HEC-RAS/GIS를 이용한 홍수 범람지역 분석

안승섭,이증석,김종호 한국환경과학회 2004 한국환경과학회지 Vol.13 No.1

The purpose of the study was to construct a forecast system of flood inundation area at natural stream channels. The study built the system to interpret the flood inundation area in four stages ; constructing topography data around the stream channel, interpreting flood discharge, interpreting flood elevation in the stream channel, and interpreting the flood inundation and mapping. According to the result of the analysis, as for the characteristic of flood inundation around the area within the purview of this study, although there were areas where flood inundation over a bank caused a flooded area, the failure of the internal drainage in the ground lower than flood elevation caused more serious problems. Rather than the existing method where only the estimated flood elevation data is used based on the hydrographical stream channel trace model(such as the HEC-RAS model) to establish the flood inundation area, if the procedure introduced in this study was applied to interpret the floodplain, actual flood inundation area could be visibly confirmed.

수공구조물이 하천환경에 미치는 영향에 관한 연구(II) : 수질 및 생태학적특성 Water Quality and Ecological Characteristics

안승섭,최윤영,이수식 한국환경과학회 2002 한국환경과학회지 Vol.11 No.4

In this study, water protection reservoir is selected as the target which is located at the estuary of Taehwa river to analyze and examine the effects of hydraulic structure on river environment. This study examined the water quality variation characteristics among many effects of hydraulic structure on river environment before and after removal of the sediment protection reservoir when low flow is yielded. This study aims at the definition of factors which cause the change of ecological environmental friendly river space development through the comparison of stream variation conditions(depth, velocity, and etc.) and riverbed variation characteristics with ecological depth condition of Taehwa-river's channel for each representative species of fish and examination those. Firstly, form the examination result of water quality when low flow is yielded before and after removal of the sediment protection reservoir for problems about water quality of river due to flow amount decrease in river, it is found that DO decreases about 0.78~0.86ppm at the lower stream of Myeongchon-gyo, and BOD decreases about 0.06~0.24ppm from right upper stream to the direction of estuary when the sediment protection reservoir is removed. It is known from the above that there is some improvement of water quality from the lower stream of Taehwa-gyo to the estuary in case of removal the sediment protection reservoir. Nextly, it is thought that the effects on ecosystem due to water depth and draw down in channel is not serious on the basis of the examination of water quality analysis result according to removal of sediment protection reservoir and hydraulic depths for reservation of ecosystem, these are 10~40㎝ for breeding season, 10~50㎝ for fry period, and 10~100㎝ for adult period of the representative species of fish in Korea.

수공구조물이 하천환경에 미치는 영향에 관한 연구(I) : 수리학적특성 Hydraulic Characteristics

안승섭,최윤영,이수식 한국환경과학회 2002 한국환경과학회지 Vol.11 No.3

In this study, water protection reservoir is selected as the target which is located at the estuary of Teahwa river to analyze and examine the effects of hydraulic structure on river environment. This study aims at the definition of factors which cause the change of ecological environment of river due to the effects of the sediment protection reservoir, and the proposal of the direction of environmental friendly river space development through the analysis and examination of stream variation conditions and riverbed variation characteristics among many effects of hydraulic structure on river environment before and after removal of the sediment protection reservoir when design flow is yielded. Firstly, in case of removal the existing sediment protection reservoir, the hydraulic variation characteristics like depth drop due to removal of the sediment protection reservoir are thought of little because it is examined that depths drop with about 0.01m and 0.01~0.56m when low flow is yielded and design flood yielded, respectively. Nextly, as the examination result of the variation characteristics of flow velocity in case of removal the existing sediment protection reservoir, it is thought that the concern about riverbed erosion is not serious according to the analyzed result as the mean velocity of the channel section where the velocity varies in case of removal the sediment protection reservoir is about 0.07~1.36m/s when low flow is yielded, and is about 1.02~2.41m/s when design flood is yielded despite riverbed erosion is concerned as it is examined that flow velocity is getting increase as about 0.01m/s when low flow is yielded and about 0.01~0.44m/s when design flood is yielded. Lastly, from the prediction result of riverbed variation for each flow amount condition before and after removal the sediment protection reservoir, it is known that the variation range of riverbed is nearly constant when flow amount of the channel exceeds a specific limit as it is analyzed that the more flow amount, the more erosion and sediment in the channel section of down stream part of the sediment protection reservoir and the sediment protection reservoir-Samho-gyo, and the variation ranges according to flow amount between flood condition and design flood condition have little difference in the channel section of the upstream of Samho-gyo.

지형공간 특성자료를 이용한 하천유역의 강우-유출해석

안승섭,이증석,도준현 한국환경과학회 2003 한국환경과학회지 Vol.12 No.9

The subject basin of the research was the basin of Yeongcheon Dam located in the upper reaches of the Kumho River. The parameters of the model were derived from the results of abstracting topological properties out of rainfall-runoff observation data about heavy rains and Digital Elevation Modeling(DEM) materials. This research aimed at suggesting the applicability of the CELLMOD Model. a distribution-type model, in interpreting runoff based on the topological properties of a river basin, by carrying out runoff interpretation for heavy rains using the model. To examine the applicability of the model, the calculated peaking characteristics in the hydrograph was analyzed in comparison with observed values and interpretation results by the Clark Model. According to the result of analysis using the CELLMOD Model proposed in the present research for interpreting the rainfall-runoff process, the model reduced the physical uncertainty in the rainfall-runoff process, and consequently, generated improved results in forecasting river runoff. Therefore it was concluded that the algorithm is appropriate for interpreting rainfall-runoff in river basins. However, to enhance accuracy in interpreting rainfall-runoff. it is necessary to supplement heavy rain patterns in subject basins and to subdivide a basin into minor basins for analysis. In addition, it is necessary to apply the model to basins that have sufficient observation data, and to identify the correlation between model parameters and the basin characteristics(channel characteristics).

최소차 하천의 임계면적에 따른 유역 지형매개변수의 변화특성

안승섭,박노삼,김종호,임기석,송시훈 한국환경과학회 2005 한국환경과학회지 Vol.14 No.1

The size of minimum order stream has a very sensitive effect on runoff analysis model using the divergence characteristic of stream. Therefore, in this study, the threshold area of minimum order stream has been examined the change characteristic of topographical parameters. The subject basin of the research was the upper basin of the Kumho water gage station which is located in the middle of the Kumho river. The 1:25,000 numerical geography which was constructed 10×lOm mesh was used. The range of investigation of topographical parameters are number of stream order, length, area, slope, basin relief, sinuosity ratio, drainage density and total stream length etc. It was found from the result of analysis that the threshold value of minimum order stream has a very big effect on topographical parameters of basin. It was found that the threshold area of minimum ord er stream revealed under 0.10km². Furthermore, the parameters showed a serious change except for over 0.10km².

소양호에서 세균수와 세균 체적의 계절적 수심별 변화

안태석,최승익,변명섭,박호완 江原大學校 附設 環境硏究所 1998 環境硏究 Vol.15 No.-

To define the ecological roles of bacteria in Lake Soynng, the depth profiles of bacterial numbers and their biovolume were estimated temporally. In August, 1992, the bacterial numbers and biovolume were ranged from 12×10^(5) to 28×10^(5) cells ml^(-1) and from 0.4 to 1.0 ㎛³ cell^(-1), respectively. At 30m depth, the biovolume was highest as 1.0㎛³ cell^(-1) while the numbers were not changed. These large bacteria might be allochthonous bacteria originated from terrestrial during the heavy rain. In October, 1882, the bacterial numbers were ranged from 6×10^(5) to 17×10^(5) cells ml³ , and biovolumes at epilimnion were about 0.5 ㎛³ cell^(-1), while at metalimnion and hypolimnion, larger than 0.9 ㎛³ cell^(-1). In this time, zooplankton grazing pressure and nutrients release from sediment might affect the bacterial numbers and biovolume. In April, 1993, when Asterionella and Fragifaria were dominant species of phytoplankton only in epilimnion, the bacterial numbers were about 20×10^(5) cells ml^(-1), and biovolumes were about 0.8㎛³ cell^(-1). While at other depths, the numbers and biovolumes were smaller. These results suggest that the bacterial numbers were dynamically changed with season, while their mean cell volume were commonly stable as 0.5㎛³ cell^(-1). But by the allochthonous bacteria, organic materials released by phytoplnnkton and grazing pressure by zooplankton might increase the biovolume.

신경망모델을 이용한 일유출량 해석

安勝燮,金成原 慶一大學校 1997 論文集 Vol.14 No.2

The objectives of this study is to introduce and apply neural network theory to real hydrologic systems for predicting of daily runoff discharge in the river basin. Back propagation algorithm of neural network model is applied for the estimation of daily stochastic runoff discharge using past daily rainfall and observation results. As a result of analysis, it is presented that method 3 model which has much input layer processing elements than any other model is adjacent model as to observation runoff discharge. Therefore, as a foundation of this study, it is considered that continuous studies are need to the development of adaption network algorithm for the flood prediction including real time analysis and a field concerning with optimal decision system for dam operating.

영양염류 제거를 위한 생물막 공정의 적용에 관한 연구

안승섭,박노삼,이수식,이관영,박상현 한국환경과학회 2000 한국환경과학회지 Vol.9 No.5

In this study, the removal possibility of nutrients of T-P, NH_3-N, NO_3-N, and T-N is examined through a positive experimental study using submerged biofilter of media packing channel method. From the analysis of nutrients removal efficiency for each run of the collected sample, following results are obtained. Firstly, the result of N/P surveying for inflow shows serious value that excess the limit value of 20 as the values are in the range of 12.0∼42.7 and the average is 25.73. Secondly, the highest concentration of the incoming NH_3-N reaches double of the standard since the concentrations of NH_3-N, and NO_3-N for inflow shows 0.06㎎/ℓ , and 2.5∼3.8㎎/ℓ respectively, and the average removal rate which passed the submerged biofilter adopted in this study is a satisfactory level. Next, the average removal rate of T-P of 51.5% shows the possibility of entrophication removal since the removal rate of T-P of 66.8∼68.8% in relative low temperature period of RUN 1∼2 appeared higher than in RUN 3∼6, and T-N shows relatively poor result with the average removal rate of 34.1%. And it is known that the bigger BOD/P and BOD/N are, the more removal rate increases from the examination result of the relation between BOD/P and BOD/N, and the treatment water T-P and T-N to decide the relation with the concentration of organic matters, and thought that the appropriate proportion is necessary for effective removal of nitrogen and phosphorus.

인공지능기법을 이용한 하천유출량 예측에 관한 연구

안승섭,신성일,정순돌 한국환경과학회 2004 한국환경과학회지 Vol.13 No.7

The Neural Network Models which mathematically interpret human thought processes were applied to resolve the uncertainty of model parameters and to increase the model's output for the streamflow forecast model. In order to test and verify the flood discharge forecast model eight flood events observed at Kumho station located on the midstream of Kumho river were chosen. Six events of them were used as test data and two events for verification. In order to make an analysis the Levengerg-Marquart method was used to estimate the best parameter for the Neural Network model. The structure of the model was composed of five types of models by varying the number of hidden layers and the number of nodes of hidden layers. Moreover, a logarithmic-sigmoid varying function was used in first and second hidden layers, and a linear function was used for the output. As a result of applying Neural Networks models for the five models, the N10-6model was considered suitable when there is one hidden layer, and the N10-9-5model when there are two hidden layers. In addition, when all the Neural Network models were reviewed, the N10-9-5model, which has two hidden layers, gave the most preferable results in an actual hydro-event.

소규모 농업용 저수지의 저류량-용수공급능력 결정에 관한 연구

안승섭,정순돌,이증석,윤경덕,장인수 한국환경과학회 2002 한국환경과학회지 Vol.11 No.12

This study aims at the effective estimation of water supply capacity of small scale reservoir and the proposal of the data which is necessary to establish the water resources management plan of down stream area of the reservoir in the future by comparison and examination about reservoir operation technique for the security of agricultural water in small scale reservoir. The result of flow calculation by Tank model is used for the input data as the inflow data which is needed for the analysis of water supply capacity. Stochastic method, simulation method, and optimization method are used to examine the water supply capacity, and water security amount is compared with each method. From the analyses of water supply capacities by each method, slightly different results are shown in spite of the effort to compare them equally using input data such as inflow data under equal conditions, and the comparison of water supply capacities by each method are follows; linear planning method, and transition probability matrix method in the order of amount from the largest. It is thought that the simulation method in which comparatively reasonable application of the inflow data is possible and is simulated in successive time series dam operation of the three methods used in this study thus, simulation model is proper to estimate the water supply capacity of agricultural small scale reservoir. And it is judged that the heightening of efficiency of water resources utilization according to the development of downstream area of dam may be possible using the upward readjusted water supply amount of 55.18×10^6ton at 95% and 90% supply reliability respectively which are above the planning water supply amount of 50.0×10^6ton when the simulation method is introduced as the standard.