Studies on the Rainfall Characteristics in Chungnam Region(I) Probable Rainfall Intensity in Short Duration in Daejeon Area

충남지방(忠南地方)의 강우특성(降雨特性)에 관(關)한 연구(硏究)(I) 대전지역(大田地域)의 단시간(短時間) 확률강우강도(確率降雨强度)

  • Ahn, Byoung Gi (Dept. of Agricultural Engineering, Coll. of Agriculture, Chungnam Natl. Univ.)
  • Published : 1981.06.30

Abstract

The characteristic of rainfall intensity in short duration is very important to calculate short-term runoff in small watershed by Rational method. Therefore, the purpose of this study is to derive the most proper formula on the probable rainfall intensity in each return period in Daejeon area. And the results of this study could be utilized for the design of drainage-structures in small watershed, drainage system in urban area and flood control in small river basin. The result s of this study are summerized as follows. 1. Gumbel-Chow method which shows the mean value was chosen to calculate the probable rainfall in tensity in each return periods. 2. According to statistical judgement, probable rainfall intensity formula of Japanese type($I={\frac{a}{t+b}}$, see Table-6) shows the most proper one among other types of formula like Talbot type, Sherman type and Characteristic coefficient method. Probable rainfall in tensity value of Japanese type in Daejeon area shows well coincidence with the one obtained by applying prof. Park's n-coefficient to Monobe formula $I=({\frac{R_{24}}{24}})({\frac{T}{t}})^{0.5486}$. On the other hand, the value by Monobe formula with n-coefficient of 2/3 which is being used as a disign criterison by M. O. C. shows large difference from the fore-mentioned results (see Table-7). Consequently the value by Monobe formula might be judged that it is too much overestimated one as a design criterion. 3. Short-term runoff in small water shed could be calculated more reasonably in Daejeon area through this probable rainfall in tensity formula.

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Acknowledgement

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