摘要

The runoff variation characteristics of Dongting Lake were analyzed by applying the methods of concentration degree, concentration period, Mann-Kendall trend test, and variation coefficient. The analysis showed that: 1) The runoff concentration period of Dongting Lake occurs mainly between June and July of each year, with the peak time in late June-early July, and the composite vector directions in concentration period range from 103.2 degrees to 190.2 degrees; 2) The runoff variation coefficient ranges from 0.194 to 0.761, which indicates the instability of runoff. Extreme ratios of inflow and outflow are over 0.6 with an obvious attenuation; 3) The alternating pattern between wet years and dry years showed that the water distribution of the four rivers is relatively equal, while Ouchikou from three bayous is more violent, accounting for 32.79% of wet years and 57.38% of dry years respectively. The drastic change of annual water allocation is adverse to rational utilization of water resources.

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