Document Type : Research Paper
Ph. D Student of Water Resources Engineering, Department of Water Science and Engineering, Faculty of Agriculture, University of Birjand, Birjand, Iran
Associate Professor, Department of Water Science and Engineering, Faculty of Agriculture, University of Birjand, Birjand, Iran 3- Department of Research Group of Drought and Climate Change, University of Birjand, Birjand, Iran
Associate Professor, Department of Water Science and Engineering, Faculty of Agriculture, University of Birjand, Birjand, Iran Department of Research Group of Drought and Climate Change, University of Birjand, Birjand, Iran
Assistant Professor, Department of Civil and Environmental Engineering, San Jose State University, San Jose, California, United States
Effective and timely drought monitoring can contribute to the development of drought systems and the optimal management of water resources, and these systems in turn can minimize the costs of drought. The purpose of this study is to investigate drought using Landsat satellite data and meteorological and agricultural drought indices in three regions with different climatic conditions (Birjand, Shiraz and Rasht). For this purpose, drought indices based on satellite data including Normalized Difference Vegetation Index (NDVI), Soil Adjustment Vegetation Index (SAVI) and Simple Ratio (SR) were extracted from Landsat images for the period 2002, 2014 to 2020. Then the results of these indices were compared with the values of standard precipitation index (SPI) and Reconnaissance Drought Index (RDI). The study of indicators shows that the amount of indicators is high in all studied years in Rasht region. In Shiraz region, a significant decrease in the average value of indicators occurred in August and September from 2015 to 2020. Also, this decrease was seen in the average value of indicators in Birjand region from September 2002 to 2020. On the other hand, among the studied months, September 2015 in Rasht and Shiraz regions and 2014 (September) Birjand had the most drought in terms of remote sensing indicators. The results showed that in all three regions, remote sensing indices including NDVI and SAVI have a high correlation with SPI and RDI indices. With the difference that the RDI index is superior to the SPI index for drought monitoring and prediction. As a result, the RDI index takes into account evapotranspiration in addition to rainfall and is more sensitive especially in dry areas such as Shiraz and Birjand where evapotranspiration is higher than rainfall.