• Journal of Korean Society of Forest Science
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• v.112 no.4
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• pp.490-501
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• 2023

Laboratory column tests were conducted to analyze infiltration and water redistribution processes on the basis of rainfall. To efficiently measure moisture content within soil layers, this research developed a predictive model grounded in a convolutional neural network (CNN), a deep learning technique. The digital images obtained during the column tests were incorporated into the established CNN. The moisture content of each soil layer over time was effectively measured. The measured values were also in relatively good agreement with the moisture content determined using the moisture sensors installed for each soil layer. The use of CNN enabled a comprehensive understanding of continuous moisture distribution within the soil layers, as well as the infiltration process according to soil texture and initial moisture content conditions.

• Journal of Korea Water Resources Association
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• v.52 no.1
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• pp.51-60
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• 2019

The major purpose of this study is to construct an in-situ soil moisture verification network employing Frequency Domain Reflectometry (FDR) sensors for Cosmic-ray soil moisture observation system operation as well as long-term field-scale soil moisture monitoring. The test bed of Cosmic-ray and FDR verification network system was established at the Sulma Catchment, in connection with the existing instrumentations for integrated data provision of various hydrologic variables. This test bed includes one Cosmic-ray Neutron Probe (CRNP) and ten FDR stations with four different measurement depths (10 cm, 20 cm, 30 cm, and 40 cm) at each station, and has been operating since July 2018. Furthermore, to assess the reliability of the in-situ verification network, the volumetric water content data measured by FDR sensors were compared to those calculated through the core sampling method. The evaluation results of FDR sensors- measured soil moisture against sampling method during the study period indicated a reasonable agreement, with average values of $bias=-0.03m^3/m^3$ and RMSE $0.03m^3/m^3$, revealing that this FDR network is adequate to provide long-term reliable field-scale soil moisture monitoring at Sulmacheon basin. In addition, soil moisture time series observed at all FDR stations during the study period generally respond well to the rainfall events; and at some locations, the characteristics of rainfall water intercepted by canopy were also identified. The Temporal Stability Analysis (TSA) was performed for all FDR stations located within the CRNP footprint at each measurement depth to determine the representative locations for field-average soil moisture at different soil profiles of the verification network. The TSA results showed that superior performances were obtained at FDR 5 for 10 cm depth, FDR 8 for 20 cm depth, FDR2 for 30 cm depth, and FDR1 for 40 cm depth, respectively; demonstrating that those aforementioned stations can be regarded as temporal stable locations to represent field mean soil moisture measurements at their corresponding measurement depths. Although the limit on study duration has been presented, the analysis results of this study can provide useful knowledge on soil moisture variability and stability at the test bed, as well as supporting the utilization of the Cosmic-ray observation system for long-term field-scale soil moisture monitoring.

• Journal of Korea Water Resources Association
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• v.49 no.2
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• pp.133-144
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• 2016

In this study, Frequency Domain Reflectometry (FDR) and COSMIC-ray soil moisture (SM) stations were installed at Sungkyunkwan University in Suwon, South Korea. To provide reliable information about SM, soil property test, time series analysis of measured soil moisture, and comparison of measured SM with satellite-based SM product are conducted. In 2014, six FDR stations were set up for obtaining SM. Each of the stations had four FDR sensors with soil depth from 5 cm to 40 cm at 5~10 cm different intervals. The result showed that study region had heterogeneous soil layer properties such as sand and loamy sand. The measured SM data showed strong coupling with precipitation. Furthermore, they had a high correlation coefficient and a low root mean square deviation (RMSD) as compared to the satellite-based SM products. After verifying the accuracy of the data in 2014, four FDR stations and one COSMIC-ray station were additionally installed to establish the Soil Moisture site with FDR and COSMIC-ray, called SM-FC. COSMIC-ray-based SM had a high correlation coefficient of 0.95 compared with mean SM of FDR stations. From these results, the SM-FC will give a valuable insight for researchers into investigate satellite- and model-based SM validation study in South Korea.

• The Journal of Engineering Geology
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• v.7 no.3
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• pp.191-205
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• 1997

Measurements on subsurface movement of the Songsanri tomb site including the Muryong royal tomb was conducted using a tiltmeter system for the period of 15 months form July 7, 1996 to September 30, 1997. Two coordinate tilt monitoring data shows the biggest movement rate of 2.3mm/m/yr toward south in the frontal wall(N-S tilt) of the Muryong royal tomb. Southward tilting of bricks above the southern fire place in the western wall of the Muryong royal tomb is a proof of southward tilting of the royal tomb since its excavation in 1971. The eastern wall of the Muryong royal tomb is also tilting toward inside the tomb with the rate of 1.523mm/m/yr. Furthermore, tilting rate of wall increases twice in rainy season. It is interpreted tbat infiltration of water into the tomb and nearby ground in rainy season results in dangerous status for the safety of tomb structure. On the whole, normal component tilting of the walls of the 5th tomb is large than its shear component. It shows a small displacement toward one direction without no abrupt change in its direction and amount of tilting. The tilting rate of walls of the 6th tomb is about 8.8mm/m/yr in the dry season which is much bigger than those of other tombs in rainy season. Deformation events of walls of the tombs are closely related to amount of precipitation and variation of temperature. In comparison with different weather conditions, tilting is much bigger during the period of rainy weather than sunny weather. It is interpreted that rainwater flew into the turm through faults and nearby ground. High water content in nearby ground resulted strength of ground. The tilting event of walls shows a hysterisis phenomenon in analysis of temperature effect on tilting event. The walls tilt rapidly with steep rising of temperature, but the tilted walls do not come back to original position with temperature falling. Therefore, a factor of steep increase of the temperature must be removed. It means the tomb have to be kept with constant temperature. The observation of groundwater level using three boreholes located in construction site and original ground represented that groundwater level in construction site is higher than that of original ground during the rainy season from the end of June to August. It means that the drainage system of the Muryong royal tomb is worse than original ground, and it is interpreted that the poor drainage system is related to safety of tomb structure. As above mentioned, it is interpreted that artificial changes of the tomb environment since the excavation, infiltration of rainwater and groundwater into the tomb site and poor drainage system had resulted in dangerous situation for the tomb structure. According to the result of the long period observation for the tomb site, it is interpreted that protection of the tomb site from high water content should be carried out at first, and the rise of temperature by means of the dehumidifier inside the tomb must be removed.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.6
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• pp.1203-1210
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• 2012

As the area of upland crops increase, it is become more important for farmers to understand status of soil water at their own fields due to key role of proper irrigation. In order to estimate daily water balance and soil water content with simple weather data and irrigation records, we have developed the model for estimating water balance and soil water content, called AFKAE0.5, and verified its simulated results comparing with daily change of soil water content observed by soil profile moisture sensors. AFKAE0.5 has two hypothesis before establishing its system. The first is the soil in the model has 300 mm in depth with soil texture. And the second is to simplify water movement between the subjected soil and beneath soil dividing 3 categories which is defined by soil water potential. AFKAE0.5 characterized with determining the amount of upward and downward water between the subjected soil and beneath soil. As a result of simulation of AFKAE0.5 at Gongju region with red pepper cultivation in 2005, the water balance with input minus output is recorded as - 88 mm. the amount of input water as precipitation, irrigation, and upward water is annually 1,043, 0, and 207 mm, on the other, output as evapotranspiration, run-off, and percolation is 831, 309, and 161 mm, respectively.

• Journal of Bio-Environment Control
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• v.29 no.4
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• pp.344-353
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• 2020

Plants native in Korea have not only ornamental values but also have excellent environmental adaptability, so they can be used as garden plants. Studies on proper volumetric water content (VWC) of substrates have been reported, but many have been conducted in glasshouse conditions where environmental factors were controlled. When considering garden planting, it is necessary to perform the automated irrigation system in outdoor conditions where rainfall occurs at frequent intervals. This research aimed to investigate the VWC suitable for the growth of Minuartia laricina, Arenaria juncea, and Corydalis speciosa in open filed. Sandy soil which consisted of particles of weathered rock was used, and the VWC of 0.15, 0.20, 0.25, and 0.30 ㎥·m^-3 was maintained using an automated irrigation system with capacitance soil moisture sensors and a data logger. No significant differences in growth and antioxidant enzymes activity of A. juncea were observed among VWC treatments. However, the survival rate was low at VWC 0.30 ㎥·m^-3 treatment, which was the highest soil moisture content. Even considering the efficiency of water use, we recommended that VWC 0.15-0.20 ㎥·m^-3 is suitable for the cultivation of A. juncea. Minuartia laricina showed better growth with lower VWC. Because of frequent rainfall in open field, plant volume and survival rate was high even in VWC 0.15 ㎥·m^-3 treatment. In C. speciosa, the plant height, number of shoots and lateral shoots, and fresh and dry weight were higher in plants grown in VWC 0.25 ㎥·m^-3 as compared with that in the plants grown at 0.15, 0.20, and 0.30 ㎥·m^-3. Based on these results, M. laricina needed less water in open filed, and A. juncea and C. speciosa required higher VWC, but excessive water should be avoided.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.1774-1778
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• 2008

유량 환산에 이용되는 수위-유량 관계곡선식은 하천의 흐름을 정상 등류상태로 가정하고 유속계를 하천에 투입하여 년간 정해진 횟수의 유량측정을 실시하여 이로부터 갱신하여 작성하고 있다. 평수기에는 이렇게 기기를 이용하여 유량측정이 가능하지만 홍수기나 갈수기에는 접촉식 유속계를 이용한 하천유량 측정이 불가능한 실정이다. 홍수기에는 기기 손상과 관측자의 안전이 위협받는 실정이고, 갈수기에는 유속이 너무 느려서 (0.1 m/s 이하) 프로펠러 유속계의 경우 유속의 정확한 관측이 힘들다. 또한 전지구적 빈번한 이상기후의 현실정에서 가장 중요한 기초 수문자료인 홍수량의 정확한 측정 자료는 많지 않다. 홍수유량을 측정하기 위해서 현재에도 기존의 봉부자를 이용하거나 유비쿼터스 센서를 장착한 봉부자를 이용하는 유량측정 기법이 향해지고 계속적으로 소개되고 있는 실정이지만 봉부자의 특성상 정확한 유량을 계산하기에는 어려움이 많다. 현재 선진국에서는 흐름과 비접촉식 방법을 이용한 하천유량측정 방법이 지난 10 여년간 꾸준이 연구되어 왔다. 그중 대표전인 것이 전자파를 이용한 방법과 영상해석에 의한 방법이다. 전자의 경우 국내에서는 수자원공사에서 10년 이상 연구 개발하여 상품화 시킨바 현업에서 이를 이용하여 홍수유량측정을 실시하고 있다. 후자의 방법은 유체역학 분야에서 흐름해석에 주로 이용되어지던 PIV(particle image velocimetry) 기법을 하천과 같이 대규모의 흐름영역에 적용가능하도록 개발된 기술로 LSPIV (large-casle particle image velocimetry)라 불리우는 기술이다. 본 연구에서는 미국 Iowa 대학에서 개발한 LSPIV를 이용하여 홍수파의 진행시 수위와 유량의 두 변수 사이에 나타나는 Loop rating curve의 이론적인 관계를 하천현장에서 일정시간 간격으로 실측을 통하여 파악하고자 하였다. 현장실험을 위한 대상지점으로 미국 Iowa주 Coralville 시내 Clear Creek의 USGS (US Geologival Survey) 수위관측소 지점을 선택하여 본 연구에서 실시한 유량측정 결과의 비교가 가능토록 하였다. LSPIV는 그 특성상 야간에는 적용하는데 어려움이 있어 아침시간부터 해가 지기 직전까지의 자연채광 조건의 영상취득이 가능한 시간대에서 표면유속을 측정하였고 이에 수심평균유속환산계수를 적용하여 유량을 계산하였다. 강우의 발생으로 인한 홍수파의 진행시 총 43회의 유량을 측정하였는바 이를 이용하여 이 지점의 수위-유량 관계식과 비교한 결과 거의 일치하는 결과를 나타냈다. 특히 홍수파의 진행시 고수위 영역에서의 측정한 결과는 수위의 상승기에는 최고로 7.5% 까지 측정유량이 수위-유량관계식에서 계산한 유량보다 컸으며, 수위의 하강기에는 반대로 최고 5.4% 정도까지 측정유량이 수위-유량관계식에서 계산한 유량보다 작게 나타났다. 또한 최대유량의 발생시기는 최고수위 발생직전의 수위라는 것이 파악되었다. 이러한 경향은 수위-유량 관계곡선의 이론과 잘 일치하는 것이다.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.469-469
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• 2017

기후 변화 및 환경오염으로 인하여 물부족 국가가 세계적으로 증가하고 있는 추세이며, 특히 집중형 강우의 형태가 많아짐에 따라 홍수피해 및 상수공급의 문제가 사회적으로 큰 이슈가 되고 있다. 최근 20여 년간의 급속한 경제성장과 도시화 과정에서 인도네시아는 인구와 산업의 과도한 도시집중으로 지난 1960-80년대 한국이 산업화 과정에서 겪었던 것보다 훨씬 심각한 환경문제에 직면하고 있으며, 자카르타와 반둥을 포함하는 광역 수도권 지역의 물 부족과 수질 오염, 환경문제가 이미 매우 위험한 수준에 도달하고 있는 실정이다. 특히, 찌따룸강 중상류에 위치한 인도네시아 3대 도시인 반둥시는 고질적인 용수부족 문제를 겪고 있다. 2010년 현재 약 일평균 15 CMS의 용수가 부족한 상황이며, 2030년에는 지속적인 인구증가로 약 23 CMS의 용수가 추가로 더 필요한 것으로 전망된다. 이러한 용수공급 문제 해결을 위해 반둥시 및 찌따룸강 유역관리청은 댐 및 지하수 개발, 유역 간 물이동 등의 구조적인 대책뿐만 아니라 비구조적인 대책으로써 기존 및 신규 저수지 연계운영을 통한 용수이용의 효율성을 높이는 방안을 모색하고 있다. 이에 따라 본 연구에서는 해당유역의 용수공급 부족 문제를 해소할 수 있는 비구조적인 대책의 일환으로써 다양한 댐 및 보, 소수력 발전, 취수장 등 유역 내 수리 시설물의 운영 최적화를 위한 지능형 물관리 시스템 적용 방안을 제시하고자 한다. 본 연구의 지능형 물관리 시스템은 센서 및 사물 인터넷(Internet of Things, IoT), 네트워크 기술을 바탕으로 시설물 및 운영자, 유관기관 간의 양방향 통신을 통해 유기적인 상호연계 체계를 제공 할 수 있다. 또한 유역의 수문상황과 시설물의 운영현황, 용수공급 및 수요 현황을 실시간으로 확인함으로써 수요에 따른 즉각적인 용수공급량의 조절이 가능하다. 또한, 빅데이터 분석 및 기계학습(Machine Learning)을 통해 개별 물관리 시설물에 대한 최적 운영룰을 업데이트할 수 있으며, 유역의 수문상황과 용수 수요 현황을 고려하여 최적의 용수공급 우선순위를 선정할 수 있다. 지능형 물관리 시스템 개발의 목적은 찌상쿠이 유역의 수문현황을 실시간으로 모니터링하고, 하천시설물의 운영을 분석하여 최적의 용수공급 및 배분을 통해 유역의 수자원 활용 효율성을 향상시키는 데 있다. 이를 위해 수문자료의 수집체계를 구축하고 기관간 정보공유체계를 수립함으로써 분석을 위한 기반 인프라를 구성하며, 이를 기반으로 유역 유출을 비롯한 저수지 운영, 물수지 분석을 수행하고, 분석 및 예측결과, 과거 운영 자료를 토대로 새로운 물관리 시설 운영룰 및 시설물 간 연계운영 방안, 용수공급 우선순위 의사결정 등을 지원하고자 한다. 본 연구의 지능형 물관리 시스템은 통합 DB를 기반으로 수리수문 현상의 모의 분석을 통해 하천 시설물 운영의 합리적 기준을 제시함으로써 다양한 관리주체들의 시설물운영에 대한 이견 및 분쟁을 해소하고, 한정된 수자원과 다양한 수요 간의 효율적이고 합리적인 분배 및 시설물 운영문제를 해결하기 위한 의사결정도구로써 활용할 수 있을 것으로 기대된다.

• Journal of Korean Society of Disaster and Security
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• v.14 no.2
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• pp.13-23
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• 2021

This study intended to assess the reliability of topographic data using satellite imaging data. The topographical data using actual instrumentation data and satellite image data were established and applied to the rainfall-leak model, S-RAT, and the topographical data and outflow data were compared and analyzed. The actual measurement data were collected from the Water Resources Management Information System (WAMIS), and satellite image data were collected from MODIS observation sensors mounted on Terra satellites. The areas subject to analysis were selected for two rivers with more than 80% mountainous areas in the Han River basin and one river basin with more than 7% urban areas. According to the analysis, the difference between instrumentation data and satellite image data was up to 50% for peak floods and up to 17% for flood totals in rivers with high mountains, but up to 13% for peak floods and up to 4% for flood totals. The biggest difference in the video data is Landuse, which shows that MODIS satellite images tend to be recognized as cities up to 60% or more in urban streams compared to WAMIS instrumentation data, but MODIS satellite images are found to be less than 5% error in forest areas.

• Journal of the Geological Society of Korea
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• v.54 no.5
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• pp.545-556
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• 2018

This study was conducted to estimate the deep percolation using numerical modeling and field observation data based on rainfall in Haean basin. Soil moisture sensors were installed to monitoring at 30, 60 and 90 cm depths in four sites (YHS1-4) and automatic weather station was installed to around YHS3. Soil moisture and meteorological data was observed from March 25, 2017 to March 25, 2018 and May 06, 2016 to May 06, 2018, respectively. Numerical analysis was performed from June to August, 2017 using the HYDRUS-1D. Average soil moisture contents were high to generally in YHS3 for 0.300 to $0.334m^3/m^3$ and lowest in YHS1 for 0.129 to $0.265m^3/m^3$ during the soil moisture monitoring period. The results of soil moisture flow modeling showed that field observations and modeling values were similar but the peak values were larger in the modeling result. Correlation analysis between observation and modeling data showed that r, $r^2$ and RMSE were 0.88, 0.77, and 0.0096, respectively. This show high correlation and low error rate. The total deep percolation was 744.2 mm during the period of modelling at 500 cm depth. This showed that 61.3% of the precipitation amount (1,214 mm) was recharged in 2017. Deep percolation amount was high in the study area. This study is expected to provide basic data for the estimation of groundwater recharge through unsaturated zone.