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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Korea Water Resources Association
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Journal DOI :
Korea Water Resources Association
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Volume & Issues
Volume 33, Issue 6 - Dec 2000
Volume 33, Issue 5 - Oct 2000
Volume 33, Issue 4 - Aug 2000
Volume 33, Issue 3 - Jun 2000
Volume 33, Issue S1 - May 2000
Volume 33, Issue 2 - Apr 2000
Volume 33, Issue 1 - Feb 2000
Selecting the target year
An Investigation of the Recurrence Possibility of Long Dry Periods shown in the Annual Rainfall Data at Seoul
Yu, Cheol-Sang ;
Journal of Korea Water Resources Association, volume 33, issue 5, 2000, Pages 519~526
This study is to investigate the recurrence possibility of consecutive dry years such as the long dry period around 1900 in the annual rainfall data at Seoul station. The truncation levels, as the criterion for the dry years, are decided such as to make the occurrence of dry years follow the Poissonian distribution, which assures independent occurrence of dry years. For the truncation level of mean-0.5stdv, the occurrence of dry years is found to satisfy the Poissonian distribution weakly with 99% significance level, but for those of mean-0.75stdv and mean-stdv with 95% significance level. For these truncation levels, the long dry period around 1900 is divided into several short consecutive dry years. The Poisson process has then been applied to derive the occurrence probability of consecutive dry years. For the truncation level of mean-0.75stdv or below, the Poisson process was found to reproduce similar occurrence probabilities to the observed. Especially for the lowest truncation level used in the study (mean-stdv), we could see that the occurrence probability of consecutive dry years estimated for the data collected before the long dry period around 1900 was higher that those for the data collected after the long dry period, thus, it could be concluded that the possibility of long dry periods is decreasing recently.cently.
An Analysis on the Relationship between Discharge and Pollution Load on the Tributary Basin of Kum River
Jeong, Sang-Man ; Im, Gyeong-Ho ; Choe, Jeong-Hyeon ;
Journal of Korea Water Resources Association, volume 33, issue 5, 2000, Pages 527~536
This study estimates the pollution load in a basin by regional groups analyzing the relationship between the discharge and pollution load. The study area is placed in the Miho stream basin known as the main tributary of the Kum river. Four major Telemetary streamflow stations are chosen. In this research, discharge and water quality in a dry season and a flood season from the observed discharge in the stream are analyzed. The Rating-Curve and the Pollutograph are drawn analyzing discharge and water quality at the major stations. The characteristics of runoff for each stream are analyzed and the change of water quality are analyzed for rainfall period. The relationship between discharge and water quality has been investigated. The relationship between the discharge and pollution load is analyzed and a representative equation is derived. These relationships permit an estimates of the pollution load at the Miho stream basin. basin.
A Study on the Forecasting of Daily Streamflow using the Multilayer Neural Networks Model
Kim, Seong-Won ;
Journal of Korea Water Resources Association, volume 33, issue 5, 2000, Pages 537~550
In this study, Neural Networks models were used to forecast daily streamflow at Jindong station of the Nakdong River basin. Neural Networks models consist of CASE 1(5-5-1) and CASE 2(5-5-5-1). The criteria which separates two models is the number of hidden layers. Each model has Fletcher-Reeves Conjugate Gradient BackPropagation(FR-CGBP) and Scaled Conjugate Gradient BackPropagation(SCGBP) algorithms, which are better than original BackPropagation(BP) in convergence of global error and training tolerance. The data which are available for model training and validation were composed of wet, average, dry, wet+average, wet+dry, average+dry and wet+average+dry year respectively. During model training, the optimal connection weights and biases were determined using each data set and the daily streamflow was calculated at the same time. Except for wet+dry year, the results of training were good conditions by statistical analysis of forecast errors. And, model validation was carried out using the connection weights and biases which were calculated from model training. The results of validation were satisfactory like those of training. Daily streamflow forecasting using Neural Networks models were compared with those forecasted by Multiple Regression Analysis Mode(MRAM). Neural Networks models were displayed slightly better results than MRAM in this study. Thus, Neural Networks models have much advantage to provide a more sysmatic approach, reduce model parameters, and shorten the time spent in the model development.
Diagnosis of Water Environment and Assessment of Water Quality Restoration in Lake Shihwa
Kim, Dong-Seop ; Go, Seok-Gu ;
Journal of Korea Water Resources Association, volume 33, issue 5, 2000, Pages 551~559
In order to diagnose the water environment and assess the water quality restoration, long term trend of water environment has been surveyed at 3-R stations from 1994 to 1999 in Lake Shihwa. Annual mean values of
, Chlorophyll a, total nitrogen, total phosphorus and Secchi depth are ranged in 5.2-15.1 mg/L, 7.3-14R.1 jlg/L, 1.50-4.84 mgN/L, 0.055-0.281 mgP/L and 0.5 -1.4 m, respectively, during the study periods. Carson's trophic state indeies were varied from mesotrophy in 1994 and 1995, hyper-eutrophy in 1996 and 1997, to meso eutrophy in 199R and 1999. After dike construction, water quality were rapidly deteriorated by allochthonous and autochthonous loading of high nutrients and organic carbon. Eutrophication phenomena were characterized by massive phytoplankton blooms and high concentration of COD. However, after onset of restoration program, lake water quality was rapidly restored to the level of just after sea-dike construction. The diversion of waste water inflowing from the Panwol and the Sihwa industrial districts which was started from March, 1997 has contributed to improve water quality in the surface layer. And the tidal mixing (sea water inflowing) through the continuous gate operation was the most effective measure to the whole lake restoration.ration.
The Fish Migration through Fishlock at Youngam Lake
Hwang, Jong-Seo ;
Journal of Korea Water Resources Association, volume 33, issue 5, 2000, Pages 561~568
The dimension of the fishlock at the Youngam Lake is 6.6m wide and 30m long, and it has been used for both fish migration and ship passage. The capacity of attraction freshwater is
, and the water depth of the fishlock varies between 1.9m - 5.7m due to the tide. Fishes were sampled weekly by using 3m wide maze net from April to June, 1999, and by using purse seine covering the entire space of fishlock from July to November, 1999. 116,014 samples were comprised of 25 species, and 99.5% of the samples were 10 kinds of diadromous fishes. The order of the diadromous fishes in abundance was Hemirhamphus kurumeus, Hypomesus olidus, Coilia ectens, and Mugil cephalu, where these four species consist 99% of the individuals, and the other six species contribute only a few of individuals. Each species had unique peak migration period. The peak migration of Hypomesus olidus, Mugil cephalus, Coilia ectens, and Hemirhamphus kurumeus happened on July 20, July 15, May 10, and May 1, respectively.tively.
Analysis of the Changes in Rainfall Quantile according to the Increase of Data Period
An, Jae-Hyeon ; Kim, Tae-Ung ; Yu, Cheol-Sang ; Un, Yong-Nam ;
Journal of Korea Water Resources Association, volume 33, issue 5, 2000, Pages 569~580
To account for the influence of heavy storm in Korea by climate change like global warming, the frequency analyses for annual maximum rainfall sequence in 12 rainfall gauge stations are carried out. In order to analyze the temporal change, the rainfall quantile of each station is estimated by the 30-yr data period being moved from 1954 to 1998 with 1-yr lag. Through the analysis for l00-yr rainfall quantile it has been shown that the recent heavy storms increase comparing with storms in the past. From the additional estimating of the rainfall quantile of each station by the 30-yr data period being cumulated from 1954 to 1998 with 1-yr, the change of the probable rainfall by including the heavy storm duration is realized. When the hydraulic structures are determined, it is important to select the data size and necessary to reestimate the flood prevention capacity in existing river systems.ystems.
Numerical Investigation of Turbulence Structure and Suspended Sediment Transport in Vegetated Open-Channel Flows
Gang, Hyeong-Sik ; Choe, Seong-Uk ;
Journal of Korea Water Resources Association, volume 33, issue 5, 2000, Pages 581~592
Turbulence structure and suspended sediment transport capacity in vegetated open-channel flows are investigated numerically in the present paper. The
model is employed for the turbulence closure. Mean velocity and turbulence characteristics including turbulence intensity, Reynolds stress, and production and dissipation of turbulence kinetic energy are evaluated and compared with measurement data available in the literature. The numerical results show that mean velocity is diminished due to the drag provided by vegetation, which results in the reduction of turbulence intensity and Reynolds stress. For submerged vegetation, the shear at the top of vegetation dominates turbulence production, and the turbulence production within vegetation is characterized by wakes. For emergent condition, it is observed that the turbulence generation is dominated by wakes within vegetation. In general, simulated profiles compares favorably to measured data. Computed values of eddy viscosity are used to solve the conservation equation for suspended sediment, yielding sediment concentration more uniform over the depth compared with the one in the plain channel. The simulation reveals that the suspended load decreases as the vegetation density increases and the suspended load increases as the particle diameter decreases for the same vegetation density.
Deriving a Reservoir Operating Rule ENSO Information
Kim, Yeong-O ;
Journal of Korea Water Resources Association, volume 33, issue 5, 2000, Pages 593~601
Analyzing monthly inflows of the Chung-Ju Dam associated with EI Nino Southern Oscillation (ENSO), Kim and Lee(2000) reported that the fall and winter inflows in EI Nino years tended to be low while those in La Nina years tended to be high. This study proposes a methodology of employing such a teleconnection between ENSO and inflow in reservoir operations. The ENSO information is used as a hydrologic state variable in stochastic dynamic programming (SDP) to derive a monthly optimal rule for operating the Chung- Ju Dam. An alternative operating rule is also derived with the SDP with no hydrologic state variable. Both of the SDP operating rules are simulated and compared to examine the value of using the ENSO information in operations of the Chung-Ju Dam. The simulation results show that the operating rule using the ENSO information increases energy generation and reliability of water supply as well as reduces spill. spill.
A Study of Distribution of Rainfall Erosivity in USLE/RUSLE for Estimation of Soil Loss
Park, Jeong-Hwan ; U, Hyo-Seop ; Pyeon, Jong-Geun ; Kim, Gwang-Il ;
Journal of Korea Water Resources Association, volume 33, issue 5, 2000, Pages 603~610
Climate factors such as rainfall, temperature, wind, humidity, and solar radiant heat affect soil erosion. Among those factors, rainfall influences soil erosion to the most extent. The kinetic energy of rainfall breaks away soil particles and the water flow caused by the rainfall entrains and transport them downstream. In order to estimate soil erosion, therefore, it is important to determine the rainfall erosivity. In this study, the annual average Rainfall Erosivity(R) in Korea, an important factor of the Universal Soil Loss Equation(USLE) and Revised Equation(RUSLE), has been estimated using the nationwide rainfall data from 1973 to 1996. For this estimation, hourly rainfall data at 53 meterological stations managed by the Meterological Agency was used. It has been found from this study that the newly computed values for R are slightly larger than the existing ones. It would be because this study is based on the range of rainfall data that is longer in period and denser in the number of gauging stations than what the existing result used. The final result of this study is shown in the form the isoerodent map of Korea.
Groundwater Flow Analysis Using Finite Difference Method in Volcanic Island
Choe, Yun-Yeong ; Lee, Sun-Tak ;
Journal of Korea Water Resources Association, volume 33, issue 5, 2000, Pages 611~622
In this study, MODFLOW model is used to analyze the groundwater flow system of Seoguipo area in Cheju island, The final parameters of permeability coefficient and storage coefficient of target area can be obtained by trial and error method using the measured data of pumping rate as initial values. And it is found that the applicability for groundwater flow system is reflected well from the simulation result of the model. Seoguipo area spring water is thought to appear by relatively stable groundwater recharge below EL. 400m according to head distribution through the analysis of observed data considering topographic and geological characteristics, Lee's study(996), and the simulation result. Also it is known that point II, III, and VI show relatively large velocity vectors, and groundwater flows through the movement path which is distributed in various directions of I, II, III, IV, V, VI, and VIl form the result of velocity vector analysis using head distribution result values to analyze the groundwater flow path under unsteady flow condition.dition.
Analysis of River Flow Change Based on Some Scenarios of Global Warming
Sin, Sa-Cheol ;
Journal of Korea Water Resources Association, volume 33, issue 5, 2000, Pages 623~634
This study describes results of numerical simulations on river flow response due to global warming. Forecasts of changes in climatic conditions are required to estimate the hydrologic effects of increasing trace gas concentrations in the atmosphere. However, reliable forecasts of regional climate change are unavailable. In there absence, various approaches to the development of scenarios of future climatic conditions are used. The approach in this study is to prescribe climatic changes for a river basin in a simplified manner. As a rule, such scenarios specify air temperature increases from
and precipitation change (increase or decrease) in the range of 0% to 15%. On the basis of acceptable supposition of warming scenarios. future daily streamflow is simulated using rainfall-runoff model in the Andong Dam basin. The numerical experiments have quantitatively revealed the change of discharge at 2010, 2020, 2030 and 2050 for each warming scenarios and compared it with the results for a non-warmmg scenano.cenano.
Improvement of Low Water Level Rating Curve in Tidal River Taehwa
Jo, Hong-Je ; Hwang, Jae-Ho ; Mun, Seong-Jun ;
Journal of Korea Water Resources Association, volume 33, issue 5, 2000, Pages 635~645
In tidal rivers, the river level, discharge and tide are interrelated. Therefore, the stage-discharge relation that takes no account of tidal effects is inaccurate. For the calculation of river discharge in low water level, this paper attempts to formulate a multiple regression equation of stage-discharge curve to calculate the river discharge in low water level with variables as river level and differences between sea level and river level. Numerical application were perfonned on Ulsan gaging station in Taehwa river, and the comparison with existing rating curve equation showed good applicability of this multiple regression equation.uation.
The Economic Impacts of Water Supply Constraints During a Drought Using input-output Analysis
Choe, Jang-Hwan ; Heo, Eun-Nyeong ; Sim, Myeong-Pil ;
Journal of Korea Water Resources Association, volume 33, issue 5, 2000, Pages 647~658
The purpose of this study is to estimate the forward impact of water supply bottleneck using a supply-side input-output model. The failure cost analysed in this study can be used to estimate the values of the water supply reliability and can provide the bases of policy decision for the effective reallocation when water supply constraint will occur. So the position of water supply in the national economy is identified, and direct and indirect impacts are estimated by means of the interindustry analysis. Also the failure cost index is suggested to determine the prior order of water supply important in drought. By the way, the occurrence of drought having regional properties, the failure cost of the regional level using a national input-output table may be overestimated or underestimated. For the preceding reason, the failure cost estimated by a national input-output table is compared with and analysed to a regional input-output table for Kyung- Nam.g- Nam.