Inter-annual and spatial variation of altitudinal increase in rainfall over Mount Inthanon and Mae Chaem Watershed, Northern Thailand

Abstract

To understand the inter-annual and spatial variation of altitudinal increase in rainfall amount, duration and intensity over Doi (Mount) Inthanon and Mae Chaem Watershed, Northern Thailand, we have conducted rainfall observations in this area since 1997. Ten years of continuous data for 18 rain gauge stations were accumulated. Altitudinal increases in rainfall were observed for all nine years. Annual rainfall hours also had an altitudinal increase, whereas mean rainfall intensity had no clear altitudinal increase for the nine year period. Not only altitudinal rainfall increase but also inter-annual rainfall fluctuation was determined from the variations of rainfall hours. There was no difference in the intensity of altitudinal increases in rainfall between the western and eastern slopes of Doi Inthanon.