• Journal of the Korean Society of Hazard Mitigation
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• v.6 no.4 s.23
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• pp.37-47
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• 2006

Urban development results in increased runoff volume and flowrates and shortening in time of concentration, which may cause frequent flooding downstream. Flow retardation structures to limit adverse downstream effects of urban storm runoff are used. There are various types of flow retardation measures include detention basins, retention basins, and infiltration basins. In basic planning phase, a number of planning models of detention ponds which decide storage volume by putting main variables were used to design detention ponds. The characteristics of hydrological parameters $\alpha,\;\gamma$ which are used in planning models of detention pond were analyzed. In this study, detention ponds data of Disaster Impact Assessment report at 22 sites were analyzed in order to investigate correlation between characteristic of urban drainage basin parameter and characteristics of detention pond parameter due to urbanization effects. The results showed that storage volume was influenced by peak discharge ratio $\alpha$ more than runoff coefficient ratio $\beta$ and peak discharge ratio $\alpha$ was influenced by runoff coefficient ratio $\beta$ less than regional parameter n. Storage ratio was mainly influenced by duration of design rainfall in the case of trapezoidal inflow hydrograph such as Donahue et al. method.

• Journal of Korea Water Resources Association
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• v.45 no.12
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• pp.1213-1226
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• 2012

Evolutionary algorithms, which are frequently used in an automatic calibration of watershed runoff simulation models, are unconstrained optimization algorithms. An additional method is required to impose constraints on those algorithms. The purpose of the study is to modify the SCE-UA (shuffled complex evolution-University of Arizona) to impose constraints by a penalty function and to improve performance of the automatic calibration module of the SWMM (storm water management model) linked with the SCE-UA. As indicators related to peak flow are important in watershed runoff event simulation, error of peak flow and error of peak flow occurrence time are selected to set up constraints. The automatic calibration module including the constraints was applied to the Milyang Dam Basin and the Guro 1 Pumping Station Basin. The automatic calibration results were compared with the results calibrated by an automatic calibration without the constraints. Error of peak flow and error of peak flow occurrence time were greatly improved and the original objective function value is not highly violated in the automatic calibration including the constraints. The automatic calibration model with constraints was also verified, and the results was excellent. In conclusion, the performance of the automatic calibration module for watershed runoff event simulation was improved by application of the penalty function to impose constraints.

• Journal of Korea Water Resources Association
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• v.50 no.3
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• pp.169-179
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• 2017

Recently, due to global warming and climate change in Korea, local heavy storm occurs frequently. In this study, the risky areas for flooding in urban areas are analyzed for flood inundation based on two-dimensional urban flood runoff model (XP-SWMM) focusing on coastal high flood-risk urban areas. In addition, the MCDM (Multi-Criteria Decision Making) technique is utilized in order to establish the flood defense structural measures. The alternative flood reduction method are compared and the optimum flood defense measures are selected. A simulation model was used with three structural flood prevention measures (drainage pipe construction, water detention, flood pumping station). In order to decrease the flooding area, flood assessment criteria are suggested (flooded area, maximum inundation depth, damaged residential area, construction cost). Priorities of alternatives are determined by using compromise programming. As a result, the optimal flood defence alternative suggested for Janghang Zone 1 is flood pumping station and for Janghang Zone 2, 3 are drainage pipe construction.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.6
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• pp.113-120
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• 2008

This study analyzed the spatial correlograms of minutely rainfall data with respect to various accumulation times. A bivariate mixed lognormal distribution was applied for rainfall modelling. A total of 26 minutely rainfall data sets from rain gauge stations in the central part of Korean peninsula were analyzed, also repeated for several storm types like Jang-Ma, typhoon and convective storms for their comparison. The accumulation times 1, 2, 3, 5, 10, 30 and 60 minutes were considered in this study. As results, it was found that the minutely rainfall data available was not good enough for estimating minutely rainfall intensity at ungaged locations. It seems more practical to use the hourly rainfall data with much higher rain gauge density, if proper methods for interpolation and data dis-aggregation are provided.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.6
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• pp.93-100
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• 2008

Dense of population construction and high density of skyscraper, and geological characteristics caused natural disasters(e.g. typhoon, tsunami, flood, storm, earthquake, etc.) and manmade disasters(e.g. fire, collapse, explosion, traffic accident, etc.). the extent and scale of the disaster are getting larger. To cope with such problems, Busan City has established the basic plan to secure the life and property of the citizens through model strategy and design of Ubiquitous-Safety Busan. This study quantitatively analyzed the ripple effect on local economy through the fulfillment of Ubiquitous-Safety. The production inducing effect of 250 billion won directly and indirectly can be estimated due to the realization of Ubiquitous-Safety. The value added effect of 115 billion won can be estimated. the employment effect of 5,580 persons can be generated with income effect of 51 billion won.

• Journal of The Korean Society of Agricultural Engineers
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• v.59 no.2
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• pp.81-90
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• 2017

Recent floodplain data are important for river master plan, storm and flood damage reduction comprehensive plan and pre-disaster impact assessment. Hazard map, base of floodplain data, is being emphasized as important method of non-structural flood prevention and consist of inundation trace map, inundation expected map and hazard information map. Inundation trace map describes distribution of area that damaged from typhoons, heavy rain and tsunamis and includes identified flood level, flood depth and flood time from flooding area. However due to lack of these data by local government, which are foundational and supposed to be well prepared nationwide, having hard time for making inundation trace map or hazard information map. To overcome this problem, time consumption and budget reduction is required through various research. From this study, DEM (Digital Elevation Model) from image material from UAVS (Unmanned Aerial Vehicle System) and numeric geographic map from National Geographic Information Institute are used for calculating flooding damaged area and compared with inundation trace map. As results, inundation trace map DEM based on image material from UAVS had better accuracy than that used DEM based on numeric geographic map. And making hazard map could be easier and more accurate by utilizing image material from UAVS than before.

• Journal of Wetlands Research
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• v.18 no.1
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• pp.84-93
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• 2016

As a transition region between ocean and land, coastal wetlands are significant ecosystems that maintain water quality, provide natural habitat for a variety of species, and slow down erosion. The energy of coastal waves and storm surges are reduced by vegetation cover, which also helps to maintain wetlands through increased sediment deposition. Wave attenuation by vegetation is a highly dynamic process and its quantification is important for understanding shore protection and modeling coastal hydrodynamics. In this study, laboratory experiments were used to quantify wave attenuation as a function of vegetation type as well as wave conditions. Wave attenuation characteristics were investigated under regular waves for rigid model vegetation. Laboratory hydraulic test and numerical analysis were conducted to investigate regular wave attenuation through emergent vegetation with wave steepness ak and relative water depth kh. The normalized wave attenuation was analyzed to the decay equation of Dalrymple et al.(1984) to determine the vegetation transmission coefficients, damping factor and drag coefficients. It was found that drag coefficient was better correlated to Keulegan-Carpenter number than Reynolds number and that the damping increased as wave steepness increased.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.1032-1035
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• 2008

제주도 연악해역의 해일재해의 현황을 파악하기 위하여 제주도 연안해역의 폭풍해일과 기상조에 등에 의한 해일발생 및 피해의 자료를 분석 검토하고 제주도 연안해일의 위험도를 분석하기 위하여 제주도 연안해역을 대상으로 과거 태풍 중 각종 기록경신과 많은 피해규모를 준 태풍들을 대상으로 바람장 및 해일고를 분석 검토하여 태풍의 진로에 따른 해수면 상승을 산정하기위해 폭풍해일 수치모형(POM) 실험을 실시하여 폭풍해일고를 산정하였다. 제주항과 서귀포항 주변해역의 폭풍해일고를 산출하기 위해 16년간($1987{\sim}2003$)까지의 우리나라에 영향을 미친 태풍 중 8개를 선정(Maemi, Rusa, Prapiroon, Olga, Yanni, Janis, Gladys, Thelma)하여 폭풍해일고를 산출하였다. 수치모의 한 결과를 보면, 제주와 서귀포 연안해역에서 발생한 8개의 태풍에 대한 폭풍해일고의 발생시각은 대체적으로 관측된 해일고의 발생시각 보다 약간 늦게 해일이 발생하였지만 전체적인 해일의 시간변화나 크기는 비교적 잘 재현된 것으로 나타났다. 제주항 연안해역의 서귀포항 연안해역보다 높은 해일고를 보였으며, 해일고는 제주항, 서귀포항 모두 1m를 넘지 않았다. 제주항이 서귀포항에 비해 약간 높게 나온 이유는 태풍의 위치, 지형 및 수심, 태풍이 통과할 당시의 조석상황 등의 차이인 것으로 사료된다. 또한, 제주항과 서귀포항 연안해역이 폭풍해일고가 서해안이나 남해안에 비해 작게 나타났는데, 이는 제주도 해안선이 비교적 평탄하고 평행하게 이루어 졌으며 남해안에 비해 수심이 깊고 만의 형태나 V자형 및 긴내만이 발달한 지형이 없기 때문인 것으로 사료된다. 보다 정밀한 예측을 위해서는 정밀한 수심자료 및 격자를 이용한 계산의 결과가 필요하며, 연안개발로 인한 지형과 수심변화에 따른 지속적인 수치해도 DB구축이 요구된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.54-54
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• 2011

홍수로 인한 인적 물적 피해는 국가 및 지방자치단체의 치수방재노력에도 불구하고 매년 끊이지 않고 발생하고 있다. 다행히 인명피해의 경우 1970, 80년대 연간 300명 규모에서 2000년대에는 150명 가량으로 줄고 있으나, 재산상의 피해는 매년 증가하고 있는 실정이다. 또한 과거 자연재난에 의한 홍수피해에 기후변화라는 외부요인이 추가적으로 발생하고 있는 실정이며, 국가 경제 발전 및 노령화 사회로 인한 홍수취약인구 증가로 좀 더 적극적인 방재대책이 필요할 것으로 판단된다. 이러한 방재대책 등의 국가정책 수립을 위해서는 장래의 홍수피해 예측이 무엇보다 필요하게 되는데, 현재까지는 홍수피해의 빈도분석 등을 통해 이러한 예측이 이루어지고 있다. 그러나 기후변화라는 외생변수는 과거 자료의 확률적 특성을 마비시켜 이러한 방법론들은 효용성을 잃게될 것으로 전망된다. 홍수피해액을 산정하는 방법은 일반적으로 2005년 이후 하천설계기준에서 채택하고 있는 다차원법을 많이 사용하고 있는데, 이 방법은 침수구역의 물리적 피해를 고려할 수 있어 비교적 정확한 홍수피해액을 산정할 수 있는 것으로 알려져 왔다. 그러나 이 방법을 적용하기 위해서는 정확한 침수심 산정이 무엇보다 필요하게 되는데, 이를 위해서는 지리정보체계(GIS)와 수리모형의 연계가 필수적이다. 따라서 이 방법은 주로 중소유역단위의 취수사업에 적용되어 왔다. 그러나 정책결정에 필요한 대규모유역 또는 지자체단위의 피해비용 산정에의 적용은 한계를 갖게 된다. 따라서 본 연구에서는 향후 기후변화 시나리오에 적용이 가능하도록 과거 홍수피해자료와 호우사상의 강우특성을 중심으로 양자간의 히스토그램 분석을 실시하였다. 또한 실제 홍수피해 조사자료는 대부분 지방자치단체별로 조사가 되고 있는 실정이므로 본 연구에서도 행정구역별로 분석을 수행하였다. 분석 결과 지자체별 전체 피해액은 발생횟수가 높은 중규모 호우사상으로 인한 비중이 가장 높게 나타나고 있으며, 국가에서 집중해야할 치수대책 수립 대상 규모도 이를 중점적으로 고려하여야 할 것으로 판단된다.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.24 no.4
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• pp.235-246
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• 2012

Typhoon induced surge simulations are done to make an establishment of coastal disaster prevention plan. To apply efficient run-up and overtopping on vertical harbor docks, in which prevailing wet-dry scheme cannot be satisfied due to infinite steepness, an imaginary internal barrier concept introduced and analyzed. Before real application on the Mokpo harbor area, feasibility tests are done on an idealized simple geometry and as a result it is found that the moderate width of the barrier might be 1 m. The threshold value of the minimum wet depth $H_{min}$ for land area, which behaves sensitive role in inundation area and depth, depends on grid size. However it is revealed that 0.01 m is adequate value in this fine finite element with 10 m spacing. A hypothetical typhoon of 100 years return period in central pressure and maximum velocity is generated based on historical tracks. Simulation of possible inundation on Mokpo area is performed with asymmetrical vortex of hypothetical typhoon and wave coupling. Model results show general agreement in pattern compared to other's prediction, however possibility of inundation enlargement is expected in harbor area.