• Korean Journal of Agricultural and Forest Meteorology
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• v.15 no.4
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• pp.304-311
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• 2013

There have been increasing cases for farmers to install automated weather stations (AWS) at their farms and orchards in order to take countermeasures to more frequent weather disasters caused by climate variability and weather extremes. Although raw data are the same, the additive values as agrometeorological information may vary depending on data processing methods. User demands on appropriate information could also be different among crop species, cropping systems and even cultivars. We designed an internet based AWS data processing and display system to help diverse users (e.g., farmers), extension workers to access their weather data on specific demands. The system was implemented at a rural catchment with 52 $km^2$ land area where 14 automated weather stations are in operation. This note introduces the system and describes the major modules in detail. By linking regional AWS networks, a feasibility for this system as an early warning system is also discussed.

• Journal of Korea Water Resources Association
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• v.42 no.2
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• pp.117-129
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• 2009

Evaporation over the world is expected to increase owing to increase in temperature by global warming. However, pan evaporation around the world has decreased in the past few decades. This study, which has been conducted in 18 meteorological gauging stations in Korean peninsula, investigates the changes in pan evaporation and climate variables such as precipitation, temperature, relative humidity, wind speed, sunshine hours, and percentage of sunshine, which can affect evaporation processes; the changes in these variables have been recorded between 1960 and 2007. At most gauging stations, pan evaporation shows statistically significant downward trends. The relative humidity, wind speed, sunshine hours, and percentage of sunshine also show downward trends. On the other hand, precipitation and temperature show upward trends. The spatial distribution of the downward trend in sunshine hours and percentage of sunshine correspond to that of the downward trend in pan evaporation. Scatter plots imply that pan evaporation has a strong positive correlation with the sunshine hours and percentage of sunshine, while it has a negative correlation with precipitation. At the Gangneung gauging station, the open water evaporation estimated using the Penman equation does not show the significant downward trend shown by pan evaporation. This result implies that pan evaporation is not a good indicator of potential or open water evaporations during the investigation of their long-term variability. Finally, this study explains the complementary relationship between pan and actual evaporations. Decreases in the pan evaporation can act as an evidence for the ever-increasing actual evaporation.

• Journal of Korea Water Resources Association
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• v.51 no.4
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• pp.301-311
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• 2018

Recently, the flood inundation caused by heavy rainfall in urban area is increasing due to global warming. The variability of climate change is described in the IPCC 5th report (2014). The precipitation pattern and hydrological system is varied by climate change. Since the heavy rainfall surpassed the design capacity of the pipeline, it caused great damage in metropolitan cities such as Seoul and Busan. Inundation in urban area is primarily caused by insufficient sewer capacity and surplus overflow of river. Inundation in urban area with concentrated population is more dangerous than rural and mountains areas, because it is accompanied by human casualties as well as socio-economic damage to recover destruction of roads, brides and underground spaces. In addition, various factors such as an increase in impervious area, a short time of concentration to outlet, and a shortage of sewer capacity's lack increase flooding damage. In this study, flood inundation analysis was conducted for vulnerable areas using XP-SWMM. Also, three structural flood prevention measures such as drainage pipeline construction, detention reservoir construction, and flood pumping station construction are applied as flood damage prevention alternatives. The flood data for each alternative were extracted by dividing the basin by grid. The Spatial Compromise Programming are applied using flood assessment criteria, such as maximum inundation depth, inundation time, and construction cost. The purpose of this study is to reflect the preference of alternatives according to geographical condition even in the same watershed and to select flood defense alternative considering regional characteristics.

• Journal of The Korean Society of Agricultural Engineers
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• v.59 no.3
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• pp.83-96
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• 2017

This study presented a surface water quality modeling framework considering the spatial resolution of pollutant load estimation to better represent stream water quality characteristics in the Saemangeum watershed which has been focused on keeping its water resources sustainable after the Saemangeum embankment construction. The watershed delineated into 804 sub-watersheds in total based on the administrative districts, which were units for pollutant load estimation and counted as 739 in the watershed, Digital Elevation Model (DEM), and agricultural structures such as drainage canal. The established model consists of 7 Mangyung (MG) sub-models, 7 Dongjin (DJ) sub-models, and 3 Reclaimed sub-models, and the sub-models were simulated in a sequence of upstream to downstream based on its connectivity. The hydrologic calibration and validation of the model were conducted from 14 flow stations for the period of 2009 and 2013 using an automatic calibration scheme. The model performance to the hydrologic stations for calibration and validation showed that the Nash-Sutcliffe coefficient (NSE) ranged from 0.66 to 0.97, PBIAS were -31.0~16.5 %, and $R^2$ were from 0.75 to 0.98, respectively in a monthly time step and therefore, the model showed its hydrological applicability to the watershed. The water quality calibration and validation were conducted based on the 29 stations with the water quality constituents of DO, BOD, TN, and TP during the same period with the flow. The water quality model were manually calibrated, and generally showed an applicability by resulting reasonable variability and seasonality, although some exceptional simulation results were identified in some upstream stations under low-flow conditions. The spatial subdivision in the model framework were compared with previous studies to assess the consideration of administrative boundaries for watershed delineation, and this study outperformed in flow, but showed a similar level of model performance in water quality. The framework presented here can be applicable in a regional scale watershed as well as in a need of fine-resolution simulation.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.22 no.6
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• pp.353-360
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• 2010

The Kyunggi Bay in mid-west of Korea is a relatively large estuarine system that connects the Han River system with Yellow Sea. Due to macro-tidal range of more than 8 m, the urban estuary shows deep tidal channels and wide tidal flats. Since last 30 years, the coastal development is undergoing, yielding noticeable change in environment. Particularly the tidal flat dynamics are generally accepted as being related with tidal residual flows in this area (Kim et al., 2009). We have estimated the annual variation and vertical structure of residual currents with one-year long observed flows in two major tidal channels of Kyunggi Bay. The moving average method and tidal current harmonic analysis yield nearly the same results on residual flow. The residual flow in Jangbong channel ranges from 20 cm/s in summer to 30 cm/s in winter. It is noticeable that the residual flow in Jangbong channel is flood dominant throughout the year, while the flow in Seokmo channel is ebb-dominant residual flow with current speed range of 20-40 cm/s. Due to the baroclinic response of relatively shallow estuary, significant reduction of energy in bottom layers have been observed, indicating the importance of residual circulation to the tidal flat behavior.

• Journal of the Society of Disaster Information
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• v.15 no.4
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• pp.570-577
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• 2019

Purpose: The purpose of this study is to develop a system that enables quick on-site response using real-time decision-making by sharing the results of measurement and management performed in the field for safe temporary construction. Method: It is possible to take preemptive responses during construction by identifying the safety factors of construction conditions from measurement results and determining the risk factors such as soil properties and variability of climate change that can occur during construction by simultaneously using the back analysis method reflected in the measurement system and structural review. Result: we developed a back analysis algorithm of the SUNEX program to cope with the discrepancies between the design results and measured results due to inconsistency between site conditions and design properties, unexpected loads, and outdoor environment. The process of matching the measurement result with the analysis result can be confirmed in the safety management system. Conclusion: Gateway was used to communicate with real-time measurement results and safety management system program. It was made possible to preemptively respond to risk factors that may occur in the field.

• Journal of Korea Water Resources Association
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• v.54 no.9
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• pp.681-692
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• 2021

Vegetation processes have a significant impact on rainfall runoff processes through evapotranspiration control, but are rarely considered in the conceptual lumped hydrological model. This study evaluated the model performance of the Hapcheon Dam watershed by integrating the ecological module expressing the leaf area index data sensed remotely from the satellite into the hydrological partition module. The proposed eco-hydrological model has three main features to better represent the eco-hydrological process in humid regions. 1) The growth rate of vegetation is constrained by water shortage stress in the watershed. 2) The maximum growth of vegetation is limited by the energy of the watershed climate. 3) The interaction of vegetation and aquifers is reflected. The proposed model simultaneously simulates hydrologic components and vegetation dynamics of watershed scale. The following findings were found from the validation results using the model parameters estimated by the SCEM algorithm. 1) Estimating the parameters of the eco-hydrological model using the leaf area index and streamflow data can predict the streamflow with similar accuracy and robustness to the hydrological model without the ecological module. 2) Using the remotely sensed leaf area index without filtering as input data is not helpful in estimating streamflow. 3) The integrated eco-hydrological model can provide an excellent estimate of the seasonal variability of the leaf area index.

• Journal of Conservation Science
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• v.37 no.3
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• pp.209-219
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• 2021

In this study, the wind environment in an urban area near Sungneymun gate was numerically investigated in the cases of inflow directions. The wind fields for the target area were simulated using Geographic Information System data and Computational Fluid Dynamics model. Results, including vector fields, three-dimensional wind velocity components, and wind speeds, were analyzed to examine flow characteristics. Wind direction variability affected by buildings was shown in the target area. The complex flows around Sungneymun did not depend on the inflow direction as a boundary condition. The wind speed around Sungneymun was generally 3 times stronger at 14 m above ground level (AGL) compared to the surface wind at 2 m AGL and relatively high in the case of easterly inflow. The effect of wind was also analyzed to be relatively significant at the southeast side of Sungneymun. Thus, it was suggested that the assessment of wind environment affected by high-rise and high-density buildings should be necessary for the architectural heritage in urban areas.

• Atmosphere
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• v.31 no.5
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• pp.625-635
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• 2021

South Korea established the 2050 Carbon Neutral Plan in response to the climate crisis, and to achieve this policy, it is very important to monitor domestic carbon emissions and atmospheric carbon concentration. Both CO₂ and CO are emitted from fossil fuel combustion processes, but the relative ratios depend on the combustion efficiency and the strength of local emission regulations. In this study, the relationship between CO₂ and CO was analyzed using ground observation data for the period of 2018~2020 at Anmyeon-do site and the CO/CO₂ ratio according to regional origin during high CO₂ cases was investigated based on the footprint simulated from Stochastic Time-Inverted Lagrangian Transport (STILT) model. CO₂ and CO showed a positive correlation with correlation coefficient of 0.66 (p < 0.01), and averaged footprints during high CO₂ cases confirmed that air particles mainly originated from eastern and north-eastern China, and inland of Korean Peninsula. In addition, it was revealed that among the cases of high CO₂ concentration, when the CO/CO₂ ratio is high, the industrial area of eastern China is greatly affected, and when the ratio is low, the contribution of the domestic region is relatively high. The ratio of CO₂ and CO in this study is significant in that it can be used as a useful factor in determining the possibility of domestic and foreign origins of climate pollutants.

• Journal of Korea Water Resources Association
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• v.50 no.4
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• pp.233-239
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• 2017

In this study, we analyzed typhoon affecting Korean Peninsula and runoff characteristic changes according to the typhoon based on Sumjin river dam, a representative multi-purpose dam. We quantified typhoon flow by applying the typhoon domain, and will provide base data for climate change adaptation and counterstrategy through correlation analysis of the change of typhoon statistical data and Indicators of Hydrologic Alterations (IHA). Korean Peninsula impact typhoon has a great effect on the scale of peak flow and the change of occurrence time. The occurrence frequency and duration of the peak flow were analyzed to be relatively unrelated to the typhoon affected by the Korean peninsula. These changes were also confirmed in the correlation analysis results. Correlation coefficient between the peak flow (0.41) and peak flow occurrence time (correlation coefficient = 0.83) was positively correlated with the Korean peninsula influenced typhoon.