• 농업과학연구
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• 제38권2호
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• pp.309-314
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• 2011

The purpose of this study is to select the dominant discharge which mostly affects the formation of the channel shape in Yo-Stream. So far, three different discharge conditions such as bankfull discharge, discharge of a specific recurrence interval, and effective discharge have been considered as an indicator of dominant discharge. Therefore, three different discharge conditions were studied and based on the study results, dominant discharge was selected for Yo-Stream. When comparing bankfull discharge and effective discharge at Beonam stream gaging station, it has turned out that effective discharge was 10 $m^3$/sec, which is 6 times greater than bankfull discharge of 58.83 $m^3$/sec. Furthermore, when comparing bankfull discharge and discharge of a specific recurrence interval, bankfull discharge was quite similar to discharge with recurrence interval of 1.52 years. Previous study results also indicate that dominant discharge occurs with recurrence interval of similar duration. Therefore, discharge of 58.83 $m^3$/sec was considered as a dominant discharge, which corresponds to discharge with recurrence interval of 1.52 years.

• 한국환경과학회지
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• 제14권4호
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• pp.405-412
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• 2005

Groundwater in Jeju Island, flowing through main stream, is spring water from underground. To set a fixed quantity of groundwater flowing from surface in a hydrological view, 4 downstream (Woedo stream, Gangjung stream, Yeonwoe stream and Ongpo stream) were selected to calculate the characteristic of baseflow and the base-flow discharge through the data on tachometry. There were 11 to 14 level peak caused by runoff, mostly occurred during monsoon season. Also, duration of runoff was 15 to 25 hours, well reflecting the characteristic of inclined, short stream length in Jeju Island and pervious hydrogeographical feature. In case of Gangjung stream, Yeonwoe stream and Ongpo stream, variation of stream water level by baseflow rose above during summer, which was closely linked to the distribution of seasonal precipitation. From autumn to spring, water level fell below while that of Woedo stream remained the same all year round. Data on the water level observed in Woedo stream and Gangjung stream in every single minutes was applied to weir formula(equation of Oki and Govinda Rao) to calculate baseflow discharge. Also, using the data on current and water level calculated in Ongpo stream and Yeonwoe stream, water level-water flow rating was applied to assess base flow discharge.

• 한국관개배수논문집
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• 제17권2호
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• pp.71-81
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• 2010

Stream Pilot Project, which began in May 2003 and finished in December 2003, was selected to develop effective methods applicable to nature-like streams. Stream restoration projects aim to maintain or increase ecosystem goods and services while protecting downstream and coastal ecosystems. Fields environmental monitoring such as flow discharge and precipitation were conducted along the Idong stream for amount of channel zone change in 2007. This study selected three monitoring positions to measure the water level and discharge of flowing water. A stage-discharge relation is obtained from direct discharge measurements for three stations by fitting an empirical relationship to the data set. Since discharge measures are made only for low flow conditions, a curve of discharge against stage can then be built by fitting these data with a power curve. And this study used data obtained from floodmark checkup as well as HEC-RAS model to analyze the hydrodynamic characteristics of monitoring sites. Reach-averaged hydraulic parameters for the supply reach were calculated from the small area's HEC-RAS model for Idong stream, and a HEC-RAS model used to analyze hydraulics for a period in 2007, after the stream was considered bank stabilization.

• 한국지하수토양환경학회지:지하수토양환경
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• 제21권6호
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• pp.36-45
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• 2016

Variability in precipitation due to climate change causes difficulties in securing stable surface water resource, which requires understanding of relation between precipitation and stream discharge. This study simulated stream discharge in a small mountainous forested catchment using antecedent precipitation index (API) models which represent variability of saturation conditions of soil layers depending on rainfall events. During 13 months from May 2015 to May 2016, stream discharge and rainfall were measured at the outlet and in the central part of the watershed, respectively. Several API models with average recession coefficients were applied to predict stream discharge using measured rainfall, which resulted in the best reflection time for API model was 1 day in terms of predictability of stream discharge. This indicates that soil water in riparian zones has fast response to rainfall events and its storage is relatively small. The model can be improved by employing seasonal recession coefficients which can consider seasonal fluctuation of hydrological parameters. These results showed API models can be useful to evaluate variability of streamflow in ungauged small forested watersheds in that stream discharge can be simulated using only rainfall data.

• 상하수도학회지
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• 제22권1호
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• pp.39-48
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• 2008

This study was carried out to investigate the characteristics of the pollutant discharge from non-point source and to estimate the unit loads of the pollutant discharge from the upper watershed of Seomjin Dam during rainy season. The upper watershed of Seomjin Dam is located in the middle of Jeonbuk province is formed two tributaries mainly. A sub-branch stream of those tributaries is Imsil stream of which flow rate is about 13% of the main stream of Seomjin reservoir normally. On the basis of measurement result in this study, the water quality of Imsil stream was fluctuated highly and the quantity of measured pollutant discharge was higher than the value calculated with the proportion of flow rate during dry season. On the contrary, during rainy season the mean values of flow rate and water quality were higher than the quartile according to the statistical analysis. That means rainfall can influence strongly on the water quality of the upper watershed of Seomjin reservoir. Among the several criteria of water quality, SS discharge was most sensitive to the flow rate variation of stream, which was fluctuated in proportion of rainfall, basically. It was evaluated the event mean concentration (EMC) of non-point source pollutants depending on rainfall events as well. Though the pollutant discharge unit of Imsil stream was lower than the main stream of Seomjin reservoir, the EMC value of Imsil stream was higher than the main stream of Seomjin reservoir.

• 한국물환경학회지
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• 제37권3호
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• pp.190-203
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• 2021

Water quality, benthic macroinvertebrate communities, and other factors were investigated to explore the effects of the effluent discharge from a sewage treatment plant into Jwagwang stream in Busan in 2019. During the study period, the flow rate of this stream was in the range of 10,400 m³/day to 52,200 m³/day except for the discharge of about 24,000 m³/day of the effluent. After discharge, the flow velocity increased by about 65% and the water depth increased by about 40%. At sites downstream of the discharge point, BOD, COD, TOC, T-N, T-P, and other water quality values were worse than those of the upstream sites. The periphytic algal chlorophyll-a concentrations in the natural substrata were higher than those of the upstream sites, especially in May and August. However, at sites downstream of the discharge point, the individual numbers of Annelida were decreased and individual numbers of the insecta of arthropoda were increased. Also, species numbers and the diversity and dominance indexes were improved in the sites downstream of the discharge point. The functional feeding groups (FFGs) of collector-filterers were increased and the habitat orientation groups (HOGs) of sprawlers, burrowers, and clingers were especially increased at the sites with additional reclaimed wastewater effluent flow. Regardless of the effluent discharge, BMI, an indicator of ecological stream health using benthic macroinvertebrate species, did not show large gaps between the study points. Although the water quality of the sites downstream of the discharge point was much worse than those upstream, their ecosystem soundness was better than those of the upstream sites from an ecological perspective.

• 한국환경과학회지
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• 제26권12호
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• pp.1321-1331
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• 2017

This study reviewed the applicability of the existing flood discharge calculation method on Jeju Island Han Stream and compared this method with observation results by improving the mediating variables for the Han Stream. The results were as follows. First, when the rain-discharge status of the Han Stream was analyzed using the flood discharge calculation method of the existing design (2012), the result was smaller than the observed flood discharge and the flood hydrograph differed. The result of the flood discharge calculation corrected for the curve number based on the terrain gradient showed an improvement of 1.47 - 6.47% from the existing flood discharge, and flood discharge was improved by 4.39 - 16.67% after applying the new reached time. In addition, the sub-basin was set separately to calculate the flood discharge, which yielded an improvement of 9.92 - 32.96% from the existing method. In particular, the steepness and rainfall-discharge characteristics of Han Stream were considered in the reaching time, and the sub-basin was separated to calculate the flood discharge, which resulted in an error rate of -8.77 to 8.71%, showing a large improvement of 7.31 - 28.79% from the existing method. The flood hydrograph also showed a similar tendency.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2019년도 학술발표회
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• pp.152-152
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• 2019

This study demonstrates a novel approach of remotely sensed estimates of stream flow at fifteen hydrological station in the Han River Basin, Korea. Multi-temporal data of the European Space Agency's Sentinel-1 SAR satellite from 19 January, 2015 to 25 August, 2018 is used to develop and validate the flow estimation model for each station. The flow estimation model is based on a power law relationship established between the remotely sensed surface area of water at a selected reach of the stream and the observed discharge. The satellite images were pre-processed for thermal noise, radiometric, speckle and terrain correction. The difference in SAR image brightness caused by the differences in SAR satellite look angle and atmospheric condition are corrected using the histogram matching technique. Selective area filtering is applied to identify the extent of the selected stream reach where the change in water surface area is highly sensitive to the change in stream discharge. Following this, an iterative procedure called the Optimum Threshold Classification Algorithm (OTC) is applied to the multi-temporal selective areas to extract a series of water surface areas. It is observed that the extracted water surface area and the stream discharge are related by the power law equation. A strong correlation coefficient ranging from 0.68 to 0.98 (mean=0.89) was observed for thirteen hydrological stations, while at two stations the relationship was highly affected by the hydraulic structures such as dam. It is further identified that the availability of remotely sensed data for a range of discharge conditions and the geometric properties of the selected stream reach such as the stream width and side slope influence the accuracy of the flow estimation model.

• 한국수자원학회논문집
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• 제33권5호
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• pp.527-536
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• 2000

본 연구는 금강의 주요지류인 미호천 유역에 소재하고 있고 주요 텔레미터 수위표가 위치한 4개의 지점을 선정하여 유출량과 오염부하량의 상관성 분석을 통해 각 소유역의 전체 오염부하량을 추정하였다. 본 연구에서는 대상유역의 유량측정 지점을 중심으로 평·갈수시 및 홍수시의 유출량 및 수질을 분석하였다. 분석된 유출량 및 수질자료를 통해 유역의 수위-유량관계곡선과 농도변화를 분석하였다. 그리고, 유출량과 수질항목간의 상관관계를 분석하였고, 단위면적당 유출량 변화에 따른 단위면적당 오염부하량과의 상관관계 분석을 통해 유역별 상관식을 도출하였다. 이 관계식은 미호천 유역에서의 유출량 변화에 따른 오염부하량의 산정에 이용될 수 있을 것이다.

• 한국농림기상학회지
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• 제7권1호
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• pp.51-56
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• 2005

To understand the chemical changes in the streamwater and contribution of subsurface discharge during the storm event, we analyzed electric conductivity (EC), anions, and cations in Gwangneung deciduous and coniferous forest catchment. The stream water samples were collected three times in 2004 by using an auto-sampler: September 7-9 (E040907-D and -C; where D and C indicate deciduous and coniferous forest catchment, respectively), September 11-13 (E040911-D and -C), and September 16-18 (E040916-D and -C). We found a negative relationship between discharge intensity and EC in streamwater. The E040911 and E040916 showed slack change of stream discharge in comparison to E040907 due to contribution of base flow recharged by much precipitation. Moreover, NO/sub 3//sup -/ concentrations in E040911-C were highest, which may have resulted from forest management such as thinning in 2004. The relationship between pH and alkalinity in stream water showed that much of stream water have been recharged through subsurface. We conclude that subsurface discharge highly influences streamwater quality in a forested catchment, and the seperation of stream water discharge is therefore necessary to sustainable water management.