• Title/Summary/Keyword: Runoff Error

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Optimal Rain Gauge Density and Sub-basin Size for SWAT Model Application (SWAT 모형의 적용을 위한 적정 강우계밀도의 추정)

  • Yoo, Chul-Sang;Kim, Kyoung-Jun;Kim, Nam-Won
    • Journal of Korea Water Resources Association
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    • v.38 no.5 s.154
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    • pp.415-425
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    • 2005
  • This study estimated the optimal rain gauge density and sub-basin size for the application of a daily rainfall-runoff analysis model called SWAT (Soil and Water Assessment Tool). Simulated rainfall data using a WGR multi-dimensional precipitation model (Waymire et al., 1984) were applied to SWAT for runoff estimation, and then the runoff error was analyzed with respect to various rain gauge density and sub-basin size. As results of the study, we could find that the optimal sub-basin size and the representative area of one rain gauge are similar to be about $80km^2$ for the Yong-Dam dam basin.

Surface Drainage Simulation Model for Irrigation Districts Composed of Paddy and Protected Cultivation (복합영농 관개지구의 배수량 모의 모형의 개발)

  • Song, Jung-Hun;Kang, Moon-Seong;Song, Inhong;Hwang, Soon-Ho;Park, Jihoon;Ahn, Ji-Hyun
    • Journal of The Korean Society of Agricultural Engineers
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    • v.55 no.3
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    • pp.63-73
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    • 2013
  • The objectives of this study were to develop a hydrologic simulation model to estimate surface drainage for irrigation districts consisting of paddy and protected cultivation, and to evaluate the applicability of the developed model. The model consists of three sub-models; agricultural supply, paddy block drainage, and protected cultivation runoff. The model simulates daily total drainage as the sum of paddy field drainage, irrigation canal drainage, and protected cultivation runoff at the outlets of the irrigation districts. The agricultural supply sub-model was formulated considering crop water requirement for growing seasons and agricultural water management loss. Agricultural supply was calculated for use as input data for the paddy block sub-model. The paddy block drainage sub-model simulates paddy field drainage based on water balance, and irrigation canal drainage as a fraction of agricultural supply. Protected cultivation runoff is calculated based on NRCS (Natural Resources Conservation Service) curve number method. The Idong reservoir irrigation district was selected for surface drainage monitoring and model verification. The parameters of model were calibrated using a trial and error technique, and validated with the measured data from the study site. The model can be a useful tool to estimate surface drainage for irrigated districts consisting of paddy and protected cultivation.

Calculation of the Flood Runoff of the River with Imaging Equipments (영상장비를 활용한 하천의 홍수유출량 산정)

  • Kang, Bo-Seong;Yang, Sung-Kee;Jung, Woo-Yeol;Kim, Yong-Seok
    • Journal of Environmental Science International
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    • v.23 no.4
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    • pp.585-594
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    • 2014
  • This study Analyzed four of seven runoffs which had happened in 2012 in comparison with the runoffs shown in Kalesto data, using the fixed surface image velocimetry (FSIV) installed at Oedo stream, Jeju Island. As a result of identifying a runoff curve graph, it was analyzed that the flood runoffs calculated with two observation devices were almost equivalent. As the differences in peak flows were 10 $m^3/s$, 0.7 $m^3/s$ and 3 $m^3/s$, the very similar result values were calculated. Even though there were errors in RMSE(Root Mean Square Error) made by two observation devices according to the degree of the peak flow, the values of $R^2$ by flood event were 0.89, 0.87, 0.86 and 0.82, showing the result values almost close to 1. Therefore, there was a very high correlation in flood runoffs calculated with two observation devices. This research method was considered to be a very suitable method to measure unexpected flood runoffs which could happen in the island area such as Jeju island during bad weather.

Calibration and Sensitivity Analysis of LRCS Rainfall-Runoff Model(I): Theory (LRCS 강우-유출 모형의 보정 및 민감도 분석(I) : 이론)

  • O, Gyu-Chang;Lee, Gil-Seong;Lee, Sang-Ho
    • Journal of Korea Water Resources Association
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    • v.32 no.6
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    • pp.657-664
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    • 1999
  • This paper introduced the basic theory of LRCS(Linear Reservoir and Channel System) rainfall runoff model proposed by Korean researchers(Lee and Lee, 1995), and discussed the change of model output according to objective functions in sensitivity analysis and calibration process of model. It proposed "hat" matrix and affluence measures for affluence analysis of parameters in calibration, and investigated relationship between change of model output according to error propagation in parameter estimation, and sensitivity of model output according to variance of model output and change of parameters. Accuracy of parameter estimates was known by analysis of sensitivity coefficient, diagonal element $h_i$ and $D_i$._i$.

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Uncertainty assessment caused by GCMs selection on hydrologic studies

  • Ghafouri-Azar, Mona;Bae, Deg-Hyo
    • Proceedings of the Korea Water Resources Association Conference
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    • 2018.05a
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    • pp.151-151
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    • 2018
  • The present study is aimed to quantifying the uncertainty in the general circulation model (GCM) selection and its impacts on hydrology studies in the basins. For this reason, 13 GCMs was selected among the 26 GCM models of the Fifth Assessment Report (AR5) scenarios. Then, the climate data and hydrologic data with two Representative Concentration Pathways (RCPs) of the best model (INMCM4) and worst model (HadGEM2-AO) were compared to understand the uncertainty associated with GCM models. In order to project the runoff, the Precipitation-Runoff Modelling System (PRMS) was driven to simulate daily river discharge by using daily precipitation, maximum and minimum temperature as inputs of this model. For simulating the discharge, the model has been calibrated and validated for daily data. Root mean square error (RMSE) and Nash-Sutcliffe Efficiency (NSE) were applied as evaluation criteria. Then parameters of the model were applied for the periods 2011-2040, and 2070-2099 to project the future discharge the five large basins of South Korea. Then, uncertainty caused by projected temperature, precipitation and runoff changes were compared in seasonal and annual time scale for two future periods and RCPs compared to the reference period (1976-2005). The findings of this study indicated that more caution will be needed for selecting the GCMs and using the results of the climate change analysis.

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Historical changing of flow characteristics over Asian river basins

  • Ha, Doan Thi Thu;Kim, Tae-Son;Bae, Deg-Hyo
    • Proceedings of the Korea Water Resources Association Conference
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    • 2020.06a
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    • pp.118-118
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    • 2020
  • This study investigates the change of flow characteristics over 10 Asian river basins in the past 30 years (1976-2005). The variation is estimated from The Soil and Water Assessment Tool (SWAT) model outputs based on reanalysis data which was bias-corrected for Asian monsoon reagion. The model was firstly calibrated and validated using observed data for daily streamflow. Four statistical criteria were applied to evaluate the model performance, including Coefficient of determination (R2), Nash - Sutcliffe model efficiency coeffi cient (NSE), Root mean square error-observations standard deviation ratio (RSR), and Percentage Bias (PBIAS). Then parameters of the model were applied for the historical period 1976-2005. The estimates show a temporal non-considerable increasing rate of daily streamflow in most of the basins over the past 30 years. The difference of monthly discharge becomes more significant during the months in the wet season (June to September) in all basins. The seasonal runoff shows significant difference in Summer and Autumn, when the rainfall intensity is higher. The line showing averaged runoff/rainfall ratio in all basins is sharp, presenting high variation of seasonal runoff/rainfall ratio from season to season.

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A Basic Study on the River Basin Routing Using Numerical Analysis (수치해석을 이용한 자연하천의 하도추적에 관한 기초적연구)

  • Kim, Sung Woon;Koh, Byung Ryoun;Koh, Chang Jong
    • Journal of Korean Society of Water and Wastewater
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    • v.12 no.2
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    • pp.127-139
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    • 1998
  • The objectives of this study is at the development of the channel routing model which can be used for flood prediction. Among the routing models, the hydraulic technique of the implicit scheme in the dynamic equation is selected to route the unsteady varied flow in the open channel. The channel routing model is catchment runoff which computed by the conceptual and transfer function model. The conceptual and transfer function model can simulate the catchment runoff accurately. As a result of investigating the channel routing model, the optimal weighting factor ${\theta}$ which fixes two points between time line is chosen, and also, the optimal error tolerance which satisfies computing time and converge of solution is determined in this study.

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Neural Network and Its Application to Rainfall-Runoff Forecasting

  • Kang, Kwan-Won;Park, Chan-Young;Kim, Ju-Hwan
    • Korean Journal of Hydrosciences
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    • v.4
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    • pp.1-9
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    • 1993
  • It is a major objective for the management and operation of water resources system to forecast streamflows. The applicability of artificial neural network model to hydrologic system is analyzed and the performance is compared by statistical method with observed. Multi-layered perception was used to model rainfall-runoff process at Pyung Chang River Basin in Korea. The neural network model has the function of learning the process which can be trained with the error backpropagation (EBP) algorithm in two phases; (1) learning phase permits to find the best parameters(weight matrix) between input and output. (2) adaptive phase use the EBP algorithm in order to learn from the provided data. The generalization results have been obtained on forecasting the daily and hourly streamflows by assuming them with the structure of ARMA model. The results show validities in applying to hydrologic forecasting system.

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Forecasting Long-Term Steamflow from a Small Waterhed Using Artificial Neural Network (인공신경망 이론을 이용한 소유역에서의 장기 유출 해석)

  • 강문성;박승우
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.43 no.2
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    • pp.69-77
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    • 2001
  • An artificial neural network model was developed to analyze and forecast daily steamflow flow a small watershed. Error Back propagation neural networks (EBPN) of daily rainfall and runoff data were found to have a high performance in simulating stremflow. The model adopts a gradient descent method where the momentum and adaptive learning rate concepts were employed to minimize local minima value problems and speed up the convergence of EBP method. The number of hidden nodes was optimized using Bayesian information criterion. The resulting optimal EBPN model for forecasting daily streamflow consists of three rainfall and four runoff data (Model34), and the best number of the hidden nodes were found to be 13. The proposed model simulates the daily streamflow satisfactorily by comparison compared to the observed data at the HS#3 watershed of the Baran watershed project, which is 391.8 ha and has relatively steep topography and complex land use.

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Long-term Water Balance Analysis of Irrigation Reservoir using Open Water Management Program (개방형물관리 프로그램을 이용한 관개용 저수지의 장기물수지 분석)

  • Kim, Sun-Joo;Kim, Phil-Shik
    • Proceedings of the Korean Society of Agricultural Engineers Conference
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    • 2003.10a
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    • pp.235-238
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    • 2003
  • In this study, we developed Open Water Management Program (OWMP) with an open architecture to deal with newly arising upgrade problems for a water management automation system. When we executed OWMP with data produced from an experimental field in Korea, the relative errors of this simulation were less than 5%. We developed runoff calculation model and verified it with measured data of 4 basins included in IHP. The relative errors came out less than 5% in all basins, except for one basin. We also applied OWMP to seongju irrigation reservoir to simulate daily runoff from 1998 to 2002, and the day, month, and year relative error between measured and simulated value was 0.25-0.05. Therefore the OWMP can be a tool nicely adapted to the optimal water management of irrigation reservoir.

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