows: Fe-Al>Cr-Al>Fe-Cr>Mn-Fe. The correlation coefficient of the irregular samples were the following: Fe-Al>Fe-Cu is positive; and Pb-Cu>Ni-Al is negative. Measured pollutant loads of heavy metals in the valley watershed were : 2.047 kg $day^{-1}$ of Al, 0.008 kg $day^{-1}$ of Cd, 0.034 kg $day^{-1}$ of Cr, 0.311 kg $day^{-1}$ of Cu, 0.601 kg $day^{-1}$ of Fe, and 0.282 kg $day^{-1}$ of Zn in 2006; while in 2007, the following were observed: 2.535 kg $day^{-1}$ of Al, 0.026 kg $day^{-1}$ of Cd, 0.055 kg $day^{-1}$ of Cu, 0.727 kg $day^{-1}$ of Fe, and 0.317 kg $day^{-1}$ of Zn. In the analysis of data gathered, the loading rates of effluents from the valley watershed during the rainy season were : 79.8% of Al, 69.1% of Cu, 82.5% of Fe, and 69.1% of Zn in 2006; while 69.9% of Al, 67.5% of Cu, 70.4% of Fe, and 67.5% of Zn in 2007.

• Journal of Wetlands Research
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• v.15 no.3
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• pp.347-356
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• 2013

To provide the information for the wetland management considering the water treatment ability of macrophytes, the growth characteristics and primary production by reed (Phragmites australis) and cattail (Typha angustifolia), and the decomposition rate of organic matter produced were investigated in two sub-wetlands (Banweol and Donhwa wetlands) of the Sihwa Constructed Wetland (CW) with different chemistry of inflows. The shoot height of P. australis and Typha angustifolia began to increase in March, and reached its peaks in July and August (340cm and 320cm, respectively). The shoot density of P. australis ranging $100{\sim}170EA/m^2$ was higher than that of T. angustifolia (max. $78EA/m^2$). Standing biomass of P. australis ranged from $1,350{\sim}1,980gDM/m^2$, with maximal biomass in Banwol Upper Wetland. And it was larger in upper wetlands than lower wetlands. On the other hand standing biomass of T. angustifolia ($1,940gDM/m^2$) was similar to that of P. australis in Banwol Upper Wetland. Primary productivity of P. australis was in the order of Banwol Upper Wetland ($2,050gDM/m^2/yr$) > Donghwa Lower Wetland ($1,840gDM/m^2/yr$) > Banwol Lowerr Wetland ($1,570gDM/m^2/yr$) ${\fallingdotseq}$ Donghwa Lower Wetland ($1,540gDM/m^2/yr$), and that of T. angustifolia ($2,210gDM/m^2/yr$) was higher than P. australis. Annual production of organic matter produced by P. australis and T. angustifolia was 845 ton DM/yr (423 ton C/yr), and about 90% was comprised of that by P. australis. From the litter decomposition rate (k) (P. australis: leaf 0.0062/day, stem 0.0018/day; T. angustifolia: leaf 0.0031/day, stem 0.0018/day), leaf was rapid degraded compare to stem in both P. australis and T. angustifolia. The litter decomposition rate of leaf was two times rapid P. australis than T. angustifolia, whereas that of stem was same in both. Annual litter decomposition amount of P. australis than T. angustifolia was 285 ton C/yr(67.3% of organic matter produced by macrophytes), indicating that 32.7% of organic matter produced by macrophytes is accumulated in the Sihwa CW.

• Korean Journal of Ecology and Environment
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• v.36 no.2 s.103
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• pp.124-138
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• 2003

This paper aimed to analyze the relationship between alga3 bloom patterns and hydrological, limnological data which were collected from major reservoirs in Korea for 8 years (1990${\sim}$1997). Water temperature of river-type reservoirs showed wider seasonal fluctuations than that of lake-type. pH of lake-type reservoirs was low in winter season but high in summer season. In contrast, river-type reservoirs showed high pH in spring and autumn seasons as well, and very low in summer season. COD of lake-type reservoirs and Paldang reservoir was lower (2${\sim}$3 mg/L) than that of Geumgang and Nagdonggang reservoirs (6${\sim}$9 mg/L). Dissolved oxygen (DO) of river-type reservoirs was higher than that of lake-type reservoirs. Seasonal fluctuation pattern of DO saturation in river-type reservoirs was high (80 ${\sim}$100%) and remained relatively constant whereas lake-type reservoirs showed the highest level (93%) in late spring or early summer, which gradually decreased entering winter season(46${\sim}$06%). And monthly variation of DO saturation showed inverse proportion to water volume in lake-type reservoirs. Nutrients concentration in river-type lake is higher than lake-type. Seasonal fluctuation of nutrients (T-N, T-P) in lake-type reservoirs was relatively small than that of river-type reservoirs. Annual mean N/P mass ratio of lake-type reservoirs was higher than that of river-type. Transparency tended to related with the suspended solid concentration in river-type reservoirs. Algal bloom of lake-type and river-type reservoirs occurred at any time except rainfall and winter periods. And it dominated in summer and early autumn, respectively. Algal bloom of river-type reservoirs was higher than that of lake-type. Relationship between rainfall and chlorophyll- a in lake-type reservoirs was relatively high, however river-type reservoirs showed insignificant.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.5
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• pp.3279-3285
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• 2014

This study aimed to understand seasonal and geographical characteristic of chlorophyll-${\alpha}$ (chl-${\alpha}$), COD (chemical oxygen demand) and Escherichia coli at Gwangyang Bay during the period from February 2010 to November 2012. The bay is divided into three different zones based on the pollutant levels and geographical characteristics. During the study periods, water temperature, salinity, Chl. ${\alpha}$, and chemical oxygen demand (COD) varied in the range of $4.68-28.63^{\circ}C$, 1.94-33.84 psu, 0.31-35.10 ${\mu}gL^{-1}$, and 0.70-13.35 $mgL^{-1}$, respectively. Total chl-a concentration were high at the zone I, which can be characterized as a semi-enclosed eutrophic area, and it were low at the zone III, which is influenced by low nutrients of surface warm water current from offshore of the bay. The high concentration of COD was observed at inner bay during the four seasons and the water quality level was kept to be bad condition during spring season at the zone II, which is influenced by Seomjin River water. The highest colony form of E. coli was recorded to be 3550 $cfuL^{-1}$ during summer at station 1 (zone I), whereas it was relatively kept low level during all seasons at the zone III. As a result, the E. coli was correlated with water temperature (r=0.31 p<0.05) and salinity (r=-0.55 p<0.05), implying that those parameters have play an important crucial role in proliferation of E. coli. Consequently, our results indicated that the E. coli can be significantly promoted within pollutant sources including the high nutrients supplied by rive discharge during spring and summer rainy seasons in semi-enclosed area of Gwangyang Bay.

• Journal of Korea Water Resources Association
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• v.55 no.1
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• pp.1-10
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• 2022

Irrigation water supplied to the paddy field is consumed in the amount of evapotranspiration, underground infiltration, and natural and artificial drainage from the paddy field. Irrigation return flow is defined as the excess of irrigation water that is not consumed by evapotranspiration and crop, and which returns to an aquifer by infiltration or drainage. The research on estimating the return flow play an important part in water circulation management of agricultural watershed. However, the return flow rate calculations are needs because the result of calculating return flow is different depending on irrigation channel water loss, analysis methods, and local characteristics. In this study, the irrigation return flow rate of agricultural watershed was estimated using the monitoring and SWMM (Storm Water Management Model) modeling from 2017 to 2020 for the Heungeop reservoir located in Wonju, Gangwon-do. SWMM modeling was performed by weather data and observation data, water of supply and drainage were estimated as the result of SWMM model analysis. The applicability of the SWMM model was verified using RMSE and R-square values. The result of analysis from 2017 to 2020, the average annual quick return flow rate was 53.1%. Based on these results, the analysis of water circulation characteristics can perform, it can be provided as basic data for integrated water management.

• Korean Journal of Ecology and Environment
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• v.54 no.4
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• pp.346-362
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• 2021

A sediment control dam is an artificial structure built to prolong sedimentation in the main dam by reducing the inflow of suspended solids. These dams can affect changes in dissolved organic matter (DOM) in the water body by changing the river flow regime. The main DOM component for Yeongju Dam sediment control of the Naeseongcheon River was analyzed through 3D excitation-emission matrix (EEM) and parallel factor (PARAFAC) analyses. As a result, four humic-like components (C1~C3, C5), and three proteins, tryptophan-like components (C2, C6~C7) were detected. Among DOM components, humic-like components (autochthonous: C1, allochthonous: C2~C3) were found to be dominant during the sampling period. The total amount of DOM components and the composition ratio of each component did not show a difference for each depth according to the amount of available light (100%, 12%, and 1%). Throughout the study period, the allochthonous organic matter was continuously decomposing and converting into autochthonous organic matter; the DOM indices (fluorescence index, humification index, and freshness index) indicated the dominance of autochthonous organic matter in the river. Considering the relative abundance of cyanobacteria and that the number of bacteria cells and rotifers increased as autochthonous organic matter increased, it was suggested that the algal bloom and consequent activation of the microbial food web was affected by the composition of DOM in the water body. Research on DOM characteristics is important not only for water quality management but also for understanding the cycling of matter through microbial food web activity.

• Atmosphere
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• v.32 no.1
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• pp.61-70
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• 2022

This study evaluates the economic values for the several first precipitation events during Changma period. The selected three years are 2015, 2019, and 2020, where average precipitation amounts across the 58 Korean stations are 12.8, 20.1 and 13.3 mm, respectively. The four categories are used to assess the values including air quality improvement, water resource acquisition/accumulation, drought mitigation, and forest fire prevention/recovery. Economic values for these three years are estimated 50~150 billion won. Among the four factors considered, the effect of air quality improvement is most highly valued, amounting to 70 to 90% of the total economic values. Wet decomposition of air pollution (PM₁₀, NO₂, CO, and SO₂) is the primary reason. The next valuable element is water resource acquisition, which is estimated 9~15 billion won. Effects of drought mitigation and fire prevention are deemed relatively small. This study is the first to estimate the value of the precipitation events during Changma onset. An analysis for more Changma years will be performed to achieve a more reliable estimate.

• Korean Journal of Remote Sensing
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• v.39 no.5_4
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• pp.1135-1144
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• 2023

Many agricultural reservoirs in South Korea, constructed before 1970, have become aging facilities. The majority of small-scale reservoirs lack measurement systems to ascertain basic specifications and water levels, classifying them as unmeasured reservoirs. Furthermore, continuous sedimentation within the reservoirs and industrial development-induced water quality deterioration lead to reduced water supply capacity and changes in reservoir morphology. This study utilized Light Detection And Ranging (LiDAR) sensors, which provide elevation information and allow for the characterization of surface features, to construct high-resolution Digital Surface Model (DSM) and Digital Elevation Model (DEM) data of reservoir facilities. Additionally, bathymetric measurements based on multibeam echosounders were conducted to propose an updated approach for determining reservoir capacity. Drone-based LiDAR was employed to generate DSM and DEM data with a spatial resolution of 50 cm, enabling the display of elevations of hydraulic structures, such as embankments, spillways, and intake channels. Furthermore, using drone-based hyperspectral imagery, Normalized Difference Vegetation Index (NDVI) and Normalized Difference Water Index (NDWI) were calculated to detect water bodies and verify differences from existing reservoir boundaries. The constructed high-resolution DEM data were integrated with bathymetric measurements to create underwater contour maps, which were used to generate a Triangulated Irregular Network (TIN). The TIN was utilized to calculate the inundation area and volume of the reservoir, yielding results highly consistent with basic specifications. Considering areas that were not surveyed due to underwater vegetation, it is anticipated that this data will be valuable for future updates of reservoir capacity information.