• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.374-374
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• 2023

Groundwater is the main source of water on which relies many countries in case of emergency, this is the case of Japan in 2011 after the great Sendai Earthquake. This important resource is found to be heavily influenced by human induced factors such as wetland area reduction. For groundwater sustainable management in perfect cohesion with wetland it is important to understand the relationship between both resources. Wetlands have a strong interaction with both groundwater and surface water, influencing catchment hydrology and water quality. Quantifying groundwater-wetland interactions can help better identify locations for wetlands restoration and/or protection. This study uses observation data from piezometers and wetland to study the qualitative and quantitative aspects of the correlation. Groundwater level, wetland area, chemical, organic and inorganic contaminants are the important parameters used. the results proved that few contaminants in the wetland are found in groundwater and in general the wetland quality does not affect that much groundwater quality. The strong linear relationship found between wetland water level and nearest groundwater level proved that, in term of quantity, groundwater and wetland are strongly correlated. While wetland becoming dry, groundwater level has dropped in the region about 0.52m. The area of wetland was found to be lightly correlated with groundwater level, proving that wetlands dry has contributed to groundwater level declining. This study has showed that whilst rainfall variability contributed to the decline and loss of wetlands, the impacts from landuse changes and groundwater extraction were likely to be significant contributors to the observed losses.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.2B
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• pp.215-224
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• 2008

The effect of streamflow considering future land use change and vegetation index information by climate change scenario was assessed using SLURP (Semi-distributed Land-Use Runoff Process) model. The model was calibrated and verified using 4 years (1999-2002) daily observed streamflow data for the upstream watershed ($260.4km^2$) of Gyeongan water level gauging station. By applying CA-Markov technique, the future land uses (2030, 2060, 2090) were predicted after test the comparison of 2004 Landsat land use and 2004 CA-Markov land use by 1996 and 2000 land use data. The future land use showed a tendency that the forest and paddy decreased while urban, grassland and bareground increased. The future vegetation indices (2030, 2060, 2090) were estimated by the equation of linear regression between monthly NDVI of NOAA AVHRR images and monthly mean temperature of 5 years (1998-2002). Using CCCma CGCM2 simulation result based on SRES A2 and B2 scenario (2030s, 2060s, 2090s) of IPCC and data were downscaled by Stochastic Spatio-Temporal Random Cascade Model (SST-RCM) technique, the model showed that the future runoff ratio was predicted from 13% to 34% while the runoff ratio of 1999-2002 was 59%. On the other hand, the impact on runoff ratio by land use change showed about 0.1% to 1% increase.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.4
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• pp.475-483
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• 2012

Recently, agricultural lands decrease sharply, which was caused by urbanization, land consolidation, road construction, and innovation city construction, etc. In particular, Goyang, Chenan and Wonju city were had severe land use change. Therefore, we analyzed changes of land use, soil properties, and soil information in order to provide the basic soil information and soil management practice in these cities. The results are summarized as follows. The area of crop cultivated land in Korea (2011) was reduced to 17.3ha compared to ones from the previous year (2009). The paddy field decreased by 24.2 ha but, upland field increased by 7.0 ha. The reasons for the reduction of the paddy field were converting paddy field to upland (20.7 ha) > public facilities (3.2) ${\geq}$ building (3.2) > idle land (1.3) > and others (0.9). Other reasons for reduction in the upland field were switching upland to paddy field, (20.7 ha) > land developed (4.5) > and restoration (0.3) respectively. The main reason of converting paddy field to upland was changing from rice to more profitable upland or greenhouse crops. The cropland area (paddy fields, upland, orchard) of Goyang, Cheonan, and Wonju city were reduced to 1,466 ha, 9,708 ha and 6,980 ha respectively. The ratio of cropland area in each city was reduced by 45~25% dramatically compared to upland soil survey project in Korea (1995~1999). These data were compared with MiFAFF statistics data to use for land use cover map of Ministry of environment. But they were differences significantly. Therefore, intensive investigation should be advised throughout the utilization plan. The paddy fields located in small valley in Wonju city were changed into upland or orchard. The drainage classes of soil have been deteriorated because the flows of water were intercepted by road construction and other disturbance to water flows. In particular, paddy fields have been changed to not only upland, orchard, greenhouse cultivation but also to fallow and soil dressing on paddy in Wonju city. The soil suitability classes of paddy field in Wonju innovation city were the 3rd grade for 70.8% of the area and the 4th grade for 29.2%. The soil suitability classes of upland was the 4th grade for 88.7% of the area. Fortunately, good soil suitability classes were not belong to innovation city in Wonju. So, the good farm land should be conserved and revise the related law.

• Journal of Wetlands Research
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• v.24 no.4
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• pp.331-344
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• 2022

This study analyzed the characteristics of the soil and hydrological environment of abandoned paddy wetlands examined the changes in land cover type in the ecological affect area, analyzed the environmental factors of abandoned paddy wetlands, and examined the changes in land cover type in the ecological impact area. The ecological environment characteristics of the reference abandoned paddy wetlands were investigated through literature research, environmental spatial information service, and preliminary exploration of the abandoned paddy wetlands, and the basic data for the restoration of abandoned paddy wetlands ware provided by examining the changes in land cover type in the ecological impact area for 40 years. Through this study, it will be possible to manage the rapidly increasing number of abandoned farmland to be converted into wetlands so that it can perform functions equivalent to or greater than that of natural wetlands. In particular, as we checked the clues that abandoned paddy wetlands could spread to surrounding ecological influences through land cover changes, the study sites are highly likely to be reference wetlands, and if the topography, soil, water circulation system, and carbon reduction performance are analyzed carefully, it will be possible to standardize the development process. In addition, through the change in land cover, clues were confirmed that the abandoned paddy wetlands could spread to the surrounding ecological affect areas. The land cover type in the ecological impact area, forests was mainly distributed, but generally decreased rapidly in the last 10-20 years, and forests were changing from coniferous forests to broad-leaved forests, mixed forests, or grassland. It has not yet been fully called to the wetland, and it is found that it has maintained the form of barren or grassland, and as can be seen in the case of natural wetlands after more than 30 years after abandoned, it is expected that the transition will gradually proceed to wetlands that are structurally and functionally similar to natural wetlands.

• Journal of Wetlands Research
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• v.16 no.4
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• pp.303-318
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• 2014

Baseflow gives a significant contribution to stream function in the regions where climatic characteristics are seasonally distinct. In this regard, variable baseflow can make it difficult to maintain a stable water supply, as well as causing disruption to the stream ecosystem. Changes in land use can affect both the direct flow and baseflow of a stream, and consequently, most other components of the hydrologic cycle. Baseflow estimation depends on the observed streamflow in gauge watersheds, but accurate predictions of streamflow through modeling can be useful in determining baseflow data for ungauged watersheds. Accordingly, the objectives of this study are to 1) improve predictions of SWAT by applying the alpha factor estimated using RECESS for calibration; 2) estimate baseflow in an ungauged watershed using the WHAT system; and 3) evaluate the effects of changes in land use on baseflow characteristics. These objectives were implemented in the Gapcheon watershed, as an ungauged watershed in South Korea. The results show that the alpha factor estimated using RECESS in SWAT calibration improves the prediction for streamflow, and, in particular, recessions in the baseflow. Also, the changes in land use in the Gapcheon watershed leads to no significant difference in annual baseflow between comparable periods, regardless of precipitation, but does lead to differences in the seasonal characteristics observed for the temporal distribution of baseflow. Therefore, the Guem River, into which the stream from the Gapcheon watershed flows, requires strategic seasonal variability predictions of baseflow due to changes in land use within the region.

• Korean Journal of Soil Science and Fertilizer
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• v.50 no.2
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• pp.81-92
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• 2017

Recently, agricultural lands have decreased sharply, which was caused by huge housing site, urbanization, land consolidation, and road construction etc. In particular, Yangju city near Seoul city has the most severe land use change in Korea. Therefore, we analyzed changes of land use, soil properties, and soil information in order to provide the basic soil information and soil management practices in this city. The area of crop cultivated land in Korea (2015) reduced by 12,090 ha compared to ones from the previous year (2014). The paddy field decreased by 25,421 ha but, upland field increased by 13,331 ha. One of the reasons for the reduction of the paddy field was converting paddy field to upland (20,916 ha) > others (3,056) > building (2,571) > public facilities (847) > idle land (217). But, reasons for increase of upland field were switching paddy to upland (20,916 ha) > land developed (634). The main reason of converting paddy field to upland was changing from rice to more profitable speciality crops or pulses. The cropland area (paddy fields, upland, orchard) of Yangju city reduced by 1,412 ha (2015/2014). The ratio of cropland area in each city reduced by 22.9% dramatically compared 2015 to 1999. The paddy fields located in alluvial plains in Yangju city were changed into upland or green house. The drainage classes of soil have been deteriorated because the flows of water were intercepted by road construction and other disturbance to water flows. In particular, paddy fields have been changed to not only upland, orchard, greenhouse cultivation but also to fallow and soil dressing on paddy in Yangju city. To analyze result of soil survey of Yangju city, 858 soil codes (soil phases) were used and the area was 105.17ha. The number of soil series increased from 60 to 65, and that of soil phase increased from 105 to 124. The largest increased area was Noegog soil series. 125.7ha of Neogog soil series was incorporated from the existing Sachon, Yecheon and Eungog soil series. The soil suitability class of paddy field in Ogjung huge housing site of Yangju city was the 4th grade for 32.6% of the area. The soil suitability classes of upland were 2nd and 3rd grade for 72.4% of the area. Farm land with high quality should be conserved by related law.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.664-668
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• 2005

근래 지속적으로 진행된 도시화 및 산업화로 인하여 이전보다 불투수 지역이 많이 증가하였고 도심지역에는 대부분 하수관거가 매설되어 있는 등 물순환이 과거에 비해 현저하게 왜곡되어 있다. 이를 올바르게 바로잡기 위해서는 과거와 현재의 수문학적 상태에 대한 정확한 이해가 우선적으로 요구된다. 본 연구에서는 안양천 유역의 지류인 학의천을 대상유역으로 선정하고 유출 수량 및 오염물질 발생량을 PCSWMM(Storm Water Management Model)과 PLOAD(Pollutant Loading)를 이용하여 모의하였다. PCSWMM은 하수관거를 포함하여 연속유출모의를 수행할 수 있으며 PLOAD는 GIS를 기반으로 하는 Screening 모형으로 토지이용별 원단위를 이용하여 소유역에서 발생하는 오염량을 추정할 수 있다. 기준년도 2002년에 대해 모든 조건은 동일한 상태에서 토지이용만 1975년, 2000년, 2016년으로 변화시켜 모의를 수행하였다. 1975년, 2000년, 2016년의 불투수 면적비는 각각 $2.6\%,\;22.8\%,\;24.1\%$이며 침투량은 1975년의 $23\%$에서 2000년과 2016년에 각각 $17.9\%와\;17.6\%$로 감소하였고, 이로 인해 지표유출량은 1975년의 $48.1\%$보다 2000년과 2016년에 각각 $55.0\%,\;55.4\%$로 증가하였다. 또한 오염물질이 유역에서 발생하여 하천으로 전달되는 유달량은 유역전체로 보면 1975년 보다 2000년에 BOD는 4.0배, COD는 3.3배, SS는 2.7배, TN은 1.3배, TP는 1.6배 증가하였다. 이러한 모의 결과는 학의천 유역에 대해 소유역별로 발생하는 연도별 유출량 및 오염물질 유달량을 정량적으로 제시하므로 유역관리방안을 도출하는데 효과적으로 활용될 수 있다.최대화하기 위한 환경관리 방안 제시에 중점을 두어 수행하였다.ncy), 환경성(environmental feasibility) 등을 정성적으로(qualitatively) 파악하여 실현가능한 대안을 선정하였다. 이렇게 선정된 대안들은 중유역별로 검토하여 효과가 있을 것으로 판단되는 대안들을 제시하는 예비타당성(Prefeasibility) 계획을 수립하였다. 이렇게 제시된 계획은 향후 과학적인 분석(세부평가방법)을 통해 대안을 평가하고 구체적인 타당성(feasibility) 계획을 수립하는데 토대가 될 것이다.{0.11R(mm)}(r^2=0.69)$로 나타났다. 이는 토양의 투수특성에 따라 강우량 증가에 비례하여 점증하는 침투수와 구분되는 현상이었다. 경사와 토양이 같은 조건에서 나지의 경우 역시 $Ro_{B10}(mm)=20.3e^{0.08R(mm)(r^2=0.84)$로 지수적으로 증가하는 경향을 나타내었다. 유거수량은 토성별로 양토를 1.0으로 기준할 때 사양토가 0.86으로 가장 작았고, 식양토 1.09, 식토 1.15로 평가되어 침투수에 비해 토성별 차이가 크게 나타났다. 이는 토성이 세립질일 수록 유거수의 저항이 작기 때문으로 생각된다. 경사에 따라서는 경사도가 증가할수록 증가하였으며 $10\% 경사일 때를 기준으로 $Ro(mm)=Ro_{10}{\times}0.797{\times}e^{-0.021s(\%)}$로 나타났다.천성 승모판 폐쇄 부전등을 초래하는 심각한 선천성 심질환이다. 그러나 진단 즉시 직접 좌관상동맥-대동맥 이식술로 수술적 교정을 해줌으로써 좋은 성적을 기대할 수 있음을 보여주었다.특히 교사들이 중요하게 인식하는 해방적 행동에 대한 목표를 강조하여 적용할 필요가 있음을 시사하고 있다.교하여 유의한 차이가 관찰되지 않았다. 또한 HSP 환자군에서도 $IL1RN^{*}2$ a

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.194-198
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• 2008

Significant soil erosion and water quality degradation issues are occurring at highland agricultural areas of Kangwon province because of agronomic and topographical specialities of the region. Thus spatial and temporal modeling techniques are often utilized to analyze soil erosion and sediment behaviors at watershed scale. The Soil and Water Assessment Tool (SWAT) model is one of the watershed scale models that have been widely used for these ends in Korea. In most cases, the SWAT users tend to use the readily available input dataset, such as the Ministry of Environment (MOE) land cover data ignoring temporal and spatial changes in land cover. Spatial and temporal resolutions of the MOE land cover data are not good enough to reflect field condition for accurate assesment of soil erosion and sediment behaviors. Especially accelerated soil erosion is occurring from agricultural fields, which is sometimes not possible to identify with low-resolution MOD land cover data. Thus new land cover data is prepared with cadastral map and high spatial resolution images of the Doam-dam watershed. The SWAT model was calibrated and validated with this land cover data. The EI values were 0.79 and 0.85 for streamflow calibration and validation, respectively. The EI were 0.79 and 0.86 for sediment calibration and validation, respectively. These EI values were greater than those with MOE land cover data. With newly prepared land cover dataset for the Doam-dam watershed, the SWAT model better predicts hydrologic and sediment behaviors. The number of HRUs with new land cover data increased by 70.2% compared with that with the MOE land cover, indicating better representation of small-sized agricultural field boundaries. The SWAT estimated annual average sediment yield with the MOE land cover data was 61.8 ton/ha/year for the Doam-dam watershed, while 36.2 ton/ha/year (70.7% difference) of annual sediment yield with new land cover data. Especially the most significant difference in estimated sediment yield was 548.0% for the subwatershed #2 (165.9 ton/ha/year with the MOE land cover data and 25.6 ton/ha/year with new land cover data developed in this study). The results obtained in this study implies that the use of MOE land cover data in SWAT sediment simulation for the Doam-dam watershed could results in 70.7% differences in overall sediment estimation and incorrect identification of sediment hot spot areas (such as subwatershed #2) for effective sediment management. Therefore it is recommended that one needs to carefully validate land cover for the study watershed for accurate hydrologic and sediment simulation with the SWAT model.

• Atmosphere
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• v.26 no.1
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• pp.111-126
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• 2016

In the numerical weather model, surface properties can be defined by various parameters such as terrain height, landuse, surface albedo, soil moisture, surface emissivity, roughness length and so on. And these parameters need to be improved in the Seoul metropolitan area that established high-rise and complex buildings by urbanization at a recent time. The surface roughness length map is developed from digital elevation model (DEM) and it is implemented to the high-resolution numerical weather (WISE-WRF) model. Simulated results from WISE-WRF model are analyzed the relationship between meteorological variables to changes in the surface roughness length. Friction speed and wind speed are improved with various surface roughness in urban, these variables affected to temperature and relative humidity and hence the surface roughness length will affect to the precipitation and Planetary Boundary Layer (PBL) height. When surface variables by the WISE-WRF model are validated with Automatic Weather System (AWS) observations, NEW experiment is able to simulate more accurate than ORG experiment in temperature and wind speed. Especially, wind speed is overestimated over $2.5m\;s^{-1}$ on some AWS stations in Seoul and surrounding area but it improved with positive correlation and Root Mean Square Error (RMSE) below $2.5m\;s^{-1}$ in whole area. There are close relationship between surface roughness length and wind speed, and the change of surface variables lead to the change of location and duration of precipitation. As a result, the accuracy of WISE-WRF model is improved with the new surface roughness length retrieved from DEM, and its surface roughness length is important role in the high-resolution WISE-WRF model. By the way, the result in this study need various validation from retrieved the surface roughness length to numerical weather model simulations with observation data.

• Spatial Information Research
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• v.19 no.6
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• pp.11-18
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• 2011

Urban space is the main contributor of greenhouse gas emissions, a primary cause of global warming. In order to reduce greenhouse gas emissions, planning at a city-level is necessary. The aim of this research is to develop a carbon emission model which can be used to create and manage urban spaces. In order to achieve this aim, the following methodologies were utilized. First, urban planning criteria related to population, landuse, and activity level were selected through theoretical speculation. Second, carbon dioxide emission was calculated based on electricity, gas energy, heating, petroleum, and water usages. Third, Seoul was selected as a case study city, and a carbon emission model was developed through a relational analysis between Seoul's urban planning criteria and carbon emissions. Thus far, various efforts have been made to respond to climate changes in urban spaces, but these have been limited to analyzing contributing factors in terms of their total amounts of carbon emissions in the entire city. However, the carbon emission model of this study is derived from urban planing criteria at a detailed scale. This sets our study apart from other studies by demonstrating a specific model in a local setting which can be utilized for lowering carbon emissions at a city level.