Study on error control technique of rainstorm intensity formula in arid area under the background of climate change

Frequent extreme precipitation events make it more and more difficult to control the errors in rainstorm intensity formula. Based on minute precipitation data of national meteorological stations in Yinchuan from 1961 to 2016, using curve fitting in the form of Index, Gumbel to fit rainfall intensity-return period and P-Ⅲ least square, Gauss-Newton methods to carry out the calculation of rainstorm intensity formula parameters, we compiled rainstorm intensity formula in Yinchuan and discussed its error control in arid area and optimal strategy. The results show that:(1) the heavy rain in arid areas has less samples and large variability. According to the defects that error is difficult to control in the process of two important steps of the experience frequency curve fitting of rainstorm intensity formula and parameters solution, we design a new error control strategy to change the error of two step control to the comprehensive control, which can minimize the formula error. (2) The average temperature in Yinchuan in summer has increased significantly since the middle and late 1990s. The short-term rainfall intensity (especially 30-180 min) present a consistent increasing trend, and the change rate has increased. (3) As a combined calculation scheme of the rain intensity component and general formula for Yinchuan, we optimize the Gumbel distribution curve fitting together with Gaussian Newton method to solve formula, it has been well compiled the new generation rainstorm intensity formula for Yinchuan, which provides some ideas for the formulation of rainstorm intensity formula in arid area.