• Korean Journal of Soil Science and Fertilizer
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• v.42 no.spc
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• pp.57-61
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• 2009

To clarify the impact of the rice-duck farming system on the regional environment and the surrounding, a case study was carried out at Hongdong Reservoir valley of Hongdong-myeon and Janggok-myeon, Hongseong-gun, Chungcheongnam-do where the density of livestock grazing is the highest and rice cultivation with the rice-duck farming system is extensively practiced. The soil characteristics and water qualities at paddy fields were compared between two rice cultivation methods of rice-duck farming system and conventional farming system. The organic matters and available phosphate contents in soil of paddy fields where the rice-duck farming system was practiced were higher than those of paddy fields where conventional farming system was practiced. However, the available phosphate content was lower than the optimum for rice cultivation and the mean concentration of paddy soil in Korea. The surface water quality of the paddy field with the rice-duck farming system was practiced had higher EC (137 %), $COD_{Cr}$ (220 %), T-N (172 %), and T-P (226 %) contents than that with the conventional farming system was practiced. Especially, $COD_{Cr}$ and T-P were more than 2 times higher, which tells that the possibility of water pollution by drainage water of paddy field is higher in the paddy fields with the rice-duck farming system practiced than in those with the conventional farming practiced. The higher contents of T-P and $COD_{Cr}$ in surface water at the paddy field of rice-duck farming system practiced were directly caused by soil particles in the muddy water. Consequently, it is necessary to thoroughly manage the irrigation and drainage system of rice-duck farming system practiced to prevent outflow of surface water from paddy and pollution of surrounding water system.

• Journal of Wetlands Research
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• v.2 no.1
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• pp.59-67
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• 2000

The aim of this study is to identify the role of this natural treatment system, which consists of Oenanthe javanica and wasted concrete as bio-media. Therefore, it was designed to experiment water quality, BOD, SS, T-N, T-P to recognize the efficiency of treatment system with one biofilter tank using wasted concrete and vegetation bed using Oenanthe javanica. It was also designed to compare two different biofilter reactors, which are air lift and upflow methods. In the result, it was demonstrated that upflow method is more efficient system to control water quality of polluted streams. The vegetation bed using Oenanthe javanica has the treatment efficiency of 41 % (BOD), 52 % (COD), 60% (SS), 36 % (T-P), 70 % ($NH_4-N$). It was therefore proved that removal rates of nutrients are not so good except $NH_4-N$ concentration with nitrification.

• Journal of Environmental Science International
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• v.7 no.2
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• pp.165-170
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• 1998

The purpose of thins study was to investigate the pollutions of water Qualities in 30 water samples from Nakdong River Western Nakdong River, and Suyoung Stream. COB, BOD. T-N and negative ion(F, Cl+, NO3-, SO42-) of water samples were analysed and the correlationships between water qualities were examined. The mean concentrations of COD(20.26ppm), BOD(25.36ppm), and T-N(18.05ppm) were the highest in the water sample of Suyoung Stream among the three streams and those of F-(0.25ppm), Cl+(2770ppm), and SO42-(37.66ppm) In Western Nakdong River, that of NO3-(10.8 ppm) in Nakdong River. The water quality of Suyoung Stream was the worst among the three streams in hsn area. The correlationships between water qualities were as follows , BOD and COD showed very high correlationship(correlation cofficient, r=0.97),50,2- and NO3'did high one(0.75), and NOa'and COD, BOD did relatively high ones(0.56 and 0.48, respectively).

• Water for future
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• v.25 no.2
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• pp.89-97
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• 1992

This study is to verify the applicability of statistical models for predicting flood frequency at the stage gaging stations selected by considering whether the flow is natural condition in the Han River basin. From the result of verification, this statistical flood frequency models showed that is fairly reasonable to apply in practice, and also were compared with sampling variance to calibrate the statistical dfficiency of the estimate of the T year flood Q(T) by two different flood frequency models. As a result, it was showed that for return periods greater than about T=10 years the annual exceedence series estimate of Q(T) has smaller sampling variance than the annual maximum series estimate. It was showed that for the range of return periods the partial duration series estimate of Q(T) has smaller sampling varianed than the annual maximum series estimate only if the POT model contains at least 2N(N:record length)items or more in order to estimate Q(T) more efficiently than the ANNMAX model.

• Korean Journal of Ecology and Environment
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• v.41 no.3
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• pp.283-293
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• 2008

The objectives of the study were firstly to provide fundamental data for establishment of total maximum daily load (TMDL) management in Ulsan City, and secondly to make practical application of stream health assessment with tolerance range by each species when physiochemical and fish investigations were carried out together. A total of 44 sites in Taehwa River, Hoiya River, Dong Stream, and Cheongryang Stream were selected to monitor water qualities seasonally and fish investigation was performed in August 2006. Among the parameters of water quality, biological oxygen demand (BOD) and dissolved oxygen (DO) related to respiration, total nitrogen (T-N) and total phosphorus (T-P) related to nutrient and eutrophication, and total suspended solids (TSS) and $NH_4$-N were compared with vertical box plot by 8 dominant species. According to the fish investigation, 12 families 33 species were found including endangered species (Pungitius kaibarae) and introduced species (Lepomis macrochirus, Micropterus salmoides), and appearance rate of Korean endemic species was greater in Taehwa River (29.2%) than others. As the results of tolerance range by species, Zacco koreanus, Rhynchocypris oxycephalus, Iksookimia longicorpa, and Squalidus gracilis majimae had limited low range by water quality parameters indicating preference of good water quality. Whereas, Carassius auratus and Pseudorasbora parva were found downstream and urban-streams which were exposed from frequent inflow of pollutants. It concludes that the results help distinguishing sensitive, intermediate, and tolerant species when we evaluate stream health assessment with fish, and further making practical application for conservation and restoration of aquatic ecosystem.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1B
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• pp.51-60
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• 2006

Water quality improvement in mattress/filter system using porous material like slag from industrial activity and zeolite that has been studied for environment improvement and pollution abatement is very useful in polluted stagnant stream channel. Slag is consisted of CaO, $SiO_2$, $Al_2O_3$ and $Fe_2O_3$. Slag with large specific surface area of porosity has been used such as sludge settling and adsorptive materials. Because slag is porous, it can be used for purification filter. As slag is used as filled materials of mattress/filter system and the system has good advantages for the waste water treatment, water recycling, and the improvement of water quality at the same time and so on. Because zeolite has much advantage of cation exchange, adsorption, catalyst and dehydration characteristics, It is used for environment improvement of livestock farms, treatment of artificial sewage and waste water, improvement of drinking water quality, radioactive waste disposal and radioactive material pollution control. In this study, according to verifying effects of water quality improvement of fill materials by porosity that 38.6%, 45.8% and 49.8% respectively in the stagnant stream channel, water quality monitoring of inflow and outflow was conducted on pH, DO, BOD, COD, SS, T-N and T-P. Mattress/filter system was able to accelerate water quality improvement by biofilter as waste water flows through gap of mattress/filter fill materials and by contact catalysis, absorption, catabolism by biofilm. Mattress/filter system used slag and zeolite forms biofilm easily and accelerates adsorption of organic matter. As a result, mattress/filter system increases water self-purification and accelerates water quality improvement available for stream water clean-up.

• Journal of The Geomorphological Association of Korea
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• v.21 no.4
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• pp.1-17
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• 2014

This study analyzed characteristics of landform relieves on 12 bedrock whole(W) areas and 24 mountain(M) and valley(V) areas. Based on this result, characteristics and relations between bedrocks and landform relief were classified as follows. 1) gneiss-height M and granite-height W, M, V areas show active stream incision for uplift. However these areas have relatively low relief and grade compared to high altitude, because effect of denudation don't pass on whole slope. 2) gneiss-height W, V, gneiss-mid M, schist M, granite-mid M, volcanic rock W, M, sedimentary rock-height(conglomerate) W, M, V, sedimentary rock-mid (sandstone and shale) M, limestone W, M areas have active stream erosion and mass movement, but landform relieves are on the high side, because these have resistant bedrock and geological structure against weathering and erosion. 3) gneiss-mid W, V, schist W, V, granite-mid W, V, volcanic rock V, sedimentary rock-mid W, V, sedimentary rock-low(shale) M, limestone V areas landform relieves are on the low side, because these have weak resistance and active weathering, mass movement, erosion, transportation and deposit. 4) gneiss-low W, M, V, granite-low W, M, V, sedimentary rock-low W, V areas landform relieves are very low, because these don't have active erosion and mass movement as costal area with low altitude.

• Journal of Korea Water Resources Association
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• v.57 no.8
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• pp.519-532
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• 2024

This study aims to investigate stream drying phenomena and determine ecological flow in upper Jungnangcheon basin(118.2 km²) of Han River basin. Satellite imagery was used to compare historical and current land cover, and field surveys, including fish surveys, were conducted to assess stream drying conditions. Satellite image analysis revealed a significant increase in impervious surface area due to the expansion of residential and commercial areas. Streamflow and water quality measurements at Hannae Bridge in study area during the dry season showed and average minimum flow of 1.39 m³/sec and elevated SS levels, indicating poor water quality for T-P and TOC. The representative fish species in the study area was P.herzi. Optimal habitat suitability index for depth, velocity, and substrate were 0.3~0.5 m, 0.1~0.3 m/sec, and sand, respectively. Using PHABSIM, the ecological flow for the study area was estimated as 1.00 m³/sec. The derived ecological flow can be used as a reference flow for stream drying mitigation strategies.

• Journal of Korea Water Resources Association
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• v.41 no.12
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• pp.1187-1198
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• 2008

Many reservoirs in Korea and their downstream environments are under increased pressure for water utilization and ecosystem management from longer discharge of turbid flood runoff compared to a natural river system. Turbidity($C_T$) is an indirect measurement of water 'cloudiness' and has been widely used as an important indicator of water quality and environmental "health". However, $C_T$ modeling studies have been rare due to lack of experimental data that are necessary for model validation. The objective of this study is to validate a coupled three-dimensional(3D) hydrodynamic and particle dynamics model (ELCOM-CAEDYM) for the simulation of turbid density flows in stratified Daecheong Reservoir using extensive field data. Three different groups of suspended solids (SS) classified by the particle size were used as model state variables, and their site-specific SS-$C_T$ relationships were used for the conversion between field measurements ($C_T$) and state variables (SS). The simulation results were validated by comparing vertical profiles of temperature and turbidity measured at monitoring stations of Haenam(R3) and Dam(R4) in 2004. The model showed good performance in reproducing the reservoir thermal structure and propagation of stream density flow, and the magnitude and distribution of turbidity in the reservoir were consistent with the field data. The 3D model and turbidity modeling framework suggested in this study can be used as a supportive tool for the best management of turbidity flow in other reservoirs that have similar turbidity problems.

• Journal of Wetlands Research
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• v.13 no.2
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• pp.343-353
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• 2011

Variations of load in both DOM and RDOM of inflowing rivers to lakes were in the range of 5.01-7.29(${\times}10^2$ kg/day) for AD lake and 1.23-3.75(${\times}10^3$ kg/day) for JY lake during the research period excluding the period directly affected by the strong rainy season and the monsoon and typhoon season. We observed a good relationship($R^2$ > 0.8) between SS load and DOM load (including RDOM) in both inflowing rivers to JY lake. Therefore, it was determined that SS would be an alternative parameter with a rapid and energy-efficient method for the analysis of both DOC and RDOC, which require the analytical equipment and a long time period. Both AD lake and JY lake may act as a DOM(including RDOM) source through primary production in the fall season. Because AD lake and JY lake may not act as a DOM buffer zone, both lakes couldn't control the DOM and RDOM in spring before the rainy season. Therefore to improve water quality in downstream rivers is needed to remove pollutants such as DOM and RDOM before inflowing to these lakes in upstream rivers, or to have the unique landscape of wetlands as a buffer zone.