洪湖水位对不同时间尺度SPEI/SP干旱指数的响应研究

Response of Lake Water Level of Honghu Lake to SPEI/SPI Drought Indices at Different Time Scales

流域洪涝与干旱对流域水资源利用及生态平衡具有重要影响。探讨流域水文要素与气候因子的关系，是应用气候指数进行流域旱涝监测和影响评估的重要前提。基于四湖流域8个气象站及洪湖湖区水位代表站逐月观测资料，从月、季及连续时间序列月平均标准化水位距平与不同时间尺度SPEI／SPI干旱指数的相关分析，研究洪湖水位对不同时间尺度SPEI／SPI指数的响应。结果表明：四湖流域洪涝与干旱主要受降水控制，洪湖水位与SPEI／SPI干旱指数具有较好的相关性，但其相关程度因不同月份和季节及干旱指数的时间尺度存在一定差异，总体上洪湖水位与4～6个月时间尺度sPEI／sPI干旱指数相关性最为密切，表明洪湖水位对降水及蒸散发导致的水分盈亏的响应具有时滞效应和累积效应，当前月洪湖水位受当月及前3～5个月水分盈亏的共同影响。基于5个月时间尺度的SPEI／SPI干旱指数监测历史时期洪湖水位变化具有很好的一致性。研究结果为基于常规气象观测资料进行四湖流域旱涝监测提供了理论依据，同时可为其他流域旱涝监测与评估提供借鉴。

Drought and flood have significant impacts on catchment water use and ecological balance. To develop practical drought/flood monitoring indicators that only need a few climate variables, it is funda- mentally necessary to explore the relationship between hydrology variables and climate variables for the specific catchment. This study investigates the correlations between lake water level and various time-scale climatological indices according to the standardized precipitation index （SPI） and the standardized precipi- tation evapotranspiration index （SPED, based on the monthly water level records from Honghu Lake rep- resentative gauging stations and the monthly observations of 8 meteorological stations in the Four-Lake Ba- sin. The results showed that extreme droughts and floods are primarily controlled by precipitation variabil- ity over the Four-Lake Basin, and both SPEI and SPI are well related with lake water [eve[ of Honghu Lake while the degree of the correlation varies between different seasons and SPEI/SPI time scales, with the highest correlations for rainy summer and autumn months. Generally, the 4--6 month scale SPEI/SPI drought index is most closely correlated with lake water level of Honghu Lake, showing an apparent re- sponse of lake water level to the current and former months~ water surplus and deficiency. When comparedwith the historical time series of monthly average lake water level of Honghu I.ake, the 5 month scale SPEI/SPI agrees well with the variability of the lake water level. The response relationship found during the study can not only aid the monitoring and forecasting of flood and drought conditions in the Four-Lake Basin based on conventional weather data, but also provides some references for other places of China.