• Journal of the Korean Society for Aviation and Aeronautics
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• v.17 no.1
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• pp.17-23
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• 2009

The purpose of this study is possibility of the heavy rainfall prediction using instability index. The convective instability index using this study is Convective Available Potential Energy(CAPE) concerned the growth energy of the storm, Bulk Richardson Number(BRN) concerned the type and strength of the storm, and Sotrm Relative Helicity(SRH) concerned maintenance of the storm. To verify the instability index, the simulation of heavy rainfall case experiment by Numerical Weather Prediction(NWP) model(MM5) are designed. The results of this study summarized that the heavy rainfall related to the high instability index and the proper combination of one more instability index made the higher heavy rainfall prediction.

• Journal of Wetlands Research
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• v.8 no.2
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• pp.75-81
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• 2006

In this study, runoff simulation was carried out in order to derive operational improvement of small urban storm water pumping station under heavy storm rainfall conditions. The flood inflow hydrograph of Guri city heavy storm in July, 2001 was successfully simulated by HEC-HMS, a GIS-based runoff simulation model. For the runoff simulation, ArcView, as an effective GIS tool, was used to provide input data of the model such as land use data, soil distribution data and SCS runoff curve number.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.804-806
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• 2003

Probable Maximum Precipitation (PMP) is essential in the design of hydraulic structures such as dams, weirs and flood control structures. Up to the present, PMP has been derived from any proper single storm which can have a large error. PMP values should be evaluated from many historic heavy storm events from all over the country. Since this can be done at the spots of storm occurring and the calculated PMP from all spots in the country can be correlated. The objectives of this study are therefore to evaluate PMP from historic heavy storm data from 1972 to 2000 by using meteorological method, then to correlate and to present the results using GIS. The maximized rainfall depths can be calculate from depth of heavy rainfall and dew point temperature, and then can be analyzed for each rainfall duration to obtain spatial rainfall distribution by using GIS. The depth-area-duration relationship of maximized rainfall can be obtained and this helps to develop enveloped curves . The results from this study are a set of contour maps of PMP for each rainfall duration for all over the country and the depth-area-duration relationships for the area of 100 to 50,000 km.$^{2}$ at duration of 1, 2 and 3 days.

• Spatial Information Research
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• v.15 no.2
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• pp.159-167
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• 2007

In this study, we investigated the application of extending the Huff's method to design discharge being used at present up to the event of concentrated rainfall. As our field study site, we selected Odae Cheon basin in Pheongchang, which was affected by concentrated rainfall in July 2006. Actual concentrated rainfall and design rainfall derived from the Huff's method were used to calculate the discharge and storm water levels, which were compared with the directly measured water-level marks of storm discharges. The results showed that the peak storm discharge from the torrential rainfall was twice higher than the design rainfall. The short term discharges from concentrated rainfall closely corresponded to the rainfall discharges of 150 years storm frequency.

• Atmosphere
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• v.18 no.4
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• pp.317-338
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• 2008

Analyses of observational data and numerical simulations were performed to understand the mechanism of MCSs (Mesoscale Convective Systems) occurred on 13-14 July 2004 over Jindo area of the Korean Peninsula. Observations indicated that synoptic environment was favorable for the occurrence of heavy rainfall. This heavy rainfall appeared to have been enhanced by convergence around the Changma front and synoptic scale lifting. From the analyses of storm environment using Haenam upper-air observation data, it was confirmed that strong convective instability was present around the Jindo area. Instability indices such as K-index, SSI-index showed favorable condition for strong convection. In addition, warm advection in the lower troposphere and cold advection in the middle troposphere were detected from wind profiler data. The size of storm, that produced heavy rainfall over Jindo area, was smaller than $50{\times}50km^2$ according to radar observation. The storm developed more than 10 km in height, but high reflectivity (rain rate 30 mm/hr) was limited under 6 km. It can be judged that convection cells, which form cloud clusters, occurred on the inflow area of the Changma front. In numerical simulation, high CAPE (Convective Available Potential Energy) was found in the southwest of the Korean Peninsula. However, heavy rainfall was restricted to the Jindo area with high CIN (Convective INhibition) and high CAPE. From the observations of vertical drop size distribution from MRR (Micro Rain Radar) and the analyses of numerically simulated hydrometeors such as graupel etc., it can be inferred that melted graupels enhanced collision and coalescence process of heavy precipitation systems.

• Journal of Korea Water Resources Association
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• v.33 no.5
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• pp.569-580
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• 2000

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.

• Journal of Korea Water Resources Association
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• v.30 no.4
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• pp.389-399
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• 1997

The heavy strom of July 26-28, 1996, which occurred over the Northern Kyungi Province and Western Kangwon Province, is analyzed to investigate the hydrometeorological characteristics and frequency of occurrences of the storm. The study region is limited to the watershed area of Hantan River on which the partially destructed Yeonchon Dam is located. Hourly rainfall data at 21 rain gauging stations in and near the Hantan river basin are collected and the cumulative rainfall mass curves constructed and compared each other to judge the credibility and consistency of rainfall data at nearby stations. In order to analyze the spatially moving characteristics of rain storm the isochrones based on real time are constructed using the several fixed-percentage cumulative rainfalls at the stations. The basin average rainfalls of various durations are computed for Yeonchon dam and the return period of July/1996 storm are evaluated based on the rainfall frequency curves at Cheolwon and Yeonchon rain gauging stations. A comparison is also made between the July/1996 storm and PMP of the region, which demonstrated the severity of the heavy storm.

• Journal of the Korean Geographical Society
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• v.33 no.3
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• pp.395-409
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• 1998

The purpose of this paper is to determine the atmospheric conditions in whih urban areas affect the precipitation processes and to evaluate whether certain weather types show more apparent urban effect on precipitation modification over five cities in the southem United States. Each heavy rainstorm is classified into one of three synoptic weather types (frontal storm, airmass storm or tropical disturbance storm). Heavy rainstorm day is defined as day producing rainfall totals that equal o exceed 2 inches (50.08 mm). Houston, Dallass and San Antonio show possible urban effects on rainfall totals and frequencies of heavy rainstorms by airmass storm type while New Orleans and Memphis do not reveal any distinct precipitation enhancements through the synoptic analysis. The results of TSA (Trend Surface Analysis) show that frontal and tropical disturbance storm types have stronger climatic gradients than airmass types and the patterns of rainfall totals have stronger trends than those of rainfall frequencies for the five cities. The results suggest that airmass type events may well reveal possible precipitation enhancements due to urban effects since they are less influenced by a strong climate gradient and they provide favorable conditions for development of urban heat islands. Residual analysis confirms that rainfall totals and frequencies of heavy rainstorms by airmass storm type have positive residuals over the city or the major effect area.

• Magazine of the Korean Society of Agricultural Engineers
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• v.26 no.2
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• pp.69-84
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• 1984

This study was carried out to investigate the time distribution of single storms and to establish the model of storm patterns in korea. Rainfall recording charts collected from 42 metheorological stations covering the Korean peninsula were analyzed. A single storm was defined as a rain period seperated from preceding and succeeding rainfall by 6 hours and more. Among the defined single storms, 1199 storms exceeding total rainfall of 80 mm were qualified for the study. Storm patterns were cklassified by quartile classification method and the relationship between cummulative percent of rainfalls and cummulative storm time was established for each quartile storm group. Time distribution models for each stations were prepared through the various analytical and inferential procedures. Obtained results are summarized as follows: 1. The percentile frequency of quartile storms for the first to the fourth quartile were 22.0%, 26.5%, 28.9% and 22.6%, respectively. The large variation of percentile frequency was show between the same quartile storms. The advanced type storm pattern was predominant in the west coastal type storm patterns predominantly when compared to the single storms with small total rainfalls. 3. The single storms with long storm durations tended to show delayed type storm patterns predominantly when compared to the single storms with short storm durations. 4. The percentile time distribution of quartile storms for 42 rin gaging stations was estimated. Large variations were observed between the percentiles of time distributions of different stations. 5. No significant differences were generally found between the time distribution of rainfalls with greater total rainfall and with less total rainfall. This fact suggests that the size of the total rainfall of single storms was not the main factor affecting the time distribution of heavy storms. 6. Also, no significant difference were found between the time distribution of rainfalls with long duration and with short duration. The fact indicates that the storm duration was no the main factor affecting the time distribution of heavy storms. 7. In Korea, among all single storms, 39.0% show 80 to 100mm of total rainfall which stands for the mode of the frequency distribution of total rainfalls. The median value of rainfalls for all single storms from the 42 stations was 108mm. The shape of the frequency distribution of total rainfalls showed right skewed features. No significant differences were shown in the shape of distribution histograms for total rainfall of quartile storms. The mode of rainfalls for the advanced type quartile storms was 80~100mm and their frequencies were 39~43% for respective quartiles. For the delayed type quartile storms, the mode was 80~100mm and their frequencies were 36!38%. 8. In Korea, 29% of all single storms show 720 to 1080 minutes of storm durations which was the highest frequency in the frequency distribution of storm durations. The median of the storm duration for all single storms form 42 stations was 1026 minutes. The shape of the frequency distribution was right skewed feature. For the advanced type storms, the higher frequency of occurrence was shown by the single storms with short durations, whereas for the delayed type quartile storms, the higher frequency was shown gy the long duration single storms. 9. The total rainfall of single storms was positively correlated to storm durations in all the stations throughout the nation. This fact was also true for most of the quartile storms. 10. The third order polynomial regression models were established for estimating the time distribution of quartile storms at different stations. The model test by relative error method resulted good agreements between estimated and observed values with the relative error of less than 0.10 in average.

• Korean Journal of Ecology and Environment
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• v.38 no.spc
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• pp.39-43
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• 2005

The dynamics of water quality with the storm events were analyzed in a small reservoir for irrigation, Lake Wangkung. Water quality of the inflowing stream fluctuated seasonally with the variation of flow rate. Thermal stratification was consistent from April to October below 2 m depths and anoxic layer was developed below 2 m depth in summer. The unique feature of temperature showed that thermal stratification was disrupted by a heavy rain event during monsoon, but hypolimnetic hypoxia were reestablished after a few days. Phosphorus and nitrogen increased immediately following storm events. The marked increase may be due to the input of P-rich storm runoff from the watershed. Internal phosphorus loading can be one of the explanations for TP increases in summer. When there was a storm, total populations of phytoplankton and zooplankton was reduced immediately following the storm, indicating possible flushing of algae and zooplankton. After a lag period of low-density the plankton population bloomed to a peak again within five days after the storm. Turbid water in lake became clear again which coincided with the time of the phytoplankton buildup. The results demonstrate that water quality is regulated greatly by rainfall intensity in Lake Wangkung.