基于SWAT模型的渭河流域干旱时空分布

Spatiotemporal patterns of droughts based on SWAT model for the Weihe River Basin

以渭河流域为例,从流域水文循环的角度出发,在SWAT(Soil and Water Assessment Tool)分布式水文模型和Palmer干旱指数(Palmer Drought Severity Index)原理的基础上提出了干旱分析模型SWAT-PDSI,对渭河流域干旱的时空演变规律和发生频率进行了分析。研究结果表明:1经率定和验证的SWAT模型能够较好地模拟渭河流域的水文变化过程;2利用SWAT-PDSI对典型干旱事件(1995年干旱)的评估结果显示,该模型能较好地反映渭河流域干旱的时空差异和变化规律;3渭河流域、渭河干流和泾河流域均表现为变干的趋势,而北洛河流域表现为变湿的趋势,但均未通过95%的置信水平检验;4渭河流域多数子流域的SWAT-PDSI多年平均值处于-1~1,说明该流域多数地区处于正常状态;5渭河流域北部的北洛河流域和泾河流域的上游地区易发生干旱,发生中等以上、严重以上和极端干旱事件的频率最高。

Drought is a complex natural hazard that is difficult to define and assess. By considering the hydrological cycle of river basins, a drought evaluation model SWAT-PDSI was constructed based on the Palmer Drought Severity Index(PDSI) and simulated results of SWAT(Soil and Water Assessment Tool) in the Weihe River Basin. Moreover, characteristics of the spatiotemporal distribution and frequency of drought hazard in the basin were analyzed. Results showed that:(1) The calibrated and validated SWAT model can be used to predict the hydrological process in the Weihe River Basin since it results in similar simulated trend of change as the observed data;(2) The SWAT-PDSI model based on SWAT and PDSI well describes the characteristics of drought in the Weihe River Basin as verified by the drought indices in 1995;(3) Temporally, the Weihe River Basin, Weihe River mainstream, and Jinghe River Basin showed a drying trend and the Beiluohe River Basin showed a wetter trend, but these were not statistically significant at the 0.05 confidence level;(4) Spatially, the annual average of SWAT-PDSI was between-1 and 1 in most subbasins;(5) High frequency drought areas were mainly distributed in the upstream of the Beiluohe River Basin and the Jinghe River Basin.