배수효과를 고려한 도시 내배수시스템 실시간 운영모형 개발

이양재 고려대학교 대학원 2007 국내석사

Recently, flash floods occur frequently around urban areas resulting in huge monetary damage and losses on human lives. To prevent the damage of flash floods, lots of research attentions have been made on the flood drainage system for urban watersheds. In general, the flood drainage system consists of two major systems :flood drainage facilities and operating practices. The facilities are composed of sewer networks, gates, and pumping stations to drain the flood efficiently to outer rivers. The operating practice consists of pump or gate operation. Among them, the improvement of the operating practice has more research attentions currently. To develop an efficient pump operating rule for a retard basin, it is necessary to estimate inflow to the retard basin accurately which is affected by the backwater effect on the retard basin. The magnitude of the backwater effect is dependant on the depth of a retard basin; however, the depth is determined by the amount of inflow and outflow. Thus, a real time simulation system which is able to simulate urban runoff (possible maximum inflow) and the pump operation (outflow) and to consider the backwater effect is required to estimate the actual inflow to a retard basin. With this system, the efficient pump operating rule can be developed to diminish the possible flood damage on urban areas. In this study, a realtime simulation system is developed using the SWMM 5.0 DLL and Visual Basic 6.0 equipped with EXCEL to estimate inflow considering the backwater effect on realtime basis. It is done by updating realtime input data such as minutely observed rainfall and the depth of a retard basin. Using those updated input data, the model estimates the actual inflow, the amount of outflow discharged by pumps and gates, the depth of each junction, and flow rate at each sewer pipe on realtime basis For developing efficient pump operating rules, two new rules are suggested. The first rule is designed to operate pumps considering the condition of sewer networks such as depths of each junction. The second is to discharge all the amount of inflow at each time step, which is to maintain the maximum discharge capacity at an outlet conduit of a sewer network. Results obtained by those rules are compared with one by the current pump operating rule which is able to consider only the depth of the retard basin. The developed model and the pump operating rules are applied to the JoongGok retard basin and there are three observations made: ∙The backwater effect cannot be ignorable to estimate the amount of inflow. The peak flow with the backwater effect is reduced about 25% of the one without the backwater effect. Thus, the backwater effect should be considered when calculating the amount of inflow. ∙ From the view point of reducing flood damage, the suggested pump operating rules produce more stable operating results than the current pump operating rule. ∙ The first rule may be more reasonable than the second one since it requires less number of pump operations to obtain almost same results. Therefore, the developed model and the pump operating rules are verified their applicability for reducing flood damage on urban watersheds and willcontribute to establish better operating practices for the flood drainage system. 최근 급증한 도시유역의 집중호우는 많은 인명피해와 재산피해를 발생시키고 있다. 이러한 현상에 대처하고자 도시 내배수시스템에 대한 관심이 증가하고 있는 실정이다. 내배수시스템은 우수관망, 배수문, 빗물펌프장 등의 시설물과 배수문의 개폐여부, 빗물펌프장의 펌프운영 결정 등의 운영 방법이 있으며, 최근 운영방법에 관한 많은 연구가 진행되고 있다. 유수지 유입유량은 유수지의 수위에 의한 배수효과에 의해 달라진다. 유수지의 수위는 유입유량과 배제량 및 유수지 구조에 따라 매 시간 달라진다. 따라서 본 연구에서는 실시간으로 변하는 유수지의 수위를 고려하여 실무에 적용이 가능하도록 배수효과를 고려한 도시 내배수시스템 실시간 운영모형을 개발하였다. 본 연구에서는 최근 발표된 SWMM 5.0 DLL을 이용하여 SWMM 5.0과 동일한 결과를 도출하는지에 대해 검토하였고, 또한 유수지의 수위에 따른 배수효과의 영향을 검토하고자 서울시 동대문구에 위치한 용두 배수펌프장 유역을 대상으로 유수지의 수위에 따른 배수효과의 영향 정도에 대해 모의하였다. 유수지의 수위가 높을수록 유수지의 유입량은 감소하였으며, 상류단의 침수지역 및 침수량은 증가하였고, 과부하 발생관거의 개수 및 발생시간 역시 증가하였다. 따라서 본 연구에서는 Visual Basic 6.0과 SWMM 5.0 DLL, MS Excel을 이용하여 실시간으로 변하는 유수지의 수위를 고려하여 유입량을 산정하도록 하였다. MS Excel을 통한 입력자료를 실시간으로 갱신하여 유수지 유입유량 및 절점에서의 수위를 비롯한 관거에서의 유량을 매 시점별로 산정할 수 있도록 하였다. 개발된 모형을 서울시 광진구에 위치한 중곡 빗물펌프장 유역에 적용하였다. 펌프 운영조건은 유수지의 수위에 따른 운영조건, 내배수시스템의 상황을 고려한 운영조건, 유입유량을 전량 배제하는 운영조건의 3가지로 나누어 본 연구에서 개발된 실시간 유입량 산정 모형과 결합하여 모의한 결과 내배수시스템의 상황을 고려하여 운영하는 경우 다른 2가지 경우에 비해 합리적이고 안정적인 운영이 가능한 것으로 모의되었다.

u-City 구축을 위한 발전된 상수관망 운영시스템의 개발 : Smart Water Network

조문수 고려대학교 대학원 2007 국내석사

본 연구에서는 u-City 구축을 위한 발전된 상수관망 운영시스템을 개발하였으며 이 시스템을 SWN(Smart Water Network)로 지칭하였다. SWN은 관의 누수 및 파괴와 시스템의 비정상상태를 실시간으로 감지할 수 있는 시스템이다. 연구는 크게 3부분으로 구성되어 있다. 첫번째는 국내 상수관망의 특성에 알맞은 한국형 SWN이 갖추어야할 요소들을 제안하였다. 두번째는 기존 상수관망 시스템에 SWN의 적용시의 이익을 정량화하기 위하여 수용가불편시간이란 개념을 사용하였으며 수용가불편시간은 관의 누수 및 파괴로 인한 압력저하와 복구 공사로 인한 단수로 인해 수용가가 불편을 느끼는 시간이다. 마지막으로 SWN의 주요 센서인 Smart Pipe와 On-line 압력계의 설치 위치를 선택하는 방법을 개발하였다. Smart Pipe의 설치위치는 전환돈(2005)이 개발한 알고리즘을 사용하였으며 On-line 압력계의 경우 영향지수행렬(Effect Index Matrix)와 행렬의 Column Search를 통하여 설치위치를 결정하는 방법을 개발하였다. 그리고 수용가불편시간과 SWN의 주요센서의 적용성을 확인하기 위하여 미국과 국내의 상수관망에 적용하였다.

Aquacycle을 利用한 都市流域의 물循環 解析

이지호 고려대학교 대학원 2007 국내석사

Water cycle analysis is important in assessing the healthiness of water cycle by quantifying various elements of water cycle including evapotranspiration, infiltration, and runoff. Only after such assessment of water cycle is made, one can devise an improvement plan to address the problems identified. In this study, water cycle analysis was performed for Gunja drainage located in metropolitan Seoul using Aquacycle model developed in Australia to assess the problems of urban water cycle. In addition, feasibility analysis of reuse scenarios such as rainwater use and wastewater reuse was performed to examine their influences on improving the water cycle. From the analysis of water cycle of Gunja drainage, it was shown that hydrologic components such as evapotranspiration and surface runoff were highly dependent upon the change of impervious area. From the simulation of urban water cycle, it was found that, of total of 1,388 rainfall, 306 was lost through evapotranspiration. Surface runoff of 1,044 occurred, of which 937 at impervious area and 107 at pervious area. Finally, 99 of rainfall was recharged into groundwater. In summary, 75% of total rainfall occurred in the form of surface runoff, and groundwater recharge only accounted for about 7%. This suggests serious distortion of water cycle which can be attributed to urbanization. When compared to the water cycle in rural region (Pyungtaek in the vicinity of Seoul), it was found that impervious area of urban region was 9 times bigger, thereby reducing evapotranspiration by 39% and increasing surface runoff by 154%, and groundwater recharge has decreased by 75%. Along with water cycle analysis, the effect of rainwater use and wastewater reuse on water cycle was also evaluated using Aquacycle model for the study area. Reusable water was confined to use with irrigation and toilet water, and the analysis showed that the amount of reusable water was 890 combining rainwater and wastewater reuse. For the reuse, rainwater storage with a capacity of 20,000 was determined as optimal capacity in case of rainwater use and the wastewater treatment plant with a capacity of 2,700 in case of wastewater reuse. With rainwater use, it was shown that imported water supply of 312 can be saved through rainwater use, and that is water supply savings of 10% and surface runoff reduction of 26%. On the other hand, with wastewater reuse, it was shown that water supply savings of 31% and wastewater reduction of 30% can be achieved. There is not much rainfall except during summer season in Korea whereas the amount of wastewater occurs steadily in large volume throughout the year. For this reason, it can be said that wastewater reuse has an advantage over rainwater use in providing consistent water supply. The groundwater store level is getting low about 11cm per a year due to the forced pumping and groundwater use. Thereby river dry steam is on going. Also the groundwater recharge evaluated with SCS-CN was shown differences 4.2% of total rainfall according to soil classes in the study area. This study summarizes the application results of Aquacycle model as a tool for water cycle assessment and feasibility analysis of various reuse alternatives. With gloomy outlook on water supply for the future, the interest in alternative water resources such as rainwater and treated wastewater has increased substantially. As a science-based approach to shaping up of reuse options and comparing alternatives, Aquacycle looks to be a promising tool that can provide analytical muscle needed in both planning and implementation stage of water recycling program.

상수관망의 신뢰도 추정을 위한 Segment기반 Minimum cutset method

박재일 고려대학교 대학원 2007 국내석사

Reliability assessment of water distribution systems plays an important role in improving the service quality of the system and establishing efficient operating and maintenance plans. However, most of the reliability assessment models may assess the reliability inaccurately due to insufficient network and operation data and unrealistic assumptions such as the determination of failure impacted range. Also, they assume that more than two pipes cannot fail at the same time so that the probabilities of multiple pipe failure combinations are omitted for reliability assessment. In general, these assumptions may be acceptable for small water distribution systems but for large systems, errors resulted from these assumptions are accumulated, ending up with inaccurate reliability assessment. In this study, a segment-based minimum cutset method to assess the nodal and overall system reliabilities is suggested. The suggested model considers actual failure impacted ranges adopting the extended segment concept and the probabilities of multiple pipe failure combinations using the success approach for calculating the reliability. The extended segment concept covers various types of reasons which stop water supply such as a segment that is a subsystem isolated by closing adjacent valves, the unintended isolation where is disconnected from water sources, and hydraulic pressure limitation ranges where are supplied with water at lower pressure head. To calculate the reliabilities of the nodal and overall system, the success approach considers only success probabilities of components. In the suggested model, the component is defined as a minimum cutset resulting in stopping water supply or hydraulic failure at demand node(s). Thus, the system can be in the normal operating condition only when all of the minimum cutsets are in success and this allows us to consider multiple component failure combinations indirectly. Using these concepts, the actual failure impacted range by a single pipe failure and the multiple pipe failure combinations are considered for assessing the reliabilities. Applying the suggested model to real networks efficiently, the author developed a program consisting of the EPANET DLL and modules identifying failure impacted ranges and assessing the nodal and overall system reliabilities. Two real networks, Cherry Hill and Chester Water Authority, are selected to compare reliability assessment results by the suggested model and two previous models. As results, it is found that the suggested model assesses the reliabilities more accurate and efficient than the previous models. As the size of water distribution systems increases, the discrepancy between the suggested model and the previous models becomes distinct. For further applications of the suggested model, the optimal design of water distribution systems with the predefined reliability and the determination of the optimal valve locations will be possible.

유역 경사 정보를 기반으로 한 하천 유역의 균일 설계 홍수유출량 산정 공식 개발

박상호 부산대학교 2023 국내박사

하천 관리의 기본인 하천기본계획 수립에 있어서 홍수유출량 산정 모델의 정확성은 매우 중요한 요소이다. 홍수유출량을 과대 추정하면 예산 낭비가 발생하고, 과소 추정하면 안전 문제를 야기할 수 있기 때문이다. 현재까지는 기존의 경험적 자료를 기반으로 홍수유출량을 산정하여, 지형이 복잡하고 경사가 자주 변화하는 유역에는 기존의 방법을 적용하기에는 문제점이 발생하고 있는 실정이다. 따라서, 금회 연구에서는 하천의 길이(L), 고도(H) 차이, 경사(S)와의 관계에 기반하여 새로운 공식을 제안하였으며, 해당 공식을 Clark 단위도법에 적용하여 홍수유출량을 계산한다. 분석결과 기존에 가장 많이 쓰이는 2개의 공식(연속형 Kraven, 서경대 공식)의 경우 경사가 매우 완만하거나 매우 급한 경우 유속이 산정 유역별로 연속성 없이 하나의 유속으로 고정되는 결과로 나타났다. 이러한 경험공식의 한계성으로 인하여 유속이 고정, 과소 추정되는 경우 저류상수의 과대추정으로 홍수량이 작게 산정되거나 유속이 높게 산정되었음에도 기준경사 계수에 따라 저류상수가 과대 추정되는 등의 문제점이 발생한다. 계측 유역에 대해서는 기존에 축척된 자료로 과소, 과대 추정되는 부분을 보완하여 수정이 가능하지만 미계측 유역에서는 유속 고정, 계수에 따른 저류상수-유속의 비선형 관계는 하천 관리에 어려움을 초래하게 된다. 현재까지 경험공식을 활용하여 급경사, 완경사, 보통경사별 적절한 공식을 적용하여 분석하고 있다. 하지만, 실제 하천의 경우 상류부로부터 하류부까지 경사율이 매우 상이하며, 특히 국토 대부분이 산지로 이루어져 있어 하천의 경사 변화가 많은 우리나라의 경우에는 기존의 홍수유출량 산정 공식은 적합하지 않았다. 그리하여 본 연구에서는 유역이 매우 완만하거나 급한 경우에도 적용 가능한 새로운 공식을 개발하였다. 개발 공식은 유속-저류상수의 연속성이 유지되어 하천 홍수유출량 산정이 보다 정확해질 것으로 기대된다.

確率降雨量 算定을 爲한 EDA 槪念의 適用

박현근 고려대학교 대학원 2007 국내석사

This study applied the EDA(Exploratory Data Analysis) for the frequency analysis of rainfall. The EDA is a methodology to estimate data statistics using data structures like median and quartiles. Eventhough the traditional statistics based on the method of moment are very sensitive to the extreme observations, these derived based on the EDA found to be stable. Two different frequency analysis routines are proposed in this study. Fist routine is to transform the raw data to follow the normal distribution, estimate quantiles for give occurrence probabilities, and do inverse-transform to estimate the rainfall quantiles. Second routine is the same but estimate statistics of transformed data by applying the EDA, also the statistics of the raw data by doing inverse-transform. These two routines have been applied to the rainfall data collected at the Seoul rain gage station. The first routine was found to be in appropriate as it could that reproduce the skewness at all. However, by following the second routine, the mean, variance, and the coefficient of skewness of the raw data are found to well reproduced. The methodology proposed in this study was also applied to the rainfall data collected at Pohang, Ulsan rain gage stations. However, in this part, the main focus was given to the temporal variability of rainfall quentiles mainly due to extreme event newly occurred. Different from the traditional frequency analysis based on the method of moments, the methodology using the EDA proposed in this study was found to provide a very stable estimates of rainfall quantiles. 본 연구에서는 기후변화 등에 의한 극치사상이 반영될 경우, 확률강우량의 변동성에 대해 분석하였다. 또한 극치사상의 포함여부에 따라 큰 변동폭을 보일 수밖에 없는 전통적(traditonal) 확률강우량 산정방법의 문제점을 보완하기 위하여 탐색적 자료분석(Exploratory Data Analysis: EDA)의 적용성을 검토하였다. 이러한 과정을 통해 이상치의 포함여부와 상관없이 안정적인 확률강우량을 산정할 수 있는 개선방안을 제시하였다. EDA 기법을 적용한 빈도해석 하는 방법은 크게 두 가지로 나누어 볼 수 있다. 첫 번째 방법(EDA #1)은 변환된 자료를 EDA 기법을 적용하여 정규분포로 정의하고, 주어진 재현기간에 대하여 이 분포를 따르는 분위수를 결정한다. 결정된 분위수의 역변환하여 확률강우량을 추정하는 방법이다. 두 번째 방법(EDA #2)은 정규화된 자료의 통계치를 EDA 기법을 적용하여 추정하고 이를 역변환하여 원자료의 매개변수를 결정한다.이 두 가지 EDA 기법의 빈도해석 방법을 검토하였다. 그 결과 두 번째 방법이 적절한 EDA 기법의 빈도해석 방법으로 확인되었다. 본 연구에서는 최소 자료기간을 30년으로 한 후 추가로 자료를 1년씩 누가해가며 지점별로 확률강우량을 산정하고 그 변동특성을 분석하였다. 전통적 방법에서는 극치사상이 추가됨에 따라 평균, 표준편차, 왜곡도 등 통계특성이 크게 변동하였다. 전통적 방법에 의한 확률강우량은 극치값을 가지는 자료의 추가에 따라 크게 증가함을 보였다. 그러나 EDA 기법에 의하여 산정된 확률강우량은 전통적 방법과 비교하여 큰 변화를 보이지 않는 것으로 파악되었다.

矩形펄스模型과 EOF 解析을 利用한 우리나라 가뭄의 時·空間的 特性의 定量化

김대하 고려대학교 대학원 2007 국내석사

Drought is assumed a big disaster with flood having tremendous impact on the rise and fall of a country or empire, from past to present. National Oceanic Atmospheric Association (NOAA) announced great disasters in the 20th century including four drought, which among top five. In this raking, the first is the drought in China in 1907, the second is the drought in Soviet Union in 1922, the fourth is the drought in India in 1967, and fifth is the drought in Sahel in Africa in 1975. These droughts caused total results including 5 million, 1.5 million, 0.6 million deaths, respectively. United Nations(UN) also announced that about one hundred million people were starving due to drought in 2000 in Asia. These are good examples that the drought can damage seriously to human life worldwisely including. In this study a theoretical drought severity-duration-frequency analysis is performed based on a simple Rectangular Pulses Poisson Process Model(RPPM). The return periods of the important drought events occurred in Seoul are estimated using the results of the study. If the return period of an event is assumed to be the longest one among those with various durations, the return periods of some important event in Seoul are estimated to be between 14 and 35 years. These return periods are not so long to indicate that these droughts can occur frequently. In addition, This analysis applied to characterize the spatial pattern of drought over the Korean peninsula using the rainfall data of the 59 rain gauge stations. As a result, the drought severity in the southern part of the Korean peninsula was found to be generally high for any return period. And, 3-month SPI data from 59 stations over the Korean peninsula are analyzed by deriving and spatially characterizing the EOFs. Also, the coefficient time series of EOF are applied to the time series model to generate the time series of 10,000 years, to average them to estimate the areal average, and to decide the maximum drought severity for given return periods. Finally, the drought prevention ability is evaluated by considering the effective storage of dam within the basin and the size of agricultural area. Especially for the return period of 30 years, only the Han river basin has the potential to overcome the drought. Other river basins like Youngsan river basin, which has a large portion of agricultural area but less water storage, are found to be very vulnerable to the rainfall-sensitive agricultural drought.

상수관망의 신뢰성 향상에 관한 연구

김석현 고려대학교 대학원 2008 국내석사

New methods are presented to improve reliability of a water distribution system reasonably. For the work, the Park's model(2006) is chosen as a tool to analyze systems and study improvements of system reliability. On the basis of the results from the analysis of the model, the methods improving the system reliability are summarized as follows. The first method is increasing durability of each pipe belonging to minimum cut sets. The second method is reforming a system by installing valves to reduce damage or unintended isolations. As results of the applications, the methods should be combined adequately to improve it effectively. To combine them, the following procedures are adopted. The first procedure is to determine types of reinforcement(Type 1~3) for all pipes. Firstly, pipes in the "Type 1" do not need to be reinforced. Secondly, in the "Type 2", they are reinforced by increasing their durability. Finally, one or two valves are installed on pipes in the "Type 3" to isolate them. As the second procedure, two rules are proposed which have their own purpose respectively. The "Rule 1" is focused on the reliability considering total construction cost. On the other hand, the "Rule 2" has a purpose of decreasing extent of damage by pipe failures. As a result, the "Rule 1" is more effective than the "Rule 2" to increase the system reliability while the "Rule 2" is more effective than the "Rule 1" to decrease the extent of damage. They should be applied to a system according to what the purpose is. In conclusion, the methods can be guidelines on plans to improve the system reliability under restricted capability to maintain and manage systems.

HEC-HMS를 이용한 격자 강우장의 유출 해석 및 평가

김병수 고려대학교 대학원 2008 국내석사

This study focuses on the use of radar rainfall for the rainfall-runoff analysis. It is well known that the radar rainfall itself does not have enough accuracy for the rainfall-runoff analysis. Various correction methods have been introduced to improve the quality of the radar rainfall. Especially, in this study, G/R corrected radar rainfall data, synthetic rainfall data of radar and rain gauge rainfall by co-Kriging, and synthetic rainfall data by the successive correction method(SCM) are compared by applying them to the rainfall-runoff analysis. Original radar rainfall data provided by the Mt. Kwanak radar system and distributed rain gauge rainfall by block-Kriging are also considered for the comparison. This study considers the typhoon Maemi, Rusa and Jangma during the summer of 2003. The rainfall data prepared have all been applied for the rainfall-runoff analysis of the Chungju Dam Basin, located in the middle of the Korean Peninsula. Obviously, the true rainfall field is unavailable. In this study, however, the rainfall field generated by applying the block-Kriging for the rain gauge rainfall was assumed the true rainfall field for the evaluation of the synthetic rainfall field generated. The number of rain gauges used for generating the true rainfall field is twice that for other cases of rainfall field generation or correction. The rainfall-runoff analysis model used in this study is the Modified Clark. In conclusion, the original radar rainfall and the G/R corrected rainfall resulted in significant underestimates of the runoff observed. On the other hand, other synthetic rainfall data resulted in very comparable results with the observed. Runoff peak and peak time also showed a good match with the observed. Especially, among the rainfall fields generated for the comparison in this study, the synthetic rainfall field by the co-Kriging also resulted in well matched runoff results with the observed, as well as that with the synthetic rainfall field by the SCM. Considering that the SCM is a very simple and easily applicable data assimilation method, it may easily and effectively be applied for the rainfall-runoff analysis to the small urban basins with a short concentration time, where no time-consuming data correction method can be applied.

Fuzzy C-Means 알고리즘을 이용한 하수관거개량지표의 개발

이원우 고려대학교 대학원 2008 국내석사

하수관거 개량사업에 있어 국내의 경우 여러 가지 기준들을 반영을 하고 있으나 서로 다른 평가인자들의 각각의 정량적 척도의 차이를 반영하지 못하는 실정이다. 또한 하수관거 개량사업의 우선순위를 결정하는데 있어 기준이 모호하여 합리적인 방법을 제안하지 못하고 있다. 실제 하수관거 개량사업의 경우 고려해야하는 인자들이 다양하기 때문에, 이러한 다양한 인자들을 고루 반영하여 하나의 정량적 평가를 할 수 있는 지표의 산정이 시급한 실정이다. 본 연구에서는 하수관거 개량사업에 있어 고려해야할 인자들을 산정하였고, 이들 각 인자들의 정량적 척도를 산정하기 위하여 각 인자의 소속정도를 파악할 수 있는 멤버쉽 함수를 산정하였다. 이렇게 산정된 멤버쉽 함수를 통해 소속정도를 파악하였고, 다양한 인자들을 동시에 고려할 수 있는 개량지표를 산정하였다. 기존에 사용하지 않은 FCM 알고리즘을 사용하여 정량적 가치의 척도가 다른 여러 인자들을 동시에 고려하여 하나의 지표로 산정하였고, 이를 중곡배수분구에 적용하여, 여러 인자들을 동시에 반영하는 하수관거 개량지표를 산정하였다. 또한, 특성이 비슷한 소유역의 군집화를 실시 하수관거 개량사업 우선순위를 제안하였다.