Author(s): Chanjoo Lee; Donggu Kim; Bongju Jang; Won Kim
Linked Author(s): Won Kim, Donggu Kim
Keywords: Pit-gauge; Multiple pit-gauge (MPG); Rainfall
Abstract: Accurate measurement of ground rainfall is a fundamental job for hydrological studies. Conventional cylindrical rain gauges generally have bias due to under-catch caused by wind as well as random error. To avoid it, use of a pit-gauge is well recommended when a reference gauge is needed. A Pit-gauge is a rain gauge installed to collect rain on ground-level with grid to minimize rain splash from around it. However, it is still necessary to evaluate accuracy of a pit-gauge for use of testing an electromagnetic wave rain sensor. In this study, we evaluated rainfall measurement accuracy using a large-scale pit-gauge which is composed of multiple unit rain gauges. We designed and made a 12 m x 12 m size metal grid frame to set 25 tipping-bucket rain gauges with bucket volume of 0.5 mm. We assumed rainfall in a 144 sq. m area is spatially uniform. After installation, we observed 12 rainfall events of which ranges are from 4.5 to 150 mm during the summer season in 2017. Besides data from three erroneous gauges, 22 gauges indicate coefficient of variation of 0.5~5.2%. Deviation from the mean increases with decrease of event rainfall. Based on the student-t distribution, 95% confidence intervals in percent were given for different rainfall, number of gauges and sample standard deviation conditions.
Year: 2018