Development of estimation method of the rainfall uncaptured by rain gauge in mountainous basin

2017 Fiscal Year Final Research Report

• Project/Area Number: 26450189
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Forest science
• Research Institution: Tokyo University of Agriculture and Technology
• Principal Investigator: Wakahara Taeko 東京農工大学, (連合)農学研究科(研究院), 研究員 (70599589)
• Co-Investigator(Renkei-kenkyūsha): ISHIKAWA YOSHIHARU 東京農工大学, 農学部, 名誉教授 (70285245)
• Project Period (FY): 2014-04-01 – 2018-03-31
• Keywords: 降雨捕捉率 / 山地斜面 / 風向風速 / 林内雨 / 林外雨 / 雨量計 / 樹冠遮断

Outline of Final Research Achievements

The purpose of this study is to analyze the difference between the actual rainfall and the rainfall captured by the rain gauge, these were measured in mountainous areas. At the slope with open sky and relatively constant wind direction, the wind speed and the captured rate of the rain gauge were inversely proportional, in the case of the rainfall of 3mm or more. The rain capture rate of the rain gauge was about 60-80% of verification device which close to the true value of rainfall. Moreover, when the average wind speed exceeded 5m, it decreased to about 50%. Comparing the rainfall inside and outside the forest, the rainfall trapping rate was lower in the outside of the forest. This is considered to be because the wind speed outside the forest is strong and the wind direction has large variations. In conclusion, it was shown that the rainfall measured under strong wind had large trapping loss, therefor there is the necessity of rainfall evaluation including wind speed.

Free Research Field

農学