URBANIZATION AND RAINFALL PATTERN CHANGE IN BANGKOK METROPOLITAN ADMINISTRATION

摘要

Urbanization which has been taking place for decades in Bangkok Metropolitan Administration (BMA), Thailand shows by rapid increment of the number population in the area since 1947. At present condition from total land area of 1,568.737 km~2 about 700 km~2 is urbanized area. Corresponds to the urbanization in BMA area, analysis of rainfall pattern change is conducted in the related area. Data of daily rainfall data from 1969 up to 2007 from three rainfall stations, i.e. Bangkok Metropolis, Bang Na, and Don Muang station is used as the basic data of rainfall pattern analysis. Whereas daily rainfall data from 30 rainfall stations in BMA area from 1991 upto 2007 is used as the basic data for rainfall spatial distribution analysis in BMA area. Analysis of rainfall pattern change is conducted by examining the stability of mean of daily, monthly, and annual rainfall. The change of annual total wet days (PRCPTOT), the number consecutive wet days (CWD) and the number of consecutive dry days (CDD) are examined using Mann-Kendall's test. At 95% confident level, the results indicate the increasing trend of rainfall in the whole area of BMA during 1969 - 2006 and significant increasing trend of PRCPTOT and CWD at Bang Na station. Data of electricity use is used to represent the energy consumption in BMA area. During the period of January 2007 up to June 2008 the isohyet of monthly rainfall is superimposed to the isohyet of electricity use in BMA area. It is conducted to observe the relation of urbanization impacts to the spatial distribution of rainfall over time. It shows that the area which has higher electricity use does not receive the heaviest rainfall. However, the analysis of rainfall pattern shows a strong evident that the urbanization in BMA area occured along with the rainfall pattern change at the region.