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Internationally recognized Golestan forests are among the most endangered features threatened by anthropogenic activities. Being located in north-west of Iran, south-east of Caspian Sea, Gorganroud watershed is mostly influenced by deforestation activities. In this study the identification of regional atmospheric and hydrologic patterns and their role in conforming floods in Gorganroud water basin are discussed. A 33-year period (1970-2003) was taken in to consideration in the process of data gathering. Gradual change from Mediterranean to Semi-arid climate during recent decades in Gorganroud watershed indicates regional climate change. Increased share of 24 hour precipitation in average annual precipitation in one hand and decreasing rate of snowy on rainy days ratio on the other hand stipulate this climate change. The relatively sharp ascending pattern of annual peak flow of the basin during recent years maybe considered as an alarming factor concerning streams inundation. Climate study in suspected water basins may provide invaluable data concerning flood forming potential of regional precipitations. The results of this study confirm the fact that precise analysis of climatic and hydrologic in watersheds threatened by flood-forming run-offs may be used efficiently in monitoring such areas and saving human lives.