• Ocean and Polar Research
• /
• v.33 no.spc3
• /
• pp.385-395
• /
• 2011

Time-series sediment traps were deployed at 1,000 m water depth of the northwestern subtropical Pacific from July 2009 to June 2010, with the aim of understanding temporal and spatial variations of sinking-particle fluxes. The opening and closing of the traps was synchronized at 18-day periods for 20 events. Total mass fluxes showed distinct seasonal variations with high values for the summer-fall seasons and relatively low values for winter-spring. This seasonal variation at two stations was characterized by a distinct difference in $CaCO_3$ fluxes between the two seasons. The enhanced $CaCO_3$ flux in the summer - fall seasons might be attributed to an increased planktonic foraminiferal flux. Total mass flux at FM10 station was nearly 50% higher than that at FM1 station. The difference in $CaCO_3$ fluxes between two stations contributed nearly 70% of the difference of total mass fluxes. The $CaCO_3$ flux was a major component controlling temporal and spatial variation of sinking - particle fluxes in the western subtropical Pacific Ocean.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.10 no.3
• /
• pp.22-30
• /
• 2007

It is difficult to generate DTM using aerial photographs because trees usually cover disaster occurred areas. So, this study proposed how to filter by moving window using digital aerial photographs and generate accurate DTM. The results were compared with those of adaptive filtering by commercial digital photogrammetry software (Socet set) to find out the effect of tree removal by window size in forest soil sediment disaster. And then they were compared with DTM generated from LiDAR data. As a result, it was showed that the accuracy of moving filtering DTM was lower than that of LiDAR DTM while it was higher by 6m than that of Adaptive filtering.

• Journal of Korean Society of Forest Science
• /
• v.98 no.3
• /
• pp.272-278
• /
• 2009

This study was conducted to develope calculation method of standard rainfall, which was used for predicting the outbreaking time of disaster by using Tank model, on warning and evacuation for soil sediment disaster. We investigate adeption possibility of developed method through comparing storage function method with Tank model. We calculated storage amount rainfall by storage function method and Tank model with 36 hillslope failures which have record on outbreaking time of disaster. The result in case of Sedimentary (quarternary period) showed that the difference of outbreaking time was 1.6 hour in case of tank model, but 3.2 hour in case of storage function method. In addition, the deviation of the peak storage were 7% in case of tank model, but 63% in case of storage function method. Total evacuation period was analyzed by using observed 5 years (1993-1997) rainfall data as well as each standard rainfalls which were determinated by two methods. The result showed that evacuation time by storage function method was about twice as many as that by tank model. Therefore, we concluded that calculation by tank model for predicting the outbreaking time of disaster was more useful and accurate than storage function method.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.3
• /
• pp.1-9
• /
• 2020

Acritical function of a nation is to protect its people's lives and properties from natural disasters such as a drought. A drought affects many aspects of human life, including social, economic, and industrial activities. Approximately 75.7% of reservoirs in Korea are over 50 years old.Sedimentation over the years may have caused a situation where storage capacity of the reservoirs is no longer sufficient and compliant with the original reservoir specifications. This study analyzes storage capacities for ten aged reservoirs using the autonomous navigation USV. It compares these capacities with sediment estimated by conventional empirical equations. Comparisons were made to the original specifications for the reservoirs.Storage capacity of six reservoirs decreased in a range between 16.2%-55.3% and storage capacity of 4 reservoirs increased in a range between 1.5%-380.2%. This data was compared to data derived from estimating sediment by empirical equations. Yoon's equation(1982) appeared more accurate than Sur's equation(1988) in Uhlinzi and Yongpo reservoirs, and Sur's equation(1988), however, appeared more accurate than Yoon's equation in Daegok, Ugok2 and Ochi reservoirs. The significant ranges of sedimentation shown in this study suggest that it is worth continuously surveying reservoirs to ensure their efficient management and operation.

• Korean Journal of Soil Science and Fertilizer
• /
• v.49 no.5
• /
• pp.440-448
• /
• 2016

Nonpoint sources of pollution (NPS) is defined as diffuse discharges of pollutants (e.g., nutrient, pesticide, sediment, and enteric microorganism) throughout the natural environment and they are associated with a variety of farming practices. Previous studies found that water soluble anionic polyacrylamide (PAM) is one of the highly effective measures for enhancing infiltration, reducing runoff, preventing erosion, controlling nonpoint source of pollutants, and eventually protecting soil and water environment. Potential benefits of PAM treatment in agricultural soil and water environments have been revealed by many research and they include low cost, easy and quick application, and suitability for use with other Best Management Practices (BMPs) for NPS control. This study reviews the various applications of PAM and discusses its further potentials in agricultural environment.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2019.05a
• /
• pp.148-148
• /
• 2019

The 2006 Millennium Ecosystem Assessment (MA) defines ecosystem services (ES) as "the benefits people obtain from ecosystems". Identifying where ES originates, whom it benefits and how it is changing over a period of time is critical in rapidly developing country like Nepal, where the risk of ES loss is high. In the context of various ecosystem services provided by watershed, this study, particularly deals with water yield, Soil loss and Carbon sequestration computation and evaluation in Bagmati Basin of Nepal. As Bagmati Basin incorporates capital city Kathmandu of nepal, land use change is significant over decades and mapping of ES is crucial for sustainable development of Basin in future. In this regard, the objectives of this study are 1) To compute the total and sub-watershed scale water yield of the basin, 2) Computation of soil loss and sediment retention in the basin, and 3) Computation of carbon sequestration in the basin. Integrated Valuation of Environmental Services and Tradeoffs (InVEST), a popular model for ecosystem service assessment based on Budyko hydrological method is used to compute Ecosystem services. The scenario of ES in two periods of time can be referenced for various approaches of prioritization and incorporation of their value into local and regional decision making for management of basin.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.14 no.2
• /
• pp.80-89
• /
• 2009

The rates of sediment oxygen demand(SOD) and denitrification(DNF) were measured using $^{15}N$ isotope pairing technique in intact sediment cores in the shelf of Dok Island. The SOD and DNF in the continental shelf of Dok Island were ranged from 1.04 to $9.08\;mmol\;m^{-2}\;d^{-1}$ and from 7.06 to $37.67\;{\mu}mol\;m^{-2}\;d^{-1}$, respectively. The SOD and DNF values in this study are higher than typical deep sea sediment. The SOD and DNF in this study were high in the high organic matter content sediment and high organic matter content was promotive of coupled nitrification-denitrification. Organic carbon contents in surface sediment ranged from 1.8 to 2.4%, which is higher than typical deep sea sediments. Therefore we conclude that the organic matter content in surface sediment is determined by the nature of the export production not the water depth in East sea sediment and the nature of the export production also determines remineralization processes such as SOD and DNF in East sea/Ulleung Basin sediment.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.21 no.2
• /
• pp.1-11
• /
• 2018

As a result of climate change, mountain sediment disasters due to localized heavy rain and mountain development are occuring more frequently, thus, increasing social attention to and demand for soil erosion control projects. However, since 2011 Seoul Wumyeon Mountain landslide, the public is expressing increasing anxiety as well as negative perception regarding defective project results. Therefore, this study investigated promotional terms and information media related to soil erosion control projects according to the consumer in order to increase awareness of soil erosion control projects. In this study, the information consumers were divided into experts and the general public and conducted a survey related to promotional terms and media for communicating relevant information. In the result, the experts chose landslide prevention and recovery projects (41.8%) as an appropriate promotional term for soil erosion control projects. The general public, however, chose mountain sediment disaster prevention projects (32.5%) as the appropriate promotional term. However, the analysis showed that it would be necessary to develop an promotional term that can encompass the concept of 'disaster prevention' including forest and soil disaster as the word 'landslide' can suggest soil erosion control is limited to landslides only. In the survey regarding the media for communicating information related to soil erosion control projects according to the consumer type, the experts preferred radio and TV as media to communicate the relevant information, while, among the general public, the youths preferred social media such as Facebook and Twitter (22.22%) and adults radio and TV (34.07%), As for the most effective way to promote soil erosion control projects, the experts chose traditional promotinal media such as newspaper, radio, and TV (0.172) whereas the adults and youths preferred the internet and Facebook (0.089). It appears that using the preferred media for communicating information related to soil erosion control projects according to the consumer type will be effective way to promote soil erosion control projects.

• Proceedings of the Korean Society of Disaster Information Conference
• /
• 2016.11a
• /
• pp.391-392
• /
• 2016

본 연구에서는 우리나라 댐 저수지의 퇴사위 결정 방법에 대해 고찰해보고자 한다. 현재 우리나라에서 시행되고 있는 댐 저수지의 퇴사위 결정 방법에 대해서 조사하고 국외 여러나라에서의 퇴사위 결정 방법과의 비교를 통한 결과, 퇴사위 결정 방법에서는 경험적면적감소법(Empirical area reduction method)이 좀 더 논리적으로 기인한 것을 확인할 수 있었다. 향후, 댐 계획 및 설계시 구조적인 차원에서 짚고 넘어가야 할 문제일 것으로 판단되며, 설계기준 재정립시 이러한 사항을 수정 및 보완해야 할 것으로 사료된다.

• Proceedings of the Korean Society of Disaster Information Conference
• /
• 2015.11a
• /
• pp.261-264
• /
• 2015

본 연구에서는 해안 침식의 원인 중 유역 개발로 인한 해안으로의 표사 공급원이 감소를 검토하고, 그에 따른 표사계의 미래 해안 침식률을 분석하였다. 우리나라 서해의 경우 유역 개발로 인해 하천으로부터의 표사 유입 차단은 심각한 수준이다. 아직 그 영향이 해안으로 완전히 파급되지 못하여 그로 인한 장기 해안 침식이 두드러지지 않고 있다. 또한 피해가 심각해지기 시작하면 돌이킬 수 없는 재앙이 될 측면도 많다. 따라서 본 연구에서는 금강유역을 연구대상지역으로 설정하여 유역 개발로 인한 표사 유입량 감소를 계산하여 주변 표사계 내 미래 해안의 침식률을 산정하였다. 이는 향후 유역개발로 인한 미래 침식 위험 지역의 판단과 침식 위험도 평가 도입시 유용하게 사용될 수 있을 것으로 기대된다.