| Summary: | 碩士 === 國立中央大學 === 水文所 === 97 === Long-term observed hydrological data including precipitation, discharge, and temperature of the Tamsui River basin were analyzed to investigate temporal and spatial variations. First both linear regression and non-parametric trend examination were applied to examine trends and variations of hydrological data in time domain, then the Principle Component Analysis (PCA) and the Cluster Analysis (CA) were further used to investigate spatial variations.
Temperature trend is positive significant in the basin. Annual precipitation and daily rainfall intensity are increase and significant, while variations of dry spell days are insignificant. In whole analysis trend is increase more in this section. Monthly rainfalls were analyzed by the PCA. The PCA1 (the first principle component) stands for comprehensive climate characteristics, the PCA2 illustrates topography effects, and the PCA3 is location factor. Correlation analyses between ENSO/SOI indices and PCA scores show basin rainfall was slightly affected by the EI Nino. Results of the CA reveal that daily rainfall intensity in the Shishmen Reservoir has the most significant increasing trend watershed in the past decade. Results of PCA were further applied to estimate rainfall at ungauged locations. Rainfall at assumed unknown gauge can be reasonable estimated.
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