Calibration of tipping bucket hyetographs

The Institute for Hydraulics and Hydrology of the Technical University Graz , Austria operates two hydrological observation nets - one in the area of E astern Styria and the other one in the city of Graz. Precipitation, meteoro logical and runoff data are collected. Comparative measurements of the tipping bucket hyetographs have shown the d eviation between the recorded and the real precipitation intensity. Aim. of the presented project was to get calibration curves for all tested precipi tation gauges. The following steps were necessary: a) Development of a micro processor controlled calibration system. The cali bration instrument is able to record a series of measurements for determini ng calibration factors. b) Development of a control software for the calibration device, that is ab le to take over the menu control with a laptop and store the determined val ues in an MS Excel worksheet. These values are used for calculating correct ion values and to display them in an adequate graphical way. c) Development of a practicable application software for correction of the measured precipitation data. The determined correction factors permit to consider the source of failure (e.g. location, ageing and wear of the material) and make available improve d hydrological data. (C) 2001 Elsevier Science Ltd. All rights reserved.