• ALGAE
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• v.23 no.4
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• pp.277-288
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• 2008

The relationship between nutrients and phytoplankton dynamics was investigated daily from 12 April to 22 July 2003 in Sagami Bay, Japan. According to multidimensional scaling (MDS) and cluster analysis, phytoplankton community was divided into four distinct groups. The first group was consisted of centric diatom species, such as Guinardia spp., Detonula spp., Letocylindrus danicus, Skeletonema costatum, Eucampia zodiacus and Chaetoceros spp.. The second and third clusters comprised mainly diatoms and dinoflagellates, respectively. The other cluster was restricted to the samples collected during the last sampling period when the rainfall and river discharge was frequently recorded. Canonical correspondence analysis (CCA) was applied to analyze four groups respectively, which focused on the effects of nutrients concentration and ratio on phytoplankton variations. Based on CCA analysis, most species of centric diatom were negatively correlated with DSi concentrations and Si/N ratio. Nutrients were strongly limited phytoplankton growth during the summer when the rainfall was not observed, whereas river discharge by rainfall and counterclockwise coastal currents (although the surface circulation pattern is often altered by Kuroshio Current, the counterclockwise coastal currents are generally dominant) has brought phytoplankton population accumulation and triggered the micoalgae growth in western part of the bay. Phosphorous (P) was strongly limited after significantly increases in the phytoplankton abundances. However, silicate (Si) was not a major limiting factor for phytoplankton production, since Si/DIN and Si/P ratio did not create any potential stoichiometric limitation. This indicates that high Si availability contributes favorably to the maintenance of diatom ecosystems in Sagami Bay.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.5
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• pp.645-654
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• 2018

Extreme rainfall events caused severe damage to human life and property due to the inundation in major urban areas. In particular, the increase in the intensity of rainfall due to climate change causes changes in the design flood discharge. As a result, it causes uncertainty in the design criteria of hydraulic structures. However, quantitative analysis results have not been provided due to the limitations of climate scenarios and the uncertainty in climate changes. Therefore, this research chose Bulgwangcheon basin as the target basin to analysis the discharge considering climate change. As the result, it is necessary to strengthen design standards since the amount of discharge increased by 14.2% even in the near future.

• Journal of the Korean Data and Information Science Society
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• v.27 no.5
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• pp.1119-1131
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• 2016

The Neyman-Scott Rectangular Pulses Model (NSRPM) is mainly used to construct hourly rainfall series. This model uses a modest number of parameters to represent the rainfall processes and underlying physical phenomena, such as the arrival of storms or rain cells. In NSRPM, the method of moments has often been used because it is difficult to know the distribution of rainfall intensity. Recently, approximated likelihood function for NSRPM has been introduced. In this paper, we propose a hierarchical model for applying a spatial structure to the NSRPM parameters using the approximated likelihood function. The proposed method is applied to summer hourly precipitation data observed at 59 weather stations (Korea Meteorological Administration) from 1973 to 2011.

• Korean Journal of Agricultural Science
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• v.51 no.1
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• pp.79-86
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• 2024

As the frequency and intensity of heavy rains increase, the vulnerability of agriculture to disasters also increases. Consequently, there is a need to improve flood and inundation predictions. To enhance the accuracy of inundation predictions, it is essential to monitor water level and discharge data within agricultural areas. This study was conducted to monitor water levels and rainfall in the Cheongju Sindae area from 2022 to 2023, and the data was utilized as input and validation data for agricultural inundation modeling. Four irrigation drainage canals were installed to a square-shaped concrete structure where the water level gauge is. It was then confirmed that the water level rises with rainfall. The flow velocities were monitored during periods of heavy rainfall. The rating curve, which estimates water level and flow velocity based on observations, was estimated using the software K-HQ. The resulting curve was presented with the Coefficient of Determination (R²). K-HQ was also used to calculate the equation for the rating curve, taking outliers into account at each data point. Outliers were extracted and the rating curve was recalculated. As the coefficient of determination of three out of four stations exceeded 0.95, the estimated rating curve may be considered reliable for discharge estimation. This study provides critical data for enhancing agricultural inundation modeling accuracy and drainage improvement projects.

• Water Engineering Research
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• v.1 no.3
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• pp.209-222
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• 2000

A spectral formalism was applied to quantify the sampling errors due to spatial and/or temporal gaps in soil moisture measurements. The lack of temporal measurements of the two-dimensional soil moisture field makes it difficult to compute the spectra directly from observed records. Therefore, the space-time soil moisture spectra derived by stochastic models of rainfall and soil moisture was used in their record. Parameters for both models were tuned with Southern Great Plains Hydrology Experiment(SGP'97) data and the Oklahoma Mesonet data. The structure of soil moisture data is discrete in space and time. A design filter was developed to compute the sampling errors for discrete measurements in space and time. This filter has the advantage in its general form applicable for all kinds of sampling designs. Sampling errors of the soil moisture estimation during the SGP'97 Hydrology Experiment period were estimated. The sampling errors for various sampling designs such as satedlite over pass and point measurement ground probe were estimated under the climate condition between June and August 1997 and soil properties of the SGP'97 experimental area. The ground truth design was evaluated to 25km and 50km spatial gap and the temporal gap from zero to 5 days.

• Journal of Environmental Health Sciences
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• v.34 no.3
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• pp.247-254
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• 2008

Non-point source pollution that originates from surface applied chemicals in either liquid or solid form is a part of urban activities and it appears in the surface runoff caused by rainfall. This study investigates the characteristics of non point source pollution in relation to storm events and the first washing effect in the Study area, which is comprised of different land use types. Then, a Best Management Practices (BMP) model, for urban areas, is applied with the Storm water Management Model (SWMM) Windows Interface which was developed by the EPA in the USA. During the storm event analysis of the hydrographic and pollutographic data showed that the peak of pollutants concentration was within the peak flow, 30 to 60 minute into the storm event in the Study area. The results of simulation using SWMM Windows Interface, Structure Techniques as applied in the study were highly efficient for removal of pollutants. Predicted removal efficiency was 26.0% for SS, 22.1 for BOD, 24.1% for COD, 20.6% for T-N, and 21.6% for T-P, respectively.

• Korean Journal of Remote Sensing
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• v.16 no.4
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• pp.293-303
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• 2000

The typhoon Jelawat, which was formed over the tropical Pacific ocean on August 1, 2000 and made a landfall over China on August 10, 2000, was observed by Korea Multi-purpose Satellite (KOMPSAT-1) Ocean Scanning Multispectral Imager (OSMI), Tropical Rainfall Measuring Mission (TRMM)/Precipitation Radar(PR) and Quick Scatterometer (QuikSCAT). In spite of discontinuous observation, important mesoscale features of typhoon depending on life cycle were detected prominently. It is possible to distinguish on the OSMI photograph between the eye-wall convection and the stratiform and other convective clouds near the center of typhoon Jelawat. The TRMM/PR observations show quite clearly the eye-wall convection, stratiform regions, and convective bands. Vertical cross section of rainfall in the genesis stage of typhoon Jelawat exhibits circular ring of intense convection surrounding the eye. The mature stage of typhoon Jelawat consists of a strong rotational circulation with clouds which are well organized about a center of low pressure. The OSMI, TRMM/PR and QuikSCAT measurements presented here agree qualitatively with each other and provide a wealth of information on the structure of typhoon Jelawat.

• Membrane and Water Treatment
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• v.10 no.1
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• pp.67-74
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• 2019

Apparent changes in the natural hydrologic cycle causing more frequent floods in urban areas and surface water quality impairment have led stormwater management solutions towards the use of green and sustainable practices that aims to replicate pre-urbanization hydrology. Among the widely documented applications are infiltration techniques that temporarily store rainfall runoff while promoting evapotranspiration, groundwater recharge through infiltration, and diffuse pollutant reduction. In this study, a laboratory-scale infiltration device was built to be able to observe and determine the factors affecting flow variations and corresponding solids removal through a series of experiments employing semi-synthetic stormwater runoff. Results reveal that runoff and solids reduction is greatly influenced by the infiltration capability of the underlying soil which is also affected by rainfall intensity and the available depth for water storage. For gravel-filled structures, a depth of at least 1 m and subsoil infiltration rates of not more than 200 mm/h are suggested for optimum volume reduction and pollutant removal. Moreover, it was found that the length of the structure is more critical than the depth for applications in low infiltration soils. These findings provide a contribution to existing guidelines and current understanding in design and applicability of infiltration systems.

• Journal of Korean Society of Water and Wastewater
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• v.31 no.6
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• pp.567-575
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• 2017

It is not cost effective to raise the density of catch basins in preparation for heavy rainfall in terms of construction and maintenance. Our researchers have developed the new catch basin for increasing interception capacity of runoff with internal filtration structure. To compare interception capacity of an existing catch basin with the invented catch basin, a hydraulic experiment device with 4% of road gradients and 0.2% of road gradients was constructed. For runoff conditions of 4.4 l/s, 6.7 l/s and 10.4 l/s, capability of runoff and separation capability of debris (sand and leaves) were evaluated. As the main experimental results, the effectiveness of the developed catch basin has been verified with an increase in interception rate of approximately 22% for the runoff of 6.7 l/s as heavy rainfall. However, the results of invented catch basin showed only 4.5% of settlement rate of debris regarding sand. Therefore, the authors proposed an improved tilted screen structure additionally. After reviewing the performance of improved catch basin, application of the invented catch basin is expected to drain runoff effectively when it is applied to the faulty road drainage section.

• Journal of the Korean Geosynthetics Society
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• v.15 no.4
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• pp.105-115
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• 2016

This paper describes a restoration of retaining wall, which was collapsed by rainfall. The failure causes was analyzed by field case, and then the countermeasure was suggested. The failure causes confirmed that observance of design and construction criteria was insufficient. It also was the climate condition like a rainfall and inappropriate construction management. The stability analysis for retaining wall, soil improvement and reinforced earth wall was conducted to confirm validity of the countermeasure. The analysis results showed that the suggested construction method satisfied in required safety factors. Therefore, it should be secured the stability of the structure based on the application of appropriate design method and construction management, when structure was constructed.