• Korean Journal of Ecology and Environment
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• v.56 no.3
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• pp.187-195
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• 2023

Almost all of the water from agricultural dams located to the upper of the Yeongsan river is supplied as irrigation water for farmland and thus is not discharged to the main stream of the river. Also, most of the irrigation water does not return to the river after use, adding to the lack of flow in the main stream. As a result, the water quality and aquatic health of the river have become the poorest among the four major rivers in Korea. Therefore, in this study, several strategies for water quality improvement of the river were developed considering pollution reduction and flow rate increase, and their effect analysis was performed using a water quality model. The results of this study showed that the target water quality of the Yeongsan river could be achieved if flow increase strategies (FISs) are intensively pursued in parallel with pollution reduction. The reason is because the water quality of the river has been steadily improved through pollution reduction but this method is now nearing the limit. In addition, rainfall-related FISs such as dam construction and water distribution adjustment may be less effective or lost if a megadrought continues due to climate change and then rainfall does not occur for a long time. Therefore, in the future, if the application conditions for the FISs are similar, the seawater desalination facility, which is independent of rainfall, should be considered as the priority installation target among the FISs. The reason is that seawater desalination facilities can replace the water supply function of dams, which are difficult to newly build in Korea, and can be useful as a climate change adaptation facility by preventing water-related disasters in the event of a long-term megadrought.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.24 no.1
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• pp.37-45
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• 2006

Damage of rivers construction is serious to natural disaster by concentration rainfall in summer. Specially, increase of soil erosion breeds flood calamity of river bed accumulation and pondage decline etc., and erosion increase in upper stream shows in rivers flood of earth and sand, farm land and form of urban district burying. Flood damage investigation through on-the-spot probe until present need effective and scientific modelling techniques because is not efficient. This research wished to examine practical use of monitoring data of high resolution satellite image through satellite image analysis of various space resolution. Research analyzed abstraction possibility of soil disaster information using high resolution satellite image. Also, studied soil disaster damage present condition interpretation practical use possibility through various resolution satellite image analysis, and studied practical use of KOMPSAT image for interpretation of river topography change analysis.

• International Journal of Highway Engineering
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• v.13 no.3
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• pp.31-38
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• 2011

As the percentage of permeable ground is reduced due to the increased impermeable roads of major cities, a heat island phenomenon can be dominantly observed, resulting in increased temperature. In addition, rainfall that would have been naturally absorbed and retained by the permeable ground is overflowed due to large volumes of run-off water, resulting in more sewer failures and increased erosion. In terms of permeable pavement system, block paving has been used anywhere as well as provides many years of service. The permeable block paving is an effective alternative to the more traditional asphalt or plain concrete for minor roads; furthermore, it looks a lot better than other pavements. In this study, the functional drainage evaluation of block paving was carried out, considering the usage of experimental sludge and wheel tracking test, in order to simulate the field condition of roads.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.4
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• pp.859-866
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• 1994

It is difficult to make an exact estimate of the peak discharge or the runoff depth of flood and establish the proper measure for the flood protection since the water stage or discharge has been nearly measured at most medium or small river basins. The objective of this study is to estimate parameters of the discrete, linear, input-output model for medium or small river basin. The On-Cheon River basin in Pusan was selected for the study area. The runoff data used in the study has been observed since June 1993, and the effective rainfall was determined using the storage function method. The parameter sets of the discrete, linear, input-output model were estimated using the least squares method and the correlation function method, respectively. The calculated hydrographs by the discrete, linear, input-output model regenerated the observed outflow hydrographs well, and also the simulated flood hydrograph was comparable to the observed one. Therefore, it is believed that the discrete, linear, input-output model is simpler than other runoff analysis methods, and can be applied to a medium or small river basin.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.1
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• pp.21-30
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• 2020

In this paper, we predicted the propagation loss for the air-to-ground (A2G) channel between the ground control system and the unmanned aerial vehicle (UAV) using the prediction model for the aircraft recommended by the International Telecommunication Union (ITU). We analyzed the network coverage of the aerial relay system based on the medium altitude UAVs by expanding it into the air-to-air (A2A) channel. Climate and geographic factors in Korea were used to predict propagation loss due to atmospheres. We used the measured data published by the Telecommunication Technology Association (TTA) for regional rainfall-rate and effective earth radius factors to increase accuracy. In addition, the aerial relay communication system used the key parameter of the common data link (CDL) system developed in Korea recently. Prediction results show that the network coverage of the aerial relay system broadens at higher altitude.

• Journal of the Korean Association of Geographic Information Studies
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• v.13 no.1
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• pp.74-88
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• 2010

In this study, the points of LiDAR were modified in order to generate various DEM resolutions by applying LiDAR data in Ulsan. Since the LiDAR data have points with 1m intervals, the number of points for each resolution was modified to the size of 1, 5, 10, 30, 50, 100m by uniformly eliminating the points. A runoff analysis was performed on Taehwa river and its tributary, Dongcheon, with 200 year rainfall exceedance probability. 2-dimensional inundation analysis was performed based on the density of LiDAR data using FLUMEN, which was used to establish domestic flood risk map. Once DEM data obtained from LiDAR survey are used, it is expected that the study results can be used as data in determining optimal grid spacing, which is economical, effective and accurate in establishing flood defence plans including the creation of flood risk map.

• Journal of the Korean Geosynthetics Society
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• v.4 no.2
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• pp.47-56
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• 2005

Recently, geosynthetic reinforced earth walls are gradually replacing conventional concrete retaining walls for reasons of economy, expediency of construction, and aesthetics. A number of reinforced soil walls having more than 10m heights have been constructed to make more effective development in the country. However, mistakes in design and construction of reinforced earth walls have resulted in many troubles such as failure of reinforced earth walls, horizontal deformationor breakdown of facings, and so forth during or after construction. In this paper, a case study on global sliding failure of a geogrid-reinforced tiered wall is carried out to investigate the causes of the failure and suggest the proper countermeasures. From the subsurface investigation and field instrumentation, It is found that the cause of the global sliding failure was occurred by decreasing of bearing capacity of foundation ground induced by infiltration of rainwater.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.2 no.2
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• pp.43-52
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• 1999

This study was carried out to verify results of the nursery seedbeds. From November of 1997 to September of 1998, the artificial banking slopes in the greenhouse of the College of Agriculture and Life Sciences, Seoul National University were seeded with the mixtures of those species. Most of exotic species showed relatively poor development of root as short as 30cm. Also the green weight of root biomass of the native species was more than two times than that of the exotic species. On the other hand, it was found that the exotic species have relatively well-developed fine roots. Thus, it was concluded that the seed-mixture of the native species with long and thick roots and the exotic species with fine roots be the most effective method for topsoil erosion control on banking-slopes. The artificial rainfall system treatment(30mm/hr, 60mm/hr, 100mm/hr) on $30^{\circ}$ banking-slopes did not cause any significant change in the amount of soil loss by erosion. The root system was best developed in the plot of 1,000 seedlings per square meter and it performed well for soil erosion control. Consequently, in the case of seeding of single herbaceous species without mixing any woody seeds, the expected seedlings were 1,000 to 2,000 per square meter.

• Journal of Korean Society on Water Environment
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• v.28 no.4
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• pp.495-504
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• 2012

In recent years, urbanization has been a hot issues in watershed management due to increased pollutant loads from impervious urban areas. The Soil and Water Assessment Tool (SWAT) model has been widely used in hydrology and water quality studies at watershed scale. However, the SWAT has limitations in simulating water flows between HRUs and hydrological effects of LID practices. The Storm Water Management Model (SWMM) has LID capabilities, but it does not simulate non-urban areas, especially agricultural areas. In this study, a SWAT-SWMM coupled model was developed to evaluate effects of LID practices on hydrology and water quality at mixed-landuse watersheds. This coupled SWAT-SWMM was evaluated by comparing calibrated flow with and without coupled SWAT-SWMM. As a result of this study, the $R^2$ and NSE values with SWAT are 0.951 and 0.937 for calibration period, and 0.882 and 0.875 for validation period, respectively. the $R^2$ and NSE values with SWAT-SWMM are 0.877 and 0.880 for validation period. Out of four LID scenarios simulated by SWAT-SWMM model, the green roof scenario was found to be most effective which reduces about 25% of rainfall-runoff flows.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.752-757
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• 2009

In the last decade, many methods such as greet chamber, reservoir, or debris barrier, have been utilized to manage and prevent muddy water problem. The Vegetative Filter Strip (VFS) has been thought to be one of the most effective methods to trap sediment effectively. The VFS are usually installed at the edge of agricultural areas adjacent to stream or drainage ditches, and it has been shown that the VFS effectively removes pollutants transported with upland runoff. But, if the VFS is installed without any scientific analysis of rainfall-runoff characteristics, soil erosion, and sediment analysis, it may not reduce the sediment as much as expected. Although Soil and Water Assessment Tool (SWAT) model has been used worldwide for many hydrologic and Non-Point Source Pollution (NPSP) analysis at a watershed scale. but it has many limitations in simulating the VFS. Because it considers only 'filter strip width' when the model estimates sediment trapping efficiency, and does not consider the routing of sediment with overland flow option which is expected to maximize the sediment trapping efficiency from upper agricultural subbasin to lower spatially-explicit filter strip. Therefore, the SWAT overland flow option between landuse-subbasins with sediment routing capability was enhanced with modifications in SWAT watershed configuration and SWAT engine. The enhanced SWAT can simulate the sediment trapping efficiency of the VFS in the similar way as the desktop VFSMOD-w system does. Also it now can simulate the effects of overland flow from upper subbasin to reflect the increased runoff volume at the receiving subbasin, which is what is occurring at the field if no diversion channel is installed. In this study, the enhanced SWAT model was applied to small watershed located at Jaun-ri in South Korea to simulate diversion channel and spatially-explicit VFS. It was found that approximately sediment can be reduced by 31%, 65%, 68%, with diversion channel, the VFS, and the VFS with diversion channel, respectively.