Boosik Kang

Dankook University · Department of Civil and Environmental Engineering

Because of multifunctional weirs installed as part of large river regulation works in Korea, water quality problems have arisen from environmental changes in tandem with decreased flow rates. However, there has been limited research into the green algae removal effect, water quality improvement in congested waters, dam and weir operations, and cons...

Low-flow quantiles at ungauged locations are generally estimated based on hydrological methods, such as the drainage area ratio and frequency analysis methods. In practice, the drainage area ratio approach is a popular but simple linear model. When hydrologically nonlinear characteristics govern the runoff process, the linear approach leads to sign...

Because urban flooding occurs frequently, it is important to calculate the areal extent of flooding based on flood volumes and water levels, and thus, the extent of expected damage can be effectively estimated. In this study, urban inundation from heavy rainfall and the contribution of topographic scales to urban river drainage basins in Seoul, Kor...

In the design flood estimation procedure, the areal reduction factor (ARF) is used to convert ground-level point rainfall records into areal design rainfall for a reference area. Practically, the ARF is estimated through the fixed-area (ARF fa) scheme but has limitations as a statistical approach based on sparse ground-observation density. The ARF...

Recently, South Korea has been increasingly experiencing large changes in precipitation patterns, in particular, a storm may transition from a mild to a torrential rainfall within a few hours, which may ignite extreme urban flood inundation. This urban flood inundation is increased mainly by changing landcover, which is characterized by an increase...

Changes in rainfall patterns due to climate change will change the hydrological elements in the stream and the riverbed changes that will occur consequently. In addition, dredging and multi-functional Weir installation was finished along the Nakdong River, South Korea in 2012 as a part of the Four Major River Restoration Project. Due to the project...

A new methods were presented to estimate streamflow with the aid of low-cost optical, infrared, and microwave imagery in a controlled experimental hydraulic channel. The River Experiment Center in Andong, Korea was used as a test site for calibration and validation. The suggested methodologies uses the remotely sensed channel width and the derived...

For the last several decades, great efforts have been put into converting point precipitation into mean areal precipitation in the design of hydraulic and hydrologic infrastructures. The ratio between point and areal precipitation, called the Areal Reduction Factor (ARF), has been identified to vary significantly depending on a variety of factors,...

The nationwide mid-sized basin unit technical small hydropower potential is estimated using the gridded flow accumulative model using the digital elevation model has 30 m resolution and the areal rainfall in the basins. The rainfall data was reconstructed to the same resolution of the digital elevation model using 10 years averaged rainfall data of...

The precipitation of General Circulation Model (GCM) output for Han River Basin, Korea was downscaled into a regional watershed using the Artificial Neural Network (ANN) model with multiple statistical processors of Nonstationary Quantile Mapping (NSQM) and a Stochastic Typhoon Model (STM). The stochastically generated typhoon rainfall was synthesi...

Previously, understanding of the fluvial process from the ecological, morphological, and hydrodynamic perspectives has largely relied on the limited scale of in-situ field observation or the sparse spatial and temporal scale of satellite-based remote sensing. However, with the recent advent of unmanned aerial vehicles (UAVs) and concurrent advances...

A hydro-environmental model chain in the Doam dam basin, Korea, was developed for an impact assessment under the IPCC’s A1B scenario. The feasible downscaling scheme composed of an Artificial Neural Network and Nonstationary Quantile Mapping was applied to the GCM (Global Climate Model) output. The impacts under climate and land use change scenario...

The effective rainfall is calculated considering the soil moisture. It utilizes observed data directly in order to incorporate the soil moisture into the rainfall-runoff model, or it calculates indirectly within the model. The rainfall-runoff model, IHACRES, used in this study computes the catchment wetness index (CWI) first varying with temperatur...

For reliable prediction of sediment yield in a watershed, fine-scale projections for hydro-climate components were first obtained using the statistical bias correction and downscaling scheme based on the combination of an Artificial Neural Network (ANN), Nonstationary Quantile Mapping (NSQM) and Stochastic Typhoon Synthesis (STS) sub-modules. Succe...

The evapotranspiration is an important component of the hydrologic water balance estimation. However, regardless of point or basin-wide estimation the acquisition of reliable data for evapotranspiration is very limited. In this study, the complementary relationship between actual (ETa) and potential (ETp) evapotranspiration with moisture availabili...

An analysis of the riverbed variations according to the river flow characteristics after the installation of dams for irrigation for the Four-River Project is a critical issue to the management of rivers. In addition, rainfall pattern variations result in frequent record-breaking heavy rains, which in turn changes the hydraulic environment of river...

Frequently torrential rain is occurred by climate change and urbanization. Urban is formed with road, residential and underground area. Without detailed topographic flooded analysis consideration can take a result which are wrong flooded depth and flooded area. Especially, flood analysis error of population and assets in dense downtown is causing a...

The methodology of synthetic unit hydrograph using geomorphic characteristics was suggested. Six geomorphic components over 19 watersheds were used to estimate synthetic unit hydrograph and the test watersheds were classified into two groups on the basis of the area of 200km^2. The regression formulas between standardized geomorphic characteristics...

Population and development are concentrated by urbanization. Consequently, the usage of underground area and the riverside area have been increased. By increasing impermeable layer, the urban basin drainage is depending on level of sewer. Flood damage is occurred by shortage of sewer capacity and poor interior drainage at river stage. Many of resea...

In ecohydrologic projection, the evapotranspiration is the key component in hydrologic water balance cycle. The complementary relationship was established based on the physics of energy and mass transfer at land surface—atmosphere interface and defines the large-scale interaction between actual (ETa) and potential (ETp) evapotranspiration with resp...

Flow input from the basin will not remain the same as before due to climate changes. Since the predictions on river discharge due to climate change is given by scenarios, various discharge scenarios were prepared in this study. For a long term and reach prediction, semi-two dimensional sediment transport model, GSTARS, was used. The flood water sur...

The inflow estimation at large multipurpose dam reservoir is carried out by considering the water balance among the discharge, the storage change during unit time interval obtained from the observed water level near dam structure and area-volume curve. This method can be ideal for level pool reservoir but include potential errors when the inflow is...

Prediction of hydrological water balances in dam reservoir water storage on long-term continuous rainfall–runoff estimation is highly important for accurate operational decision making related to sustainable water management planning, flood control and supply planning, etc. The physically based engineering model has been used conventionally, but re...

As the most important source for the climate change assessment in the future, IPCC fifth Assessment Report provides a various models for RCP scenario. However, there are too much data and large uncertainty to select a suitable model for the current climatic environment in Korea. Therefore, BMA(Bayesian Model Averaging) method, one of Multi-Model En...

Until recently, hydrological impacts and prediction caused by climate change have been popular issues. However, a basin-scale hydro-environmental study has begun to attract attention recently due to the difficulties in watershed model calibration and uncertainty propagation in the data relaying procedure from the GCM (General Circulation Model) pro...

The climate change impacts on drought in the Korean peninsula were projected using Global Climate Model (GCM) output reconstructed regionally by an artificial neural network (ANN) model. The reconstructed model outputs were subsequently used as an input to project drought severity evaluated by Standard Precipitation Index (SPI). The original GCM ou...

Recently, the increased high-risk weather events have caused more frequent threats of natural disasters, e.g. inundations, floods, land slides and infrastructure damages. In addition even equivalent strength of severe weather events could result in varied physical damages and associated economic losses. In this study, the natural disaster Hazard In...

As meteorology is the driving force for lake thermodynamics and mixing processes, the effects of climate change on the physical limnology and associated ecosystem are emerging issues. The potential impacts of climate change on the physical features of a reservoir include the heat budget and thermodynamic balance across the air-water interface, form...

In this paper, we examined the peak flow distribution on a realization of networks obtained with stochastic network models. Three network models including the uniform model, the Scheidegger model, and the Gibbsian model were utilized to generate networks. The network efficiency in terms of drainage time is highest on the Scheidegger model, whereas...

This research was carried out for suggesting design criteria and procedure for maximizing flood control capacity by building flood control facilities like flood retention basin built in connection with existing facilities in order to cope with increased uncertainty due to factors such as urbanization and climate change. We suggested the procedure f...

This study have implemented finding the optimal water temperature parameter set for Hapcheon dam reservoir using CE-QUAL-W2 model. In particular the sensitivity analysis was carried out for four water temperature parameters of wind sheltering coefficient (WSC), radiation heat coefficient (BETA), light extinction coefficient (EXH2O), heat exchange c...

The goal of this study is to evaluate and rank the effectiveness of the Korean governments’ Four Major River Restoration Projects. A hydraulic simulation model and geographic information system tools are used to analyze the flood mitigation effects provided by these projects. In addition, the rankings of four major rivers are derived using two sens...

In Korea, the rainfall is concentrated in summer under the influence of monsoon climate. Thus, even a small climate change can be significant problems in water resources. As a result, a lot of attention has been focused on climate changes and a number of researches have been conducted in a manner commensurate with the attention to the climate chang...

The quantile mapping is utilized to reproduce reliable GCM(Global Climate Model) data by correct systematic biases included in the original data set. This scheme, in general, projects the Cumulative Distribution Function (CDF) of the underlying data set into the target CDF assuming that parameters of target distribution function is stationary. Ther...

In this research, the integrated modeling system by coupling of a watershed model, a reservoir model, and a river model has been constructed in Doam reservoir watershed. Because of domestic climate characteristics, it is inevitable to construct the dam for control of flood, water use, and power production due to the heavy rain in the summer. Especi...

Improved methodology of Synthetic Unit Hydrograph (SUH) utilized generally in hydrologic design work was suggested. In this study, regression analysis between peak hydrological data and geospatial data was applied to estimate specific peak flow and peak time for determining shape of SUH. Regression formulas for specific peak flow with respect to sh...

Recently, climate change causes climatic anomaly such as global warming, the typhoon and severe rain storm etc. and it brings damage frequently. Climate change and global warming are prevalent all over the world in this century and many researchers including hydrologists have studied on the climate change. In this study, Seonakdong river watershed...

This paper presents a prototype framework for sustainable flood management at the national level which features stakeholder participation, and is modified and applied to a case study. Through literature reviews and an interview survey of South Korea (the case study country), the causes of recent flood damage are found to be heavy rainfall due to cl...

We analysed daily precipitation data at the rain gauge stations in North Korea over a period of 25 years from 1983 to 2007, and in South Korea over a period of 35 years from 1973 and 2007. We found a striking trend of decreasing summer precipitation across North Korea. By contrast, in South Korea, the trend is opposite: there is a major increase in...

Climate change can impact hydrologic processes of a watershed system. The integrated modeling systems need to be built to predict and analyze the possible impacts of climate change on water environment for the optimal water resource operation and management. In this study, Namgang Dam watershed in the Nakdong River basin was selected as a study are...

Based on the statistical annual report, there are 17,649 reservoirs are operating for the purpose of agricultural water supply in Korea. 58 % of entire agricultural reservoirs had been constructed before 1948 which indicate the termination of required service life and rest of those reservoirs have also exposed to the dam break risk by extreme flood...

For the purpose of enhancing usability of NWP (Numerical Weather Prediction), the quantitative precipitation prediction scheme was suggested. In this research, precipitation by leading time was predicted using 3-hour rainfall accumulation by meso-scale numerical weather model and AWS (Automatic Weather Station), precipitation water and relative hum...

This paper reports results of a joint experimental and numerical investigation of the causes of near-transducer errors due to the combined effect of acoustic and ADCP-induced flow disturbance near the ADCP transducer. The laboratory study focused on an isolated ADCP (deployment without boat). Measurements of the flow disturbance produced by the ADC...

The methods of the rational formula and Kajiyama formula have been widely used for estimating the peak flood for design to all kind of hydraulic structure. However, there are many limitations and we have to apply these methods to ungauged basin. These methods require to calculate the Probable Maximum Precipitation (PMP) before determining the Proba...

Physically-based resampling scheme for roughness coefficient of surface runoff considering the spatial landuse distribution was suggested for the purpose of effective operational application of recent grid-based distributed rainfall runoff model. Generally grid scale(mother scale) of hydrologic modeling can be greater than the scale (child scale) o...

Recently, various new devices have been introduced, which are capable of quickly measuring river hydrodynamic and morphologic features in the very broad riverine area. These devices are changing paradigm of understanding river characteristics in terms of data-driven aspect rather than the conventional numerical modeling approaches based on the limi...

While the assessment of mean flow field is very important to characterize the hydrodynamic aspect of the flow regime in river, the conventional methodologies have required very time-consuming efforts and cost to obtain the mean flow field. The paper provides an efficient technique to quickly assess mean flow field by developing and applying spatial...

1] Analysis of Next Generation Weather Radar rainfall data indicates that for the central United States, rainfall exhibits a composite behavior with respect to its spatial and temporal scaling characteristics. Our data analysis shows that rainfall fluctuations at spatial scales smaller than a reference scale exhibit self‐similarity and that at scal...

The web-based assessment for flood forecasting system (WAFFS) was developed to evaluate the flood forecasting and warning system and to revise the existing management overview for flood forecasting system (MOFFS) Ver.3 suggested by the World Meteorological Organization (WMO) in early 1990s. The WAFFS is an evaluation system that represents the resu...

The mid-range streamflow forecast was performed using NWP(Numerical Weather Prediction) provided by KMA. The NWP consists of RDAPS for 48-hour forecast and GDAPS for 240-hour forecast. To enhance the accuracy of the NWP, QPM to downscale the original NWP and Quantile Mapping to adjust the systematic biases were applied to the original NWP output. T...

The objective of this study is to evaluate the future potential climate and vegetation canopy change impact on a dam watershed hydrology. A dam watershed, the part of Han-river basin which has the watershed outlet at Chungju dam was selected. The SWAT model was calibrated and verified using 9 year and another 7 year daily dam inflow data. The Nash-...

Regional hydrologic time series data sets including groundwater level, surface water level (river level), and precipitation are collected and analyzed for identifying climate change effects on hydrologic components. Most gauge stations are selected so as to have distance between stations to be less than 5 km to preserve the hydrologic similarity. A...

The aim of this study is to evaluate prediction accuracy and sensitivity of a distributed hydrologic model. Accurate predictions of runoff are needed where reservoir operations are used to control flooding and to manage water resources. The study area consists of watershed areas that are influent to reservoirs in the 967 km 2 Yongdam basin, and the...

According to recent frequent local flash flood due to climate change, the very short-term rainfall forecast using remotely sensed rainfall like radar is necessary to establish. This research is to evaluate the feasibility of GIS-based distributed model coupled with radar rainfall, which can express temporal and spatial distribution, for multipurpos...

A sensitivity analysis of the flood safety of Yongdam Dam using a regional climate change simulation is presented. Based on the output of the CCSM (Community Climate System Model) general circulation model, the SNURCM (Seoul National University Regional Climate Model) computes regional scale output with 60 km spatial resolution and 21 vertical laye...

We examine the response of streamflow to long-term rainfall variability under climate change by coupling downscaled global climate model precipitation to a distributed hydrologic model. We use daily output of the coupled global climate model ! CGCM2" of the Canadian Centre for Climate Modelling and Analysis corresponding to the Intergovernmental Pa...

In water resources management, streamflow prediction is one of the essential components that effects on the operators' decision making. For effective water use, e.g. water allocation or hydropower generation, long-term (more than monthly unit) streamflow prediction based on precipitation forecast is necessary. One of the typical methods for mid- an...

Recently, very short-term rainfall forecast using radar is required for regional flash flood according to climate change. This research is to evaluate the feasibility of GIS based distributed model using radar rainfall which can express temporal and spatial distribution in actual dam watershed during flood runoff period. Vflo model which was develo...