• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.491-494
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• 2006

The output performance characteristics for surveyed sites were analyzed, using developed model. It consists of two main parts, the deciding flow duration characteristic of river and performance prediction model to estimate the output characteristics of small hydropower plants. As a result, it was found that the flowrate concerning with 25% of time ratio on flow duration curve can be selected to design flowrate of small hydropower plants, and the output characteristics of small hydropower plants having overflow dam are different from large scale hydropower plants.

• Journal of the Korean Association of Geographic Information Studies
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• v.23 no.3
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• pp.174-191
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• 2020

In this study, we analyzed the vulnerable areas of non-point source pollutants and management pollutants and management time by subwatershed curves in the Seohwacheon basin located upstream of Daecheongho. First, in order to create a load duration curve, a long-term flow model SWAT was constructed to create a flow duration curve, and the result was multiplied by the target water quality to create a load duration curve. For the target water quality, monitoring data values measured from November 2017 were used for the management of nonpoint source pollutants in Seohwacheon, and a value corresponding to 60 percentile of the measured data was set as the target water quality. At this time, the target water quality was limited to"slightly good"(II) when the calculated value exceeded"slightly good"(II) of the river living environment standard. The vulnerable areas of non-point source of pollution were selected using the excess rate exceeding the target water quality, and the excess pollutant was judged as a management substance and the management time was selected through seasonal evaluation.

• Journal of Korean Society on Water Environment
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• v.29 no.6
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• pp.762-776
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• 2013

Load duration curve was applied to determine important water quality parameter control term for improvement of Paldang lake water quality. Load duration curve was analyzed with long term data from 1985 to 2012 including water quality, flow rate and climate state of Paldang water environment. From the result of flow rate patterns of paldang lake, differences between high and low flow rate of each year showed tendency of increase because rainfall characteristics of paldang lake watershed were changed by climate exchange. Both of land use state of upper Paldang lake watershed and number of limit excess from load duration curve indicated that seasonal action related with land use such as agricultural fertilizer distribution in upper watershed affected Paldang lake water quality. So focused BOD (biological oxygen demand) management during spring season from march to June is required to control organic materials in Paldand lake. The main affecting factor of TOC (total organic carbon) increase in Paldang lake was initial rainfall after march. T-N (total nitrogen) kept increasing during research period, so enhancement of T-N standard is needed to T-N control. Initial rainfall and increase of temperature during spring season from March to June showed a positive correlation with TP (total phosphorus) and Chl-a, respectively.

• Journal of Environmental Science International
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• v.28 no.10
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• pp.873-885
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• 2019

In this study, a load duration curve was applied to the Jangseongcheon, one of the tributaries of the Yeongsan River, to assess whether the target water quality was achieved. In addition, pollution of the water body was investigated to develop and suggest the optimal management time with respect to polluted flow sections and monthly conditions. The average flow rates of sections JS1 and JS2 were $0.25m^3/s$ and $1.08m^3/s$, respectively. The BOD and T-P for water-quality standards at JS1 were rated at II, whereas the COD and TOC were rated at III, thus indicating a fair level of water quality. By contrast, the BOD at JS2 was rated at III, the T-P at IV, and the TOC at V, indicating poor water quality in this section. The load duration curve was plotted using the actual flow data measured in eight-day intervals for eight years from 2011 to 2018 at locations JS1 and JS2 in the Jangsungcheon Basin. In an assessment using the load duration curve on whether the target water quality was met at location JS1, all of the water quality parameters (BOD, COD, TOC, T-N, T-P, and SS) satisfied the target water quality. By contrast, at location JS2, parameters COD, TOC, T-N, and T-P exceeded target values by more than 50%, indicating the target water quality was not met. The discharge loads of locations JS1 and JS2 were analyzed to identify the reasons the target water quality was exceeded. Results revealed that the land system contributed considerably. Furthermore, the discharge load of JS2 accounted for more than 80% of the load on the entire basin, excluding that of JS1. Therefore, the best method for restraining the inflow of pollutants into the stream near location JS2 must be applied to manage the water quality of the Jangsungcheon.

• Journal of Korean Society on Water Environment
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• v.35 no.6
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• pp.497-509
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• 2019

After the Total Maximum Daily Loads(TMDLs) was applied, it became beyond the limit of concentration management. However, it does not adequately reflect the characteristics of various watersheds, and causes problems with local governments because of the standard flow set. Thus, in this study, the Han River system is organized into four groups in estimating the Pollution Contribution by applying the Flow Duration Curve(FDC) created by the daily flow of data from the HSPF. And the method of this study is expected to be valuable as basic data for the TMDLs. As a result, Group I contains the main watersheds with no large hydraulic structures and tributary watersheds. There is no specificity in the FDC and the Pollution Contribution is estimated as rainfall runoff. Group II contains watersheds near the city where the FDC is maintained above a certain level during the Low Flow Conditions and the Pollution Contribution is estimated as the discharge flow of large scale point pollution facilities. Group III contains the main watersheds in which the large hydraulic structures are installed and FDC is curved in the Low Flow Conditions. So the Pollution Contribution is estimated as the water quality of the large hydraulic structures. Group IV contains the upstream in mainstream watersheds in which the large hydraulic structures are installed and the FDC is disabled before the Low Flow Conditions. As the flow is concentrated in the High Flow Conditions, the non-point pollution sources are estimated as the Pollution Contribution.

• Journal of the Korean Association of Geographic Information Studies
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• v.24 no.3
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• pp.41-57
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• 2021

This study evaluated the application of water quality management measures using the SWAT model and the effectiveness of the measures using the load duration curve targeting the Seohwacheon watershed located upstream of Daecheongho. As water quality management measures, artificial wetlands, reduction of neglected livestock, reduction of runoff from greenhouses, restoration of ecological rivers, application of LID technology, and management of point sources were applied. The applied technology evaluated the efficiency of water quality improvement measures by using the target water quality excess rate and the degree of load reduction for each sulfur through the load duration curve. The load duration curve was created by creating a long-term flow duration curve using SWAT and multiplying it by the target water quality. For the target water quality, the value corresponding to the 60th percentile was set as the target water quality using the 10-year data from the Okcheoncheon water quality observation point located in the downstream of Seohwacheon. Through this study, it was possible to confirm the applicability of various water quality measures through the SWAT model, and to examine the applicability of each period according to the sulfur through the load retention curve.

• Journal of Korea Water Resources Association
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• v.47 no.11
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• pp.997-1005
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• 2014

This study evaluated hydrological drought the using the annual minimum flow and the annual maximum deficit method and proposed the new concept of water deficit-duration-frequency curves similar to rainfall intensity-duration-frequency curves. The analysis results of the annual minimum flow, the return periods of hydrological drought in the most duration of 1989 and 1996yr were the longest. The analysis results of the annual maximum deficit, the return periods of 60-days and 90-day deficit which are relatively short duration were the longest in 1995yr, about 35-year, Hydrological drought lasted longer was in 1995, the return period was about 20-year. Though duration as well as magnitude is a key variable in drought analysis, it was found that the method using the annual minimum flow duration not distinguish duration.

• Journal of Korean Society on Water Environment
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• v.29 no.3
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• pp.343-353
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• 2013

Flow duration curve (FDC) can be developed by linking the daily flow data of stream flow monitoring network to 8-day interval flow data of the unit watersheds for the management of Total Maximum Daily Loads. This study investigated the applicable method for the development of long term FDC with the selection of the stream flow reference sites, and suggested the development of the FDC in 4 river basins. Out of 142 unit watersheds in 4 river basins, 107 unit watersheds were shown to estimate daily flow data for the unit watersheds from 2006 to 2010. Short term FDC could be developed in 64 unit watersheds (45%) and long term FDC in 43 unit watersheds (30%), while other 35 unit watersheds (25%) were revealed to have difficulties in the development of FDC itself. Limits in the development of the long term FDC includes no stream monitoring sites in certain unit watersheds, short duration of stream flow data set and missing data by abnormal water level measurements on the stream flow monitoring sites. To improve these limits, it is necessary to install new monitoring sites in the required areas, to keep up continuous monitoring and make normal water level observations on the stream flow monitoring sites, and to build up a special management system to enhance data reliability. The development of long term FDC for the unit watersheds can be established appropriately with the normal and durable measurement on the selected reference sites in the stream flow monitoring network.

• Journal of Korean Society on Water Environment
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• v.28 no.5
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• pp.693-703
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• 2012

Load Duration Curve(LDC) is a useful tool for analyzing water quality characteristics under various stream flow conditions. This study investigated the methods to identify impaired waterbodies in the assessment of water quality goal attainment by using LDC for the management of Total Maximum Daily Loads (TMDLs). Three methods were proposed. Non-typical regime exclusion method is a method to exclude water quality observations in the non-typical extreme flow conditions in order to minimize the influence of non-ordinary water quality. Flow regime weighted average method is a method to calculate weighted mean water quality instead of arithmetic mean in order to consider water characteristics properly on stream flow regime in addition to the effect of Non-typical regime exclusion method. Load exceeded interval comparison method is a method to compare the intervals between the attained and non-attained load duration periods on the LDC. The assessment of water quality goal attainment can be performed more reasonably and precisely considering water quality variations on stream flow conditions by applying these proposed methods.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.132-132
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• 2020

유황곡선은 하천유량의 변동성을 함축적으로 나타내고 연간유량 분석방법(calendar-year method)과 전 자료기간유량분석방법(total-period method)을 이용하여 작성하고 분석할 수 있다. 본 연구는 유황곡선 상에서 유역특성인자들을 포함시켜 작성하는 방법을 제시하였고 지형 및 기상학적 인자를 통해 지역화 시킨 유황곡선을 통해 미계측 유역의 유황곡선을 추정할 수 있는 곡선을 개발하고자 한다. 이를 위해 유역의 특성인자자료를 수집하여 독립변수로 설정하였고 다중회귀분석을 실시하여 변수들을 지역화 시켰다. 지역화 시킨 변수들을 유황곡선에 반영하여 대상지역에서 하나의 유황곡선으로 나타내었다. 도출한 유황곡선을 자료가 있는 지역을 미계측유역이라 가정하고 검증하였다. 검증결과 실제자료와 유사하게 나타나는 것을 확인할 수 있었고 이를 통해 미계측 유역의 유출량 자료가 부족한 유역에 대한 예측과 과거 많은 부분이 결측된 유역에 대한 유출량 예측도 가능할 것이라 판단된다. 또한 강우시나리오를 통해 지형인자가 고려된 유황곡선을 이용한 다양한 자료분석을 실시할 수 있을 것이라 판단된다.