Assessing the Impact of Climate Change on the Annual River Discharge in Different Climate Classification Areas: ۴۸۲ U.S. Watersheds

Global temperature in the last decades of the ۲۱st century was nearly ۱ °C higher than the whole ۲۰th century. The climate change and temperature variations directly impact on watersheds and consequently river discharge which is the main clean water resource in the world. In this research, the impact of temperature on annual potential evaporation (PE) and mean annual watershed discharge (Q) was investigated using ۴۸۲ watersheds in the United States. The selected watersheds were classified into four climate conditions; (i) arid, (ii) semi-arid, (iii) sub-humid, and (iv) humid areas. According to the results, the temperature variations showed a stronger impact on the evaporation and discharge rate in the arid and semi-arid areas in comparison to watersheds in the sub-humid and humid areas. For example, by increasing the temperature from ۲ to ۱۲ °C, the Q decreased from ۰.۰۶ to ۰.۰۰۴ mm/d (۹۳%) in arid and from ۱.۲۸ to ۰.۲ mm/d (۸۵%) in the humid area, respectively. Ultimately, an experimental model was developed based on average temperature to predict the discharge. Our findings suggested that climate change (i.e. temperature) has a direct impact on watershed discharge through changing the watershed mean potential evaporation amount.

کلیدواژه ها:

Watershed discharge ، Climate change ، Evaporation ، Experimental modeling ، River flow rate