Abstract
This study investigated the changes in rainfall in the Upper Pong River Basin. In 20 years from the 1981
to 2000 and Rainfall data from global climate models ECHAM4 A1B series and ECHAM4 A2 series. In 50
years from 1981 to 2000 and from 2021 to 2050. In order to compare the average monthly rainfall, Annual
rainfall from the measurement of global climate model. The comparison showed the average monthly rainfall
of each month, with similar values and studied the severity of the drought on the benchmark SPI. Measured
from the year 1981 to 2000. The results showed that in 1981, 1993 and 1997 have a very little rainfall. The
analysis of changes in rainfall from ECHAM4 A1B series from 2021 to 2050. That years with moderate rainfall
and very rainfall include the years 2044, 2043, 2034, 2040, 2046, 2047, 2523 and 2049, respectively. Years
with moderate little rainfall and very little rainfall include the years 2037, 2021, 2029, 2027 and 2030,
respectively. And changes in rainfall from the series ECHAM4 A2 series from 2021 to 2050. That years with
moderate rainfall and very rainfall and the most rainfall include the years 2042, 2032, 2024 and 2026,
respectively. Years with moderate little rainfall and very little rainfall include the years 2031, 2036, 2034 and
2021, respectively.