1961-2020年中国西北地区干旱时空演变特征及其对植被的影响  

Characteristics of Spatial and Temporal Evolution of Drought and Its Impact on Vegetation in Northwest China,1961-2020

作　　者：胡铁军 张亮 HU Tie-jun;ZHANG Liang(Gansu Province Wuwei Hydrological Water Resources Survey Centre,Wuwei 733300,Gansu Province,China;Wuwei Water Conservancy Science and Technology Promotion Center,Wuwei 733009,Gansu Province,China;National Field Scientific Observation and Research Station on Efficient Water Use of Oasis Agriculture,Wuwei 733009,Gansu Province,China)

机构地区：[1]甘肃省武威水文水资源勘测中心,甘肃武威733300 [2]武威市水利科技推广中心,甘肃武威733009 [3]甘肃武威绿洲农业高效用水国家野外科学观测研究站,甘肃武威733009

出　　处：《节水灌溉》2025年第4期96-102,117,共8页Water Saving Irrigation

基　　金：甘肃省水文科研项目(23GSWK004);武威市科技计划项目(WW24A01RPZ003)。

摘　　要：西北地区独特的地理和气候条件使得该地区干旱频发,明确干旱演变特征对于区域防灾减灾具有重要意义。此外,在季节尺度上,干旱对植被的影响及周期性研究相对较少。鉴于此,选用标准化降水蒸散指数(SPEI)表征气象干旱,基于连续小波变换和旋转经验正交函数(REOF),研究1961-2020年中国西北地区季节尺度干旱演变规律特征,并利用Pearson相关性分析、交叉小波和小波相干分析1982-2020年归一化植被指数(NDVI)对SPEI的响应。结果表明:①REOF将研究区干湿状况分为4个亚区,空间分布上具有一定差异;干湿突变年存在明显的季节性差异。②在季节尺度上SPEI具有明显的周期性,震荡周期的发生时段集中在1991-2001年间,但周期长度不同。③干旱发生频率具有明显的季节性和地域性,季节上,夏季>春季>秋季;干旱程度上,中度>轻度>重度>极端。④季节干旱均严重影响西北地区植被生长,超过50%的地区SPEI与NDVI呈正相关关系,通过小波相干和交叉小波分析了SPEI和NDVI的变化关系,二者具有明显的年际变化周期性。The unique geographical and climatic conditions of the northwestern region contribute to the frequent occurrence of droughts,making it crucial to understand the evolution characteristics of droughts for regional disaster prevention and reduction.Additionally,limited seasonal studies exist on the effects of droughts on vegetation and their periodicity.Therefore,this study adopts the Standardized Precipitation Evapotranspiration Index(SPEI)to characterize meteorological drought.Utilizing continuous wavelet transform and Rotating Empirical Orthogonal Function(REOF),this research examines the seasonal evolution characteristics of droughts in northwestern China from 1961 to 2020.Furthermore,Pearson correlation analysis,cross wavelet analysis,and wavelet coherence analysis are employed to investigate the response of the Normalized Difference Vegetation Index (NDVI) to SPEI from 1982 to 2020. The results indicate: ① REOF divides the studyarea into four subregions based on wet and dry conditions, with distinct spatial distribution differences. There are significant seasonalvariations in the years of wet and dry transitions. ② SPEI exhibits notable periodicity at the seasonal scale, with oscillation periodsconcentrated between 1991 and 2001, though the lengths of these cycles vary. ③ The frequency of drought occurrence shows clear seasonalityand regionality, with summer > spring > autumn. In terms of drought severity, moderate drought > mild drought > severe drought > extremedrought. ④ Seasonal drought significantly impacts vegetation growth in the northwestern region, with over 50% of the area demonstrating apositive correlation between SPEI and NDVI. The relationship between SPEI and NDVI variations, analyzed through wavelet coherence andcross wavelet methods, exhibits clear interannual periodicity.

关 键 词：干旱 周期性 小波分析 时空特征 植被 旋转经验正交函数 西北地区 

分 类 号：S271[农业科学—农业水土工程]