Evolution Of Precipitation And Runoff And Characteristic Of Flood/Drought In Jinjiang Basin

Based on the runoff data observed in the past years by the perennial precipitation data obtained by Anxi, Yongchun, Nan'an and Jinjiang Weather Stations andAnxi and Shilong Hydrological Stations, the basin evolution laws of precipitation and runoff are deeply probed by using the Mann-Kendall method, the R/S method and the Morlet wavelet, and finally the drought/waterlogging situation is analyzed and predicted by using the gray theory and establishing GM(1,1) model. The main conclusions are as follows:1) Since 1960s, the annual runoff distribution in Jinjiang River Basin has become more and more non-uniform and changed gradually from uniformity upstream to non-uniformity downstream. Due to topographical effect, the annual precipitation distribution is obviously non-uniform in Jinjiang Area. Compared with the southeast coastal area, the precipitation is more abundant with clearer non-uniformity and concentration in the northwest hilly area of the Jinjiang River Basin, and the concentration period of annual precipitation in Jinjiang River Basin is consistent with the time of major flood period.2) The fluctuation tendency of annual upstream and downstream runoff in Jinjiang River Basin is unsharp and relatively smooth. In the future, the annual runoff at the upper reach will show a decreasing trend, while the annual runoff will present an increasing trend and have no significant jump. The results show that there are obvious multiple time scales (6a,10a and 32a) in the annual runoff variation process and the 6a and 10a time scales change more greatly. The total annual precipitation of four representative weather stations in Jinjiang River Basin increase progressively and will have a significant increasing trend in the future. The annual precipitation in Anxi, Yongchun and Jinjiang Stations will show a sharp increasing trend in the future. The research on periodicity of precipitation change in Jinjiang River Basin shows that there are main periods in three time scales (about 7a,10a and 46a), of which the oscillation energy at the main period of 7a is the most great.3) The results show that there is a high probability for heavy waterlogging, extreme waterlogging, great drought and partial drought. The drought or waterlogging may occur more probably in the middle phase (June-August) of the rainy season and (December-January) of the dry season, but less probably in the early phase (October-November) and later phase (February) of the dry season. In either the whole year or the rainy season, the variation of the drought/waterlogging always tends gradually from more drought to more waterlogging. Recently, it is prone to drought in Jinjiang River Basin. Therefore, it is feasible to adopt the gray prediction GM(1,1) model to predict drought-flood disaster in Jinjiang River Basin.