三种气象干旱指数在塔里木河流域应用的对比分析

Comparison and Analysis of Three Meteorological Drought Indexes in the Tarim River Basin

为分析塔里木河流域的干旱情况,选取K指数、降水距平百分率(P_a)指数和S指数,对比分析三种气象干旱指数在塔里木河流域的时空分布特征和典型年的干旱评价结果。结果表明,三种指数对降水量敏感性较高。流域干旱变化趋势评价结果中,K指数和P_a指数结果呈湿润化,S指数则相反;流域干旱频率的评价结果中,K指数和S指数保持一致,频率自西南向东北递减,而P_a指数为递增趋势;K指数对干旱频率高的地区评价结果较好。典型干旱年的验证结果表明,K指数和P_a指数能较好监测到流域重特旱年的干旱站点,S指数各等级的监测效果较差。综合分析表明,K指数在塔里木河流域的干旱监测适用性较好,研究结果对干旱半干旱地区的干旱监测具有重要参考价值。

In order to analyze the drought conditions in the Tarim River Basin, the spatial-temporal variation of drought and drought evaluation results of typical years in the basin were compared and analyzed by choosing K index, precipitation anomaly percentage （Pa index） and S index. The results show that the three indexes have high sensitivities to precipitation. The aridity trend of K index and Pa index is that the whole basin is going to be humid, while the result of S index is opposite. The drought frequency of K index and S index shows that the basin＇s frequency decreases gradually from southwest to northeast, while the frequency of Pa index from southern to northeast has an increasing trend. K index has a good evaluation result over the regions with high drought frequency in history. In the verification of typical drought years, K index and Pa index can be used to monitor severely dry years and extremely dry years, and S index has a poor monitoring effect in each level. In conclusion, K index is applied well in the drought monitoring in the Tarim River Basin, and the research results have important reference values for drought monitoring in arid and semi-arid areas.