Study On Relationship Between Runoff/Soil Moisture And Climate Change In Hexi Region

Climate change and its impacts have been paid more attention by many countries and scientists in the world. At present, it is necessary for the social economic and ecological sustainable development to promote the monitoring and prediction level, develop the impact research and increase the adapting and countermeasure research. Based on the past study, this paper aims at the relations research between climate change and mountain runoff/soil moisture in Hexi Region through the methods of trend analysis and test, the wavelet analysis and correlation analysis.The results indicate: the variation rate of air temperature in mountain areas in the mid-west Hexi corridor, Gansu Province, is bigger than that in plains, and in the east part it is on the contrary. The main periods of air temperature are 11a, 15a and 5a or so, which the 5a period is the most stable one. The variation rate of precipitation is increasing in. the west part, and it is not so obvious in the mid-east part. While the east part is decreasing, the mountain runoff in the mid-west is increasing less significantly but earlier, and they are all changing at 8-9a interval. The soil moisture in the mid-east is increasing, but it has a decreasing trend in the west. The soil moisture is mainly affected by 6a and about 14a periods.The relations between air temperature in mountain areas and mountain runoff are complex in Hexi Region. It is positive significantly in Shiyang River Basin and Heihe River Basin, and it is negative in Shulehe River Basin. The relation between precipitation in mountain areas and mountain runoff in three Basins has the same trend. The mountain runoff is sensitive to precipitation, which affects the runoff directly and plays a important indicate role.The soil moisture in Spring wheat field in Hexi Region is mainly affected by the local air temperature at seasonal time scale, and has a negative relation with the air temperature. When the rain in last same year or the same time period of wheat growth is much more, there will much water available for the crops at the next year. The rain changes the soil moisture heavily, and the correlation between soil moisture and precipitation becomes less with the soil profile depth increasing. The air temperature and the precipitation change the soil moisture commonly, especially the upper soil layer. In different months of Spring wheat growth, the higher the air temperature is, the lower the soil moisture is. With the coming of the rainy season, the more the rain is, the higher the moisture is. Furthermore, at month time scale, the soil moisture has a feedback role to the air temperature and the precipitation, but the impact is not so serious.