• Journal of Korea Water Resources Association
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• v.54 no.12
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• pp.1329-1338
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• 2021

Rain radar provides high spatio-temporal radar rainfall that can be used as input data to short-term precipitation forecasting models. Korea Institute of Civil Engineering and Building Technology (KICT) has developed a flash flood forecasting system that is providing flash flood forecasting based on short-term rainfall forecasts estimated by the radar rainfall. Accuracy of the radar rainfall as well as the short-term rainfall forecasts, however, can deteriorate when radar polarimetric variables have error. In this study, we develope real-time program that can correct the error inherent in the radar polarimetric variables. First, effect according to the correction of the error was verified using 363 rainfall events on non real-time. The accuracy (1-NE) of the radar rainfall was approximately 70% and correlation coefficient was higher than 0.8 after correcting the error on non real-time. The accuracy (1-NE) using the real-time program was also approximately 70% after correcting the error.

• Journal of Wetlands Research
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• v.20 no.4
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• pp.370-382
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• 2018

The purpose of this study is to quantitatively and effectively evaluate the factors affecting flood damage by watershed. National Water Resource Plan(MOCT, 2001) has been developed Potential Flood Damage(PFD) which indicates flood vulnerability. But, it is only a simple grouping and it does not provide guidelines for flood control planning based on detailed evaluation of sub-components. In this study, we used PFD in the Han River basin according to the method applied in the National Water Resource Plan (existing method) and improvement based on actual flood hazard area and data. As an application method, after analyzing by yearly change(2009~2014), we compared and analyzed the tendency of the sub - components that constitute the potential and risk rather than the current grouping. As the result, it was possible to accurately evaluate the existing and improved methods, and it was possible to derive the vulnerability rankings, but the existing methods have different results from the actual watershed tendency. Therefore, the PFD of the improvement method that correctly reflects past history and watershed characteristics is more appropriate for the evaluation of flood vulnerability in the watershed. In addition, it is reasonable to establish a flood control plan referring to this and prevent flood damage in advance.

• Journal of Multimedia Information System
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• v.5 no.4
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• pp.235-244
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• 2018

Potential maximum soil moisture retention (S) is a dominant parameter in the Soil Conservation Service (SCS; now called the USDA Natural Resources Conservation Service (NRCS)) runoff Curve Number (CN) method commonly used in hydrologic modeling for event-based flood forecasting (SCS, 1985). Physically, S represents the depth [L] soil could store water through infiltration. The depth of soil moisture retention will vary depending on infiltration from previous rainfall events; an adjustment is usually made using a factor for Antecedent Moisture Conditions (AMCs). Application of the method for continuous simulation of multiple storms has typically involved updating the AMC and S. However, these studies have focused on a time step where S is allowed to vary at daily or longer time scales. While useful for hydrologic events that span multiple days, this temporal resolution is too coarse for short-term applications such as flash flood events. In this study, an approach for deriving a time-variable potential maximum soil moisture retention curve (S-curve) at hourly time-scales is presented. The methodology is applied to the Napa River basin, California. Rainfall events from 2011 to 2012 are used for estimating the event-based S. As a result, we derive an S-curve which is classified into three sections depending on the recovery rate of S for soil moisture conditions ranging from 1) dry, 2) transitional from dry to wet, and 3) wet. The first section is described as gradually increasing recovering S (0.97 mm/hr or 23.28 mm/day), the second section is described as steeply recovering S (2.11 mm/hr or 50.64 mm/day) and the third section is described as gradually decreasing recovery (0.34 mm/hr or 8.16 mm/day). Using the S-curve, we can estimate the hourly change of soil moisture content according to the time duration after rainfall cessation, which is then used to estimate direct runoff for a continuous simulation for flood forecasting.

• Journal of Environmental Health Sciences
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• v.45 no.3
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• pp.238-246
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• 2019

Objective: The purpose of this study was to investigate the distribution of mineral components, health and taste index for water supply plants, spring water located in northern Gyeonggi area and bottled waters in market to analyze Ca, K, Mg Na, Si, $F^-$ and $SO_4{^{2-}}$. Method: The samples were source and tap water in 15 water supply plants over 9 river basin, 172 spring water and 20 bottled water. The Ca, K, Mg Na and Si were analyzed by ICP-OES. The $F^-$ and $SO_4{^{2-}}$ were determined by Ion Chromatograph. Then, taste and health index were calculated using Hashimoto equation. Results: The average concentration of major minerals showed in same order of Ca > Na > Mg > K for all kinds of drinking water from water supply plants, spring waters and bottled waters. Total concentration of major minerals (Ca, K, Mg, Na) was calculated that showed 26.79 mg/L of tap water, 21.81 mg/L of spring water, 32.94 mg/L of bottled water on average. So, the spring waters indicated the lowest minerals sum. The tap water from water supply plants was categorized to Group I, II for 33.3, 44.4% according to K-index and O-index. Otherwise, spring water was classified as Group I, II for 44.0, 46.3%. Conclusion: According to the results of K and O-index, water from water supply plant showed higher K-index which means good for the health. Otherwise, spring water indicated higher O-index that people can feel more delicious than tap water. Futhermore, the mineral distribution of source water from water supply plants and spring water had indicated high correlation with geological effect.

• Korean Journal of Heritage: History & Science
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• v.52 no.1
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• pp.242-257
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• 2019

The Demilitarized Zone (DMZ) stretches two kilometers north and south from the Military Demarcation Line (MDL) of South and North Korea. This area was established as a weapons-free buffer zone when an armistice agreement was signed in 1953. However, there have been several very high-tension military standoffss over the past 65 years. On the South Korean side, civilian access to the Civilian Control Line (CCL) and beyond to the north has been restricted, and natural heritage has been well maintained. Natural heritage is defined as living things, their habitat and non-living things of the ecosystem which deserve to be protected. Research shows that a variety of flora and fauna, their habitat, marshes and geographical structures are found across the DMZ region. Although the DMZ region has not been such a good place for habitat conservation, we can say that this area may be the best location for restoration in terms of its variety of ecosystems and considerable land size. Restoration of course depends on future plans and management policies. This area, including the DMZ and the well-protected north of the CCL, will be the best habitat for endangered species of wild fauna and flora if we classify the various habitat types and create a habitat map. In doing this project, we need to include the estuary of the Han River and the lagoon (brackish water lake) of the East Sea coast. In addition, we must establish long-term plans for conservation and sustainable use and do international scientific research across the DMZ region in collaboration with scientists of South and North Korea and international experts. Mutual cooperation between the two Koreas for investigation and conservation efforts is paramount.

• Journal of Korea Water Resources Association
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• v.52 no.5
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• pp.337-347
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• 2019

This study proposes the framework to select the representative general circulation model (GCM) for climate change projection. The grid-based results of GCMs were transformed to all considered meteorological stations using inverse distance weighted (IDW) method and its results were compared to the observed precipitation. Six quantile mapping methods and random forest method were used to correct the bias between GCM's and the observation data. Thus, the empirical quantile which belongs to non-parameteric transformation method was selected as a best bias correction method by comparing the measures of performance indicators. Then, one of the multi-criteria decision techniques, TOPSIS (Technique for Order of Preference by Ideal Solution), was used to find the representative GCM using the performances of four GCMs after the bias correction using empirical quantile method. As a result, GISS-E2-R was the best and followed by MIROC5, CSIRO-Mk3-6-0, and CCSM4. Because these results are limited several GCMs, different results will be expected if more GCM data considered.

• Korean Journal of Ichthyology
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• v.31 no.1
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• pp.16-22
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• 2019

Investigations on the study of the distribution aspects and extinction threat evaluation of the Korean endemic species, Iksookimia pacifica were done from 2017 to 2018 in Korea. During the study period, the samples of I. pacifica were collected in 17 streams, 46 sites (from Baebongcheon Stream of Goseong-gun to Gunsuncheon Stream of Gangneung-si) among the noted 33 streams and 104 sampling sites investigated. The population size of I. pacifica was relatively large in streams such as Bukcheon, Baebongcheon, Hwasangcheon, Cheonjincheon, Ohhocheon Stream etc., but the population size was small in streams such as Sacheoncheon, Namcheon, Gangneung Namdaecheon Stream etc. The main habitat of I. pacifica was the downstream pool of clean water with slow velocity and sand bottoms, and their sensibility was estimated to be due to river work and water pollution. Comparing the previous records of the appearance of I. pacifica, they were first seen in Sampocheon Stream, but they did not appear in Jusucheon, Jeoncheon, Samcheok Osipcheon Stream. Given this evidence as noted for the 19.5% reduction in occupancy within 3 generations, in small appearance range ($1,343km^2$) and small occupancy area ($184km^2$), the number of locations were many (18) and the population was relatively large within the range of habitat. Therefore, I. pacifica is now considered a Near Threatened (NT) based on the IUCN Red List categories and criteria.

• Korean Journal of Plant Resources
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• v.32 no.2
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• pp.201-206
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• 2019

Alien invasive species are introduced with or without intent and spreading all over Korea. They are known to have negative effects on biodiversity such as economic and environmental damage and causing decrease or loss of native species. The habitats like wetland, reservoir and riverside are especially in danger of being invaded by alien species due to stress and disturbance. Therefore, Korea National Arboretum is steadily working on research and studies on managing alien invasive species. This research aims to collect basic information of Ludwigia peploides subsp. montevidensis (Spreng.) P.H. Raven which was found near riverside in Suwon-si and is concerned to become an invasive alien species. We expect the description, diagram and pictures of this taxon will be helpful for early detection and effective management.

• Journal of Cadastre & Land InformatiX
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• v.51 no.1
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• pp.97-110
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• 2021

This study estimated the delay factor, which is the ratio of travel time at the speed limit and travel time at the actual speed using real-time traffic information in Seoul. The actual travel speed on the road was lower than the maximum speed of the road and the travel speed was the slowest during the rush hour. As a result of accessibility analysis based on travel speed during the rush hour, the travel time at the actual speed was 37.49 minutes on average. However, the travel time at the speed limit was 15.70 minutes on average. This result indicated that the travel time at the actual speed is 2.4 times longer than that at the speed limit. In addition, this study proposedly defined the delay factor as the ratio of accessibility by the speed limit and accessibility to actual travel speed. As a result of delay factor analysis, the delay factor of Seoul was 2.44. The results by the administrative district showed that the delay factor in the north part areas of the Han River is higher than her south part areas. Analysis results after applying the relationship between road density and traffic volume showed that as the traffic volume with road density increased, the delay factor decreased. These results indicated that it could not be said that heavy traffic caused longer travel time. Therefore, follow-up research is needed based on more detailed information such as road system shape, road width, and signal system for finding the exact cause of increased travel time.

• Journal of Environmental Impact Assessment
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• v.30 no.3
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• pp.164-174
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• 2021

Information on biodiversity plays an important role in conservation planning for ecosystem. As existing biodiversity indices are calculated and predicted only based on the number of individuals and species, it is difficult to explain aspects of genetic and ecological diversity. Phylogenetic diversity can indirectly evaluate ecological diversity as well as genetic diversity overlooked by existing biodiversity assessments. In this study, typical metrics of biodiversity (e.g., species diversity, species richness, etc.) and phylogenetic diversity were evaluated together using a long-term monitoring data of winter birds in Jungrang, Cheonggye and Anyang stream where are designated as Seoul migratory bird reserves. Then discussed the meaning of each assessmentresult. In Jungrang and Anyang stream, the number of individuals generally decreased overtime, whereas in Cheonggye stream, there was no significant change. In addition, species abundance increased over time slightly in Cheonggye stream, while there was no significant change in Jungrang and Anyang stream. Species diversity temporally increased in Jungrang and Cheonggye stream, excluding Anyang stream, but phylogenetic diversity showed a tendency to increase only in Cheonggye stream. These changes in the biodiversity assessment indices are thought to be due to anthropogenic disturbances such as construction that occurred within each site, and it was shown that species diversity and phylogenetic diversity do not always lead to the same assessment results. Therefore, this study suggests that biodiversity assessment needs to be considered from various contexts such as genetic and ecological perspectives.