• 한국환경과학회지
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• 제8권3호
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• pp.331-336
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• 1999

The monthly water quality data measured at 14 stations located in the Geum-River watershed were clustered into 2 to 7 clusters. Furthermore, factor analyses were conducted on Gabcheon and Yugucheon to characterize the water qualtiy, based on the information obtained from the results of culster analysis. The results of cluster analysis show that the water quality charactersitic of main stream of the Geum-River is somewhat different from that of substream of the Geum-River. Furthermore, the water quality characteristic of Gabcheon which is expected to have the most serious water quality problems in the Geum-River watershed shows the most different water quality characteristic from Yugucheon. Based ont he factor loadings in each factor, Gabcheon and Yugucheon have their own water quality characteristics. This is mainly because of composite factors such as different population density, industrial activities, and land use conditions in Gabcheon and Yugucheon subwatersheds.

• 한국물환경학회지
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• 제31권6호
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• pp.700-714
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• 2015

The characteristic of the water quality and pollutant discharge was analyzed at the units watershed of the total amount management in Han-river basin, and after classified in a similar area by multivariate statistical analysis, the main trend such as the water quality trend and pollutant discharge characteristic were analyzed. As a result of this study, the density of the pollutant at the unit watershed is not necessarily identified as discharge density, and the primary management watershed and targeted substances were analyzed depending on the operating status of the environmental infrastructure in watershed and the main pollution factor and discharge path per pollutants. As a result of cluster analysis, watersheds were classified into four groups according to discharge characteristics. It will be used when selecting target area of primary management that is appropriate to the characteristics of each river and establishing efficient water quality improvement plans.

• 상하수도학회지
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• 제34권6호
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• pp.503-512
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• 2020

Identifying the water circulation status is one of the indispensable processes for watershed management in an urban area. Recently, various water circulation models have been developed to simulate the water circulation, but it takes a lot of time and cost to make a water circulation model that could adapt the characteristics of the watershed. This paper aims to develop a water circulation state estimation model that could easily calculate the status of water circulation in an urban watershed by using multiple linear regression analysis. The study watershed is a watershed in Seoul that applied the impermeable area ratio in 1962 and 2000. And, It was divided into 73 watersheds in order to consider changes in water circulation status according to the urban characteristic factors. The input data of the SHER(Similar Hydrologic Element Response) model, a water circulation model, were used as data for the urban characteristic factors of each watershed. A total of seven factors were considered as urban characteristic factors. Those factors included annual precipitation, watershed area, average land-surface slope, impervious surface ratio, coefficient of saturated permeability, hydraulic gradient of groundwater surface, and length of contact line with downstream block. With significance probabilities (or p-values) of 0.05 and below, all five models showed significant results in estimating the water circulation status such as the surface runoff rate and the evapotranspiration rate. The model that was applied all seven urban characteristics factors, can calculate the most similar results such as the existing water circulation model. The water circulation estimation model developed in this study is not only useful to simply estimate the water circulation status of ungauged watersheds but can also provide data for parameter calibration and validation.

• 환경영향평가
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• 제22권6호
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• pp.695-703
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• 2013

Soil erosion and sediment delivery ratio(SDR) were estimated by using HSPF model in 3 tributaries of upper stream of Geum river-basin. Meteorological data and other input data were constructed from 2006 to 2011 year by the HSPF model. Flow and suspended solid results were relatively matched with the measurement data through the calibration and validation of the model. Soil erosion was proportional to the amount of rainfall and the area of watershed based on the results of model calibration and validation. SDR in Moojunamdea stream was the highest and one in Cho stream was the lowest. This was effected by the geographical characteristic. SDR was 17.6% Moojunamdea stream, 9.1% Cho stream and 13.2 % Bocheong stream. As the SDR was effected by watershed area and shape factor in this study area.

• 한국물환경학회지
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• 제30권3호
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• pp.351-360
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• 2014

The allocation of margin of safety (MOS) at a uniform rate to all areas of the unit watershed makes it very difficult to keep the load allotment stable in the area for lack of reduction measures like forest land. This study developed an equation to calculate margin of safety differentially according to the regional characteristics. The equation was formulated on the basis of the regional characteristic factors such as a load contribution factor for land use type and a site conversion factor for the unit watershed. The load contribution factor represents a contribution of loads from a particular land use. The site conversion factor was derived from the site conversion ratio of a unit watershed. Margin of safety for the non-point pollution load in the land use sector decreased by 20~25% in three river basins. The margin of safety in the unit watersheds with low site occupation ratios decreased in high rate, while in the unit watersheds with large urban area decreased in low rate. With the application of the differential margin of safety considering regional characteristics, not only the reduction of pollution loads can become lighter but also it can be easier to develop plans for Total Maximum Daily Loads (TMDLs) even where the reduction measures are not available.

• 한국농공학회논문집
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• 제57권5호
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• pp.89-99
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• 2015

In this research, 1,032 data of precise safety inspection from 2004 to 2013 are gathered and constructed for finding effective safety inspection systems. Items are extracted from constructed data and factors for typology are decided with statistical method such as principle component analysis and cluster analysis. For factor decision, we extruded independent characteristics such as morphological and geographical characteristic, and deleted items which can be expressed by combination of independent characteristics. Four factors such as total storage, watershed ratio, levee length ratio, and spillway length ratio are extracted in this process. In cluster analysis, levee length ratio is excluded because it is not separated as cluster. Finally nine types of agricultural reservoir are extruded by total storage, watershed ratio, and spillway length ratio with frequency analysis.

• 한국수자원학회논문집
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• 제55권5호
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• pp.371-381
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• 2022

지류 하천은 본류에 비해 수질 변동성이 심하므로, 지류하천에 대한 효과적인 수질관리를 위해서 단일 수질 항목에 의한 평가보다 다항목의 영향을 고려한 종합적인 평가 방법이 도입되고 있으나 유역 특성이 고려되지 못하는 한계가 발생한다. 본 연구에서는 한탄강 중권역을 도시화율 및 가축분뇨 발생량, 산업폐수 배출량으로 도시 유역과 비도시 유역을 분류하고 수질 특성 분석 및 CCME WQI, RTWQI, NSFWQI 산정을 통해 유역 특성별 수질지수의 적합성을 평가하고자 한다. 수질지수 산정시 사용되는 수질항목이 수질지수 결과에 미치는 영향을 파악하고자 요인분석을 활용하였다. 요인분석 결과, CCME WQI와 TC, FC의 관계가 도출되었으며, 도시 유역에서 RTWQI와 DO, SS, 비도시 유역에서 NSFWQI와 FC의 관계가 나타났다. 하천생활환경기준 항목인 BOD, T-P 등급과 수질지수 비교를 통해 적합성을 평가하였을 때 도시 유역에서는 수질지수의 적합성이 낮은 것으로 나타났으며, 비도시 유역에서 RTWQI를 활용한 종합적인 수질 평가가 가능한 것으로 해석되었다.

• 한국지리정보학회지
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• 제17권1호
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• pp.91-106
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• 2014

본 연구는 다변량 통계분석기법을 이용하여 한국 수자원단위지도의 전국 795개 표준유역에 대하여 수문학적 군집화를 수행하였다. 국내 유역의 종합적인 특성인자 산정을 위해 지형, 하천, 기상, 토양, 토지이용 및 수문학 관련 유역특성인자 30개를 선정하였다. 다변량 통계기법인 요인분석을 통해 유역특성인자들 간의 상관관계를 분석하여 16개의 대표 유역특성인자들을 추출하였으며, 유역의 특징을 결정짓는 인자는 토양특성, 유역위치, 유역크기, 기상 및 수문특성에 관련된 인자들로 나타났다. 군집분석을 위해 전국의 기상, 강우, 수위관측소의 자료를 수집하고 양질의 자료보유현황을 검토하여 73개의 계측 유역을 구분하였다. 이 73개의 계측유역을 기준으로 하여, 나머지 미계측 유역 간에 16개의 대표 유역특성인자들과의 유클리드 거리를 계산함으로써 수문학적 군집화를 수행하였다. 그 결과 각 권역별로 동일권역 내 표준유역 사이의 유사성은 한강이 87%, 낙동강이 69%, 금강이 41%, 섬진강이 52%, 영산강이 27%로 분석되었다.

• 한국물환경학회지
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• 제34권4호
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• pp.409-422
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• 2018

The purpose of this study is to find the characteristics of organic matters based on the distribution and oxidation rates, as noted according to the spatial and temporal variations from 2008 to 2016. Generally speaking, the Han River system is separated into one lower course and two upper courses which are the Namhan River and Bukhan River. The seasonal factor is one of the most important causes of water quality changing in both of the upper courses as a result of a few pollution sources. The concentration of organic matter was measured as higher in the lower course into which great streams with point and non-point sources were identified. According to seasonal variations, however, the change of the organic matter in the lower course is comparatively slighter than that of organic matters in the upper courses. The oxidation rates related to the BOD were 15 %, 17 % and 26 % in the Bukhan River, Namhan River and the lower course, respectively. These results could be explained that more biodegradable organic matter were seen to have existed in the lower courses comparing to the activity in the upper course. The oxidation rates of the BOD were noted as relatively higher in the eutrophicated places with phytoplankton. Therefore the BOD is one of the good index models to find the characteristic of the eutrophicated water. On the other hand BOD would not be enough to estimate concentration of refractory organic matters in the Bukhan and Namhan river. Consequently, both of the TOC and BOD are necessary indices to understand the identified refractory and/or biodegradable characteristics of organic matter.

• 한국수자원학회논문집
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• 제54권spc1호
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• pp.1183-1193
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• 2021

Low flow는 하천수의 공급관리 및 계획, 관개용수 등 다양한 분야에 영향을 미친다. 이러한 유황곡선을 산정하기 위해서는 30년 이상의 충분한 기간의 유량자료의 확보가 필수적이다. 하지만 국가하천 단위 이하의 하천의 경우 장기간의 유량자료가 없거나 중간에 일정기간 동안 결측된 관측소가 있어 하천별 유황 곡선을 산정하기에 한계가 있다. 이에 과거에는 미계측 유역의 유황을 예측하기 위해 다중회귀분석(Multiple Regression Analysis), ARIMA 모형 등 통계학적 기반의 기법들을 사용하였지만, 최근에는 머신러닝, 딥러닝 모형의 수요가 증가하고 있다. 이에 본 연구에서는 최신 패러다임에 맞는 머신러닝 기법인 DNN기법을 제시한다. DNN기법은 ANN기법의 단점인 학습과정에서 최적 매개변수 값을 찾기 어렵고, 학습시간이 느린 단점을 보완한 방법이다. 따라서 본연구에서는 DNN 모형을 이용하여 미계측 유역에 적용 가능한 유황곡선을 산정하고자 한다. 먼저, 유황곡선에 영향을 미치는 인자들을 수집하고 인자들 간의 다중공선성 분석을 통해 통계적으로 유의한 변수를 선정하여, 머신러닝 모형에 입력자료를 구축하였다. 통계적 검증을 통해 머신러닝 기법의 효용성을 검토하였다.