Effects of climate change on the discharge basin hydrology model (case study: Galikesh Watershed in Golestan)

Background and objectives: Climate change is one of the most important challenging problems that has affected different parts of the human life on the Earth. Warmer climatic conditions intensify the water cycle, change precipitation, and it also changes the amount of runoff and its appearance time. The North part of the Iran is the most Vulnerable area to the climate change due to the special climatic condition and the importance of agriculture.
.Hence, the current study tries to assess the impacts of climate change on Galikesh basin hydrological conditions by hydrological modeling. Ashofte and Massah (2008) studied the effect of uncertainty of climate change on peak discharge of Aidoghamoosh basin in the 2040-2069 period and for A2 scenario. Results show demonstrate that the basin temperature will increase 1 to 6 degree compared with base period in the 2050 period (3).

Material and methods:In this study, at first in order to down scale the output data of HADCM3 with A1B, A2 and B1,LARS-WG was used then the situation of area surface runoff was studied under the influence of climate change scenarios and by IHACRES hydrology model. The basin runoff was simulated in 2011-2030 period by introducing the values of temperature and precipitation to the IHACRES model.

Results: The results while confirming the efficiency of the model, indicated that future climate conditions of temperature and precipitation for 2011-2030 period compared with the observation period (1985-2010) will decrease and increase, respectively. Finally the results of IHACRES model demonstrated that runoff will decline in the future period compared to the observation period in three scenarios to the amounts of 6.37, 4.43 and 7.94 cubic meter per second, respectively that indicates the effect of climate change on basin discharge in the future period. The results of this study while showing the importance of the climate change effects, emphasizes their usage for adoption of necessary decisions which are compatible with climate change in future policies.

Conclusion: Checking the climate change scenarios of temperature and precipitation of HADCM3 model shows that basin temperature will increase in 2011-2030 period for three scenarios and the maximum increase is for B1 scenario. Simulating the monthly runoff of basin in future period and comparing the amounts of it with observation period, indicates the average decline of long term annual runoff in future period for three scenarios which is acceptable according to the decline of precipitation and decrease of temperature and the maximum decline is for B1 scenario.