Agricultural drought monitoring based on remote sensing-based Evapotranspitation Condition Index in the Jarahi Zohreh basin

Subject Areas : Natural resources and environmental management

Maedeh Behifar ¹ (Remote Sensing Department, University of Tehran.)
Ata Abdollahi ² (university of tehran)
Majid Kiavarz ³ (University of Tehran)
Ghasem Azizi ⁴ (University of Tehran)

Received: 2022-04-11 Accepted : 2022-05-17 Published : 2023-09-23

Keywords: evapotranspiration, drought, drought index, remote sensing,

Abstract :

Drought is one of the most important natural hazards in Iran that has many destructive environmental and economic effects. Drought is affected by various factors, and different indices have been developed to monitor it. Drought studies have been performed using temperature and vegetation data, but few studies have used satellite evapotranspiration data. In this research, vegetation condition index, temperature condition index, and evapotranspiration condition index have been used to study drought in Jarahi and Zohreh catchments. For this purpose, drought indices have been calculated on a monthly basis using MODIS satellite products from the 2000 to 2017 period. The six-month Standardized Precipitation Index was used to evaluate the remote sensing-based drought indices. The results showed that the evapotranspiration condition Index had the highest correlation with the six-month SPI index and was considered the most appropriate index to study the drought. The correlation of ETCI with SPI was equal to -0.57 and the RMSE was 0.47. A drought severity map was prepared using remote sensing indices to depict six classes of drought severity including severe drought, moderate drought, mild drought, near normal, and without drought for 2008, 2009, and 2016, when the study area was suffering from drought. The results of the spatial assessment showed that the central part of the basin which contains ecologically important protected areas was the most vulnerable part during dry years, and during the study period, it has experienced over 10 months of severe drought. In this period, the coastal part had the lowest drought intensities. However, during different years, the wetland area of the basin, which is one of the protected water ecosystems, has decreased. The results showed that compared to other indices, the satellite-based evapotranspiration data can provide a good tool for monitoring drought in hot areas with sparse vegetation such as Iran.