토양수분 저류 기반의 간결한 준분포형 수문분할모형 개발

최정현 ( Jeonghyeon Choi ),김령은 ( Ryoungeun Kim ),김상단 ( Sangdan Kim ) 한국물환경학회(구 한국수질보전학회) 2020 한국물환경학회지 Vol.36 No.3

Hydrologic models, as a useful tool for understanding the hydrologic phenomena in the watershed, have become more complex with the increase of computer performance. The hydrologic model, with complex configurations and powerful performance, facilitates a broader understanding of the effects of climate and soil in hydrologic partitioning. However, the more complex the model is, the more effort and time is required to drive the model, and the more parameters it uses, the less accessible to the user and less applicable to the ungauged watershed. Rather, a parsimonious hydrologic model may be effective in hydrologic modeling of the ungauged watershed. Thus, a semi-distributed hydrologic partitioning model was developed with minimal composition and number of parameters to improve applicability. In this study, the validity and performance of the proposed model were confirmed by applying it to the Namgang Dam, Andong Dam, Hapcheon Dam, and Milyang Dam watersheds among the Nakdong River watersheds. From the results of the application, it was confirmed that despite the simple model structure, the hydrologic partitioning process of the watershed can be modeled relatively well through three vertical layers comprising the surface layer, the soil layer, and the aquifer. Additionally, discussions were conducted on antecedent soil moisture conditions widely applied to stormwater estimation using the soil moisture data simulated by the proposed model.

무유출의 고려를 통한 간헐하천 유역에 확률기반의 격자형 수문모형의 구축

이동기,안국현 한국수자원학회 2020 한국수자원학회논문집 Vol.53 No.6

This study presents a probabilistic distributed hydrological model for Ephemeral catchment, where zero flow often occurs due to the influence of distinct climate characteristics in South Korea. The gridded hydrological model is developed by combining the Sacramento Soil Moisture Accounting Model (SAC-SMA) runoff model with a routing model. In addition, an error model is employed to represent a probabilistic hydrologic model. To be specific, the hydrologic model is coupled with a censoring error model to properly represent the features of ephemeral catchments. The performance of the censoring error model is evaluated by comparing it with the Gaussian error model, which has been utilized in a probabilistic model. We first address the necessity to consider ephemeral catchments through a review of the extensive research conducted over the recent decade. Then, the Yongdam Dam catchment is selected for our study area to confirm the usefulness of the hydrologic model developed in this study. Our results indicate that the use of the censored error model provides more reliable results, although the two models considered in this study perform reliable results. In addition, the Gaussian model delivers many negative flow values, suggesting that it occasionally offers unrealistic estimations in hydrologic modeling. In an in-depth analysis, we find that the efficiency of the censored error model may increase as the frequency of zero flow increases. Finally, we discuss the importance of utilizing the censored error model when the hydrologic model is applied for ephemeral catchments in South Korea. 본 연구에서는 우리나라의 기후 특성의 영향으로 종종 발생하는 무유출량의 간헐하천 유역(Ephemeral catchment)에 확률기반 격자형 수문 모형을 구축하였다. 격자형 모형의 구축을 위하여 Sacramento Soil Moisture Accounting Model (SAC-SMA) 유출 모형을 사용하였으며 라우팅 모형의 결합으로 격자형 강우-유출 모형을 구축하였다. 확률 모형의 표현을 위하여 에러 모형을 결합시켰으며 간헐하천 유역에 적합하게 표현하기 위해서 검열된 오류 모형(censoring error model)을 사용하였다. 기존에 많이 사용되는 정규화된 오류 모형과의 비교를 통하여 본 연구에서 구축한 모형의 적합성을 평가하였다. 먼저 과거 주된 연구와 유역에 대한 검토를 통하여 그 필요성을 논하였으며 우리나라에서 수문 모형에 많이 사용되는 용담댐을 선정하여 수문 모형을 구축하였다. 결과적으로 본 연구에서 구축한 두개의 모형이 둘 다 신뢰할 만한 결과를 보여주지만 검열된 오류 모형의 사용이 더욱 적합한 결과를 보여주는 것을 확인하였다. 이 과정에서 기존의 방법론은 확률 기반의 유출량의 표현에 있어서 0 이하의 음수값을 상당히 표현하였으며 이는 현실이지 못한 수문 모델링의 표현을 의미한다. 본 연구에서는 또한 두 모형의 심층적인 비교를 위하여 심화된 간헐하천 유역을 구축하고 수문 모델링을 하였다. 결과적으로 무유출의 빈도 증가에 따라 무유출량을 고려하는 검열된 오류 모형의 효율이 증가하는 것을 알 수 있었다. 본 연구에서 얻은 결과는 우리나라의 수문 모델링에 있어서 간헐하천 유역에 대한 고려가 필요하다는 것을 의미한다.

COMFARM을 이용한 농업용저수지 유역 수문 모델링

송정헌,박지훈,김계웅,류정훈,전상민,김진택,장태일,송인홍,강문성,Song, Jung-Hun,Park, Jihoon,Kim, Kyeung,Ryu, Jeong Hoon,Jun, Sang Min,Kim, Jin-Taek,Jang, Taeil,Song, Inhong,Kang, Moon Seong 한국농공학회 2016 한국농공학회논문집 Vol.58 No.3

The component-based modeling framework for agricultural water-resources management (COMFARM) is a user-friendly, highly interoperable, lightweight modeling framework that supports the development of watershed-specific domain components. The objective of this study was to evaluate the suitability of the COMFARM for the design and creation of a component-based modeling system of agricultural reservoir watersheds. A case study that focused on a particular modeling system was conducted on a watershed that includes the Daehwa and Dangwol serial irrigation reservoirs. The hydrologic modeling system for the study area was constructed with linkable components, including the modified Tank, an agricultural water supply and drainage model, and a reservoir water balance model. The model parameters were each calibrated for two years, based on observed reservoir water levels. The simulated results were in good agreement with the observed data. In addition, the applicability of the COMFARM was evaluated for regions where reservoir outflows, including not only spillway release but also return flow by irrigation water supply, substantially affect the downstream river discharge. The COMFARM could help to develop effective water-management measures by allowing the construction of a modeling system and evaluation of multiple operational scenarios customized for a specific watershed.

도시화에 따른 물순환 영향 평가 모형의 개발 및 적용(I) - 모형 개발 -

김현준,장철희,노성진 한국수자원학회 2012 한국수자원학회논문집 Vol.45 No.2

본 연구의 목적은 도시개발의 영향을 평가하고 물순환 개선시설의 적절한 배치를 설계하기 위한 물순환 해석 모형을 개발하는 것이다. 개념적 매개변수를 사용하는 기존의 집중형 수문모형으로는 도시개발로 인한 토지이용 변화 등의 유역 특성 변화를 적절히 모의하는데 한계가 있으며, 최근 활발히 연구되고 있는 분포형 수문모형은 입력자료 구축 및 모형구동에 많은 시간과 노력이 필요하여 다양한 도시설계 대안을 평가하기에는적절하지못하다. 유역 물순환 해석 모형(Catchment hydrologic cycle Analysis Tool, 이하 CAT)은 이러한 배경을 토대로 개발된 물리적 매개변수 기반의 링크-노드 방식의 물순환 정량화 모형이다. CAT은 기존 개념적 매개변수 기반의 집중형 수문모형과 물리적 매개변수 기반의 분포형 수문모형의 장단점을 최대한 보완하여, 도시유역 개발 전 후의 장 단기적인 물순환 변화 특성을 정량적으로 평가하고 물순환 개선시설의 효과적인 설계를 지원하기 위한 물순환 해석 모형이다. 개발된 모형의 평가를 위하여 설마천 유역을 대상으로 모의를 수행하였으며 출구점인 전적비교의 6개년(2002~2007) 동안의 시간별 하천 유출량 자료를 이용하여 모형의 보정(2002~2004)과 검정(2005~2007)을 실시한 결과, 보정과 검정기간의 Nash-Sutcliffe 모형효율계수는 각각 0.75와 0.89로 나타났다. The objective of this study is to develop a catchment hydrologic cycle assessment model which can assess the impact of urban development and designing water cycle improvement facilities. Developed model might contribute to minimize the damage caused by urban development and to establish sustainable urban environments. The existing conceptual lumped models have a potential limitation in their capacity to simulate the hydrologic impacts of land use changes and assess diverse urban design. The distributed physics-based models under active study are data demanding; and much time is required to gather and check input data; and the cost of setting up a simulation and computational demand are required. The Catchment Hydrologic Cycle Assessment Tool (hereinafter the CAT) is a water cycle analysis model based on physical parameters and it has a link-node model structure. The CAT model can assess the characteristics of the short/long-term changes in water cycles before and after urbanization in the catchment. It supports the effective design of water cycle improvement facilities by supplementing the strengths and weaknesses of existing conceptual parameter-based lumped hydrologic models and physical parameterbased distributed hydrologic models. the model was applied to Seolma-cheon catchment, also calibrated and validated using 6 years (2002~2007) hourly streamflow data in Jeonjeokbigyo station, and the Nash-Sutcliffe model efficiencies were 0.75 (2002~2004) and 0.89 (2005~2007).

Streamflow, stomata, and soil pits: Sources of inference for complex models with fast, robust uncertainty quantification

Dwelle, M. Chase,Kim, Jongho,Sargsyan, Khachik,Ivanov, Valeriy Y. C.M.L. Publications 2019 ADVANCES IN WATER RESOURCES Vol. No.

<P><B>Abstract</B></P> <P>The scale and complexity of environmental and earth systems introduce an array of uncertainties that need to be systematically addressed. In numerical modeling, the ever-increasing complexity of representation of these systems confounds our ability to resolve relevant uncertainties. Specifically, the numerical representation of the governing processes involve many inputs and parameters that have been traditionally treated as deterministic. Considering them as uncertain introduces a large computational burden, stemming from the requirement of a prohibitive number of model simulations. Furthermore, within hydrology, most catchments are sparsely monitored, and there are limited, heterogeneous types of data available to confirm the model’s behavior. Here we present a blueprint of a general approach to uncertainty quantification for complex hydrologic models, taking advantage of recent methodological developments. We rely on polynomial chaos machinery to construct accurate surrogates that can be efficiently sampled for the ecohydrologic model tRIBS-VEGGIE to mimic its behavior with respect to a selected set of quantities of interest. The use of the Bayesian compressive sensing technique allows for fewer evaluations of the computationally expensive tRIBS-VEGGIE. The approach enables inference of model parameters using a set of observed hydrologic quantities including stream discharge, water table depth, evapotranspiration, and soil moisture from the Asu experimental catchment near Manaus, Brazil. The results demonstrate the flexibility of the framework for hydrologic inference in watersheds with sparse, irregular observations of varying accuracy. Significant computational savings imply that problems of greater computational complexity and dimension can be addressed using accurate, computationally cheap surrogates for complex hydrologic models. This will ultimately yield probabilistic representation of model behavior, robust parameter inference, and sensitivity analysis without the need for greater investment in computational resources.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A general approach to uncertainty quantification with a complex, process-rich model. </LI> <LI> Construction of efficient surrogate models with Bayesian compressive sensing. </LI> <LI> Robust parametric inference using heterogeneous sources of process-scale data. </LI> <LI> Simultaneous characterization of sensitivity of hydrologic outputs to uncertain variables. </LI> </UL> </P>

A system dynamics based socio-hydrological model for agricultural wastewater reuse at the watershed scale

Jeong, H.,Adamowski, J. Elsevier Scientific Pub. Co 2016 Agricultural water management Vol.171 No.-

<P>The purpose of this study was to develop and verify a socio-hydrological model using system dynamics (SD), thereby combining a deterministic conceptual hydrological model and a social model incorporating population, land use, economics, technology, and policy dimensions. Applied to a central South Korean watershed where wastewater is reused for paddy irrigation, the present model was verified in terms of structure and behavior. Structural validity was confirmed when expected simulation sensitivity and consistency criteria were met during behavior sensitivity and extreme conditions tests. The model's behavioral validity in predicting hydrological processes including evapotranspiration, stream flow, and groundwater level, was also confirmed as the calibrated model performance during the validation period showed good agreement with those of the Soil and Water Assessment Tool (SWAT) model, validated for the study watershed, as well as observed groundwater levels. The values of Nash-Sutcliffe efficiency (E-NS), percent bias (PBIAS), and R-2 which compared model results with those of the SWAT model were 0.77,3.0%, and 0.79, respectively, for the evapotranspiration, and 0.69, 1.4%, and 0.75, respectively, for the stream flow, while the generated and observed groundwater levels exhibited a linear relationship with an R-2 value of 0.70. The validated model indicated that urbanization within the study watershed could lead to increased stream flow and greater wastewater reuse. Instream flow regulation led to a decrease in stream flow tied to a lower base flow, and a decrease in social benefits associated with a decline in wastewater reuse. An assessment was made of the SD-based socio-hydrological model's usefulness when acting as an element of an integrated framework in providing a better understanding of small-scale socio-hydrological systems' interactions and the underlying causes of general trends and problems. SD-based socio-hydrological modeling was deemed a suitable decision-support framework for designing water resource policies contributing to successful integrated water resources management practice. (C) 2016 Elsevier B.V. All rights reserved.</P>

마코프 체인 몬테카를로 및 앙상블 칼만필터와 연계된 추계학적 단순 수문분할모형

최정현 ( Choi Jeonghyeon ),이옥정 ( Lee Okjeong ),원정은 ( Won Jeongeun ),김상단 ( Kim Sangdan ) 한국물환경학회(구 한국수질보전학회) 2020 한국물환경학회지 Vol.36 No.5

Hydrologic models can be classified into two types: those for understanding physical processes and those for predicting hydrologic quantities. This study deals with how to use the model to predict today's stream flow based on the system's knowledge of yesterday's state and the model parameters. In this regard, for the model to generate accurate predictions, the uncertainty of the parameters and appropriate estimates of the state variables are required. In this study, a relatively simple hydrologic partitioning model is proposed that can explicitly implement the hydrologic partitioning process, and the posterior distribution of the parameters of the proposed model is estimated using the Markov chain Monte Carlo approach. Further, the application method of the ensemble Kalman filter is proposed for updating the normalized soil moisture, which is the state variable of the model, by linking the information on the posterior distribution of the parameters and by assimilating the observed steam flow data. The stochastically and recursively estimated stream flows using the data assimilation technique revealed better representation of the observed data than the stream flows predicted using the deterministic model. Therefore, the ensemble Kalman filter in conjunction with the Markov chain Monte Carlo approach could be a reliable and effective method for forecasting daily stream flow, and it could also be a suitable method for routinely updating and monitoring the watershedaveraged soil moisture.

Markov-Chain Monte Carlo 기법을 이용한 준 분포형 수문모형의 매개변수 및 모형 불확실성 분석

최정현 ( Choi Jeonghyeon ),장수형 ( Jang Suhyung ),김상단 ( Kim Sangdan ) 한국물환경학회(구 한국수질보전학회) 2020 한국물환경학회지 Vol.36 No.5

Hydrological models are based on a combination of parameters that describe the hydrological characteristics and processes within a watershed. For this reason, the model performance and accuracy are highly dependent on the parameters. However, model uncertainties caused by parameters with stochastic characteristics need to be considered. As a follow-up to the study conducted by Choi et al (2020), who developed a relatively simple semi-distributed hydrological model, we propose a tool to estimate the posterior distribution of model parameters using the Metropolis-Hastings algorithm, a type of Markov-Chain Monte Carlo technique, and analyze the uncertainty of model parameters and simulated stream flow. In addition, the uncertainty caused by the parameters of each version is investigated using the lumped and semi-distributed versions of the applied model to the Hapcheon Dam watershed. The results suggest that the uncertainty of the semi-distributed model parameters was relatively higher than that of the lumped model parameters because the spatial variability of input data such as geomorphological and hydrometeorological parameters was inherent to the posterior distribution of the semi-distributed model parameters. Meanwhile, no significant difference existed between the two models in terms of uncertainty of the simulation outputs. The statistical goodness of fit of the simulated stream flows against the observed stream flows showed satisfactory reliability in both the semi-distributed and the lumped models, but the seasonality of the stream flow was reproduced relatively better by the distributed model.

토양수분 공간분포 예측을 위한 수문연결성 기반 토양 매개변수 추정 기술

신승훈,김종건,박근형,이서로,신용철,장근창,천정화 강원대학교 농업생명과학연구원 2022 강원 농업생명환경연구 Vol.34 No.3

Hydrological connectivity has been proposed and utilized as an important concept to understand surface and subsurface flow processes in watershed hydrology. This can be beneficial for characterizing soil moisture variability in complex and spatially heterogeneous landscapes. Existing hydrological models have limitations in adequately explaining subsurface characteristic patterns connected with flow path continuity in unsaturated regions. Therefore, to better understand the subsurface flow spatial distribution and to improve the soil hydraulic parameter properties in hydrological modeling (Soil and Water Assessment Tool, SWAT), the parameters were revised by applying the hydrological connection algorithm based on the physical soil and land surface properties, and the model performance was evaluated. Firstly, the correlations between the soil moisture data and weightings were calculated using soil properties (sand% and clay%), normalized difference vegetation index (NDVI), and the topographic index which are related to the soil moisture spatial distribution characteristics. The hydrological connectivity analysis was performed according to various thresholds based on these weightings and using new spatial distribution data which combines physical properties. Subsequently, the available water content (Sol_AWC) and saturated hydraulic conductivity (Sol_K) variables, which are closely related to soil moisture estimates in the SWAT model, were revised according to the connectivity index. The results of this study showed that the spatial variation of soil moisture can be explained well using the hydrological connectivity index based on the physical properties, and that the existing model performance can be improved using the corrected (spatially distributed) soil hydraulic parameters.

실시간모니터링 시스템을 연계한 도시 소유역 수문예측모형 개발

김미은,장영수,강봉권,신현석 한국방재학회 2013 한국방재학회논문집 Vol.13 No.3

In recent, abnormal phenomena in nature occurs due to climate change, which result in increase of flood frequency and rainfall intensity by change of meteorologic and hydrological factors. Especially, flood inundation in urban watershed frequently happens on casualties expected and property damage. Scientific and technological adaptation are acutely needed for unexpected damage in nature, and that, it is considerably important to develop proper model of hydrological forecasting over the short periods and to build a real-time watershed monitoring system. One of important things for solving a variety of problems is to connect real-time watershed monitoring system with short term hydrologic forecasting model. In this research, Suyoung stream in Busan was determined as a study area. After that, real-time watershed monitoring system at ten minute interval has been established for flood warning and forecast in the field. The data from this system was applied to short-term hydrologic forecasting model based on the artificial neural network. When flood happens in urban, input data of forecasting model on each rainfall event was used. In conclusion, after establishing the model being possible to forecast water level from 10 to 60 minutes at 10 minute interval, as a result of simulating the model, the model performances are considerably good as RMSE 0.02~0.6 and R2 more than 0.9. It makes possible effectively to manage the watershed in urban. 기후변화로 인한 기상 및 수문요소의 변화로 홍수빈도 및 강우강도 증가 등의 이상기후현상이 나타나고 있다. 특히 도시유역내 홍수범람으로 인명 및 재산피해가 빈번히 발생하고 있다. 발생되는 피해에 대하여 과학적이고 기술적인 대응 방안이 필요하며 이를 위한 기술의 개발과 실시간 유역 모니터링 시스템과의 연계한 적정 방안이 필요한 실정이다. 본 연구에서는 도시유역으로 부산 시 소재의 수영강 유역을 시범유역으로 선정하여 홍수예경보를 위한 10분 간격의 실시간 모니터링 시스템을 구축하였다. 이를 통한 DB를 활용하여 도시 유역 내 단기 수문예측모형을 인공신경망 기반으로 구축하였다. 홍수 시 강우사상별로수문예측 모형의 입력자료로 활용하였으며 10분 간격으로 10분부터 60분까지 수위 예측을 실시한 결과 RMSE 0.02~0.6, R2 0.9 이상의 높은 예측 정도를 보이는 수문예측모형이 구축되었다. 본 연구의 연계시스템의 구축으로 도시유역 내 효율적인 하천관리를 통한 인명 및 재산피해를 감소시킬 수 있을 것이다.