• Tunnel and Underground Space
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• v.33 no.5
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• pp.399-413
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• 2023

The present study conducted a numerical modeling of CO₂ injection at the Janggi Basin using the TOUGH-FLAC simulator, and examined the hydro-mechanical stability of the aquifer and the fault. Based on the site investigations and a 3D geological model of the target area, we simulated the injection of 32,850 tons of CO₂ over a 3-year period. The analysis of CO₂ plume with different values of the aquifer permeability revealed that assuming a permeability of 10^-14 m² the CO₂ plume exhibited a radial flow and reached the fault after 2 years and 9 months. Conversely, a higher permeability of 10^-13 m² resulted in predominant westward flow along the reservoir, with negligible impact on the fault. The pressure changes around the injection well remained below 0.6 MPa over the period, and the influence on the hydro-mechanical stability of the reservoir and fault was found to be insignificant.

• Journal of Korean Society of Rural Planning
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• v.30 no.1
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• pp.15-31
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• 2024

The study primarily aims to examine the characteristics of the transition from natural landscape to modern agricultural landscape on the Daesan plain in Dong-myeon, Changwon-si, in the lower reaches of the Nakdong River. The periods covered in the transition include the late Joseon Dynasty, the early Japanese colonial period, and the late Japanese colonial period. The study concluded the following: It was found that the Daesan Plain used to function as a hydrophilic landscape before it formed into a rural landscape. This is characterized by the various water resources in the Plain, primarily by the Nakdong River, with its back marsh tributaries, the Junam Reservoir and Jucheon. To achieve its recent form, the Daesan Plain was subjected to human trial and error. Through installation of irrigation facilities such as embankments and sluices, the irregularly-shaped wetlands were transformed into large-scale farmlands while the same irrigation facilities underwent constant renovation to permanently stabilize the rural landscape. These processes of transformation were similarly a product of typical colonial expropriation. During the Japanese colonial period, Japanese capitalists initiated the construction of private farms which led to the national land development policy by the Governor-General of Korea. These landscape changes are indicative of resource capitalism depicted by the expansion of agricultural production value by the application of resource capital to undeveloped natural space for economic viability. As a result, the hierarchical structure was magnified resulting to the exacerbation of community and economic structural imbalances which presents an alternative yet related perspective to the evolution of landscapes during the Japanese colonial period. In addition, considering Daesan Plain's vulnerability to changing weather conditions, natural processes have also been a factor to its landscape transformation. Such occurrences endanger the sustainability of the area as when floods inundate cultivated lands and render them unstable, endangering residents, as well as the harvests. In conclusion, the Daesan Plain originally took the form of a hydrophilic landscape and started significantly evolving into a rural landscape since the Japanese colonial period. Human-induced land development and geophysical processes significantly impacted this transformation which also exemplifies the several ways of how undeveloped natural landscapes turn into mechanized and capitalized rural landscapes by colonial resource capitalism and development policies.

• Journal of Korean Society of Disaster and Security
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• v.16 no.4
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• pp.75-84
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• 2023

Many developing countries face challenges in estimating long-term discharge due to the lack of hydrological data for water supply planning, making it difficult to establish a rational water supply plan for decision-making on water distribution. The study area, the Bandung region in Indonesia, is experiencing rapid urbanization and population concentration, leading to a severe shortage of freshwater. The absence of water reservoir prediction methods has resulted in a water supply rate of approximately 20%. In this study, we aimed to propose an approach for predicting water reservoirs in developing countries by analyzing water safety and potential water supply using the MODSIM (Modified SIMYLD) network model. To assess the suitability of the MODSIM model, we applied the unit hydrograph method to calculate long-term discharge based on 19 years of discharge data (2002-2020) from the Pataruman observation station. The analysis confirmed alignment with the existing monthly optimal operation curve. The analysis of power plant capacity revealed a difference of approximately 0.30% to 0.50%, and the water intake safety at the Pataruman point showed 1.64% for Q95% flow and 0.47% for Q355 flow higher. Operational efficiency, compared to the existing reservoir optimal operation curve, was measured at around 1%, confirming the potential of using the MODSIM network model for water supply evaluation and the need for water supply facilities.

• Journal of Soil and Groundwater Environment
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• v.10 no.6
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• pp.45-55
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• 2005

The geothermal research has been carried out on the Heunghae, Pohang geothermal area know as having geo-heat-flow area in the Korean peninsula. This study results so far indicate that geothermal water in the area is in peripheral waters of hydrothermal area and is not in equilibrium with the reservoir rock. The average oxygen and hydrogen stable isotope values are as follows: deep groundwater $(average:\;{\delta}^{18}O=-10.1\%_{\circ},\;{\delta}D=-65.8\%_{\circ})$, intermediate groundwater (average: $(average:\;{\delta}^{18}O=-8.9\%_{\circ},\;{\delta}D=-59.6\%_{\circ})$, shallow groundwater $(average:\;{\delta}^{18}O=-8.0\%_{\circ},\;{\delta}D=-53.6\%_{\circ})$, surface water $(average:\;{\delta}^{18}O=-7.9\%_{\circ},\;{\delta}D=-53.3\%_{\circ})$ respectively. Deep groundwaters was originated from a local meteoric water recharged from distant, topographically high mountain region and not affected by the sea water. High temperature zone inferred from water geothermometers is around D-1, D-5, D-6, 1-04 well zones. The estimated enthalpy from Silica-enthalpy mixing model is near 410 kJ/kg, which corresponds to the temperature of $98^{\circ}C$, and in consistent with the result of Na-K and K-Mg geothermometer.

• Korean Journal of Ecology and Environment
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• v.40 no.2
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• pp.214-222
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• 2007

This study was conducted to assay the relationship between the characteristics of watershed and water quality, and to evaluate water quality characteristics of the classified types by TSI deviation analysis with the collected data from 490 reservoir. Relatively shallow depth (<5m) reservoirs out of selected 490 appeared to be eutrophic. The mean TP concentration in reservoirs with the PFA+UFA/watershed area of above 30% was ${\geq}0.1$ mg $L^{-1}$. The mean TN concentration in reservoirs with the PFA/watershed area of above 25% was ${\geq}2.6$ mg $L^{-1}$. Based on the TSI deviation analysis, water quality parameters in TYPE III reservoirs were in high concentration compared to other reservoirs types. Characteristics of Type III generally showed eutrophic, small DA/RA ratio, shallow depth, and large paddy field and upland field to watershed ratio compared to other types of reservoirs. Both water quality and morpho-physical parameters, Type I and II reservoirs were similar with the exceptions of BOD and chi. ${\alpha}$ concentration. Phosphorus in Type I reservoirs was not the primary limiting factor on algal growth, but significant decrease chl. ${\alpha}$ concentration with the increasing TN/TP indicated that phosphorus was the possible secondary limiting factor. Overall results indicated that type of land use, such as PFA and UFA area in watershed, was important parameters for the assessment of water quality characteristics, and phosphorus was limiting nutrient on algal growth in 490 reservoirs.

• 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 Wetlands Research
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• v.20 no.1
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• pp.20-26
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• 2018

The purpose of this study is to construct a GIS / DB by grasping a small but ecologically valuable village wetland distribution, and to propose conservation management and wise use plan. The study area is Seocheon-gun, a typical farming village. Firstly, based on the digital topographical map (1:5,000), the Arc-GIS tool was used to identify the provisional(draft) village wetlands. In addition, for the management of village wetlands, wetlands with an area of more or less than $625m^2$ each were derived and according to ecological regions study area was classified into urban areas, inland areas and coastal areas. And finally, according to the wetland identifying indicators, the village wetlands were identified as the final village wetlands through indoor and field trips. The results of the study show that there are 570 village wetlands in Seocheon - gun province, which are 74 in urban areas, 220 in inland areas, and 276 in coastal areas. The case study for village wetland identification was conducted in one out of two urban areas (Seocheon - eup), two of four coastal areas (Biin - myeon and Seo - myeon), and three of seven inland areas (Masan - myeon, Hansan - myeon, and Sicho - myeon). The distribution of village wetlands was found mainly to be a village wetland with an area of less than $625m^2$. In addition, compared with inland areas, the discrimination rate of village wetlands in coastal areas and urban areas was relatively low, indicating that inland areas were still less disturbed, and land use in urban areas and coastal areas is changing rapidly. Especially, land with less awareness such as village wetlands is relatively easily damaged, and management strategy is urgent.

• Ecology and Resilient Infrastructure
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• v.10 no.2
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• pp.40-49
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• 2023

To reduce the damage of extreme flooding caused by climate change and to create flood mitigation sections in a nature-friendly riparian area, it is necessary to restore the floodplain area by referring to the past floodplain section of the current inland waterfront area before the levee was built. This study proposed a method of selecting a location for floodplain restoration using old maps of the Geum River study section and analyzed the effect of flood level reduction through unsteady flow numerical simulations using the floodplain as a flood mitigation space. As a result of analyzing changes in the river areas using old maps, the river section was estimated to gradually reduce by 27.8% (1,059,380 m²) in 2020 compared to 1919, and it was found to have an effective storage capacity of 2,200,868 m³ when restored to offline storage. The flood level and discharge control effects analyzed based on HEC-RAS unsteady flow simulation were 16 cm and 219.01 m³/s, respectively, in the downstream cross-section. In the numerical simulation in this paper, the flood mitigation space was applied as an offline reservoir. The effect of reducing the flood level may differ if levee retreat/relocation is applied.

• Journal of Wetlands Research
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• v.26 no.3
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• pp.298-310
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• 2024

In this study, we analyzed the results of previous studies on different types of agricultural ecosystems to understand how environmental factors in soils, which serve as significant carbon reservoirs within agricultural ecosystems, a type of terrestrial ecosystem, affect soil carbon storage and soil respiration. As a result, most previous studies have been conducted on paddy field and facility cultivation area. And, the carbon storage in the soil and the soil's chemical properties, such as soil pH, electrical conductivity, soil organic matter content, and total nitrogen content, were higher in paddy field and orchard compared to field, facility cultivation area, and other cultivation area. The soil respiration in paddy field was also higher than in other types of agricultural ecosystems. Furthermore, soil carbon storage showed a significant correlation with soil organic matter (R²=0.7237, p=0.0000), total nitrogen (R²=0.8419, p=0.0000), and available phosphorus (R²=0.3123, p=0.0024), while soil respiration had a significant relationship with soil organic matter (R²=0.5644, p=0.0000). In this study, agricultural ecosystems were found to act as carbon sinks, with soil carbon storage measured at 49.1±8.9 tons C ha^-1 in orchard, 31.8±6.9 tons C ha^-1 in paddy field, and 25.3±28.0 tons C ha^-1 in facility cultivation area. Therefore, agricultural ecosystems need to manage soil carbon storage and carbon emissions through proper soil nutrient management.

• Korean Journal of Environmental Agriculture
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• v.18 no.1
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• pp.77-82
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• 1999

Three floating islands have been constructed for water quality improvement for a polluted irrigation reservoir. Each floating island consists of 10 segments. Each segment hay an area of $16m^2$(4×4m) and is made of wood frames and floats(polystyrene foam). We planted three species of aquatic macrophytes(Typha angustifolia, Zizania latifolia, and Phragmites australis) in floating island on June, 1998. They grew very well without death. We would like to evaluate Phragmites australis is the most suitable aquatic macrophyte that could be planted in a floating island because it maintained the best balance of its root and shoot among them. During their grown period, net primary productivity of Typha angustifolia was $962gDM/m^2$, Zizania latifolia was $1,115gDM/m^2$, and Phragmites australis was $523gDM/m^2$. From these data, it would be estimated to 5.0Kg uptake of nitrogen by aquatic macrophytes and phosphorus 0.8Kg in 3 floating islands. The floating islands worked well as a habitat of fish and prawns. Many kinds of insect lived on the floating islands. The floating island has not only the function of water quality treatment but also several advantages: improvement of landscape and species diversity; low cost of maintenance; low technology; unnecessary of energy; less susceptible to variations in pollutant loading. It could be evaluated a good measure of water quality improvement for an irrigation reservoir. However, it should be intensively studied to develop more light, strong, durable and low-priced frames for efficient floating islands.