POTENTIAL OF EXTENDING THE RAINFALL INTENSITY-DURATION-FREQUENCY RELATIONSHIP TO NON-RECORDING RAIN GAUGES

Maximum rainfall intensity-duration-frequency (IDF) curves are commonl y applied to determine the design rainfall in water resource projects. Normally, the IDF relationship is derived from recording rain gauges. As the network of non-recording rain gauges (daily rainfall) in Taiwa n has a higher density than recording rain gauges, attempts were made in this study to extend the IDF relationship to non-recording rain gau ges. Eighteen recording rain gauges and 99 non-recording rain gauges o ver the Chi-Nan area in Southern Taiwan provide the data sets. The reg ional IDF formulae were generated for ungauged areas to estimate rainf all intensity for various return periods and rainfall durations larger than or equal to one hour. For rainfall durations less than one hour, a set of adjustment formulae were applied to modify the regional IDF formulae. The method proposed in this study had reasonable application to non-recording rain gauges, which was concluded from the verificati on of four additional recording rain gauges. (C) 1997 by John Wiley & Sons, Ltd.