基于多变量概率分析的珠江流域干旱特征研究

根据珠江流域42个站点1960-2005年的46年日降水资料,以6个月尺度的SPI值表征珠江流域干旱情况.通过Mann-Kendall趋势分析研究了珠江流域干旱时间演变特征,同时基于多变量Copula函数,在定义的两种不同干旱情景下,根据两变量联合重现期及其对应的第二重现期,比较性地研究了珠江流域的干旱风险.研究结果表明:(1)珠江流域西部有变旱的趋势而东部有变湿润的趋势,其中显著的变旱趋势集中在11、12、1月,显著的变湿趋势集中在6、7月.同时除个别站点外,干旱历时和干旱严重程度趋势不显著；(2)珠江流域整体上干旱风险较大,东部要比西部干旱风险高.珠江流域内发生长历时干旱时,干旱严重程度也往往很大,对干旱风险管理很不利.在发生严重程度的干旱时,珠江流域东部的干旱高风险区域增加,威胁珠江三角洲地区水资源安全；(3)由于第二重现期综合考虑了各种情况,可能第二重现期对干旱风险分析的结果更稳健一些.

Spatial-temporal Patterns of Drought Risk across the Pearl River Basin

Monthly precipitation data of 42 rain stations over the Pearl River basin for the period 1960-2005 were analyzed to classify anomalously dry conditions using the 6-month standardized precipitation index. Trends of the SPI-based droughts were detected using Mann-Kendall technique. The results are shown as follows. (1) The western part of the Pearl River basin tends to be dryer and the eastern part tends to be wetter. Enhancing droughts are observed mainly in November, December, and January, and increasing wetting tendency in January and July. Meanwhile drought duration and severity show insignificant trends. (2) The drought risk across the Pearl River basin is very high and the highest drought risk is found mainly in the eastern part of the basin. Besides, the results also show that long-lasting droughts are highly probably the severe droughts. Moreover, the drought risk is greatly increased in the eastern Pearl River basin, when droughts of higher severity occur in the Pearl River basin. These results may imply tremendous challenges for the water resources management in the Pearl River basin, particularly the eastern part of the Pearl River basin. The second return period represents many situations of drought, so the result of the second return period may be more robust.