A Study on the Effects of the Uncertainity of Rainfall Spatial Distribution on the Discharge and Water Level of River on Runoff

Abstract

 There are two kinds of method to observe rainfall, ground rain gauge meter and weather radar. Due to the observation method, the measured value of rainfall intensity could be different even in the same rainfall event. The reason is that ground rain gauge measure raindrops close to the ground, whereas weather radar measure raindrops in the air. This paper discussed how the uncertainty of the rainfall intensity influenced the river discharge quantitatively. From the result, we found a relationship between control area of a rain data and the peak flow differential rate in the virtual basin, if control area of rain data is less than 64km² the peak flow differential rate will below 10% and if control area of rain data is less than 36km² less than the peak flow differential rate will below 5%. Also, if control area of rain data in a real basin is less than 10km², the coefficient of variation of the peak water level at that basin was found to be close to zero.