Water for future (물과 미래)

Korea Water Resources Association (한국수자원학회)
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Analysis of Longitudinal Dispersion Coefficient : Part I. Comparative Study of Existing Equations for Dispersion Coefficient

종확산계수에 관한 연구 : I. 기존 종확산계수 추정식 비교

  • 서일원 (서울대학교 공과대학 토목공학과) ;
  • 정태성 (서울대학교 대학원 토목공학과)
  • Published : 1995.06.01
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Abstract

Existing equations for dispersion coefficient are analyzed in depth to select proper dispersion coefficient which can represent dispersion characteristics of natural streams. Several equations are tested with measured data which were collected in 26 streams in the United States. Findings of this study are as follows. Elder's equation should not be used to estimate dispersion coefficient of the one-dimensional dispersion model because it underestimates significantly. McQuivey and Keefer's equation is overestimating, whereas Magazine et al.'s equation is underestimating. However, Iwasa and Aya's equation predicts relatively well. Fischer's equation is generally overestimating. Liu's equation predicts quite well. The performance of Liu's equation is the best of all especially in terms of accuracy. However, Liu's equation is generally overestimating in case of large river because the square of channel width is included in the equation. Therefore, it is recommended not to use Liu's equation in case of large rivers, especially rivers of which channel width is larger than 200m.

자연하천의 종확산과정을 정확하게 대표하는 종확산계수의 선정을 위하여 기 제안된 종확산계수 추정공식들을 비교 분석하였다. 종확산계수 공식 중 적용성이 비교적 우수한 공식을 선정하여 미국 언역의 26개 하천에서 수집된 실측치와 비교하였다. 본 연구에서 밝혀진 사실은 다음과 같다. Elder공식은 종확산계수를 상당히 과소 산정하기 때문에 1차원 확산모형의 종확산계수의 산정에는 부적합하다. McQuivey와 Keefer공식은 전체적으로 과대 산정하는 편이고, Magazine 등 공식은 대부분의 경우에 과소 산정하고 있다. 이들에 비해 Iwasa와 Aya공식은 비교적 양호한 거동을 보이고 있다. Fischer공식은 전체적으로 과대 산정하고 있으나, Liu공식은 양호한 거동을 보이고 있으며 특히 정확도 면에서는 가장 우수한 것으로 나타났다. 그러나 Liu공식은 하폭의 제곱 형태를 포함하고 있기 때문에 하천의 폭이 큰 대하천의 경우 종확산계수를 과대 산정하고 있다. 따라서 하폭이 큰 대하천(200m 이상)의 경우에는 Liu공식의 사용을 피하는 것이 바람직한 것으로 사료된다.

Keywords

References

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