List of Articles Vegetation Drought Index

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  1 - Application of New Agricultural Drought Index Based on Soil Moisture and Modified Vegetation Index Using Remote Sensing Data of SMAP and TERRA
  Aliakbar Karamvand Seyed Abbas Hosseini Ahmad Sharafati
  10.30495/wsrcj.2022.67163.11299
  Background and Aim: There are always challenges of spatial and temporal resolution in-situ measurement methods of factors affecting drought phenomena, and the presence of human operators is required. However, due to remote sensing's ability to measure data on the entire More

  Background and Aim: There are always challenges of spatial and temporal resolution in-situ measurement methods of factors affecting drought phenomena, and the presence of human operators is required. However, due to remote sensing's ability to measure data on the entire surface of the planet with an acceptable spatial and temporal resolution, its use in controlling and observing drought has grown more than ever, and it has become a powerful tool in the hands of experts. In this study, based on two components of surface soil moisture and modified vegetation index (EVI) by applying remote sensing data, a new agricultural drought index named (SMADIN) is proposed.Method: To achieve the goal of proposing a drought index based on soil moisture, surface soil moisture data from the SMAP satellite of 5 cm depth was used. These data were validated before use against daily field measurements provided by the Iranian Meteorological Organization over a 250-day period. Validation step error was evaluated using the root mean square error method between satellite data and field measurements. Furthermore, the EVI index was calculated using data from the TERRA satellite and the MODIS sensor. Eventually, an analytical method is used to propose a drought index based on soil moisture. In order to compare the performance of this index in different weather conditions, two regions were chosen, one representing a dry climate and the other a wet climate. Then, the correlation matrix was plotted by the Pearson method for SMADIN agricultural drought index versus vegetation health index (VHI) and the results were discussed.Results: Validation showed that field data measured in land use similar to remote sensing had an average root mean square error of 0.05 .The results indicate that the new agricultural drought index correlates up to 96% with VHI in the humid climate and 98% in arid regions. In addition, a 5-year comparison of the new SMADI and VHI time series in the study area demonstrates synchrony in peaks, minimums, increases, and decreases.Conclusion: An agricultural drought index based on soil moisture is proposed in this study. We believe that, in recent years, when the lifetime of the SMAP satellite data exceeds 7 years, it is possible to use this index in future studies. Considering the possible error of SMAP and TERRA data in providing drought index, it is suggested to use this index in future studies in dry regions such as the central and southern regions of Iran. Manuscript profile
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  2 - Analysis of agricultural drought using remote sensing indices (Case study: Marivan city)
  Karim Solaimani Shadman Darvishi Fatemeh Shokrian
  The effects of drought can be represented as water resources declinations, vegetation and consequently, reducing agricultural production. To study and monitor drought, it is necessary to quantify its effects using drought indices.  The purpose of this study was to More

  The effects of drought can be represented as water resources declinations, vegetation and consequently, reducing agricultural production. To study and monitor drought, it is necessary to quantify its effects using drought indices.  The purpose of this study was to analyze drought in Marivan city using Landsat images from 2000 to 2017. After preprocessing the images, vegetation drought index (VDI) and vegetation health index (VHI) were extracted. Assessment of the indices showed that agricultural drought in VDI index was not observed in any year, and the values of this index were close to 100 that it indicates normal and optimal conditions. So, from 2000 to 2004 the normal conditions and from 2008 to 2017 have been optimal conditions in the dominant region. The results of VHI also show the Conditions without drought in the region. According to this index, extreme drought, severe drought and moderate drought in the studied years did not occur. The largest area of mild drought in the eastern and southeastern parts of the region in 2000, 2001, 2003, and 2005 was 38.23, 38.28, 12.29 and 35.74 km2, respectively. In general, According to the main emphasis of this study, based on VDI and VHI indices, from 2000 to 2017 (with the exception of  2012), the results indicate the absence of agricultural drought in the Marivan city. Considering the benefits of satellite images such as broader coverage, higher temporal resolution, and lower cost, it is recommended to use the knowledge of remote sensing for drought study. Manuscript profile