RS
mehdi feyzolahpour
Abstract
Drought is the most expensive weather event in the world after hurricanes. Early detection of drought and prediction of its occurrence will reduce costs and save human lives. In this research, in order to evaluate the best index in estimating moisture stress and drought, 8 indices NDVI, NDWI, VCI, SR, ...
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Drought is the most expensive weather event in the world after hurricanes. Early detection of drought and prediction of its occurrence will reduce costs and save human lives. In this research, in order to evaluate the best index in estimating moisture stress and drought, 8 indices NDVI, NDWI, VCI, SR, MSI, SIWSI, NDII and NMI were used and Shadgan Wetland was investigated in the period of 2018 to 2023. LST index was also used to check temperature changes. In order to determine the most suitable index, the Pearson correlation coefficient was estimated between the indices and the effectiveness of each index was shown on the Chadwick scale. Based on this, NDWI, MSI, NMI and LST indices have the highest correlation and based on Chadwick's scale in 5 cases, NDWI and MSI indices have a strong and very strong correlation and there is a strong correlation between these two indices at around 0.99 - It has been established. The correlation between LST and NDWI indices was also negative and was estimated at -0.73. Due to the dominance of semi-arid conditions in the region, vegetation-based indices have a very weak capability in drought estimation, and the correlation between NDVI and NDWI was around 0.05. Therefore, based on this, it can be concluded that in Shadgan wetland, indicators based on humidity and temperature stress have better capabilities in drought estimation than vegetation indicators.
Geomorphology
Arezou Cheraghi; Shahram Bahrami; Somayeh Khaleghi; Kazem Nosrati
Abstract
Dolines are one of the most important karst landforms and play an important role in soil formation. In this study, the morphometry of dolines and their relationship with the physicochemical characteristics of soil in Noakoh anticline were evaluated. Chemical and physical characteristics of 36 soil samples ...
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Dolines are one of the most important karst landforms and play an important role in soil formation. In this study, the morphometry of dolines and their relationship with the physicochemical characteristics of soil in Noakoh anticline were evaluated. Chemical and physical characteristics of 36 soil samples of dolines were collected and measured in the laboratory. Also, digital elevation model (DEM; 13 cm cell size) obtaining from UAV images, was used to measure the morphometric parameters of dolines. The results showed that large dolines have higher slope, depth and roundness, as well as sandy soils, and higher EC, pH, potassium, phosphorus, water holding capacity and soil organic carbon. Also, low- elevation dolines have large area, slope, depth, roundness and clay soils, and higher EC, PH, potassium, water holding capacity, organic carbon, and saturation percentage than high elevation dolines. The dolines located in the plunge of the anticline have large area, slope, depth, roundness and clay soils, as well as more EC, PH, potassium, water holding capacity, organic carbon and saturation percentage than the dolines in the central part. The mean of the most morphometric parameters and physicochemical characteristics of the soil in high-slope dolines is higher than in low-slope dolines. Therefore, the morphometric and pedological differences of dolines show that their formation and evolution are more at lower altitudes, plunge and steep slopes. In general, vegetation, elevation, slope and type of precipitation play an important role in morphometric differences and soils in dolines.
