Elham Rafiei Sardooi; Mina Eghtedarnejad; Shapour Kohestani
Abstract
Since that the traditional methods are based on meteorological station data and more investigate meteorological drought, hence, the application of remote sensing techniques and satellite images have been considered as a useful tool for monitoring of agricultural drought. In this study, the relationship ...
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Since that the traditional methods are based on meteorological station data and more investigate meteorological drought, hence, the application of remote sensing techniques and satellite images have been considered as a useful tool for monitoring of agricultural drought. In this study, the relationship between the meteorological drought index (SPI) and remote-sensing-based indices (VCI, TCI and VHI) has been studied in Bam plain. In this regard, using Terra satellite images (Modis sensor) and precipitation data of synoptic and rain gauge stations in the study area, the occurred changes were detected over the 15-year period. In this study, with respect to high temporal accuracy and spectral coverage and accessibility, MOD13A3 and MOD11A1 products extracted from MODIS sensor were used during 2009 to 2023. Then, indices of VCI, TCI and VHI were compared with Standard Precipitation Index (SPI). The results of drought mapping with the SPI index during 2010 to 2024 showed that the drought severity has increased from north to south in the study area. So that, extremely drought is detected in the southern regions of the plain and extremely wet is detected in the northern regions. The annual correlation coefficient between SPI, VCI and SPI indices is 0.70 and 0.53, respectively. It shows high significant positive correlation at level of 0.05. The correlation coefficient between SPI and TCI is 0.11 which shows a weak correlation but significant positive at level of 0.05. Therefore, VCI and VHI Indices have more correlation with annual precipitation and have acceptable results compared with TCI Index.
Ali Azareh; Elham Rafiei Sardooi
Abstract
The purpose of this study is to investigate land use changes in the past and predict future land use using land change modeler in Halil River watershed. The detection of land use changes was performed using Landsat satellite images (L5-TM-1991, L7- ETM+-2003 and L8-OLI-2020). Transition potential modeling ...
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The purpose of this study is to investigate land use changes in the past and predict future land use using land change modeler in Halil River watershed. The detection of land use changes was performed using Landsat satellite images (L5-TM-1991, L7- ETM+-2003 and L8-OLI-2020). Transition potential modeling was done using MLP neural network method and eight variables including altitude, slope, aspect, distance to road, distance to river, distance to agricultural lands, distance to urban and Normalized Difference Vegetation Index (NDVI). Finally, the Markov chain was used to predict future land use changes. Investigating the calibration periods using kappa statistics showed that the period of 1991-2020 had the highest accuracy to predict land use for 2041. The results of land use changes indicated that during the calibration period, among the six categories namely rangeland, agricultural land, residential land, barren land, rock and orchard, the highest increase and the highest decrease in area was related to agricultural lands and rangelands by 293.7 and 382.6 km2, respectively. Also, the area of barren lands, orchard and residential lands has increased and rocky lands have remained unchanged. The degradation of rangelands has been more in line with the conversion of these lands into agricultural, orchard and residential lands. Also, the prediction of future land use map (2041) using land change modeler showed that , the area of rangelands will decrease by 201.1 km2 and the area of agricultural lands, residential lands, orchards and barren lands will increase by 158.01, 22.38, 20.2 and 0.53 km2, respectively.
