寒区农业流域综合干旱指数构建及其适用性分析

Construction of an optimized comprehensive drought index for agricultural watersheds in cold regions and its applicability analysis

以挠力河流域为寒区农业流域典型区,构建融合多源信息的综合干旱指数用于寒区农业流域干旱特征的评估,并分析其适用性。基于构建的SWAT模型模拟挠力河流域水文气象要素,计算单一的标准化降水蒸散发指数(SPEI)、标准化土壤湿度指数(SSI)和标准化径流指数(SRI),运用主成分分析法和熵权法分别对3种单一干旱指数赋权,通过最小偏差法计算最优组合权重,构建融合气象干旱、农业干旱和水文干旱信息的综合干旱指数(OCDI)。结果表明:OCDI的干旱事件监测结果与历史干旱事件吻合度较高,综合考虑多时间尺度下的OCDI对于挠力河流域干旱状况描述更为准确和全面;3种单一干旱指数监测的干旱程度空间分布差异明显,融合多源信息的OCDI能够从气象干旱、农业干旱和水文干旱多角度揭示挠力河流域综合干旱特征;OCDI与不同类型单一干旱指数均有较高的相关性,在挠力河流域上游对于干旱的综合表征能力更优且年尺度的OCDI综合表征能力优于季尺度和月尺度;OCDI能够较好地识别和区分该流域的综合干旱程度,随着OCDI所识别综合干旱程度的加重,流域实际受旱面积相应增大。

Taking the Naoli River Basin as a typical agricultural watershed in cold regions,a comprehensive drought index integrating multi-source information was constructed to evaluate the drought characteristics of agricultural watersheds in cold regions,and its applicability was analyzed.Based on the constructed SWAT model,the hydrological and meteorological elements of the Naoli River Basin were simulated,and the single standardized precipitation evapotranspiration index(SPEI),standardized soil moisture index(SSI)and standardized runoff index(SRI)were calculated.The principal component analysis method and entropy weight method were used to weight three single drought indexes,and the optimal combination weights were calculated using the minimum deviation method to construct an optimized comprehensive drought index(OCDI)that integrates meteorological drought,agricultural drought,and hydrological drought information.The results show that the monitoring results of drought events by OCDI are highly consistent with historical drought events,and considering multiple time scales,OCDI is more accurate and comprehensive in describing the drought situation in the Naoli River Basin.The spatial distribution differences of drought severity monitored by three single drought indices are significant.OCDI,which integrates multi-source information,can reveal the comprehensive drought characteristics of the Naoli River Basin from multiple perspectives of meteorological drought,agricultural drought,and hydrological drought.OCDI has a high correlation with different types of single drought indexes.In the upstream of the Naoli River Basin,OCDI has better comprehensive characterization ability for drought,and comprehensive characterization ability of the annual scale OCDI is better than the seasonal and monthly scales.OCDI can better identify and distinguish the comprehensive drought degree of the basin.With the increase of the comprehensive drought degree identified by OCDI,the actual drought affected area in the basin increases accordingly.