A STUDY OF THE SPATIAL SHIFT OF 400 mm RAINFALL CONTOURS IN THE YELLOW RIVER BASIN DURING RECENT 50 YEARS

Abstract

Based on the daily serial rainfall data of 1026 rainfall gauges (or hydrological gauges) in the Yellow river basin and its surrounding regions during the period from 1956 to 2000, and on the key data disposal platform of GIS techniques, the spatial shift of 400mm-rainfall contours in the Yellow river basin in the past 50 years has been analyzed with the method of time serials analysis and the quantified weighted average location (QWAL) token method of contours has been founded in this paper. The multi-year yearly average rainfall in the Yellow river basin was 454.62mm and the QWAL of 400mm-rainfall contours was (105~o0′4″E,36~o57′54″N) from 1956 to 2000. In the whole, the latitudinal shift of 400 mm rainfall contours in the Yellow River Basin in the recent 50 years has been a typical stationary random sequence, however the longitudinal shift serials cannot meet the requirement of the stationary random sequence. Trend test shows that spatial shift of the 400 mm rainfall contours in the Yellow river basin has the eastern and southern trends, while the eastern trend is notable. Power spectrum analysis indicates that the longitudinal shift of the 400 mm rainfall contours in the Yellow river basin has the notable cycle of 3 years, both longitudinal and latitudinal shifts have the 7-year and 2-year cycle. Hurst index shows that the displacement of QWALs of 400mm-rainfall contours has the reverse permanence features.