Calibration of tipping‐bucket flow meters and rain gauges to measure gross rainfall, throughfall, and stemflow applied to data from a Japanese temperate coniferous forest and a Cambodian tropical deciduous forest

Abstract

Tipping-bucket flow meter and rain gauge (TBFM/TBRG) are widely used for the measurement of gross rainfall (GR), throughfall (TF), and stemflow (SF) to evaluate the amount of interception loss (I). However, TBFM/TBRG cannot measure the inflow rate during tipping and underestimates the inflow rate. To correct this systematic bias, 33 total calibrations were conducted for five types of TBFM/TBRG in the laboratory. The tipping time increased with the bucket volume, and the underestimation during one tip was higher for TBFM/TBRG of larger capacity. With the use of the scaled actual inflow rate and the actual volume of a single tip from the measured static volume of a single tip when the inflow rate is zero, the common calibration curves were obtained as quadratic equations for each of the five types within an error range of AE3%. We measured GR and TF by using TBRG and TBFM with a resolution of 0.2 mm and measured SF by TBRG with a single-tip static volume of 15.7 cm 3 in a Japanese temperate coniferous forest (TCF) and a Cambodian tropical deciduous forest (TDF). At both sites, the calibration curves needed to be applied to obtain GR, TF, and SF on an event scale with an underestimation degree of less than 3%. Without applying any calibrations, the higher rainfall intensities in TDF caused larger underestimations of GR, TF, and SF and larger overestimations of I compared with results for TCF. On an annual scale, the degree of overestimation of I relative to GR (ΔI/GR) was 1.2% in TCF and 3.5% in TDF, and ΔI/I was at least 10% at both sites.

Interrelationships among dry season leaf fall, leaf flush and transpiration: insights from sap flux measurements in a tropical dry deciduous forest

“…The mean air temperature from February 2009 to January 2010 was 26.9 °C. The mean annual rainfall ( P ) of this area ranges from 1500 to 1700 mm (Iida et al , ). The duration of the analysis was from the beginning of observations to October 2011.…”

Estimation of annual forest evapotranspiration from a coniferous plantation watershed in Japan (2): Comparison of eddy covariance, water budget and sap-flow plus interception loss

“…The value of P in this study was calculated from the obtained the data without any tipping bucket correction, since we did not carry out the examination for the rainfall gauge. However, when the correction function of Iida et al (2012), which was obtained from the examination of another type of 0.5-mm rainfall gauge, was experimentally applied to our instrument and data, the difference between corrected and uncorrected annual P was 0.46% both 2007 and 2008.…”

“…A pulse count data logger (HOBO H07, Onset) was set and the timestamp was recorded when each bucket tipped. The T F and S F were estimated through application of the tipping bucket correction, which is necessary when high water flow rates into the bucket occur (Iida et al, 2012). The Appendix presents the details of the correction carried out in this study.…”

A review of stemflow generation dynamics and stemflow‐environment interactions in forests and shrublands

“…[] for saplings in Thuringia, Germany, and (top right and bottom right) Iida et al . [] in Tsukuba Experimental Forest, Japan (photos courtesy K. Nanko and S. Iida).…”