Modeling the effects of climate change on different land uses.

This study deals with the effects of the expected climate change on the hydrology of watersheds. The watershed response in terms of the water produced by the watershed has been modeled using HSPF (Hydrological Simulation Program-FORTRAN) for a time period which encompasses the first half of the twenty-first century. Climate change scenarios have been prepared based on trends expected in western Turkey and a hypothetical watershed with different land uses has been simulated. The trends have been extracted from the results of a general circulation model. The simulations have revealed that watersheds with no vegetative cover will respond to the trends in temperature and precipitation more rigorously than vegetated watersheds. Pasture or watersheds with deciduous or coniferous forests respond less to climate change due to the buffering mechanism of the vegetative cover and also due to the large quantities of water they transpire. It has also been found that monthly variations are important in predicting the future response of watersheds. While changes might seem small on a yearly scale, there are large differences in response among seasons.