Journal of The Geomorphological Association of Korea (한국지형학회지)

The Geomorphological Association of Korea (한국지형학회)
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Evaluation of Changesin the Physical Characteristics of Raindrops Under a Canopy in Central Korea

나무 아래 빗방울(雨滴)의 물리적 특성변화 분석

  • Kim, Jin Kwan (Department of Geography Education, Chonnam National University) ;
  • Kim, Min Seok (International Water Resources Research Institute, Chungnam National University) ;
  • Yang, Dong Yoon (Quaternary Geology Research Department, Geological Research Division, Korea Institute of Geoscience & Mineral Resources(KIGAM)) ;
  • Lim, Young Shin (Department of Geography Education, Seoul National University)
  • 김진관 (전남대학교 지리교육과) ;
  • 김민석 (충남대학교 국제수자원연구소) ;
  • 양동윤 (한국지질자원연구원 제4기지질연구실) ;
  • 임영신 (서울대학교 지리교육과)
  • Received : 2016.09.05
  • Accepted : 2016.09.25
  • Published : 2016.09.30
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Abstract

To evaluate the changes in the physical characteristics of open rainfall related to canopy effects and rainfall intensity in Korea, the terminal velocity of raindrops and drop size distributions(DSD) were continuously measured by an optical-laser disdrometer in an open site(Op) and in two forest stands(Th1: Larix leptolepis, Th2: Pinus koraiensis) during five rainfall events in 2008. The terminal velocity, DSD and two forms of kinetic energy(KE, $Jm^{-2}$ $mm^{-1}$; KER, $Jm^{-2}$ $h^{-1}$) of open rainfall drops were determined and were compared with those of throughfall drops under two different canopy heights. The effects of the canopy and rainfall intensity, together with wind speed, on the changes in drop size and kinetic energy of throughfall were evaluated. Throughfall drops were larger than open rainfall drops. The distribution of terminal velocities for the drop sizes measured at Th2 was lower than that at Op; however, at Th1 the distribution was similar to that at Op. The total kinetic energy of throughfall at Th1 and Th2 was higher than the total kinetic energy of open rainfall, and the kinetic energy distribution for the drop sizes wassimilar to the drop size distribution. The observed throughfall-KER at Th1 was lower than an estimate previously produced using a model. The overestimation from the modeled value at Th1 was likely to be due to overestimated values of a square root transformation of fall height and its coefficient in the model because the distributions of terminal velocity for the drop size measured at Th1 were similar to those of open rainfall.

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