• Korean Journal of Remote Sensing
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• v.34 no.5
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• pp.787-799
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• 2018

Accurate and effective mapping is critical step to monitor the spatial distribution and change of flood inundated area in large scale flood event. In this study, we try to suggest methods to use low spatial resolution satellite optical imagery for flood mapping, which has high temporal resolution to cover wide geographical area several times per a day. We selected the Sebou watershed flood in Morocco that was occurred in early 2010, in which several hundred $km^2$ area of the Gharb lowland plain was inundated. MODIS daily surface reflectance product was used to detect the flooded area. The study area showed several distinct spectral patterns within the flooded area, which included pure turbid water and turbid water with vegetation. The flooded area was extracted by thresholding on selected band reflectance and water-related spectral indices. Accuracy of these flooding detection methods were assessed by the reference map obtained from Landsat-5 TM image and qualitative interpretation of the flood map derived. Over 90% of accuracies were obtained for three methods except for the NDWI threshold. Two spectral bands of SWIR and red were essential to detect the flooded area and the simple thresholding on these bands was effective to detect the flooded area. NIR band did not play important role to detect the flooded area while it was useful to separate the water-vegetation mixed flooded classes from the purely water surface.

• Journal of the Korean GEO-environmental Society
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• v.16 no.1
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• pp.29-36
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• 2015

Current domestic research is to demonstrate the effectiveness and efficiencies of flood prevention measures through one-dimensional numerical analysis and this study's object is to help water managers to make the efficient decisions by applying the two-dimensional urban run off model XP-SWMM model in the flooded area and comparing with the flood prevention measures. Statistics were analyzed, based on the data collected from Cheongju Weather Service from 1967 to 2011 for 45 years. 50 years Flood frequency simulations of water flow capacity analysis of the target area for flooded areas $539,548m^2$, inundation depth 1.0 m, was analyzed by inundation time of 48 minutes. When comparing with the constructions of bypass road and underground storage facilities to increase the water flow capacity of A1 small drainage areas as flood protection, if you install a batching target underground detention basin with a capacity of $13,500m^3$, it is expected that the flood by rainfall with frequency of 50 years will be resolved completely. In preparation for extreme weather in the future flood mitigation measures, underground storage tank installation is considered a better efficient way.

• Journal of Korea Water Resources Association
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• v.48 no.6
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• pp.511-522
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• 2015

This study assessed the impact of uncertainties in flood data on the results of flood frequency analysis for Han river basin. To meet this aim, this study quantified assessment focused on the index flood and quantile by regional flood frequency analysis using the flood data from 17 water level gauges in Han river basin. We analysed the results categorized by three cases according to the characteristics of the measured data. Firstly, we analyzed the regional flood frequency for the water level gauge in the Pyungchang river basin to investigate the impact of water level data. The results has the error of 0.240 with respect to the mean flood. Secondly, we examined the impact of uncertainty in measurement data generated by the application of rating on the results of regional flood frequency analysis. We have compared the results by applying the rating estimated for each year to the one by the recently estimated rating. The results showed that the mean error has 0.246 in terms of the mean flood. Finally, we have inferred the regional flood frequency analysis results with the regulated flow in the downstream area of dams. The regulated specific discharge in the downstream area of dams controlled by dam operation showed a large difference to the estimated specific discharge in the downstream area of dams by extension of the natural specific discharge in the upstream area using the regionalization method.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2002.10a
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• pp.305-308
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• 2002

This study is that analyzes the flood damages caused by rainfall during typhoon and how inundated area should be affected. Using HEC-HMS for analyzing rainfall-runoff and GIS (Geography Information System) for analyzing inundated area and volume. Each model was applied to Seopyung area for runoff effect analysis. As the result, Damaged area was magnified gradually according to the increase of rainfall and GIS was good for calculating the exact flood damage area at varied time.

• Journal of Korea Water Resources Association
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• v.51 no.6
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• pp.481-490
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• 2018

Recently, the spatiotemporal patterns of flood disasters have become more complex and unpredictable due to climate change. Flood hazard map including information on flood risk level has been widely used as an unstructured measure against flooding damages. In order to product a high-precision flood hazard map by combination of hydrologic and hydraulic modeling, huge digital information such as topography, geology, climate, landuse and various database related to social economic are required. However, in some areas, especially in developing countries, flood hazard mapping is difficult or impossible and its accuracy is insufficient because such data is lacking or inaccessible. Therefore, this study suggests a method to delineate large scale flood-prone area based on topographic factors produced by linear binary classifier and ROC (Receiver Operation Characteristics) using globally-available geographic data such as ASTER or SRTM. We applied the proposed methodology to five different countries: North Korea Bangladesh, Indonesia, Thailand and Myanmar. The results show that model performances on flood area detection ranges from 38% (Bangladesh) to 78% (Thailand). The flood-prone area detection based on the topographical factors has a great advantage in order to easily distinguish the large-scale inundation-potent area using only digital elevation model (DEM) for ungauged watersheds.

• Korean Journal of Remote Sensing
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• v.21 no.4
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• pp.317-327
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• 2005

The flood is the most general and frequently occurs among natural disasters. Generally flood by the rainfall which extends superexcellently for the occurrence but flash flood from severe rain storm gets up an absurd drowsiness at grade hour. This paper aims to 1 hour real-time flash flood and predict possibility at the area where is the possible flood will occur from the rainfall hour mountain after acquiring data in GIS(Geographic Information System) base by GcIUH(Geomorphoclimatic Instantaneous Unit Hydrograph). The flash flood occurrence is set up at 0.5m, 0.7m and 1.0m in standard depth. And this study suggests standard flood alarm which designed by probable flood according to duration time. The research result shows real-time flash flood evaluation has the suitable standard in the basin when comparing with the existing official warning announcement system considering topographical information.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.1B
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• pp.61-70
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• 2010

This research presents a methodology to define and apply appropriate index that can measure the risk of regional flood damage. Pressure-State-Response structure has been used to develop the Flood Risk Index(FRI), which allows for a comparative analysis of flood risk assessment between different sub-basins. FRI is a rational assessment method available to improve disaster preparedness and the prevention of losses. The pressure and state index for flood at 117 sub-basins from the year 1980s until the t 10s showed proportional relations, but state index did not decrease even though response index increased. This shows that pressures for flood damage relatively exceed countermeasure for flood. Thus this means we need to strengthen design criteria for flood countermeasure in the future. The FRI is gradually going down in consequence of continuous flood control projects. Flood risk of Han River and Nakdong River area is relatively lower than that of Geum, Seumjin, and Youngsan River area.

• Journal of the Society of Disaster Information
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• v.11 no.1
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• pp.55-62
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• 2015

This study suggested Nationwide Inundation Analysis method for Storm and Flood Damage Insurance Rate. Suggested modified Level-Pool method considers Zoning of urban plan to reflect real inundated area and limit inundation-boundary. Inundated area, as results of modified Level-Pool method, compared with inundation risk area on "storm and flood damage mitigation total plan". Simulated inundated area by modified Level-Pool method was more matched than results of traditional method. Therefore, modified Level-Pool method could be useful to analyze nationwide inundated area.

• Journal of the Korean Association of Geographic Information Studies
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• v.10 no.3
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• pp.1-12
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• 2007

This study was conducted in order to analyze a flooded area by the overflow of a stream using hydrological and hydraulic models and to estimate the utility of the SAR satellite image by comparing a protected lowland inundation area with a past inundation area map. The research area selected for this study is Sapkyocheon, which was flooded in August 1999. The flood stage was analyzed to select an inundation area by applying flood events in August 1999. By importing analyzed flood stage data into TIN data of WMS, the inundation area of a protected lowland was selected and then compared with an flood hazard map of WAMIS. An inundation area is selected by the SAR satellite image in comparing the image of August 4, 1999 (inundation time) with the image of September 8, 2002 (after inundation). The method of selecting an inundation area with the hydraulic model of HEC-RAS can be used to select an inundation area of external overflow, but it has the limit of selecting an inundation area concerning the internal drainage. The method of using the SAR satellite image can complement the limit of an inundation area of an internal drainage but accuracy of inundation area depends on using SAR satellite image acquired at time of maximum depth.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.241-241
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• 2015

In this study, the simulations and analyses of flood flow due to a river inundation in a coastal urban area are carried out using a two-dimensional finite volume method with well-balanced HLLC scheme. The target area is a coastal urban area around Gohyun river which is located at Geoje city in Kyungnam province in Korea and was extremely damaged due to the heavy rainfall during the period of the typhoon "Maemi" in September 2003. For the purpose of the verification of the numerical model applied in this study, the simulated results are compared and analyzed with the inundation traces. Moreover, the flood flow in a urban area is simulated and analyzed based on the scenarios of inflow to the river with the increase and decrease of the intensity of the heavy rainfall.