|
According to the Tao River basin, downstream of the chin groove, Minxian lijiacun, red flag four control hydrological stations measured monthly, annual runoff data, unified series of years 1956-2006 in a total of 51 years. Interpolation and extension the the chin groove Station and Minxian station runoff data series, to natural runoff restore lijiacun station and the red flag station runoff data series. The use of different methods of runoff year Taohe, the inter-annual variation and trends analysis. Since the 1950s, the Tao River basin runoff distribution inhomogeneity is getting lower and lower, upstream to downstream changes gradually from uniform to non-uniform. Use of uneven distribution coefficient for the year, the annual distribution adjustment coefficient, concentration and centralization period variations indicators of changes in runoff analysis, these indicators showed a gradually decreasing trend in the Tao River basin runoff years, in the watershed , gradually increasing trend downstream. Tao River annual runoff mainly 7,8,9,10 months in the flood season, the the precipitation runoff Taohe main recharge source. Tao River basin runoff annual variation, the overall performance of a gradually decreasing trend, the dry year toyohira alternating. 50,70,80's Tao River runoff flat water period in the 1960s as the the Tao River runoff rainy period in the early 1990s to the 21st century Taohe runoff consecutive dry season; representatives station the levellers years appear the number up, the dry conscription age wet years at least. Equal to the coefficient of variation the upstream the chin groove Station and downstream Hongqi Station, midstream coefficient of variation, indicating that the Tao River upstream, downstream runoff interannual variability and stability; midstream part Tributary, the interannual change increase of the runoff. Inter-annual runoff extreme value ratio and interannual variations decreases gradually from upstream to downstream; the modulus ratio coefficient difference the plot values ??midstream Minxian station was significantly greater than the upstream, and lijiacun Station the chin groove Station and the the downstream red flag station, show that Taohe midstream runoff interannual change process abundance of dry season. The Tao He runoff process and rainfall presents the correspondence between changes with changes in rainfall, runoff, runoff hysteresis. Through the use of traditional the MK rank test and the EMD method to study the mutations of the Tao River runoff and periodic results show that: Tao River basin annual runoff is not significantly reduce the trend overall, significant transitions; cycle showed more than The time scale of Wet and Dry alternately characteristics. The runoff reduction mainly occurred in 1969-1972 and 1986-2002; runoff increases significantly in the years 1967-1968 and 2003-2006, and in dry years extra wet year. 2003 Taohe runoff mutations to the increasing trend by the decreasing trend; 1988, 1989, 1991, runoff reduction trend mutations Year to year, from upstream to downstream mutations showed gradual hysteresis phenomenon. Tao River basin, downstream runoff consistent trend to cyclical fluctuations laws. Runoff sequences exist 2-4a ,4-12a ,10-28a three types of scale fluctuations in the cycle, including a strong 2-4a and 10-28a time scale changes. Predict the existence of a relatively overabundant period, after the conversion of annual runoff by Feng dry, showed a gradual downward trend in 2006, 2-7a Taohe runoff.
|