• Title/Summary/Keyword: hydrological component

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Cost-effective assessment of filter media for treating stormwater runoff in LID facilities (비용 효율적 강우유출수 처리를 위한 LID시설의 여재 평가)

  • Lee, Soyoung;Choi, Jiyeon;Hong, Jungsun;Choi, Hyeseon;Kim, Lee-Hyung
    • Journal of Wetlands Research
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    • v.18 no.2
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    • pp.194-200
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    • 2016
  • The impervious surface rate increased by urbanization causes various problems on the environment such as water cycle distortion, heat island effect, and non-point pollutant discharges. The Low Impact Development (LID) techniques are significantly considered as an important tool for stormwater management in urban areas and development projects. The main mechanisms of LID technologies are hydrological and environmental pollution reduction among soils, media, microorganisms, and plants. Especially, the media provides important functions on permeability and retention rate of stormwater runoff in LID facilities. Therefore, this research was performed to assess the pollutant removal efficiency for different types of media such as zeolite, wood chip, bottom ash, and bio-ceramic. All media show high pollutant removal efficiency of more than 60% for particulate materials and heavy metals. Double layered media is more effective in reducing heavy metals by providing diverse sizes of micro-pores and macro-pores compared to the single layered media. The results recommend the use of different sizes of media application is more cost-effective in LID than a single size of media. Furthermore, soluble proportion of total heavy metal in the stormwater is an important component in proper media selection and arrangement.

Parameter Regionalization of Hargreaves Equation Based on Climatological Characteristics in Korea (우리나라 기후특성을 고려한 Hargreaves 공식의 매개변수 지역화)

  • Moon, Jang Won;Jung, Chung Gil;Lee, Dong Ryul
    • Journal of Korea Water Resources Association
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    • v.46 no.9
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    • pp.933-946
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    • 2013
  • The quantitative analysis of evapotranspiration (ET) is a key component in hydrological studies and the establishment of water resources planning. Generally, the quantitative analysis of ET is performed by the estimation method of potential or reference ET based on meteorological factors such as air temperature, wind speed, etc. Hargreaves equation is one of empirical methods for reference ET using air temperature data. In this study, in order to estimate more exact reference ET considering climatological characteristics in Korea, parameter regionalization of Hargreaves equation is carried out. Firstly, modified Hargreaves equation is presented after the analysis of the relationship between solar radiation and temperature. Secondly, parameter ($K_{ET}$) optimization of Hargreaves equation is performed using Penman-Monteith method and modified equation at 71 weather stations. Lastly, the equation for calculating $K_{ET}$ using temperature data is proposed and verified. As a result, reference ET from original Hargreaves equation is overestimated or underestimated compared with Penman-Monteith method. But modified equation in this study is more accurate in the climatic conditions of Korea. In addition, the applicability of the equation between $K_{ET}$ and temperature is confirmed.

A Derivation of Regional Representative Intensity-Duration-Frequency Relationship Using Multivariate Analysis (다변량 분석을 이용한 권역별 대표확률강우강도식의 유도)

  • Lee, Jung-Sik;Cho, Seong-Geun;Jang, Jin-Uk
    • Journal of the Korean Society of Hazard Mitigation
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    • v.7 no.2 s.25
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    • pp.13-24
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    • 2007
  • This study is to derive the rainfall intensity formula based on the representative probability distribution using multivariate analysis in Korea. The annual maximum rainfall data at 57 stations having more than 30years long records were used for 12 durations(10min, 1, 2, 3, 4, 5, 6, 8, 10, 12, 18, 24hr). 50 rainfall characteristics elements are analyzed from the collected data. The widely used 14 probability distributions are applied to the basic data in hydrologic frequency analysis. The homogeneous tests(principal component and cluster analysis) are applied to find the rainfall homogeneity. The results of this study are as followings; (1) The homogeneous test shows that there is no appropriate representative distribution for the whole duration in Korea. But hydrological homogeneous regions of point rainfall could be divided by 5 regions. (2) The GEV distribution for zones I, III, IV, V and the Gumbel distribution for zone II are determined as the representative probability distribution. (3) Comparative analysis of the results shows that the probable rainfalls of representative zones are different from those of existing researches. (4) Rainfall intensity formulas are determined on the basis of the linearization technique for the probable rainfall.

Analysis of Environmental Factors of Geomorphology, Hydrology, Water Quality and Shoreline Soil in Reservoirs of Korea (우리나라 저수지에서 지형, 수문, 수질 및 호안 토양 환경요인의 분석)

  • Cho, HyunSuk;Cho, Kang-Hyun
    • Korean Journal of Ecology and Environment
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    • v.46 no.3
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    • pp.343-359
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    • 2013
  • In order to understand shoreline environment characteristics of Korean reservoirs, the interrelationships between environmental factors of geomorphology, hydrology, water quality and shoreline soil were analyzed, and the reservoir types were classified according to their environmental characteristics in the 35 reservoirs selected by considering the purpose of dam operations and annual water-level fluctuations. Geomorphological and hydrological characteristics of reservoirs were correlated with the altitude and the size scale of reservoirs. The annual range of water level fluctuation showed a wide variation from 1 m to 27 m in the various reservoirs in Korea. The levels of eutrophication of most reservoirs were mesotrophic or eutrophic. From the result of the soil texture analysis, sand contents were high in reservoir shorelines. Range, frequency and duration of water-level fluctuation were distinctive from the primary function of reservoirs. Flood control reservoirs had a wide range with low frequency and waterpower generation reservoirs had a narrow range with high frequency in the water-level fluctuation. According to the result of CART (classification and regression tree) analysis, the water quality of reservoirs was classified by water depth, range of water-level fluctuation and altitude. The result of PCA (principal component analysis) showed that the type of reservoirs was classified by reservoir size, water-level fluctuation, water quality, soil texture and soil organic matter. In conclusion, reservoir size, the water-level fluctuation, water quality and soil characteristics might be major factors in the environment of reservoir shorelines in Korea.

Study on the influence of sewer network simplification on urban inundation modelling results (하수관망의 간소화가 도시침수 모의에 미치는 영향 분석에 관한 연구)

  • Lee, Seung-Soo;Pakdimanivong, Mary;Jung, Kwan-Sue;Kim, Yeonsu
    • Journal of Korea Water Resources Association
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    • v.51 no.4
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    • pp.347-354
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    • 2018
  • In urban areas, runoff flow is drained through sewer networks as well as surface areas. Therefore, it is very important to consider sewer networks as a component of hydrological drainage processes when conducting urban inundation modelling. However, most researchers who have implemented urban inundation/flood modelling, instinctively simplified the sewer networks without the appropriate criteria. In this research, a 1D-2D fully coupled urban inundation model is applied to estimate the influence of sewer network simplification on urban inundation modelling based on the dendritic network classification. The one-dimensional (1D) sewerage system analysis model, which was introduced by Lee et al. (2017), is used to simulate inlet and overflow phenomena by interacting with surface flow. Two-dimensional (2D) unstructured meshes are also applied to simulate surface flow and are combined with the 1D sewerage analysis model. Sewer network pipes are simplified based on the dendritic network classification method, namely the second and third order, and all cases of pipes are conducted as a control group. Each classified network case, including a control group, is evaluated through their application to the 27 July 2011 extreme rainfall event, which caused severe inundation damages in the Sadang area in Seoul, South Korea. All cases are compared together regarding inundation area, inflow discharge and overflow discharge. Finally, relevant criterion for the simplification method is recommended.

A Geomorphological Study on the Distribution Areas of Freezing during Summer Season in Korea (한국의 하계 동결현상 분포지에 관한 지형학적 연구)

  • Jeon, Young-Gweon
    • Journal of the Korean association of regional geographers
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    • v.7 no.1
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    • pp.97-106
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    • 2001
  • There are a few interesting areas which show freezing during summer season in Korea, three of them are especially important. They are located at Milyang(Gyungnam province), Uisung and Chungsong(Gyungbook province). They are named Eoleumgol(ice-valley) or Binghyul(ice-cave). The purpose of this study is to clarify geomorphological and geological characteristics about the distribution areas of freezing during summer season in Korea in relation to previous works, which have been studied in hydrological or micro-climatological viewpoints. The main results are summarized as follows. 1) The main geomorphological and geological characteristics in the distribution areas of freezing during summer season (1) Thick debris accumulated slope within deep valley (2) North facing slope (3) The component debris of volcanic rock such as andesite or rhyolite 2) The ice-cave as a system that give rise to freezing phenomenon in summer season is closely related to talus slope. The ice-cave has thick accumulated debris and lots of vacant spaces within the rock deposits, some of vacant spaces are very big and connected with underground water system. 3) A partly freezing within underground water system is required freezing phenomenon in summer season. Judging from this point of view, two ideas are suggested; one is the evaporation theory, another is that the frozen condition in winter remains untill late summer.

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A Development of Method for Surface and Subsurface Runoff Analysis in Urban Composite Watershed (I) - Theory and Development of Module - (대도시 복합유역의 지표 및 지표하 유출해석기법 개발 (I)- 이론 및 모듈의 개발 -)

  • Kwak, Chang-Jae;Lee, Jae-Joon
    • Journal of Korea Water Resources Association
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    • v.45 no.1
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    • pp.39-52
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    • 2012
  • Surface-subsurface interactions are an intrinsic component of the hydrologic response within a watershed. In general, these interactions are considered to be one of the most difficult areas of the discipline, particularly for the modeler who intends simulate the dynamic relations between these two major domains of the hydrological cycle. In essence, one major complexity is the spatial and temporal variations in the dynamically interacting system behavior. The proper simulation of these variations requires the need for providing an appropriate coupling mechanism between the surface and subsurface components of the system. In this study, an approach for modelling surface-subsurface flow and transport in a fully intergrated way is presented. The model uses the 2-dimensional diffusion wave equation for sheet surface water flow, and the Boussinesq equation with the Darcy's law and Dupuit-Forchheimer's assumption for variably saturated subsurface water flow. The coupled system of equations governing surface and subsurface flows is discretized using the finite volume method with central differencing in space and the Crank-Nicolson method in time. The interactions between surface and subsurface flows are considered mass balance based on the continuity conditions of pressure head and exchange flux. The major module consists of four sub-module (SUBFA, SFA, IA and NS module) is developed.

A Method to Estimate the Cell Based Sustainable Development Yield of Groundwater (셀기반 지하수 개발가능량 산정기법)

  • Chung, Il-Moon;Kim, Nam Won;Lee, Jeongwoo;Na, Hanna;Kim, Youn-Jung;Park, Seunghyuk
    • Economic and Environmental Geology
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    • v.47 no.6
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    • pp.635-643
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    • 2014
  • Sustaiable development yield of groundwater in Korea has been determined according to 10 year drought frequency of groundwater recharge in the standard mid-sized watershed or relatively large area of district. Therefore, the evaluation of groundwater impact in a small watershed is hard to apply. Fot this purpose, a novel approach to estimate cell based sustainable development yield of groundwater (SDYG) is suggested and applied to Gyeongju region. Cell based groundwater recharge is computed using hydrological component analysis using the SWAT-MODFLOW which is an integrated surface water-groundwater model. To estimate the potential amount of groundwater development, the existing method which uses 10 year drought frequency rainfall multiplied by recharge coefficient is adopted. Cell based SDYGs are computed and summed for 143 sub-watersheds and administrative districts. When these SDYGs are combined with groundwater usage data, the groundwater usage rate (total usage / SDYG) shows wide local variations (7.1~108.8%) which are unseen when average rate (24%) is only evaluated. Also, it is expected that additional SDYGs in any small district could be estimated.

SWAT Direct Runoff and Baseflow Evaluation using Web-based Flow Clustering EI Estimation System (웹기반의 유량 군집화 EI 평가시스템을 이용한 SWAT 직접유출과 기저유출 평가)

  • Jang, Won Seok;Moon, Jong Pil;Kim, Nam Won;Yoo, Dong Sun;Kum, Dong Hyuk;Kim, Ik Jae;Mun, Yuri;Lim, Kyoung Jae
    • Journal of Korean Society on Water Environment
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    • v.27 no.1
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    • pp.61-72
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    • 2011
  • In order to assess hydrologic and nonpoint source pollutant behaviors in a watershed with Soil and Water Assessment Tool (SWAT) model, the accuracy evaluation of SWAT model should be conducted prior to the application of it to a watershed. When calibrating and validating hydrological components of SWAT model, the Nash-Sutcliffe efficiency coefficient (EI) has been widely used. However, the EI value has been known as it is affected sensitively by big numbers among the range of numbers. In this study, a Web-based flow clustering EI estimation system using K-means clustering algorithm was developed and used for SWAT hydrology evaluation. Even though the EI of total streamflow was high, the EI values of hydrologic components (i.e., direct runoff and baseflow) were not high. Also when the EI values of flow group I and II (i.e., low and high value group) clustered from direct runoff and baseflow were computed, respectively, the EI values of them were much lower with negative EI values for some flow group comparison. The SWAT auto-calibration tool estimated values also showed negative EI values for most flow group I and II of direct runoff and baseflow although EI value of total streamflow was high. The result obtained in this study indicates that the SWAT hydrology component should be calibrated until all four positive EI values for each flow group of direct runoff and baseflow are obtained for better accuracy both in direct runoff and baseflow.

Quantitative impacts of climate change and human activities on the watershed runoff variation of the Geum River basin (기후변화 및 인간 활동이 금강 유역의 중권역 유출량 변동에 미치는 영향의 정량적 평가)

  • Oh, Mi Ju;Kim, Dongwook;Lee, Joo-Heon;Kim, Tae-Woong
    • Journal of Korea Water Resources Association
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    • v.56 no.6
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    • pp.381-392
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    • 2023
  • Precipitation, runoff, and evapotranspiration are changing worldwide due to climate change and human activities. Because watershed runoff is an important component of the hydrological cycle, it is important to investigate the changes in watershed runoff for water resources management. This study collected observed data of runoff, precipitation, temperature, and evapotranspiration in the Geum River basin as well as their synthetic data according to Representative Concentration Pathways (RCP) scenarios, investigated the trend of hydro-meteorological variables using the Mann-Kendall test, and quantitatively evaluated the effects of climate change and human activities on the watershed runoff using the climate elasticity approach and the Budyko framework. The results indicated that the relative contribution of climate change and human activity to changes in runoff varies from region to region. For example, the watershed with the greatest contribution from climate change and human activity were the Yongdam Dam (#3001) basin and the Daecheong Dam (#3008) basin, respectively. Future climate change showed an increase in precipitation and temperature in both RCP 4.5 and 8.5 scenarios, resulting in changes in runoff in the Geum River basin from 44.8% to 65.5%, respectively. We concluded that the effect on watershed runoff can be separated into climate change and human activities, which will be important information in establishing sustainable water resource management plans.