• Proceedings of the KSRS Conference
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• v.1
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• pp.426-429
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• 2006

Flood caused by Typhoon and severe rain during summer is the most destructive natural disasters in Korea. Almost every year flood has resulted in a big lost of national infrastructure and loss of civilian lives. It usually takes time and great efforts to estimate the flood-related damages. Government also has pursued proper standard and tool for using state-of-art technologies. High resolution satellite imagery is one of the most promising sources of ground truth information since it provides detailed and current ground information such as building, road, and bare ground. Once high resolution imagery is utilized, it can greatly reduce the amount of field work and cost for flood related damage assessment. The classification of high resolution image is pre-required step to be utilized for the damage assessment. The classified image combined with additional data such as DEM and DSM can help to estimate the flooded areas per each classified land use. This paper applied object-oriented classification scheme to interpret an image not based in a single pixel but in meaningful image objects and their mutual relations. When comparing it with other classification algorithms, object-oriented classification was very effective and accurate. In this paper, IKONOS image is used, but similar level of high resolution Korean KOMPSAT series can be investigated once they are available.

• Journal of Korea Water Resources Association
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• v.41 no.10
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• pp.1009-1021
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• 2008

In this study, 4 indices of hydraulic & hydrological, geomorphological, eco & environmental, social effect and 38 items are selected to calculate impact range of downstream of dam. The Analytic Hierarchy Process(AHP) was applied to determine the priority of impact range calculation indices and items. As results of indices valuation, hydraulic & hydrological effect is the first priority, the second is eco & environmental, next are geomorphological and social effect. As results of items valuation, the design flood of dam is the first priority, the second is the natural flood & design flood of channel, next are the design flood rate of channel, drainage area and back water level caused by downstream of dam. In the case of Daechung dam, impact ranges were estimated 47.21 km in terms of the design flood of dam, 45.71 km of the design flood rate of channel, 13.94 km of the drainage area.

• Journal of Wetlands Research
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• v.20 no.4
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• pp.446-457
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• 2018

Forecasting of flood wave travel time is very important in terms of river management and operation. Recently, the hydrological environment of has changed due to the construction of multi-function weir in the river. It is necessary to analyze flood wave travel time, including hydraulic structures in the channel. The flood wave travel time according to the discharge and downstream water level operating conditions was analyzed using HEC-RASver5.0.3 which is capable a two-dimentional analysis. This study showed nonlinear characteristics of flood wave travel times due to increase of discharge and operating conditions. The results of this study will be helpful for the operation of multi-function weir as well as the river operation.

• Journal of The Korean Society of Agricultural Engineers
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• v.48 no.5
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• pp.17-27
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• 2006

The objective of this study is to induce the design floods by the methodology of L-moment including test of homogeneity, independence and outlier of the data of annual maximum flood flows for 12 water level gaging stations of South Korea. To select appropriate distribution of the data for annual maximum flood flows, the distributions of Wakeby and Kappa are applied and the appropriateness is judged by Kolmogorov-smirnov (K-S) test. The parameters of selected Wakeby and Kappa distributions are calculated by the method of L-moment and the design floods are induced. Through the comparative analysis using the relative root mean square errors (RRMSE) and relative absolute errors (RAE) of design floods, the result shows that the design floods by Wakeby distribution are closer to the observed data than those obtained by the Kappa distribution.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.218-218
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• 2015

Urbanization and waterworks construction in natural watershed have been causing higher flood risks in lowland areas. Detention basins have become one of the most efficient fundamental instruments for storm water and environmental management at watershed scale. Nowadays, there are many studies coupled numerical methods of flood routing with optimization algorithms to investigate factors that impact on the efficiency of detention basins in flood reduction in a watershed, such as detention basin location, size, and cost and watershed characteristics. Although these couplings have been become more widespread but cumbersome computation and hydraulic data requirement still are their limitations. To tackle the procedure efforts due to numerical integration and data collection, simple approach is proposed to primarily estimate effects of detention basins. The approach basis is the linear system theory applied to the solution of hydrologic flood routing. The paper introduces an analytical method for estimating detention effects deriving by recent studies and innovatively analyses this equation on fractal perspective. Then, an optimization technique is performed by applying harmony search algorithms (HSA) to optimize efficiency of detention basins at watershed scale. The location and size of upstream detention basin are simultaneously obtained. Finally, the proposed methodology, practically applied for a real watershed in Kan river, Iran.

• Current Research on Agriculture and Life Sciences
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• v.2
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• pp.77-90
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• 1984

Results investigated backwater phenomena at Geumho river basin to get a basic data for Daegu basin area development plan are as the follows. 1. It is a A=0.35 L 1.848 (r = 0.97), the relationship between basin area and river length at Geumho river. 2. Dividing the rainfall of Geumho river basin as two parts, a first half rainfall and a second half rainfall, the amount of a first half rainfall appeared 57.5% comparison with total rainfall. 3. The maximum flood discharge appeared 12 hrs. continuous rainfall rather than 24 hrs. continuous rainfall. 4. Results investigated backwater phenomena from Geumho II bridge to chungchun appeared the rising water level of 69 cm, 55 cm, 44 cm, at section III in the starting point water level of 1.8 m, 2.4 m, 4.0 m respectively. 5. Results investigated backwater phenomena by the flood water level appeared a similar form. There was a average rising water level of 30 cm at section III. At the results of this computation, it was confirmed that section III was affected the highest backwater phenomena among the observed river reaches in Geumho river. In addition, this paper should be given a assistance to decide a economic and safe section in construction of bank of river and estuary barrage.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2002.10a
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• pp.105-108
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• 2002

In this study, flood influence analysis in the downstream of Sung-Ju dam was simulated using HEC-RAS model. Input data for the simulation was which measured water level, water velocity, stream section etc. HEC-RAS model could be applied to steady flow or gradually varied flow in natural or artificial stream. HEC-RAS model which can simulate real-time changing water level and compute water surface curve was supplied to show the standard influent amount of Sung-Ju dam. Through this study the submerged damage of Sung-Ju dam's downstream would be minimized.

• Magazine of the Korean Society of Agricultural Engineers
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• v.37 no.E
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• pp.55-62
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• 1995

The topographic influences for the hydraulic characteristics in the estuary were studied by the hydraulic model test. The upstream boundary is set up at the Kumkang estuary dike and the downstream boundary at the Kunsan outer port. The geometrical model scales in horizontal and vertical are 1/300 and 1/100 respectively so that the distorted ratio is 3. If there is no or little river flow through the gate, the highest water levels are varied with $\pm$ 5cm compared with those before the project. If there is a flood flow through the gate, the highest water levels in front of the estuary dike are reduced 5~2Ocm depending on the frequency of flood compared with those before the project. This means that there is no important risk of excessive water level rise after the dredging.

• Magazine of the Korean Society of Agricultural Engineers
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• v.36 no.3
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• pp.60-66
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• 1994

This paper is to validate the proposed models for the real-time forecasting for the Keum river estuary dam such as tidal-level forecasting model, one-dimensional unsteady flood routing model, and Kalman filter models. The tidal-level forecasting model was based on semi-range and phase lag of four tidal constituents. The dynamic wave routing model was based on an implicit finite difference solution of the complete one-dimensional St. Venant equations of unsteady flow. The Kalman filter model was composed of a processing equation and adaptive filtering algorithm. The processng equations are second ordpr autoregressive model and autoregressive moving average model. Simulated results of the models were compared with field data and were reviewed.

• Journal of Korea Water Resources Association
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• v.48 no.12
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• pp.1065-1075
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• 2015

In the estuary where the structure such as river-mouth weir has been installed, the flow is developed very complicatedly due to river water from upstream, tide of the sea and floodgate operation. Especially, if basin outlets more than one exists in one estuary, the boundary conditions will be significantly more complex form. Saemangeum(SMG) project area in Korea is the most typical example. There are Mankyung river and Dongjin river in upstream. The water of them inflows into SMG project area. In the downstream, river flow was drained from inland to sea over the SMG sea dike through the sluice. The connecting channel was located between Mankyung and Dongjin basins. It functions not only as transportation by ship in ordinary period but also as flood sharing by sending flood flow to each other in flood period. Therefore, in order to secure the safety against flood, it is very important to understand the flood sharing capacity for connecting channel. In this study, the flood control effect was analyzed using numerical simulation. Delft3D was used to numerical simulation and simulated period was set up with neap tide, in which the maximum flood stage occurred due to poor drainage. Actually, three connecting channels were designed in land use plan of the SMG Master Plan, but they were simplified to a single channel for conciseness of analysis in this study. According to the results of numerical analysis, the water level difference between two basins was increased and the maximum flood stage at dike sluice was also upraised depending on decrease of conveyance. And the velocity induced by same water level difference was decreased when the conveyance became smaller. In certain conveyance above, there was almost no flood control effect. Therefore, if the results of this study are considered for design of connecting channel, it will be expected to draw the optimal conveyance for minimizing dredging construction cost while maximizing the flood control effect.