Localized Torrential Rainfall Research Articles

Local Torrential Rainfall Event within a Mei-Yu Season Mesoscale Convective System: Importance of Back-Building Processes

Local Torrential Rainfall Event within a Mei-Yu Season Mesoscale Convective System: Importance of Back-Building Processes

극한강우 발생에 따른 소규모 댐 위험도 분석

The local heavy rains that didn't happen in the past, super typhoon and local torrential rainfall, generates more rainfall than the design rainfall applied to the design of the hydraulic structure this raises the anxiety about safety from natural disasters. In this study, the risk was analyzed extreme rainfall for a small dam belonging to a relatively large-scale structure among hydraulic structures and The target of analysis is the Cheongsong pumped storage plant in Cheongsong, Gyeongsangbuk-do. In Korea, extreme rainfall occurs mainly in the Jirisan area of the south coast and the east coast area. Therefore, in this study, the extreme rainfall that occurred in the eastern coastal area near the Cheongsong pumped-water power plant was selected and used for analysis. The maximum daily rainfall since 2000 in the east coast area was Typhoon Mitag in 2019, which caused a lot of rainfall in the east coast areas such as Pohang, Yeongdeok, and Uljin. In this study, it was assumed that rainfall such as typhoon Mitak occurred in the basin of the Cheongsong pumped storage plant, and the effect of dam outflow according to power generation on the downstream area was analyzed.

Climatology of Northeast China cold vortices during the warm season: A comparison of ERA5 and MERRA‐2 reanalyses

AbstractThe Northeast China cold vortex (NCCV) is an important type of synoptic scale system, which often induces local torrential rainfall events, strong winds, and lightning during warm seasons (May–September). By using an automatic identification method that involves a three‐step algorithm, NCCVs during warm seasons of 1980–2018 were identified based on ERA5 and MERRA‐2, the latest generation of reanalysis. Employing this recognition result and intensive surface observations, climatology of the NCCV was analysed. With respect to average climatic characteristics, the results indicate that the NCCV is most frequently located from the east of the Yablonov Mountains to the west of the Xiao Hinggan Mountains. The average rain belt and cold tongues resulting from NCCVs both mainly fall within Northeast China, Japan, Southeast Russia, and the Korean Peninsula, causing precipitation and temperature anomalies there, especially in Northeast China. Regarding interannual variation, the number of NCCV‐occurrence hours varies at a cycle of about 3 years, and has increased in the last 10 years compared to 1999–2008. The intensity of the NCCV also fluctuates in a cycle of approximately 3 years and shows a weakening trend, particularly from July to September. As for life characteristics, NCCVs usually form at the border area between China, Mongolia, and Russia, then develop and move eastwards, and finally disappear in areas of Heilongjiang in China, southeastern Russia, and the Okhotsk Sea. The NCCV moves in complex paths; among all 55 types of routes that occurred in warm seasons of 1980–2018, the most favoured paths are east, southeast, northeast, southeast‐to‐northeast, and circular. The above results based on the up‐to‐date reanalysis datasets with high resolutions are updates and supplements to previous studies, further improving our understanding of the NCCV in aspects of its cooling effects, weakening trends, and crucially, paths of movement and their occurrence frequency.

Engineering Properties and Economic Feasibility Evaluation of Eco-Friendly Rainwater Detention System with Red Clay Water-Permeable Block Body

An integrated rainwater management system is necessary due to the frequent occurrence of localized torrential rainfall and heat waves caused by an abnormal climate. It is necessary to develop a rainwater detention system that can implement rainwater infiltration and detention simultaneously. In this study, the safety, durability, and eco-friendliness of an eco-friendly rainwater detention system developed using an eco-friendly inorganic binder, which involves red clay, were evaluated and its economic feasibility was compared with that of the existing detention system. After 14 days, analysis of the maximum compression load and computational finite element analysis confirmed that the strength standard was satisfied and the structure was safe. No heavy metals or organic compounds were detected in the leaching test. Thus, the eco-friendly rainwater detention system is structurally safe and eco-friendly with no impact on the soil and groundwater environment, and is economically feasible because the construction cost and life cycle cost are approximately 30% and 58% lower, respectively, than those of the existing polyethylene infiltration detention tank system. These results indicate that improved safety, eco-friendliness, and economic feasibility can be achieved, compared to those of the existing system, if the eco-friendly rainwater detention system is applied in the field.

Anomaly Detection in Reservoir Water Level Data Using the LSTM Model Based on Deep Learning

Weather and hydrological phenomena have been changing due to climate change as evidenced by localized torrential rainfall and precipitation falling by more than 30% compared to the annual average. From 2013 to 2017 the ninety-nine reservoirs reached a water storage rate of 0%, making a secure stable water supply for agriculture uncertain. There is an increased need for information regarding agricultural water management to respond to the changes in the agricultural environment and climate. Therefore, automatic water level measurement facilities have been introduced to determine the real-time reservoir storage capacity and agricultural water supply. According to the Ministry of Agriculture, Food and Rural Affairs' guidelines for the installation and operation of water level measurement instruments, automatic water level facilities are currently installed at 1,734 reservoirs and 1,880 irrigation canals, with water level data generated at 10-minute intervals. The official recognition of hydrological water level data for agricultural reservoirs increased from six in 2016 to forty-nine in 2019. Anomaly detection algorithm methods for data regarding the agricultural reservoir level as well as quality control measures based on agricultural reservoir characteristics are required to minimize data quality degradation and generate reliable hydrological data over time. Though it was practically impossible to analyze the correlation between the water level or run-off and influential factors such as weather and terrain, recently a non-linear hydrological analysis has been possible using models such as Artificial Neural Networks (ANNs). This study aims to present an anomaly detection algorithm for reservoir level data using deep learning based LSTM (Long Short-Term Memory) models, in combination with other neural networks for managing quantitative information of agricultural water supply.

Empirical analysis of flood risk perception using historical data in Tokyo

Urban areas are vulnerable to natural disasters and require countermeasures to increase resilience. Cities located along coastal areas and rivers are increasingly facing flood problems. Urbanization in combination with climate change has increased localized torrential rainfall, causing more frequent floods in some areas. Local governments have implemented hard and soft measures to mitigate the potential impact; however, public awareness of flood risk is needed for these measures to be effective. This study exploited a characteristic of the hedonic price model and investigated changes in flood risk perception by assessing changes in land value over decades in flood-prone areas in Tokyo. The flood damage records show a decrease in flood damage in vulnerable low-lying areas, while the situation remains the same in high-lying areas. The land value of the most vulnerable area has increased more than that of less vulnerable areas. The results indicate that implementing effective measures and mitigating the impacts may diminish the awareness of flood risk, and the flood risk presented on the flood hazard map may not garner the expected attention. The findings also imply that investing in flood mitigation is worthwhile and could increase resilience in vulnerable areas. Furthermore, ensuring the precautionary acts of residents and confirming the effectiveness of reactive adaptation measures contribute to reducing future loss in the context of diminishing flood risk perception.

Impact of rainfall intensity on benthic macroinvertebrate communities in a mountain stream under the East Asian monsoon climate

As a consequence of the climate change, localized torrential rainfall has increased in intensity and frequency in Northeast Asia. This work aims at studying the effect of rainfall intensity on benthic macroinvertebrate communities in a mid-sized mountain stream in Korea, where the summer monsoon flood is prevalent. Sampling was conducted along reaches in Gapyeong stream (42 km in length), central Korean Peninsula, from a period of July 2008–October 2009. The sampling collection was carried out within 48 h after every major rain occasion and rainfall intensity was quantified by using the total rainfall amount for three days. Both water velocity and Froude number were found to increase with respect to the increase of rainfall at all study sites. As a consequence, the habitat environment and benthic macroinvertebrate communities were apparently affected by the rainfall intensity along the stream reaches. The species richness and abundance of benthic macroinvertebrates were significantly decreased at a rainfall over 200 mm, while much less decreased at a rainfall below 100 mm. Furthermore, the richness and abundance of species generally decreased with an increase of rainfall and their decrease was more evident at the downstream site, as compared to the upstream and midstream one.

Vulnerability assessment of forest landslide risk using GIS adaptation to climate change

ABSTRACTThe goal of the present study was to provide basic data for establishing climate change adaptation measures and to support appropriate forest management in Jeollabuk-do, Republic of Korea. An assessment of forest vulnerability to landslide caused by localized torrential rainfall was conducted for Jeollabuk-do, taking into consideration the local climate characteristics and the regional characteristics of the forest. CCGIS, a climate change adaptation software toolkit based on GIS, was used to carry out the vulnerability assessment of each city and county of Jeollabuk-do. To improve the assessment, locally specific variable weights were prepared, based on the results of a Delphi investigation targeting public forestry staff in Jeollabuk-do. The regionally specific weight was greatest for the variable of climate exposure, followed by sensitivity and adaptability. According to the vulnerability assessment over the course of time, in most of the forest the vulnerability rating decreased from 2000s to 2020s, and later it decreased once again in all urban areas. The vulnerability of forests was predicted to be greatest in the 2050s. Hence, if the local government sets up an adaptation policy using this research data that assessed the landslide vulnerability of forest in Jeollabuk-do, Korea taking account of the characteristics of the local area, we consider that an effective policy can be established and forest management can incorporate measures to adapt to climate change.

Concentration Rise of Fine Particle according to Resuspended Dust from Paved Roads after Sudden Heavy Rain in Busan

This study investigates the concentration sudden rise in fine particle according to resuspended dust from paved roads after sudden heavy rain in Busan on August 25, 2015. The localized torrential rainfall in Busan area occurred as tropical airmass flow from the south and polar airmass flow from north merged. Orographic effect of Mt. Geumjeong enforced rainfall and it amounted to maximum 80 mm/hr at Dongrae and Geumjeong region in Busan. This heavy rain induced flood and landslide in Busan and the nearby areas. The sudden heavy rain moved soil and gravel from mountainous region, which deposited on paved roads and near roadside. These matters on road suspended by an automobile transit, and increased fine particle concentration of air. In addition outdoor fine particle of high concentration flowed in indoor by shoes, cloths and air circulation.

Investigation into pluvial flooding hazards caused by heavy rain and protection measures in Shanghai, China

Flooding hazards caused by heavy rainfall in Shanghai have been reported extensively in the last 15 years. Geologically, Shanghai is sensitive to flooding hazards due to low-lying ground caused by land subsidence. Climatically, Shanghai is in the East Asia monsoon area and frequently experiences torrential rains. In this study, data from fifty-four pluvial flooding events between 2001 and 2015 were collected and analysed. The influence factors contributing to pluvial flooding are evaluated, and recommendations for protective measures are presented. The pluvial flooding prevention capacity in Shanghai is controlled by rain water storage and discharge capacity, which is associated with the sewer network, pumping stations and its sluice and pumping gates. Within the last three decades, the number of local torrential rainfall events and short-duration torrential rains has increased annually. However, the rain water storage capacity has decreased dramatically and the rain water discharge capacity has become limited during this period. In an extreme case, the discharge function of the sewer network was even temporarily lost because of flooding of the distributaries of the Huangpu River. Thus, in order to prevent flooding hazards caused by heavy rain, it is suggested that a large sluice and pumping station between the Huangpu River and the Yangtze River estuary is constructed in the near future, considering the continuous subsidence of the city and the ongoing rising sea levels.

2014년 7월 31일 대관령에서 발생한 집중호우에 관한 수치모의 연구

On 31 July 2014, there was a localized torrential rainfall (<TEX>$58.5mm\;hr^{-1}$</TEX>) caused by a strong convective cell with thunder showers over Daegwallyeong. In the surface synoptic chart, a typhoon was positioned in the East China Sea and the subtropical high was expanded to the Korean peninsula. A WRF (Weather Research and Forecasting) numerical simulation with a resolution of 1 km was performed for a detailed analysis. The simulation result showed a similar pattern in a reflectivity distribution particularly over the Gangwon-do region, compared with the radar reflectivity. According to the results of the WRF simulation, the process and mechanism of the localized heavy rainfall over Daegwallyeong are as follows: (1) a convective instability over the middle part of the Korean peninsula was enhanced due to the low level advection of warm and humid air from the North Pacific high. (2) There was easterly flow from the coast to the mountainous regions around Daegwallyeong, which was generated by the differential heating of the insolation among Daegwallyeong and the Yeongdong coastal plain, and nearby coastal waters. (3) In addition, westerly flow from the western part of Daegwallyeong caused a strong convergence in this region, generating a strong upward motion combined by an orographic effect. (4) This brought about a new convective cell over Daegwallyeong. And this cell was more developed by the outflow from another thunderstorm cell to the south, and finally these two cells were merged to develop as a strong convective cell with thunder showers, leading to the record breaking maximum rainfall per hour (<TEX>$58.5mm\;hr^{-1}$</TEX>) in July.

Assessment of the Pacific decadal oscillation’s contribution to the occurrence of local torrential rainfall in north China

On 21–22 July 2012, torrential rains hit North China, with the daily precipitation record at Beijing station reaching 160.6 mm; this event is named the Beijing 7–21 case. This paper assesses the likelihood of the occurrence of local torrential rains, such as the Beijing 7–21 case, from the perspective of climate variability. In particular, the influence of the Pacific Decadal Oscillation (PDO) is assessed. There were five extreme events, with daily precipitation records equal to or larger than 160.6 mm, at Beijing station during the period 1951–2012; all of these events happened during negative phases of the PDO. The present analysis indicates that precipitation events more extreme than the Beijing 7–21 case should happen more than once per decade during negative phases of the PDO, but only about once every four decades during positive PDO phases. The negative phase of the PDO is found to be associated with a much greater probability of daily records of southerly winds in North China during summer. Strong southerly summer monsoons are deemed favorable for increasing the occurrence of local extreme rainfall over North China.

Flood Events in Gangapur Village, Banke District: An Example of Climate Change-induced Disaster in Nepal

Climate change impacts in Nepal have resulted, among others, localized downpour which may trigger severe flooding and associated disasters in some parts of the country, particularly in the southern slope of the Siwalik. The purpose of this investigation was to evaluate the consequences of climate change impacts in the Dhondra River watershed that covers southern slope of the Siwalik and northern part of the Terai plane in Banke district, western Nepal. For the purpose, a field investigation was carried out and it indicated that Ward Nos. 5 and 6 of Gangapur Village Development Committee (VDC) were inundated in 2000 due to the blockade of the Singhya River by the deposition of flood-driven sediments brought by the Dhondra River. Consequently, about 305 families were completely displaced due to the inundation in and around their home and farmlands. The flood was resulted due to a localized torrential rainfall in Dhondra River's upper reaches in the Siwalik area. Following the year 2000, the Dhondra River started depositing sandy sediments in and around the confluence point with the Singhya River during each monsoon seasons. This paper briefly summarizes the causes of the disaster and its consequences to the displaced people, and surrounding geo-environment.Journal of Institute of Science and Technology, 2014, 19(1): 79-85

Thermodynamic characteristics associated with localized torrential rainfall events in the southwest region of the Korean peninsula

This study uses observational data from radar and radiosonde to investigate the thermodynamic conditions related to localized torrential rainfall (LTR) in the southwest region of the Korean peninsula. Three criteria were defined for selecting LTR events: 1) hourly rainfall exceeding 30 mm h−1 recorded at any of the automated synoptic observing systems (ASOS) around Gwangju, 2) an area of rainfall at > 1 mm h−1 (as estimated from radar rain rate) of less than 20,000 km2, and 3) clearly defined stages of genesis and dissipation in a group of rain cells (> 10 mm h−1) with a duration lasting less than 24 hours. As a result, 10 cases were selected from the summer season (June-August) over the last decade (2004-2013). Results showed all cases occurred during the afternoon hours and that the duration and maximum rain area of convective cells (> 30 mm h−1) was less than 6 hours and smaller than 700 km2, respectively. The majority of cases showed the following thermodynamic characteristics: 1) strong convective available potential energy (CAPE > 1,500 J kg−1) related to surface heating, 2) weak (or no) convective inhibition (CIN < 50 J kg−1), 3) adequate moisture and total precipitable water (TPW ≈ 55 mm), and 4) values of storm relative helicity (SRH) of less than 10 m2 s−2. The area of rainfall (700 km2) and the duration (6 h) in this experiment were relatively small and short, respectively, compared to those in a previous study in the middle-west region of Korea (1,000 km2, 9 h), but a higher CAPE (1,500 J kg−1) and lower SRH (10 m2 s−2) were involved in this study than in the former (800 J kg−1, 120 m2 s−2).

A Study on Inundation Analysis Considering Inland and River Flood

The objective of this study is to present countermeasures for mitigation of flood damage with inundation analysis considering the effect of inland and river flood and prediction of flood inundation area, depth and time against emergencies caused by abnormal flood and local torrential rainfall. In this study, 2-D inundation analysis was 2014년 11월 26일 접수 Received on November 26, 2014 / 2015년 1월 14일 수정 Revised on January 14, 2015 / 2015년 2월 11일 심사완료 Accepted on February 11, 2015 * 본 연구는 소방방재청 자연재해저감기술개발사업단(자연피해예측및저감연구개발사업)의 지원으로 수행한 ‘침수재해 경감 표준모델 개발 및 관리기술 고도화’[NEMA-자연-2014-75]과제의 성과임. 1 한국수자원공사 물관리센터 Water Resources Operations Center, K-water 2 경북대학교 건축토목공학부 Department of Civil Engineering, Kyungpook National University 3 한국수자원공사 조사기획처 Water Resources Investigation and Planning Department, K-water 4 한국수자원공사 용담댐관리단 Yongdam Dam Office, K-water ※ Corresponding Author E-mail : jsoo@kwater.or.kr 내수 및 외수영향을 고려한 침수해석에 관한 연구 / 조완희 · 한건연 · 김현식 · 김진수 75 fulfilled on the basis of river flood analysis applying to HEC-HMS and FLDWAV model and inundation analysis applying to SWMM model for the area of Shineum-dong, Gimcheon-si. Also expected inundation depth and area about probable rainfall of 100 and 200 years frequency were suggested. If expected inundation depth and flooding area is presented on the basis of this inundation analysis considering the effect of inland and river flood, it would be an important preliminary data to establish structural and nonstructural countermeasures for flood prevention. Also if flood risk map is prepared based on the result of inundation analysis, it would be useful to evacuate residents in high-risk area and regulate road and vehicle.

GIS를 이용한 강원지역 토석류 특성분석

우리나라에서는 매년 태풍 혹은 국지성 집중호우로 유발되는 산사태 및 토석류로 인한 피해가 발생하고 있다. 특히, 강원도 지역은 대부분 산지로 이루어져 있고 지형의 경사가 가파르고 토심 또한 얕아 많은 피해가 발생하고 있다. 본 논문에서는 강원도의 피해지역을 대상으로 5년간 현장조사를 통해 수집된 위치 및 지형특성에 관한 GIS자료를 기반으로 임상도 및 토양도 등과 함께 활용하여 토석류 발생유역의 특성을 추출하여 빈도 분석을 수행하였다. 지형적 특성은 토석류 발생유역의 발생부와 유하부의 지형적 특성에 따른 단순 계수에 의한 방법으로 빈도 분석을 수행하였으며, 임상 및 토양 특성은 GIS 기반으로 해당 속성의 면적비를 고려한 방법으로 빈도 분석을 수행하였다. 토석류 발생유역의 지형적 특성은 발생부의 경사, 폭, 심도, 거리, 경사향, 파괴 형태 등을 사용하여 분석하였으며, 또한 유하부의 유하거리, 경사, 폭, 심도 등을 사용하여 분석을 수행하였다. 토석류 발생유역의 임상 특성은 임상, 영급, 경급, 밀도 등의 속성을 사용하였으며, 토양 특성은 배수등급, 유효토심, 심토토성, 심토자갈, 침식등급, 토양모재, 표토토성 등의 속성을 사용하였다. 빈도 분석 수행결과 토석류 발생부 및 유하부에 대한 지형적 특성과 토석류 발생 유역의 임상 토양 특성을 파악할 수 있었다. 이는 토석류 피해예방을 위한 합리적인 방재대책의 개발 및 적용 등에 기초자료로 활용될 수 있을 것이다. In Korea, there are debris-flow disasters induced by typhoon and localized torrential rainfall annually. There are particularly extensive debris-flow disasters in Gangwon-do because of its geomorphological characteristics; the extensive coverage of mountainous region, steep slope, and shallow soil. In this paper, we constructed a GIS database about topological characteristics of debris-flow basin in Gangwon-do by years of field survey. Also, we conducted frequency analysis based on this database with the digital forest type map and the digital soil map. We analyzed frequencies of debris-flow by simple count for topological characteristics, whereas we analyzed by considering an area ratio based on GIS for physiognomic and geologic characteristics. We used slope, aspect, width, depth and destruction shapes for analysis about topological characteristics of debris-flow basin. Also we used attributes of forest physiognomy, diameter, age, and density about physiognomic characteristics, and i n terms of geologic characteristics, we used attributes of drainage class, effective soil depth, subsoil properties, subsoil grave content, erosion class, parent material of soil, and topsoil properties. In consequence, we figured out topographic, forest physiognomic, and geologic characteristics of debris-flow basin. This result is applicable to establish a rational disaster prevention policy as a fundamental information.

Impact of flood intensity on aquatic insect communities in a Korean stream under monsoonal climate

As a consequence of climate change, localized torrential rainfall has increased in intensity and frequency in Northeast Asia under the influence of the monsoonal climate. The purpose of this study was to evaluate the impact of flood intensity on aquatic insect communities in a Korean stream, where the summer monsoonal flood is normal. Quantitative sampling was conducted according to stream reaches (upstream, midstream, and downstream sites) in Gapyeong stream, located in the central Korean peninsula, during July 2008–October 2009. Sampling was conducted within 48 hours after every rain event during the rainy season, and flood intensity was evaluated using the total amount of precipitation for 3 days before sampling. Precipitation was categorized in 100 mm increments. Water velocity and Froude number (Fr) were measured, and mean species abundance and species richness were determined. Habitat orientation groups (HOGs) were analyzed. Data were analyzed using nonmetric multidimensional scaling (NMS) ordination and two‐way analyses of variance .As a result, the velocity increased as precipitation increased at all sites, and the Fr at the upstream and midstream sites were below critical flow for all precipitation categories. The EPT‐group (Ephemeroptera, Plecoptera, and Trichoptera) together with Diptera were &gt;90% in abundance at all study sites. The mean abundance of some major taxa (i.e., Ephemeroptera and Plecoptera) decreased significantly as precipitation increased, particularly, at the downstream site. The mean abundance of all HOGs was more influenced by the relatively large amount of precipitation (e.g., &gt;200 mm) at all sites. According to NMS ordination, the amount of precipitation was the major factor determining the composition of aquatic insect communities in the study stream. In conclusion, aquatic insect communities in the Gapyeng stream were significantly influenced by the intensity of precipitation, and the impact was intensified at the downstream site.

EFDC 모형의 낙동강 하류부 수리해석 적용성 평가

최근 지구온난화에 따른 해수면 상승과 태풍의 내습으로 인하여 발생되는 폭풍해일 및 집중호우에 대하여 낙동강 하류부의 수리거동을 수치모형(EFDC)을 이용하여 해석하였다. 낙동강 하구둑을 포함한 하류부 일대에 대해 수리거동을 해석하기 위하여 대상영역을 진동에서 가덕도를 포함한 외해부까지 확장하였다. 수치모형에 의한 수위의 재현성을 검토하기 위하여 2003년 및 2006년 발생한 태풍 호우사상을 대상으로 각 수위관측지점에서의 관측 수위와 계산수위를 비교 하였다. 금번 실시된 연구결과 수치해석에 사용된 수치모형(EFDC)은 높은 재현성을 가지고 있음을 알 수 있었고 차후 폭넓은 연구에 활용가능성이 높다고 판단되었다. This study analyzed a hydrodynamic behavior using the EFDC model (Environmental Fluid Dynamics Code) in the downstream of the Nakdong River in the case of a storm surge and a localized torrential rainfall caused by a major typhoon, and the sea level rise caused by global warming. The study area is selected Gaduk island with the lower boundary and Jindong with the upper boundary, to investigate the total river hydrodynamic behavior including the estuary. In order to verify this numerical model, the calculated results was compared with the observed stage at each gauging point in case of the storm rainfall in 2003 and 2006. From the results, it was shown that the numerical model(EFDC) has high accuracy and is useful in simulating more various cases.

군자 시험배수구역 합류식 하수관거시스템의 일일하수량 및 직접유출량 산정

A localized torrential rainfall and flash floods which are more frequently occurred by extraordinary atmospheric phenomena and rising sea surface temperature require more hydrological data collecting and analysis for small watershed. Urban watershed hydrological data monitoring system is needed because of big flood potential damage and lack of urban watershed hydrological data. Therefore, Urban Flood Disaster Management Research Center operates small experimental catchments(Sinnae1, Gunja, and Children`s Park) observing and analyzing hydrological data(rainfall, stage, and discharge). In this study, the discharge of combined sewage for Gunja experimental drainage is analyzed with weekly data and day of the week data. Through several analyses in analyzing the urban runoff characteristics and managing the urban sewage system, direct runoff is calibrated and verified by the estimated values of rainfall-runoff model(SWMM).