Spatio-temporal Change Characteristics of Precipitation in Urumqi River Basin

Based on the monthly precipitation data of seven meteorological stations in Urumqi River basin from 1961 to 2009,the spatio-temporal variation characteristics of annual precipitation were analyzed by using linear regression,climatic inclination rate and abrupt change detection methods.The main results are as follows:The were obvious vertical differentiation of precipitation in Urumqi River basin,the average value of annual precipitation is a parabola tendency with the sea level elevation.The most annual precipitation occurs at altitude of 1900 to 2600 m,and the most precipitation is 520 mm to 550 mm correspondly.The change of monthly precipitation in a year is a single peak type,the precipitation from October to March is less than that of April to September,the precipitation in the upper reaches is more than that in lower reaches.The average annual precipitation was increased by the change rate of 14.417 mm/(10a),and the change rate of annual precipitation was increased with sea level elevation in Urumqi River basin.Abrupt examination indicated that,the annual precipitation was increased abruptly in 1992 after which the mean precipitation after 1992 is more than that before 1992 by 14.5%.The variation coefficient of annual precipitation is decreased with sea level elevations.Annual precipitation has the periodic variation by the different time scales of quasi-3a,6a and 8a in Urumqi River basin.