Reservoir storage and water level information is essential for accurate drought monitoring and prediction. In particular, the agricultural drought has increased the risk of agricultural water shortages due to regional bias in reservoirs and water supply facilities, which are major water supply facilities for agricultural water. Therefore, it is important to evaluate the available water capacity of the reservoir, and it is necessary to determine the water surface area and water capacity. Remote sensing provides images of temporal water storage and level variations, and a combination of both measurement techniques can indicate a change in water volume. In areas of ungauged water volume, satellite remote sensing image acts as a powerful tool to measure changes in surface water level. The purpose of this study is to estimate of reservoir storage and level variations using satellite remote sensing image combined with hydrological statistical data and the Normalized Difference Water Index (NDWI). Water surface areas were estimated using the Sentinel-2 satellite images in Seosan, Chungcheongnam-do from 2016 to 2018. The remote sensing-based reservoir storage estimation algorithm from this study is general and transferable to applications for lakes and reservoirs. The data set can be used for improving the representation of water resources management for incorporating lakes into weather forecasting models and climate models, and hydrologic processes.
Estimation of High-Resolution Soil Moisture Using Sentinel-1A/B SAR and Soil Moisture Data Assimilation Scheme
김상우 Kim Sangwoo , 이태화 Lee Taehwa , 천범석 Chun Beomseok , 정영훈 Jung Younghun , 장원석 Jang Won Seok , 서찬양 Sur Chanyang , 신용철 Shin Yongchul
We estimated the spatio-temporally distributed soil moisture using Sentinel-1A/B SAR (Synthetic Aperture Radar) sensor images and soil moisture data assimilation technique in South Korea. Soil moisture data assimilation technique can extract the hydraulic parameters of soils using observed soil moisture and GA (Genetic Algorithm). The SWAP (Soil Water Atmosphere Plant) model associated with a soil moisture assimilation technique simulates the soil moisture using the soil hydraulic parameters and meteorological data as input data. The soil moisture based on Sentinel-1A/B was validated and evaluated using the pearson correlation and RMSE (Root Mean Square Error) analysis between estimated soil moisture and TDR soil moisture. The soil moisture data assimilation technique derived the soil hydraulic parameters using Sentinel-1A/B based soil moisture images, ASOS (Automated Synoptic Observing System) weather data and TRMM (Tropical Rainfall Measuring Mission)/GPM (Global Precipitation Measurement) rainfall data. The derived soil hydrological parameters as the input data to SWAP were used to simulate the daily soil moisture values at the spatial domain from 2001 to 2018 using the TRMM/GPM satellite rainfall data. Overall, the simulated soil moisture estimates matched well with the TDR measurements and Sentinel-1A/B based soil moisture under various land surface conditions (bare soil, crop, forest, and urban).
Analysis of the Spatiotemporal Change Patterns of Greenhouse Areas Using Aerial and Satellite Imagery - A Case of Sangnam-myeon and Samrangjin-eup at Miryang -
장민원 Jang Min-won , 조현경 Cho Hyun Kyung , 김수진 Kim Soo-jin , 백미경 Baek Mi Kyung
Analysis of the Spatiotemporal Change Patterns of Greenhouse Areas Using Aerial and Satellite Imagery - A Case of Sangnam-myeon and Samrangjin-eup at Miryang -
장민원 Jang Min-won , 조현경 Cho Hyun Kyung , 김수진 Kim Soo-jin , 백미경 Baek Mi Kyung
This study analyzed the spatio-temporal change pattern of greenhouse areas for Sangnam-myeon and Samrangjin-eup of Miryang-si in Gyeongnam, which is one of major greenhouse area. First, in order to overcome the lack of statistical data of the distribution of greenhouses, aerial and satellite images were interpreted from 1987 to 2018, and the spatial distribution of the greenhouse parcels which has continuously increased was mapped based on the digital cadastral map. Next, through the emerging hot spot tool in ArcGIS Desktop, the spatio-temporal change in transition from open-field to greenhouse cultivation was classified into 9 clusters. About 67.7% of the target area was categorized as a hot spot, and the pattern of New hot spot, which were recently converted to greenhouse parcels, covered about 34.1%. While, about 11.3% of parcels were expected to keep the existing open-field cultivation practice for a while. Overall, the greenhouse parcels have been densely developed along a river and were lately expanding even to the far neighbor. It implied that, in the future, the competition of water intake among farms would be more serious and the environmental responsibility in consideration of water quality as well as quantity would be getting strengthened due to increasing pollution loads and river intake.
Estimation of Particulate Matter and Ammonia Emission Factors for Mechanically-Ventilated Pig Houses
박진선 Park Jinseon , 정한나 Jeong Hanna , 홍세운 Hong Se-woon
Emission factors for ammonia and particulate matters (PMs) from livestock buildings are of increasing importance in view of the environmental protection. While the existing emission factors were determined based on the emission inventory of other countries, in situ measurement of emission factors is required to construct an accurate emission inventory for Korea. This study is to report measurements of ammonia and PMs emissions from mechanically-ventilated pig houses, which are common types of pig barns in Korea. Ventilation rates and concentrations of ammonia and PMs were measured at the ventilation outlets of a weaner unit, a growing pig unit and a fattening pig unit to calculated the emission factors. The PMs emission was characterized with different aerodynamic diameters (PM2.5, PM10, and total suspended particulates (TSP)). The measured ammonia emission factors for weaners, growing pigs and fattening pigs were 0.225, 0.869 and 1.679 kg animal-1 yr-1, respectively, showing linear increase with pigs’ age. The PMs emission factors for three growing stages were 0.023, 0.237 and 0.241 kg animal-1 yr-1, respectively for TSP, 0.017, 0.072 and 0.223 kg animal-1 yr-1, respectively for PM10, and 0.011, 0.016 and 0.151 kg animal-1 yr-1, respectively for PM2.5. PMs emissions were increased with pigs’ age due to increasing feed supply and animal movement. The measured emission factors were smaller than those of the existing emission inventory indicating that the existing ones overestimate the emissions from pig buildings and also suggesting that long-term in situ monitoring at various livestock buildings is required to construct the accurate emission inventory.
Characteristics of Spatial Variability in Water Quality on Stream of Lake Doam Watershed
권혁준 Kwon Hyeokjoon , 이재완 Lee Jaewan , 임정하 Lim Jungha , 우수민 Woo Soomin , 김종건 Kim Jonggun , 임경재 Lim Kyeongjae , 김동진 Kim Dongjin , 홍은미 Hong Eunmi
The Doam Lake watershed is one of the non-point source management areas announced by the Ministry of Environment, and is a constant problem for the stream ecosystem dut to Storm water. In this study, a total of 48(rainfall) and 47(non-rainfall) sites were investigated for the entire watershed (Samyangcheon, Chahangcheon, Hoenggyecheon, Yongpyeongcheon, Songcheon, Lake Doam) on August 15, 2019 and on October 18, 2019 to estimate the source of turbid water in the Doam Lake watershed. Subsequently, water quality analysis was performed on Suspended Soild (SS), Turbidity, Total Phosphorus (TP), Total Nitrogen (TN), and Biochemical Oxygen Demands (BOD) and correlation among water quality parameters was analyzed based on the analyzed samples. As a result, most of the turbid water generated during rainfall was in highland fields. During rainfall, Hoengyecheon had the highest average SS concentration among all streams, and during non-rainfall, the average SS concentration was highest in Yongpyeongcheon, so the two stream were selected as vulnerable areas. However, since Yongpyeongcheon may be a temporary phenomenon due to river construction, additional continuous monitoring is required. Therefore, in the Doam Lake watershed, intensive management is required for vulnerable areas.
Estimation of an Optimum Ecological Stream Flow in the Banbyeon Stream Using PHABSIM - Focused on Zacco platypus and Squalidus chankaensis tsuchigae -
박진석 Park Jinseok , 장성주 Jang Seongju , 송인홍 Song Inhong
The objective of this study was to estimate an optimum ecological flow rate in the Banbyeon stream based on the two representative fish species. Hydraulic stream environment was simulated with HEC-RAS for two water flow regimes and used for the PHABSIM hydraulic simulation. A dominant species of Zacco platypus and an endemic species of Squalidus chankaensis tsuchigae were selected as the representative fishes whose habitat conditions were evaluated for the spawning and adult stages. Weighted usable area (WUA) was estimated based on habitat suitability index (HSI) and PHABSIM habitat simulation. Overall deep water zone in the stream demonstrated greater WUA which implies better habitat status. The estimated WUA for Zacco platypus as the dominant species was about five times greater than Squalidus chankaensis tsuchigae at the stream flow of 12 m³/s. The optimum ecological flow rates were 15 m³/s and 25 m³/s for the respective spawning and adult stages of Zacco platypus, while 5 m³/s was estimated for both the life cycles of Squalidus chankaensis tsuchigae. Assuming that the dominant species may survive better in wider flow regimes, the optimum ecological flow rate should be determined rater based on the endemic species and flow rate of 5 m³/s was suggested for the Banbyeon stream.
Evaluation of the Irrigation Water Supply of Agricultural Reservoir Based on Measurement Information from Irrigation Canal
이재남 Lee Jaenam , 노재경 Noh Jaekyoung , 강문성 Kang Munsung , 신형진 Shin Hyungjin
With the implementation of integrated water management policies, the need for information sharing with respect to agricultural water use has increased, necessitating the quantification of irrigation water supply using monitoring data. This study aims to estimate the irrigation water supply amount based on the relationship between the water level and irrigation canal discharge, and evaluate the reliability of monitoring data for irrigation water supply in terms of hydrology. We conducted a flow survey in a canal and reviewed the applicability of the rating curve based on the exponential and parabolic curves. We evaluated the reliability of the monitoring data using a reservoir water balance analysis and compared the calculated results of the supply quantity in terms of the reservoir water reduction rate. We secured 26 readings of measurement data by varying the water levels within 80% of the canal height through water level control. The exponential rating curve in the irrigation canal was found to be more suitable than the parabolic curve. The irrigation water supplied was less than 9.3-28% of the net irrigation water from 2017 to 2019. Analysis of the reservoir water balance by applying the irrigation water monitoring data revealed that the estimation of the irrigation water supply was reliable. The results of this study are expected to be used in establishing an evaluation process for quantifying the irrigation water supply by using measurement information from irrigation canals in agricultural reservoirs.
Assessment of Irrigation Efficiency and Water Supply Vulnerability Using SWMM
신지현 Shin Ji-hyeon , 남원호 Nam Won-ho , 방나경 Bang Na-kyoung , 김한중 Kim Han-joong , 안현욱 An Hyun-uk , 이광야 Lee Kwang-ya
Agricultural drought is a natural phenomenon that is difficult to observe and quantitatively express, and agricultural water use is high and usage patterns are diverse, so even if there is a lack of rainfall. The frequency and severity of agricultural drought are increased during the irrigation period where the demand for agricultural water is generated, and reasonable and efficient management of agricultural water for stable water supply is required. As one method to solve the water shortage of agricultural water in an unstructured method, it is necessary to analyze the appropriate supply amount and supply method through simulation from the intake works to the canals organization and paddy field. In this study, irrigation efficiency was analyzed for irrigation systems from April to September over the past three years from the Musu Reservoir located in Jincheon-gun, Chungcheongbuk-do and Pungjeon Reservoir located in Seosan-si, Chungcheongnam-do. SWMM (Storm Water Management Model) was used to collect agricultural water, and irrigation efficiency analysis was conducted using adequacy indicators, and water supply vulnerability. The results of the agricultural water distribution simulation, irrigation efficiency and water supply vulnerability assessment are thought to help the overall understanding of the agricultural water supply and the efficient water management through preliminary analysis of the methods of agricultural water supply in case of drought events.
Assessment of Future Flood According to Climate Change, Rainfall Distribution and CN
곽지혜 Kwak Jihye , 김지혜 Kim Jihye , 전상민 Jun Sang Min , 황순호 Hwang Soonho , 이성학 Lee Sunghack , 이재남 Lee Jae Nam , 강문성 Kang Moon Seong
According to the standard guidelines of design flood (MLTM, 2012; MOE, 2019), the design flood is calculated based on past precipitation. However, due to climate change, the frequency of extreme rainfall events is increasing. Therefore, it is necessary to analyze future floods’ volume by using climate change scenarios. Meanwhile, the standard guideline was revised by MOE (Ministry of Environment) recently. MOE proposed modified Huff distribution and new CN (Curve Number) value of forest and paddy. The objective of this study was to analyze the change of flood volume by applying the modified Huff and newly proposed CN to the probabilistic precipitation based on SSP and RCP scenarios. The probabilistic rainfall under climate change was calculated through RCP 4.5/8.5 scenarios and SSP 245/585 scenarios. HEC-HMS (Hydrologic Engineering Center - Hydrologic Modeling System) was simulated for evaluating the flood volume. When RCP 4.5/8.5 scenario was changed to SSP 245/585 scenario, the average flood volume increased by 627 ㎥/s (15%) and 523 ㎥/s (13%), respectively. By the modified Huff distribution, the flood volume increased by 139 ㎥/s (3.76%) on a 200-yr frequency and 171 ㎥/s (4.05%) on a 500-yr frequency. The newly proposed CN made the future flood value increase by 9.5 ㎥/s (0.30%) on a 200-yr frequency and 8.5 ㎥/s (0.25%) on a 500-yr frequency. The selection of climate change scenario was the biggest factor that made the flood volume to transform. Also, the impact of change in Huff was larger than that of CN about 13-16 times.
A Study on the Spatial Variation of Target Water Quality and Excess Rate at 41 Stations in Nakdong River Basin after the Total Maximum Daily Loads
조현경 Cho Hyun Kyung , 곽은태 Kwak Eun Tae , 김상민 Kim Sang Min
The objective of this study was to assess spatial variation of the target water quality criteria and excess rate in Nakdong river basin after the Total Maximum Daily Loads (TMDLs). For this, 41 total water quality monitoring stations were selected BOD and T-P data were collected from 2003 to 2019. The annual average water quality of BOD and T-P were calculated and compared with the target water quality for each stations by peroid. As a result of analyzing the BOD, Kumho A, Nakbon F, Namgang D, Miryang B, Wicheon B and Hoecheon A exceeded the target water quality criteria for two consecutive times. For T-P, Nakbon N, Naeseung B, Miryang A, Hwanggang A and Hoecheon A exceeded the target water quality criteria twice in a row. In the case of T-P, the target water quality excess rate was relatively low after the TMDLs implementation compared to before the TMDLs implementation. However, in the case of BOD, there was no difference in the target water quality excess rate before and after TMDLs. As a result, the overall annual average water quality shows a decreasing trend, but it is necessary to manage the water quality for the Nakdong river basin that exceed the target water quality.
Development of a Long-slope Water Harvesting System in Natural Channel for Drought Mitigation in Upland
김영진 Kim Youngjin , 최용훈 Choi Yonghun , 이상봉 Lee Sangbong , 김민영 Kim Minyoung , 전종길 Jeon Jonggil
This study developed a rainwater harvesting system for the irrigation of upland on sloping area. The assessment of water supply capacity was evaluated in farm field experience. This system consists of a water catchment device and a collapsible storage tank. The water catchment device was designed to collect runoff water in natural channel of 500 mm width into a pipe of 50 mm inner diameter. The device has funnel-shaped plan and cross-section of square. The storage capacity of the collapsible water tank was caculated to meet the water demand for irrigation in 30 a cultivated land for 10-year frequancy drought. The tank has a cuboid shape with a capacity of 30 m3, 5 m in width and length, 1.2 m in height. This system can supply 92% of the water required for drop irrigation of red pepper and 88% of the water required for drop irrigation of onions in 30 a cultivation land during the month of May and June. In the case of 16-dry days of 10-years frequency, this system is capable to irrigate 100% of required water for red pepper and onion, 76.7% of required water for Omija (Schisandra chinensis), and 51.5% of required water for autumn kimchi cabbage.
Evaluation on the Effect of Relief Wells by 3D Numerical Analysis on the Embankment of an Agricultural Reservoir
Through 3D seepage analysis of pressure relief well installed on the embankment of agricultural reservoir, the effects of reducing pore water pressure and hydraulic gradient, and increasing piping safety, depending on diameter (0.2, 0.4, 0.6 m) and space (10, 25, 50 m) of relief well, were analyzed. The conclusions drawn through this study are as follows. i) At the location of pressure relief well, pore water pressure decreases by 25.3∼62.5%, and hydraulic gradient decreases by 22.4∼55.7%. ii) Between relief wells, pore water pressure decreases by 2.7∼40.3%, and hydraulic gradient decreases by 2.8∼47.0%, which are relatively less than at the cross section of installed location of relief well. iii) Piping safety factor by critical hydraulic gradient increases by 28.9∼125.6% at the location of relief well and increases by 2.9∼88.8% between relief wells. iv) Seepage analysis needs to be performed by the 3D method to make evaluation of seepage at the location of relief well and between relief wells possible. v) Additional evaluation is required for various conditions such as waterhead, engineering characteristics of embankment body and its foundation, location, diameter, spacing and depth of pressure relief well.
Future Inundation Risk Evaluation of Farmland in the Moohan Stream Watershed Based on CMIP5 and CMIP6 GCMs
전상민 Jun Sang Min , 황순호 Hwang Soonho , 김지혜 Kim Jihye , 곽지혜 Kwak Jihye , 김계웅 Kim Kyeung , 이현지 Lee Hyun Ji , 김석현 Kim Seokhyeon , 조재필 Cho Jaepil , 이재남 Lee Jae Nam , 강문성 Kang Moon Seong
Future Inundation Risk Evaluation of Farmland in the Moohan Stream Watershed Based on CMIP5 and CMIP6 GCMs
전상민 Jun Sang Min , 황순호 Hwang Soonho , 김지혜 Kim Jihye , 곽지혜 Kwak Jihye , 김계웅 Kim Kyeung , 이현지 Lee Hyun Ji , 김석현 Kim Seokhyeon , 조재필 Cho Jaepil , 이재남 Lee Jae Nam , 강문성 Kang Moon Seong
The objective of this study was to evaluate future inundation risk of farmland according to the application of coupled model intercomparison project phase 5 (CMIP5) and coupled model intercomparison project phase 6 (CMIP6). In this study, future weather data based on CMIP5 and CMIP6 general circulation model (GCM) were collected, and inundation was simulated using the river modeling system for small agricultural watershed (RMS) and GATE2018 in the Tanjung district of the Moohan stream watershed. Although the average probable rainfall of CMIP5 and CMIP6 did not show significant differences as a result of calculating the probability rainfall, the difference between the minimum and maximum values was significantly larger in CMIP6. The results of the flood discharge calculation and the inundation risk assessment showed similar to trends to those of probability rainfall calculations. The risk of inundation in the future period was found to increase in all sub-watersheds, and the risk of inundation has been analyzed to increase significantly, especially if CMIP6 data are used. Therefore, it is necessary to consider climate change effects by utilizing CMIP6-based future weather data when designing and reinforcing water structures in agricultural areas in the future. The results of this study are expected to be used as basic data for utilizing CMIP6-based future weather data.
