• Proceedings of the KSRS Conference
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• 2009.03a
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• pp.129-133
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• 2009

본 연구에서 소개할 SEBAL (Surface Energy Balance Algorithm for Land) (Bastiaanssen, 1995) 모형은 Landsat이나 NOAA 또는 MODIS 같은 원격탐사 위성으로부터 획득한 디지털 이미지 데이터(위성영상)를 이용하여, 지표에서 일어나는 증발산과 기타의 에너지 교환을 계산하는 이미지-프로세싱 모델이다. SEBAL 모형은 1995년 Bastiaanssen에 의해 처음 제안되었고, 미국의 Idaho 주립대학과 Idaho Department of Water Resources에서 NASA와 기업의 지원을 받아 활발히 연구 되었으며, 25개의 sub model들을 이용하여 지표의 증발산량과 기타 여러 에너지 교환을 계산한다. 여기서, 열적외선 방사, 표시 및 근적외선 측정은 Landsat 또는 기타 여러 위성영상을 통해 얻을 수 있으며, SEBAL 모형은 이러한 자료를 활용한다. 모형에서의 증발산량(ET)은 에너지 균형원리를 통해 pixel-by-pixel을 기준으로 계산되며, 본 연구에서 SEBAL 모형은 한강 유역 내의 경안천 유역 증발산량 map 생성을 위해 6개년도 지점 Landsat 위성영상을 이용하어 추정되었다. 연구의 목적은 SEBAL 모형을 통해 생성 된 30m 해상도의 공간 증발산량 map의 활용성 평가와 검증이며, 검증을 위해 FAO Penman-Monteith 공식을 이용하여 추정된 증발산량 값을 이용하였다. 그 결과, 오차가 2.7% 이내로 나타났다.

• Journal of Korea Water Resources Association
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• v.49 no.1
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• pp.61-72
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• 2016

In Korea, the aquifers at the coastal areas are mostly shallow alluvial unconfined aquifers. To simulate the flow and dispersion in unconfined aquifer, a FDM model has been developed to solve the nonlinear Boussinesq equation. Related analysis and verification have been executed. The iteration method is used to solve the nonlinearity, and the model shows 3-D shape because it is a 2-D y model that consider the undulation of water table and bottom. For the verification of the model, the output of flow module is compared to the 1-D analytic solution of Lee (1989) which have the drawdown or uplift boundary condition, and the two results show almost the same value. and the mass balance of dispersion module shows about 10% error. The developed model can be used for the analysis and design of the flow and dispersion in the unconfined aquifers. The model has been applied to the estuary area of Ssangcheon watershed, and the parameters have been deduced as a result : hydraulic conductivity is 90 m/day, and longitudinal dispersivity is 15 m. And the analysis with these parameters shows that the wells are situated in the influence circle of each others except for No. 7 well. Groundwater discharge to sea is $3700m^3/day$. And the chlorine ion ($cl^-$) concentration at the pumping wells increase at least 1000 mg/L if groundwater dam is not exist, so the groundwater dam plays an important role for the prevention of sea water intrusion.

• Journal of the Korean Association of Geographic Information Studies
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• v.11 no.1
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• pp.20-30
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• 2008

This study is to analyse the hydrological behavior of agricultural reservoir using SWAT model. For the upsteam watershed of Gongdo water level gauge station in Anseongcheon watershed, the streamflows at 2 reservoir (Gosam and Geumgwang) locations and Gongdo station were simulated with reservoir inclusion and exclusion. The daily water surface area and storage have been calculated considering the stage-storage curve function of the reservoir. Afterwards, the reservoir operation module in SWAT was modified from original module in SWAT for daily reservoir discharge simulated by water balance equation. Model validation results were Nash-Sutcliffe model efficiency coefficients value of 0.55, root mean square error value of 2.33 mm/day. On the other hand, the simulation results of two reservoir exclusion were Nash-Sutcliffe model efficiency coefficients value of 0.37, root mean square error value of 2.91 mm/day. The difference of Nash-Sutcliffe model efficiency coefficients between the simulation results of two reservoir inclusion and exclusion at Gongdo station was 0.18. This is caused by the storage and release operation of agricultural reservoirs for the runoff occurred at 2 reservoir watersheds.

• Journal of Environmental Science International
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• v.27 no.10
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• pp.845-851
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• 2018

In this study, the runoff characteristics of the non-rainfall period were examined using daily rainfall data from 1977 to 2017 and the data of runoff into the dam. Results showed that, the mean runoff decreases with longer non-rainfall periods in the Andong dam basin. The correlation coefficient between non-rainfall days and average runoff reaches 0.85. The results of the analysis of the runoff characteristics during the non-rainfall period, based on the preceding rainfall of Andong dam are as follows. The runoff characteristics of the entire non-rainfall period, shows that, for a rainfall of 1.0 mm or less, the runoff height was larger than the rainfall size and the base runoff larger. The correlation between the antecedent rainfall and runoff height was reached as high as 0.9864 in the 30 ~ 50 mm interval of the antecedent rainfall period, and this is the interval where the linearity of rainfall and runoff was at its maximum in the Andong dam basin. The correlation between the antecedent rainfall and the runoff height reached 0.92 for rainfalls of 100.0 mm. However, for rainfalls of 100.0 mm greater, the correlation between the antecedent rainfall and runoff height during the rainfall period was 0.64, which is relatively small. In this study, we investigated the runoff characteristics of the rainfall period in the Andong dam watershed. As a result, it was confirmed that the mean runoff decreased with rainfall duration. The linearity was found to be weak for rainfall events greater than 100.0 mm. The results of this study can be used as data for water balance analysis and for formulating a water supply plan to establish water resource management of Andong dam.

• The Journal of Engineering Geology
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• v.3 no.3
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• pp.253-266
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• 1993

GIS technique was applied for ffie work of water supply protection, and GIS rnaps were produced by this technique in Cheong-ju area. They are actual runoff rnap and regional groundwater protection map. The digital database was estabilished for creation of these maps in EGIS(Environmental Geologic information system). A lot of environmental, hydrological and geotedmical data relating to the area were collected from various sources, and used along with the results of the field investigation and laboratorv works in the interpretation of environmental geologic characteristics of the area. These special maps can be applied in the establishment of water supply protection and regional land use planning. For instant, the actaal runoff rnap is very linportant for hydrologic study, and groundwater protection map for susceptibility to groundwater contamination in the area. Actual runoff of the study area was calculated about 148mm using the method of SCS(Soil Consrevation Service) in GIS. The GIS technique was effective in watershed analysis and water balance study.

• Water for future
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• v.29 no.5
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• pp.223-233
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• 1996

Daily streamflow model, DAWAST, considering the meteorologic and geographic characteristics of the Korean watersheds has been developed to simulate the daily streamflow with the input data of daily rainfall and pan evaporation. The model is the conceptual one with three sub-models which are optimization, generalization, and regionalization models. The conceptual model consists of three linear reservoirs representing the surface, unsaturated, and saturated soil zones and water balance analysis was carried out in each soil zones on a daily basis. Optimization model calibrates the parameters by optimization technique and is applicable to the watersheds where the daily streamflow data are available Generalization model predicts the parameters by regression equations considering the geographic, soil type, land use, and hydrogeologic characteristics of watershed and is appicable to ungaged medium or small watersheds. Regionalization model cites the parameters from the analysed ones considering river system, latitude and longitude, and is applicable to ungaged large watersheds.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.385-385
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• 2011

유역 스케일의 실제 증발산량을 산정하는 대표적인 방법으로 관측 강우량과 유출량의 관계로부터 증발산량을 간접적으로 추정하는 물수지(water balance)법, 증발력과 토양수분량의 변화량 (soil moisture accounting)을 고려한 유역 수문모델링을 이용하는 방법, 잠재 증발산량과 실제 증발산량간 보완관계식(complementary relationship)을 이용하는 방법 등이 있다. 물수지법은 관측치를 기반으로 한다는 점에서 신뢰도가 높다고 할 수 있으나, 기본적으로 유역 저류량의 변화를 무시하기 때문에 연 단위와 같이 긴 시간 스케일에 적용 가능하고 작은 시간 스케일에는 적용성이 떨어진다. 유역 수문모델링을 이용하는 방법은 기상, 토양 및 식물 조건을 모두 고려하는 방법으로 유역의 불균질성을 반영할 수 있고 일 단위 등의 비교적 작은 시간 스케일에 대해서도 증발산량을 산정할 수 있는 장점이 있으나, 수많은 입력자료가 필요하며 간접적인 추정 방식이기 때문에 모형의 정확한 검증과 상당한 숙련도가 뒷받침되어야 한다. 잠재 증발산량과 실제 증발산량간 보완관계식을 이용하는 방법은 토양이나 식물 등의 지표면 조건에 대한 정보를 필요로 하지 않으며 단지 기상자료만을 이용하는 방법으로 적용하기 쉽다는 장점이 있으나 잠재 및 실제 증발산량간의 보완피드벡 매카니즘이 존재한다는 가정이 수반되어 있어 적용시 이를 입증해야 하는 어려움이 있다. 이 처럼 각기 장단점을 가진 여러 방법으로 증발산량을 산정하고 있지만, 각 방법 간의 연결고리를 맺는 연구는 심도 있게 수행되지 못하고 있다. 따라서 본 연구에서는 상기 언급한 증발산량 산정 방법 중 보완관계식을 이용하는 방법과 유역수문모형에 의한 방법 간의 연관성을 평가하고자 하였으며, 이를 위해 충주댐 상류유역에 대해서 SWAT-K에 의한 증발산량 모의치가 보완관계식을 따르는 지에 대해 고찰하였다. 모의기간동안 계산된 잠재 및 실제 증발산량을 습윤지수(humidity index)에 따라 함께 도시해본 결과, 연 단위의 경우에는 건조할수록 잠재 증발산량은 점차 커지고 실제 증발산량은 작아지는 것으로 나타나 보완관계가 성립하였고, 월 단위 경우에는 강우에 비해서 비교적 증발산량이 큰 5, 6월에 가장 명확한 관계가 보여 늦은 봄과 초여름에 보완적 관계가 뚜렷하게 발생하는 반면에 동절기에는 보완관계가 성립하지 않는 것으로 나타나는 등 분석 단위기간별로 보완관계의 성립여부를 판별할 수 있었다.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.71-71
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• 2023

국가물관리기본법에 의거하여 통합물관리 정책에 부합하는 농어촌용수 계획 및 관리를 위해 유역 및 용수구역 단위의 농업용수 공급 및 수요 분석이 요구되고 있다. 현재 농업용수는 개수로 방식 용수공급체계 및 수문 직접조작에 의한 용수배분체계로 공급량 대비 사용량의 비율이 48%에 불과하다. 또한, 농경지 상류와 하류의 공급량 차이가 크게 발생하며, 경지면적 감소가 공급 필요량 감소로 연결되지 않는다. 농업용수의 경우 기존 국가유역수자원 모델 (K-WEAP, MODISM)을 통한 물수지 분석시 순물소모량 개념의 회귀수량 산정으로 공급량과 회귀량의 왜곡이 발생하고 있으며, 이에 따른 공급량 왜곡, 유역내 복잡하고 다양한 농업용수 공급체계를 하나의 가상저수지로 단순화함으로서 유역내 들녘별 농업용수 과부족 분석 불가능, 하천과 저수지 공급 우선순위 현장과 불일치 등 농어촌용수구역의 특성 및 실제 현장을 반영하는데 한계가 있다. 본 연구에서는 기존 물수지 분석 모델을 개선하기 위한 농업용수 유역 물수지 분석 모델의 방법론을 제시하고 시범지역 적용을 통한 검증 및 적용성을 평가하고자 한다. 경기 안서 농촌용수구역을 대상으로 농어촌공사 및 지자체 관리 저수지, 양수장, 취입보, 관정 등 총 106개 개별 시설물 자료를 구축하였으며, 39개 지구로 세분화하였다. 한국농어촌공사의 계측 공급량 기반 수요량 및 개별 시설물에 대한 물수지 분석 후 지구 단위, 소유역 단위, 표준유역 단위의 상하류 및 시설물을 연계한 유역 물수지 모델을 제시하고자 한다.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.27 no.1
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• pp.1-16
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• 2024

The riparian area plays a crucial role in maintaining the balance between the aquatic and terrestrial ecosystems. The Korean government has recognized the importance of protecting riparian areas and has taken steps to purchase land and create ecobelt to reduce non-point source pollutants(NSPs) that can negatively impact water quality. However, selecting the catchment area and calculating the pollution load can be challenging due to the small area of the purchased land and the limitations of low-resolution DEMs. To address these challenges, this study proposes the use of unmanned aerial vehicles(UAVs) to create a high-resolution DEM and calculate the pollution load through land cover analysis. This approach can provide a more accurate representation of the land use status and help to identify areas that are contributing to NSPs. The quantitative comparison of the difference in water quality improvement ecosystem services according to the scenarios of additional catchment areas shows that even land purchased for the same amount of money may have different ecosystem service values, and this was quantitatively calculated. This can be used to prioritize future land acquisition. Overall, this study's approach could provide valuable insights into the effectiveness of ecobelt in reducing NSPs and inform future efforts to protect riparian areas in Korea and beyond.

• Journal of the Korean Association of Geographic Information Studies
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• v.17 no.3
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• pp.160-174
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• 2014

The purpose of this paper is to develop a meso-scale grid-based continuous hydrological model and apply to assess the future watershed hydrology by climate change. The model divides the watershed into rectangular cells, and the cell profile is divided into three layered flow components: a surface layer, a subsurface unsaturated layer, and a saturated layer. Soil water balance is calculated for each grid cell of the watershed, and updated daily time step. Evapotranspiration(ET) is calculated by Penman-Monteith method and the surface and subsurface flow adopts lag coefficients for multiple days contribution and recession curve slope for stream discharge. The model was calibrated and verified using 9 years(2001-2009) dam inflow data of two watersheds(Chungju Dam and Soyanggang Dam) with 1km spatial resolution. The average Nash-Sutcliffe model efficiency was 0.57 and 0.71, and the average determination coefficient was 0.65 and 0.72 respectively. For the whole Han river basin, the model was applied to assess the future climate change impact on the river bsain. Five IPCC SRES A1B scenarios of CSIRO MK3, GFDL CM2_1, CONS ECHO-G, MRI CGCM2_3_2, UKMO HADGEMI) showed the results of 7.0%~27.1 increase of runoff and the increase of evapotranspiration with both integrated and distributed model outputs.