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효과적인 유역관리를 위한 CN기법 기반의 침투량 산정 및 기저유출량 분석
김희원 ( Hee Won Kim ),신연주 ( Yeon Ju Sin ),최정헌 ( Jung Heon Choi ),강현우 ( Hyun Woo Kang ),류지철 ( Ji Chul Ryu ),임경재 ( Kyoung Jae Lim ) 한국물환경학회 2011 한국물환경학회지 Vol.27 No.4
Increased Non-permeable areas which have resulted from civilization reduce the volume of groundwater infiltration that is one of the important factors causing water shortage during a dry season. Thus, seeking the efficient method to analyze the volume of groundwater in accurate should be needed to solve water shortage problems. In this study, two different watersheds were selected and precipitation, soil group, and land use were surveyed in a particular year in order to figure out the accuracy of estimated infiltration recharge ratio compared to Web-based Hydrograph Analysis Tool (WHAT), The volume of groundwater was estimated considering Antecedent soil Moisture Condition (AMC) and Curve Number (CN) using Long Term Hydrologic Impact Assessment (L-TH1A) model. The results of this study showed that in the case of Kyoung-an watershed, the volume of both infiltration and baseflow seperated from WHAT was 46.99% in 2006 and 33.68% in 2007 each and in Do-am watershed the volume of both infiltration and baseflow was 33.48% in 2004 and 23.65% in 2005 respectively. L-TFIIA requires only simple data (i.e., land uses, soils, and precipitation) to simulate the accurate volume of groundwater. Therefore, with convenient way of L-TKIA, researchers can manage watershed more effectively than doing it with other models. L-THIA has limitations that it neglects the contributions of snowfall to precipitation. So, to estimate more accurate assessment of the long term hydrological impacts including groundwater with L-THIA, further researches about snowfall data in winter should be considered.
임경재 ( Kyoung Jae Lim ),박윤식 ( Youn Shik Park ),김종건 ( Jonggun Kim ),신용철 ( Yong-chul Shin ),김남원 ( Namwon Kim ),김성준 ( Seong-jun Kim ),전지홍 ( Ji-hong Jeon ),( Bernard A. Engel ) 한국농공학회 2009 한국농공학회 학술대회초록집 Vol.2009 No.-
Many hydrologic and water quality computer models have been developed and applied to assess hydrologic and water quality impacts of land use changes. These models are typically calibrated and validated prior to their application. The Long-Term Hydrologic Impact Assessment (L-THIA) model was applied to the Little Eagle Creek (LEC) watershed and compared with the filtered direct runoff using BFLOW and the Eckhardt digital filter (with a default BFImax value of 0.80 and filter parameter value of 0.98), both available in the Web GIS-based Hydrograph Analysis Tool, called WHAT (https://engineering.purdue.edu/~what). The R2 value and the Nash-Sutcliffe coefficient values were 0.68 and 0.64 with BFLOW, and 0.66 and 0.63 with the Eckhardt digital filter. Although these results indicate that the L-THIA model estimates direct runoff reasonably well, the filtered direct runoff values using BFLOW and Eckhardt digital filter with the default BFImax and filter parameter values do not reflect hydrological and hydrogeological situations in the LEC watershed. Thus, a BFImax GA-Analyzer module (BFImax Genetic Algorithm-Analyzer module) was developed and integrated into the WHAT system for determination of the optimum BFImax parameter and filter parameter of the Eckhardt digital filter. With the automated recession curve analysis method and BFImax GA-Analyzer module of the WHAT system, the optimum BFImax value of 0.491 and filter parameter value of 0.987 were determined for the LEC watershed. The comparison of L-THIA estimates with filtered direct runoff using an optimized BFImax and filter parameter resulted in an R2 value of 0.66 and the Nash-Sutcliffe coefficient value of 0.63. However, L-THIA estimates calibrated with the optimized BFImax and filter parameter increased by 33% and estimated NPS pollutant loadings increased by more than 20%. This indicates L-THIA model direct runoff estimates can be incorrect by 33% and NPS pollutant loading estimation by more than 20%, if the accuracy of the baseflow separation method is not validated for the study watershed prior to model comparison. This study shows the importance of baseflow separation in hydrologic and water quality modeling using the L-THIA model.
웹 기반의 툴을 이용한 L-THIA 모델의 자동 캘리브레이션
임경재 ( Lim Kyoung Jae ),버니엥겔 ( Engel Bernard A ),최중대 ( Choi Joongdae ),김기성 ( Kim Ki-sung ),신용철 ( Shin Yong-chul ) 한국농공학회 2004 한국농공학회 학술대회초록집 Vol.2004 No.-
본 연구에서는 L-THIA 모델을 자동으로 캘리브레이션하는 프로그램을 작성하여 L-TH1A 모델을 Calibration / Validation 을 하였다. 일 유출버젼의 L-THIA 모델을 1991년 1월 1일부터 1991년 6월 30일까지 캘리브레이션한 결과 결정계수 (R2) 가 0.71이고, Nash-Sutcliffe 계수가 0.60 이상이 되었다. 이렇게 보정된 CN 값을 이용하여 1991년 7월 1일부터 1991년 12월 31일의 일 강우자료로 일 유출량을 모의하여 실측직접유출과 비교한 결과, R2 가 0.88이고, Nash-Sutcliffe 계수가 0.60 이상이 되었다. 이 연구결과에서 보이는 바와 같이, 간단한 모델이라도 얼마나 정확한 모델 입력 변수값을 사용하느냐 따라서, 그 모의치는 기대이상으로 실측치를 반영할 수 있다는 것을 보여준다. 이렇게 보정된 모델을 이용함으로써 토지이용변화가 연구유역내의 수문과 수질에 미치는 영향을 보다 정확하게 모의 할 수 있을 것이다. Urbanization can result in alteration of a watershed's hydrologic response and water quality. To simulate hydrologic and water quality impacts of land use changes, the Long-Term Hydrologic Impact Assessment (L-THIA) system has been used. The L-THIA system estimates pollutant loading based on direct runoff quantity and land use based pollutant coefficient. Thus, the correct estimation of the direct runoff is important in assessing water quality impacts of land use changes. In this study, an automatic calibration program was developed to calibrate the L-THIA model using numerous Curve Number (CN) combinations associated with land uses and hydrologic soil groups. L-THIA calibration for the Little Eagle Creek watershed near Indianapolis, USA was performed using 1991 land use and 1991 daily rainfall data for January 1, 1991 to June 30, 1991 to exclude errors associated with use of different temporal land use data and rainfall data. For the calibration period, the Nash-Sutcliffe coefficient was 0.60 for estimated and observed direct runoff. The calibrated CN values were used for validation for July 1, 1991 to December 31, 1991, and the Nash-Sutcliffe coefficient was 0.60 for estimated and observed direct runoff. The Nash-Sutcliffe coefficient was 0.52 for January 1, 1991 to December 31, 1991 using uncalibrated CN values. As shown in this study, the use of better input parameters for the L-THIA model can improve accuracy.
Google Map과 WAMIS 자료를 이용한 직접유출/기저유출 분리 시스템의 개발
임경재 ( Lim Kyoung Jae ),박윤식 ( Park Younshik ),김종건 ( Kim Jonggun ),허성구 ( Heo Sung Gu ),신용철 ( Shin Yongchul ),유동선 ( Yoo Dong Sun ),김기성 ( Kim Ki-sung ),최중대 ( Choi Joongdae ) 한국농공학회 2007 한국농공학회 학술대회초록집 Vol.2007 No.-
The Geographic Information System has been widely used in every aspect of our lives. Many attempts have been made using freely available Google Map API, which provides various GIS and other functionalities with high-resolution satellite images all over the world. These high resolution data by the Google Map is very efficient in locating target area of interest compared with vector dataset. Therefore, the Google Map was used to develop Web GIS interface in locating the gaging station in Korea. The Web-based Hydrograph Analysis Tool (WHAT) was enhanced using the Google Map interface in this study. The Google Map interface was linked to the WAMIS web site for automatic retrieval of daily flow data for automatic baseflow separation Also, the Google Map WHAT interfaces were extended for 48 states in the US (http://www.EnvSys. co.kr/~what, http://cobweb.ecn.purdue.edu/~what/WHAT_GOOGLE). The biggest advantage of using the Google Map interface is that system developers do not need to install Web GIS system on the server, which is sometimes either expensive or heavy for the server. Also, numerous Google Map API can be integrated into the system with minor modifications, enabling very cost-effective Web GIS application. The easy-to-use Google Map interface WHAT system can be efficiently used in calibrating and validating hydrologic and water quality models. The Korea Department of Environment water quality data will be linked to the WHAT system for automatic analysis of water quality trends and pollutant loads characteristics.