Abstract:

In recent years, agriculture and animal husbandry production in the western Sichuan plateau was greatly affected by drought, therefore, it was necessary to study the applicability of remote sensing drought comprehensive index in the grassland area of the western Sichuan plateau. In this study, the vegetation condition index (VCI), the temperature condition index (TCI) and precipitation condition index (PCI) were selected to construct the scaled drought condition index (SDCI), which was suitable for the combination of the regional weight of grassland in the western Sichuan plateau, the index monitoring results were verified by standardized precipitation evapotranspiration index (SPEI) during the same period, the characteristics of summer drought from June to August during 2000-2018 were analyzed after the suitable drought grades in the study area were divided. The results show that: (1) The drought judgment index SDCI highlighted the cumulative effect of precipitation and had high monitoring accuracy. It was basically consistent with the monitoring results of SPEI on the drought events in 2006. Only in some places, the scope and intensity of the drought were slightly different from the actual situation. (2) The location of the month-scale drought was mostly distributed in the west and south of Ganzi Prefecture and the south of Aba Prefecture, and in the northeast of Zoige there was mostly no drought in summer during 2000-2018. The degree of drought was stronger in June and August, it was mainly mild to moderate drought, and in July there was mostly mild drought and no drought. (3) The frequency of drought was high and the range was wide in June and August during 2000-2018. In July, the frequency of mild drought was 60.66% in the whole region, and the frequency of drought above mild level was higher (more than 40%) in the southwest, northwest, north and east of Ganzi Prefecture, while the drought frequency in northern Aba Prefecture was lower (less than 40%). The research showed that the SDCI with prominent precipitation effect had the ability to respond to extreme drought events, it could objectively and effectively monitor the drought status of grassland in the western Sichuan plateau.

Key words: grassland region in western Sichuan plateau, remote sensing data, scaled drought condition index, validation, spatio-temporal characteristics

摘要：

近年来川西高原农牧业生产深受干旱的影响,区域受自然因素制约而监测站点稀少,因此研究遥感干旱综合指数在川西高原草地区域的适用性十分必要。选取植被状态指数(vegetation condition index,VCI)、温度状态指数(temperature condition index,TCI)和降水状态指数(precipitation condition index,PCI),通过客观赋权法构建适宜于川西高原草地区域权重组合的归一化旱情综合指数(scaled drought condition index,SDCI),该指数监测结果通过了同期标准化降水蒸散指数(standardized precipitation evapotranspiration index,SPEI)的验证,并对2000—2018年6—8月川西高原草地区域伏旱特征进行分析。结果表明:(1)突出降水累积效应的归一化旱情综合指数(SDCI)的监测精度较高,其与SPEI对2006年川西高原草地区域高温伏旱事件的监测结果基本一致,仅部分地方伏旱发生范围和强度与实况略有差异。(2)2000—2018年夏季月尺度伏旱位置多分布在甘孜州西部、南部和阿坝州南部一带,东北部若尔盖多表现为无旱;6月和8月伏旱程度较强,以轻度到中度为主,而7月多为轻旱和无旱。(3)2000—2018年6月和8月川西高原草地区域伏旱发生频率高、范围广,7月整体上轻旱频发(60.66%);其中甘孜州西南、西北部、北部及东部轻旱及以上等级发生频率较高(超过40%),而阿坝州北部地区发生干旱频率较低(小于40%)。研究表明突出降水累积效应的SDCI指数具备对极端干旱事件的响应能力,且可客观、有效地监测川西高原区域草场干旱状况。

关键词: 川西高原草地区域, 遥感数据, 归一化旱情综合指数, 验证, 时空特征