Evaluation of transitional behavior of wetness/drought regimes in the Poyang Lake Basin, China

Transitional behavior of wetness/dryness regimes is investigated using the standardized precipitation/runoff indices (SPI-SRI) and the Markov chain model, and wetness/drought conditions are predicted. Results indicate that (1) the wetness/drought hazards have large negative impacts during initial conditions in the Xiuhe River Basin and manifest their negative impacts during the development condition of the wetness/droughts in the Fuhe and Xiuhe River Basins; in the Ganjiang and Raohe River Basins, however, droughts have their greatest impacts during the lasting time intervals, (2) the occurrence of meteorological or hydrological droughts/floods individually is subject to very low probability, implying close relations between meteorological and hydrological conditions within the Poyang Lake Basin, and (3) an abrupt shift between hydrometeorological wetness and dryness events is identified, specifically in northwest and northeast parts of the Poyang Lake Basin, which could be due to intensifying precipitation regimes in these regions under the influence of increasing temperature. The prediction of droughts indicates that the transitional probability from the second condition to the hydrological drought is the lowest and the transitional probability from the first (or third) condition to the fourth condition is the largest. Results of this study will be of value for developing measures for mitigation of droughts in a changing environment.