Centre for Environmental Management, University of the Free State, South Africa; Disaster Management Training and Education Centre for Africa, University of the Free State, South Africa; Department of Geography and Environmental Science, University of Fort Hare, Private Bag X1314, Alice, 5700, Eastern Cape Province, South Africa.
Centre for Environmental Management, University of the Free State, South Africa.
J Environ Manage. 2021 May 1;285:112112. doi: 10.1016/j.jenvman.2021.112112. Epub 2021 Feb 14.
Terra MOD13Q1 satellite data were used to assess drought disaster events and its spatiotemporal patterns over the Free State Province, South Africa between 2001 and 2019. Moderate Resolution Imaging Spectroradiometer (MODIS) products and climate data downloaded from Application for Extracting and Exploring Analysis Ready Samples" (AppEEARS) and NASA: Prediction of Worldwide Energy Resource databases, respectively were used in the study area. After acquiring MODIS data with the area of interest extracted using field sample and the layers of interest: using Enhanced Vegetation Index (EVI) and pixel reliability and defining the output as GeoTIFF with geographic projection, R programming was used for the analysis. This study also evaluated Standardized Precipitation Index (SPI) to further identify meteorological drought, computed at various time scales utilising information acquired from the Global Drought Observatory database. The results show and identify the years that are water-stressed in the study area, which indicated that low vegetation abundance and high temperature in the Free State Province occurred in 2000, 2008, and 2009. The result also shows that the summer season over large parts of the study region is characterized by moderate to extreme drought while winter seasons have light drought conditions during the same time. Seasonal and inter-annual comparisons of drought events outlined in the Vegetation Condition Index (VCI) provided a useful tool for analysing the temporal and spatial evolution of regional drought and for estimating potential environmental impacts. Drought events occurrence in the study area is less frequent and milder in winter months while summer droughts of different years were more severe. The results of this study can also be used as a tool for monitoring droughts and support for decision making in the evaluation and management of regional drought, for disaster preparedness.
利用 Terra MOD13Q1 卫星数据，评估了 2001 年至 2019 年期间南非自由州省的干旱灾害事件及其时空格局。研究中使用了中分辨率成像光谱仪 (MODIS) 产品和从“提取和探索分析就绪样本的应用程序”(AppEEARS) 和 NASA：全球能源资源预测数据库下载的气候数据。在研究区域中，使用从现场样本提取的感兴趣区域获取 MODIS 数据，并使用感兴趣的图层：使用增强植被指数 (EVI) 和像素可靠性，并将输出定义为具有地理投影的 GeoTIFF，然后使用 R 编程进行分析。本研究还评估了标准化降水指数 (SPI)，以进一步识别气象干旱，利用从全球干旱观测站数据库获取的信息在各种时间尺度上计算。结果表明并确定了研究区域中水资源紧张的年份，这表明自由州省的植被丰度低和高温出现在 2000 年、2008 年和 2009 年。结果还表明，研究区域大部分地区的夏季以中度至极端干旱为特征，而同期冬季干旱条件较轻。植被状况指数 (VCI) 中概述的季节性和年际干旱事件比较为分析区域干旱的时间和空间演变以及估计潜在的环境影响提供了有用的工具。研究区域干旱事件的发生频率较低且冬季较为温和，而不同年份的夏季干旱则较为严重。本研究的结果还可作为监测干旱的工具，并为评估和管理区域干旱、灾害准备提供决策支持。
