• Journal of Korean Society of Forest Science
• /
• v.107 no.1
• /
• pp.108-111
• /
• 2018

Increasing soil surface roughness can be effective in enhancing infiltration of rainfall and depression storage capacity of forest soil and reducing surface run-off. In this study, a forest slope with hemispherical depressions shows greater infiltration of water, whereas depression storage capacity is higher in soil with depressions perpendicular to a water flow pathway. Soil pitting or forming surface depressions can be used as a countermeasure after forest fires and a practical way to reduce drought stress of forest soil.

• Atmosphere
• /
• v.26 no.3
• /
• pp.461-471
• /
• 2016

A quality check algorithm for the Weather Information Service Engine pulsed Doppler wind lidar is developed from a view point of spatial and temporal consistencies of observed wind speed. Threshold values for quality check are determined by statistical analysis on the standard deviation of 3-component of wind speed obtained by a wind lidar, and the vertical gradient of horizontal wind speed obtained by a radiosonde system. The algorithm includes carrier-to-noise ratio (CNR) check, data availability check, and vertical gradient of horizontal wind speed check. That is, data sets whose CNR is less than -29 dB, data availability is less than 90%, or vertical gradient of horizontal wind speed is less than $-0.028s^{-1}$ or larger than $0.032s^{-1}$ are classified as 'doubtful', and flagged. The developed quality check algorithm is applied to data obtained at Bucheon station for the period from 1 to 30 September 2015. It is found that the number of 'doubtful' data shows maxima around 2000 m high, but the ratio of 'doubtful' to height-total data increases with increasing height due to atmospheric boundary height, cloud, or rainfall, etc. It is also found that the quality check by data availability is more effective than those by carrier to noise ratio or vertical gradient of horizontal wind speed to remove an erroneous noise data.

• Journal of Korean Society of Water and Wastewater
• /
• v.20 no.4
• /
• pp.585-594
• /
• 2006

This study focused on the causes of fish kills and its prevention methods in Yudeung Stream, Daejeon, Korea. Intense field data, continuous water quality monitoring system and water quality modeling were applied to analyze the causes. Pollutant can be delivered to urban streams by surface runoff and combined sewer overflows in rainfall events. However, water quality analysis and water quality modeling results indicate that the abrupt fish kills in the Yudeung stream seems to be caused by combined effect of DO depletion, increase in turbidity and other toxic material. Excessive fish population in the study area may harm the aesthetic value of the stream and also has greater potential for massive fish kills. It is suggested to implement methods to reduce delivery of pollutants to the stream not only to prevent fish kills but also to keep balance of ecosystem including human uses. Frequent clean up of the urban surface and CSO, installation of detention basin will be helpful. In the long run, it seems combined sewer system has be replaced with separate sewer system for more effective pollutant removal in the urban area.

• Journal of the Korean Geotechnical Society
• /
• v.18 no.6
• /
• pp.117-127
• /
• 2002

A deterministic approach of slope stability, which is generally corresponding to the model of a simple non-linear function for slopes, is problematic in that it does not account the versatile characteristics of ground layers in an effective way. To resolve this problem, this study proposes a new way of analyzing slope stability, so-called “genetic algorithm method, ” so as to reflect some particular conditions pertaining to the grounds under concern. Similarities and differences in slope stability that may exist between homogeneous and multiple ground layers are examined in a competitive manner, Overall, though similarities deemed a little bit salient, the algorithm method turned out to be very applicable to estimating the validity of slope stability. Furthermore, an additional effort to consider long-standing sequential and dynamic changes in both the amount of rainfall and the underground water level is made in order to improve the results.

• KCID journal
• /
• v.17 no.2
• /
• pp.105-114
• /
• 2010

Tidal land reclamation provided water resources and land for agriculture and contributed stable crop production. However, climate change by global warming disrupts the hydrologic circulatory system of the earth resulting in sea level rise and more frequent flood for reclaimed arable land. Recently, Suyu reclaimed paddy field in Jindo-gun experienced prolonged inundation after heavy rainfall and there is a growing risk of flood damage. Onsite survey and flood analysis using GATE_Pro model of Korea Rural Corporation were conducted to investigate causes of flooding. To perform the analysis, input data such as inflow hydrograph, the lowest elevation of paddy field, neap tide level, management level of Gunnae estuary lake at the time of the flood were collected. Flood analysis confirmed that current drainage facilities are not enough to prevent 20year return period flood. The result of analysis showed flooding more than 24hours. Therefore, flood mitigation alternatives such as sluice gate expansion, installation drainage pumping station, refill paddy land, and catch canal were studied. Replacing drainage culvert of Suyu dike to sluice gate and installing drainage pumping station at the Gunne lake were identified as an effective flood control measures. Furthermore, TM/TC (SCADA) system and expert for gate management are required for the better management of drainage for estuary dam and flood mitigation.

• Journal of Korean Society on Water Environment
• /
• v.23 no.1
• /
• pp.52-63
• /
• 2007

The objectives of this study were to setup a laterally-averaged two-dimensional eutrophication model in Daecheong Reservoir, and to validate the model under two different hydrological conditions; drought year (2001) and wet year (2004). The suggested modeling approach was found to be very effective to simulate the dynamic variations of water temperature, nutrients, dissolved oxygen, and algae in the reservoir. The model satisfactorily replicated the algal bloom that happened between Janggae (Sta.4) and Haenam (Sta.5) during summer of 2001, although the peak concentration was slightly underestimated due to the laterally averaged assumption. The allochthonous phosphorus and algae induced from upstream and So-oak stream during several rainfall events were found to be most significant sources of algal bloom in 2001. In contrast to draught year, the flood events happened during summer months of 2004 tended to remove the hypolimnetic anaerobic conditions and dilute the dissolved phosphorus in the upper reach of the reservoir, and in turn mitigated algal bloom. It implies that the impact of hydrological and hydrodynamic conditions on the reservoir water quality is highly significant, and a drought year may be more vulnerable to algal bloom in the reservoir.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2007.05a
• /
• pp.1200-1204
• /
• 2007

최근 도시화가 진행됨에 따라 경작지, 녹지대 등의 우수저류기능이 건물이나 포장에 의해 감소하게 되어 하수관거나 하천으로 유입되는 홍수유출량이 증가하고, 홍수도달시간은 단축됨에 따라 첨두유출량도 빠르게 증가되고 있다. 일반적으로 도시유역의 홍수배제를 위한 시설중의 하나인 우수배제펌프장 설계시 우수유출량 산정에 있어서 $\ulcorner$하수도 시설기준$\lrcorner$에 제시되어 있는 합리식에 근거하여 산정하고 있다. 펌프장 설계시 합리식에 근거한 유입량 산정결과 일반적으로 과대한 결과가 도출되어 이에 대한 개선이 요구되고 있으나 아직 진부한 실정이다. 이러한 문제점을 조금이나 개선하고자 기존의 방법을 개선 유출계수(C) 대신 GIS를 이용한 유출곡선지수(CN)를 이용 유효강우량을 산정한 후, 이를 유역에 적용하여 유출에 기여하는 홍수량을 산정 기존 방법과의 비교 검토를 수행한 결과 CN을 이용한 유효강우량에 의한 유출이 C를 이용한 유출보다 첨두유출량이 작게 산정되었다. 유역의 특성을 현실적으로 반영한 결과 기존 합리식에 의거 도시지역펌프장의 설계시 보다 합리적이며 경제적인 것으로 판단되었다.

• Spatial Information Research
• /
• v.12 no.4 s.31
• /
• pp.329-337
• /
• 2004

Typhoons Rusa (2002) and Maemi (2003) struck Kangwon and Gyeongnam provinces of Korea and caused the most extensive flood damages ever blown since the foundation of Meteorological Agency in 1927. Many cities are inundated, crippling the critical facilities and resulting In high irreversible losses of human lives, and damages to infrastructures. These kinds of flood damages were among the worst natural disaster that Korean people experienced. In order to reduce flood damage, it is necessary to investigate how to use the information of water environment during the rainfall disaster. Therefore as per the result of this study, we have suggested few but effective countermeasures for controlling the flooding damages and also the advancements in the areas of disaster information dissemination and early warning system for water environmental management by using optical fiber system in Japan are discussed.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.39 no.1
• /
• pp.64-74
• /
• 1997

A CELTHYM(CEll-based Long-term HYdrologic Model), a pre-processor and a post-processor that can be integrated with geographic information system(GIS) were developed to predict the stream flow from the small agricultural watershed on the daily basis. The CELTHYM calculates the direct runoff from a grid using SCS curve number method and then sum up all of cells with respect to a sub-catchment area belonged to a stream grid and integrated to an outlet. Base flow of a watershed outlet was computed by integrating of the base flow of each stream grid that was averaged the sub-catchment deep-percolation and calculated with the release rate. Two kind of water budget equation were used to compute the water balance in a grid that was classified into not paddy field and paddy field. One of the two equation is a soil water balance equation to account the soil moisture of the upland, forest and excluding paddy field grid. The other is a paddy water balance equation for the paddy field, calculating the ponding depth, the effective rainfall, the deep percolation and the evapotranspiration.

• Journal of Industrial Technology
• /
• v.29 no.A
• /
• pp.55-60
• /
• 2009

Stabilization treatment is one of processes for wastes and their components to reduce their toxicity and migration rates to surroundings. Inorganic binders such as calcium hydroxide, blast furnace slag and red mud were tested for their potential applicability to in-situ stabilization of heavy metal contaminated tailings in the abandoned metal mines. Columns(150mm dia. ${\times}$ 450mm length) filled with mixtures of inorganic binders and tailing from the Geumjang mine with various mixing ratios of binders to tailings, 5%, 7% and 9% were applied artificial rainfall tests for 28 days. Effluents from columns filled with calcium hydroxide and tailing showed high pH's of ~12.5 and a increasing trend of concentration in Pb and Zn with a significant decrease in permeability in terms of elapsed days. Those with burning slag and tailing showed pH's of ~8.5 and significantly low concentrations in heavy metals with a stable permeability. In case of red mud, effluents showed significantly low concentrations in heavy metals but a decreased permeability with pH's of ~10.5. Conclusively, this basic study suggests burning furnace slag be a potential stabilizer for effective treatment of heavy metal contaminated mine tailings.