Establishment of the Models to Assess the Maximum Thirty- Minute Rainfall Intensity and Analysis of Change Points of the Rainfall Erosivity Index in Taipei under Climate Change
Date Issued
2012
Date
2012
Author(s)
Ni, Chen-Yeh
Abstract
The maximum thirty- minute rainfall intensity (I30) is very important in predicting soil erosion. In this study, 51 years of the rainfall data from 1961 to 2011 were collected from Taipei weather station, and effective rainfall events were selected based on the definition by Wischmeier and Smith (1978).
The model was established to predict the I30 in Taipei area applying the power function regression. The Model 1 was established only by rainfall factor and the Model 2 was by rainfall and rainfall intensity factor. Examine the accuracy of the simulation by two different models. In order to observe the variability between each decade, the study divided the rainfall data from 1961 to 2010 into 5 groups (every 10 years in one group) to calculate the coefficients of theI30 estimated model. Results proved the Model 2 with high accuracy which was more convenient and more practical than the models of the previous studies. Putting the rainfall and rainfall intensity into the Model 2 can obtain the simulate I30 for 16 years without five minutes rainfall data. Taking annual maximum I30 represent I30. The 5-year moving average trend showed instability, and the 15-year moving average was more stable and rising slowly. Although short-term changes were more unstable, the annual I30 showed a steady increase trend for the long-term in the Taipei area.
In the change point analysis, the significant change point of the rainfall erosivity index (the R factor) time series for 1961-2011 is in 1983. The R factor trend displayed by the 5-year and 15-year moving average. The short-period was unstable, but the long-period was showing steady growth trend. Statistical results of the annual R factor shows that the average and variability increased significantly through the impact of climate change. The trend also fit the result of change point analysis (1983 is the change point). Therefore, it is proven that the R factort end to extreme in Taipei area.
Subjects
The maximum thirty- minute rainfall intensity
Rainfall erosivity index
Soil erosion
Change point analysis
Climate change
SDGs
Type
thesis
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