The effects of climate change and a change on snowmelt runoff timing are very important in the rivers

with snowmelt runoff regime. In this study, the snowmelt runoff model (SRM model) and world climate

change model (ECHAM4 model) are applied in order to study the effects of climate change on snowmelt

runoff timing with two scenarios (A & B) for the next 50 years (2000- 2050) in karoon basin in the southwest

of Iran .

Research results show that a shift is observed in peak time on snowmelt runoff from spring to winter

and the winter stream flow is increased about 10% and the spring stream flow is decreased. The summer

stream flow is decreased slightly and the autumn stream flow was not changed considerably