• Water for future
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• v.9 no.1
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• pp.47-54
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• 1976

The research are intend to establish the design criteria for slopy upland reclamation, with protecting the loss of top-soil, Recently undertaken reclamation works for developing the slopy upland of 310,000 ha. have faced to the vagueness of their deign criteria. One of the most influencing factors to cause the soil erosion depends basically upon the kinematic energy of rainfall, which is developed by the rainfall intensity. Their relationship between the rainfall and its kinematic energy is expressed as EK=916+ 331 log I. Consequently, the study was carried out through analyzing each intensity of the independant rainfall through out the 14 rainfall stations. About 10,000 single storms self recording chart of more than 10mm of rainfall amout were collected and analyzed by computer. The results of research show their kinematic energy for the 14 stations, and will be available for the establishment of the design oriteria.

• Journal of The Korean Society of Agricultural Engineers
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• v.62 no.4
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• pp.13-22
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• 2020

The Doam Lake watershed has a significant impact on the downstream water system due to nutrients and sediment outflow during rainfall caused by steep slopes, soil losses, and fertilization. These non-point sources are unclear in the discharge area and are affected by land use patterns, soil characteristics, and topographical features of the watershed. Therefore, this study conducted rainfall monitoring from July to October 2019 in Songcheon upstream of the Doam Lake watershed, one of the non-point pollution source management areas. Then, after analyzing rainfall runoff, Event Mean Concentration (EMC) and Mass First Flush ratio (MFFn) were calculated to compare and analyze the characteristics of rainfall and the non-point pollutant discharge. As a result of the analysis, it showed various non-point pollutant emission characteristics for each rainfall event. In addition, the concentration of EMC and the MFFn were affected by the average rainfall intensity and the maximum rainfall intensity, and were not significantly affected by the number of antecedent drying days. In the future, it is expected that effective non-point source reduction measures and management measures according to rainfall intensity through continuous monitoring and analysis will be needed.

• Proceedings of the KIEE Conference
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• 2005.07d
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• pp.2507-2509
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• 2005

Because the rain gauges of tipping bucket type can easily use the digital signal, the rain gauges are widely used for the meteorological observation. In general, the resolution of rain gauges of tipping bucket type can be categorized by the 0.1mm, 0.5mm, and 1.0mm classes. But, the error of the tipping bucket rain gauges is made by the intensity of rainfalls and is expected to make the standard calibration method for error measurement. Thus, we developed the hardware of standard calibration facility for rain gauges by weighting measurement method and proposed the standard procedure by rainfall intensity in this study. Also, we calculated the error for the rainfall intensity and obtained useful result through the proposed calibration method.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.957-965
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• 2008

Recently, slope stability analysis in current design criteria is criticized for its unrealistic assumption of groundwater table and slope stability analysis incorporating seepage analysis considering rainfall is gaining a recognition as an alternative. However, a reasonable method for determining the rainfall used in the seepage analysis has not yet been established. Rainfall input for seepage analysis is a time series of rainfall and is similar to the hyetograph which is usually obtained from hydrology. In this paper a method to obtain the hyetograph from the intensity-duration-frequency is proposed. The resulting hyetograph can be used in the in the slope design stage. Also some considerations for practical application of slope stability analysis considering the rainfall is included.

• Journal of Environmental Science International
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• v.13 no.7
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• pp.637-643
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• 2004

A new method of automatic recording raingauge is developed to measure rainfall with 0.01mm resolution. This use two different signals to measure rainfall more accurately compare than other raingauges. One is weight of the tipping bucket with rainfall amount and the other is pulse from tipping bucket reverse. New method applied 1 mm tipping bucket mechanism and install loadcell under tipping bucket mechanism for measuring rainfall weight. Loadcell measure weight of rainfall until 1 mm with 0.01 mm resolution and more than 1 mm than bucket reverse and pulse signal generate, after that loadcell measure weight again. The validation of new instrument was examined in the room 65 mm/hour rainfall rate total 53 mm range. There is below than 1 % error of absolute rainfall amount and 0.01 mm resolution. The field test of instrument was carried out by comparing its measured values with values recorded by weight type and standard type on June 1 2003 at Terrestrial Environmental Research Center at Tsukuba University in Tsukuba of Japan, when it has recorded total amount of 40.58 mm rainfall by standard raingauge and new raingauge recorded 41.032 mm. Same rainfall intensity pattern observed in field observation with weight type raingauge. Rainfall intensity between weight type and Lee-A type raingauge reached 0.9947 correlation in 3 minute average.

• Journal of the Korea Organic Resources Recycling Association
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• v.17 no.4
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• pp.91-102
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• 2009

In this study, to estimate the transforming (runoff and leachate) rate of the organic fertilizer made of livestock resources to farm land, laboratory scale test was conducted and the results were obtained as follows: The runoff volume from farm land showed the tendency of increase according to the increase of rainfall intensity. The most rainfall leachated into the underground at the rainfall intensity of 20mm/hr, and rainfall of 5L or less leachated at the rainfall intensity of > 32.4 mm/hr. This shows that surface runoff largely depends on the rainfall intensity when soil characteristic and hardness are similar in each site. When liquid compost was fertilized, the surface runoff was similar with the results from the reactor fertilized by compost, and leachate flow was found to be lower than compost. The runoff ratio of contaminant parameters from farm land were BOD 0.00003,, $COD_{cr}$ 0.00006, TN 0.00056, TP 0.00011, TOC 0.00005, Especially, the runoff ratio of TN showed 10 folds higher than other parameters. On the other hand, the runoff ratio of SS showed higher value of 0.001, and colloid particles of soil caused this result rather than the leachate from compost fertilizer. At all ranges of rainfall intensity, fertilizer removal ratio by farm land was found to be 94.9~98.4% for compost and 85.8~98.1% for liquid compost in terms of BOD. For TN, it resulted in 96.6~98.4% for compost and 97.2~98.5% for liquid compost, and thus the most fertilizer from livestock resources were shown to be reduced through farm land application.

• Journal of Korea Water Resources Association
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• v.44 no.1
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• pp.41-49
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• 2011

This study is a research based on an existing analysis that peak values of unit hydrograph are variant according to rainfall intensity in a watershed. Differently from the fundamental assumption that an unit hydrograph is time-invariant in a watershed a variant unit hydrograph to rainfall intensity by storms is defined and applied into rainfall events, which produces out runoff hydrograph for an examination. Peak flow and time to peak of unit hydrograph used for an application are obtained from the relation equation with rainfall intensity developed by a previous study reviewed, and its shape is made by Nash unit hydrograph which is determined by the peak values. For the purpose of a comparison an invariant unit hydrograph is defined as Nash model obtained from averaged peak values of unit hydrograph which is derived by 26 rainfall storms. Peak flow and time to peak of flood hydrograph developed respectively by variant unit hydrograph with rainfall intensity and an averaged unit hydrograph are compared to those of the observed hydrograph. With comparing both hydrographs calculated by averaged unit hydrograph and revised unit hydrograph to observed hydrograph it is shown the peak flow and time to peak of hydrograph calculated by time-invariant unit hydrograph revised in this study are closer to those of observed hydrograph than those calculated by averaged unit hydrograph.

• Journal of the Korean Geotechnical Society
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• v.35 no.12
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• pp.45-58
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• 2019

In this study, a stochastic analysis procedure based on numerical analysis was proposed to evaluate a kind of intensity-duration rainfall threshold for the initiation of slope failure due to rainfall infiltration. Fragility curves were generated as a function of rainfall intensity-duration from the results of probabilistic slope stability analysis by MCS considering the uncertainty of the soil shear strength, reflecting the results of infiltration analysis of rainfall over time. In the probabilistic analysis, slope stability analyses combined with the infiltration analysis of rainfall were performed to calculate the limit state function. Using the derived fragility curves, a chart showing the relationship between rainfall intensity and slope failure-time was developed. It is based on a probabilistic analysis considering the uncertainty of the soil properties. The proposed probabilistic failure distribution analysis could be beneficial for analyzing the time-dependent failure process of soil slopes due to rainfall infiltration, and for predicting when the slope failure should occur.

• Journal of Korea Water Resources Association
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• v.37 no.2
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• pp.163-172
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• 2004

In this paper, the sub-soil storage system for utilizing urban instream flow of rainfall runoff was developed and examined through experiments. The artificial rainfall facility and sub-soil storage were installed in the experimental area. The effect of the water qualify improvement and the storage effect were analyzed through the several experiments. Through the experiments of rainfall intensity variation, which are the rainfall intensity of 20mm/hr, 30mm/hr, 40mm/hr, 50mm/hr was indicated SS concentration can be reduction until 68％. Also, the ration of the storage volume is varied from 42.8％∼79.9％ based on the rainfall intensity. The reduction rate of the BOD, CO $D_{Mn}$, SS, T-N, T-P was 30％, 42％, 68％, 39％, 26％. As the result, water quality of runoff and efficient of runoff reduction by the system are much improved. The rainfall runoff with the installation of sub-soil storage could be used for instream flow.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.6
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• pp.111-117
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• 2009

The RUSLE(Revised Universal Soil Loss Equation) has been most widely used to estimate sediment yield in Korea. However RUSLE factors have not been verified based on measured data of sediment yield. The analysis of characteristics for the rainfall erosivity factor R was performed in this study. The R factor of RUSLE is expressed as multiple of total rainfall energy and maximum 30 min rainfall intensity. In this study, the characteristics of 10 rainfall energy equations were investigated using data measured in Gangneung experimental watershed, and applicability of each equations was reviewed based on results of the correlation analysis between measured sediment yield and total rainfall, between measured sediment yield and maximum intensity, and between measured sediment yield and total rainfall energy yield. Also, the relationship of I30 and I60 was proposed using 10-min rainfall data during 9 years.