• Water for future
• /
• v.18 no.4
• /
• pp.317-325
• /
• 1985

In the analysis, monthly streamflow records atthe gauging station in Nakdong, Han and Geum river were used. Also, the fitness of monthly streamflow to Gamma and Long-normal distribution was tested by Kolomogorv-Smirnov test. The results obtained in this study can be summarized as follws (1) The fitness of monthly streamflow to two-parameter Gamma distribution was tested by Kolomorov-Smirnov test, which fits well to this Gamma distribution (2) The Run-length and Run-sum were simulated by the Gamma model. In this result, run-length and Run-sum of monthly streamflow were fit for Gamma model (3) The mean decreases (increases) the expected surplus (deficit) Run-Sum of the monthly streamflow. The higher the truncation level of negative Run-length and Run-sum the larger is the effect of mean.

• Journal of the Korean Society of Groundwater Environment
• /
• v.7 no.1
• /
• pp.8-14
• /
• 2000

The present day, interest in low flow statistics has been increased, primarily because of the increase in water demands and the contamination of water quality and the limitation of water resource development and the annual water supply stability. The model for estimating low flow statistics is points of this study chosen catchments in the Youngsan basin. For the purpose of this study. the low-flow discharge at 23 points, where absent gauging station is unmeasured and the data is used for the model. Finally, the regional formula to estimate the low flow statistics at the unmeasured point is proposed.

• Water for future
• /
• v.14 no.1
• /
• pp.51-58
• /
• 1981

This study attempts to examine and estabilish a simulation model from the stochastic analysis of daily streamflow. Daily streamflow records obstained at the main gauging stations along the Han, Nakdong and Geum River were used in the analysis. The following results were abtained. From the analysis of time series of streamflow by the correlogram and spectraal density, The serial component of one-year periodicity, serial correlation and irregular or random component were found. The coefficient of determination R2 of multilag model remaine a plateau at log-two, so that second order mu.ltilag model was Known to fit in the simulation of daily streamflow, Consequently, multilag and recised Markov model of the sewnd order give the best results in simulatin of daily streamflow. But the former generally gives better results than the latter. And theoretical markev model is unfit in the simulation of daily series without modification.

• Journal of Environmental Science International
• /
• v.19 no.2
• /
• pp.149-155
• /
• 2010

Rainfalls would increase the discharges or stages of tributary channels in natural watersheds, which in turn augment the magnitude of main stream stages. Rising of water surface elevation in main streams can affect and damage the human activities because of the possibilities of the breakdown or overflow of the embankment. Therefore it is necessary to establish the structural or non-structural alternatives for the sake of prevention or treatment of those disasters. Many mathematical models to analyze the flood flows in natural watercourses have been proposed as the non-structural alternatives so far. In this study one of the such models, FLDWAV developed by NWS(National weather Service), is applied to the downstream reach of Nakdong river. Model calibration is performed on various Manning's roughness coefficients at the gauging stations. The simulation results are compared well with hydrological estimations of flood discharges considering the effects of multipurpose dams upstream of control points.

• Water for future
• /
• v.18 no.1
• /
• pp.75-83
• /
• 1985

The applicability of ARMA(1, 1) multiseason model, which is in the beginning stage of active researches in the field of synthetic generation is evaluated with the streamflow data at the Nakdong stage gauging station on the main stem of the Nakdong River. The method of parameter estimation for the modelis reviewed and the statistical analysis of the generated seasonal streamflows such as corrlogram analysis and the computation of moments is made. The results obtained by ARMA(1, 1) multiseason model are compared with the historical streamflow data and also with those by two other multiseason models, namely, Thomas-Fiering model and Matalas AR(1) multiseason model. The seasonal streamflows grnerated by three multiseason models were annually summed up to form respective annual flow series whose statistics were compared with those of the annual flow series generated by three annual models, namely, AR(1), Matalas AR(1), and ARMA(1, 1) annual models. The possibility of ARMA(1, 1) multiseason model for the simultaneous generation of seasonal and annual streamflows is also evaluated.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
• /
• 2010.04a
• /
• pp.389-393
• /
• 2010

The Objective of this study was to develop a system for visualizing inundation area by using 1-D numerical model analyzing damage information such as inundation area, facilities, land usages, population, building, loads. In this study, we have reviewed hydraulic models to select a flood model for simulation of discharges, water depths and velocities. The study area is Namhan River from Youngwol to Paldang Dam which had a flood damage on upper and below regions of Chungju Dam by a storm event in 2006. At the first, we developed the DB system base on GIS thematic map, ortho images, cadastral maps to analyze flood damages and support decisions making. Changing the boundary conditions such as discharge at the gauging stations, flood simulations were performed and then damages were extracted from the databases information support system based on 1-D numerical hydraulic model, it is expected to be able to analyze flood damages and support a decision making for reduce flood relate damages. In the future, the system developed in this study could be applied for flood forecasting system of small scaled streams.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.30 no.6_2
• /
• pp.631-642
• /
• 2012

This study aims to predict inundation and flood-stricken areas more accurately by simulating flood damage caused by reversible flow of rain water in the upper water system through precise 3D terrain model and backwater output. For the upstream of the South Han-River, precise 3D terrain model was established by using aerial LiDAR data and backwater by area was output by applying the storm events of 2002 including the history of flood damage. The 3D flood simulation was also performed by using GIS Tool and for occurrence of related rainfall events, inundation events of the upriver region of water system was analyzed. In addition, the results of flood simulation using backwater were verified by making the inundation damage map for the relevant area and comparing it with flood simulation's results. When comparing with the results of the flood simulation applying uniformly the gauging station's water surface elevation used for the existing flood simulation, it is found that the results of the flood simulation using backwater are close to the actual inundation damage status. Accordingly, the causes of flood occurred in downstream of water system and upstream that has different topographic characteristics could be investigated and applying the simulation with backwater is proved more proper in order to procure accuracy of the flood simulation for the upriver region.

• Journal of Environmental Science International
• /
• v.25 no.10
• /
• pp.1433-1444
• /
• 2016

South Korea is a maritime nation, surrounded by water on three sides; hence, it is important to preserve in a sustainable manner. Most areas, especially those bordering the East Sea, have been suffering from severe coastal erosion. Information on the sediment yield of a river basin is an important requirement for water resources development and management. In Korea, data on suspended sediment yield are limited owing to a lack of logistic support for systematic sediment sampling activities. This paper presents an integrated approach to estimate the sediment yield for ungauged coastal basins by using a soil erosion model and a sediment delivery rate model in a geographic information system (GIS)-based platform. For applying the sediment yield model, a basin specific parameter was validated on the basis of field data, that, ranging from 0.6 to 1.2 for the 19 gauging stations. The calculated specific sediment yield ranged from 17 to $181t/km^2.yr$ in the various basin sizes of Korea. We obtained reasonable sediment yield values when comparing the measured data trends around the world with those in Korean basins.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2018.05a
• /
• pp.454-458
• /
• 2018

홍수예보 정보는 인명 및 재산 피해를 예방하기 위한 중요한 기능을 수행하고 있다. 현재 제공되고 있는 홍수예보 정보는 본류 및 일부 주요지천에 설치된 수위관측소(홍수예보지점)에 국한되어 제공되고 있다. 또한 제공되는 홍수예보 정보는 주의보 및 경보 수위로 하천내의 친수시설 및 범람 위험에 대한 홍수예보 정보를 제공하지 못하고 있다. 따라서 영산강 수계의 홍수예보 정보제공 효율성을 높이기 위해서 기존에 제공되었던 주의보 및 경보 수위에 대하여 국가 위기경보단계별 기준을 적용하여 아래 표와 같이 4단계의 홍수예보정보를 제공할 수 있는 기준을 제시하였다. 제시된 개선 사항을 영산강 수계 수위관측소에 적용하여 친수시설 및 범람 위험에 대한 추가정보를 제공할 수 있도록 하였다. 또한 관측소별로 과거 수위자료를 수집하고 발생 빈도를 산정하여 홍수예보 정보제공에 활용함으로써 보다 효율적인 홍수예보 정보제공이 가능하도록 하였다. 본 연구에서는 일부 홍수예보지점에서 제공되는 홍수예보 정보(주의보 및 경보)를 개선하고 친수시설 및 범람 위험에 대한 추가 정보를 제공하여 홍수로 인한 인명 및 재산 피해를 경감할 수 있을 것으로 판단된다. 하지만 제시된 홍수예보 정보제공 방안은 수위관측소 주변을 대상으로 단순 측량에 의해 산정된 방법으로 향후에는 하천 전체를 공간적 개념으로 적용한 홍수예보 정보제공 방안에 대한 연구가 수행될 필요가 있다.

• Journal of Korea Water Resources Association
• /
• v.40 no.12
• /
• pp.957-968
• /
• 2007

It is essential to obtain accurate and highly reliable streamflow data for quantitative management for water resources. Thereafter such real-time streamflow gauging methods as ultrasonic flowmeter and index-velocity are introduced recently. Since these methods calculate flowrate through entire cross-section by measuring partial velocities of it, rational and theoretical basis are necessary for accurate estimation of discharge. The purpose of the present study lies in analysis on the applicability of Chiu#s(1987, 1988) two dimensional velocity distribution equations by applying them to natural rivers and by comparing simulated velocity distributions with observed ones obtained with ADCP. Maximum and mean velocities are calculated from observed data to estimate entropy parameter M. Such isovel shape parameters as h and $\beta_i$ are estimated by object function based on least squares criterion. In case optimized parameters are applied, Chiu#s velocity distributions fairly well simulate observed ones. By using 14 simulated data sets which have relatively high correlation coefficients, properties of parameters are analyzed and h, $\beta_i$ are estimated for velocity-unknown river sections. When estimated parameters are adopted for verification, simulated velocity distributions well reproduce real ones. Finally, calculated discharges display rough agreement with measured data. The results of the present study mean that if parameters related are properly estimated, Chiu#s velocity distribution is likely to reproduce the real one of natural rivers.