Spatiotemporal Investigation of Soil Salinity Using Geospatial Techniques: A Case Study of Tehsil Toba Tek Singh
2022
Karim, Shahid | Hussain, Ejaz | Khan, Junaid Aziz | Hameed, Abdul | Ougahi, Jamal Hassan | Iqbal, Farhan
Soil salinity, being a major land degradation process in arid and semiarid regions, is spreading globally at a rate of two million hectares per year. Remote sensing data are widely used for detection and mapping of saline areas, hence was the objective of this study. Soil samples were collected from the field and analyzed in laboratory to check the salinity status. Results were interpolated and a salinity map of 2011 was developed. A satellite image of Landsat 5 Thematic Mapper of this area was classified, and a land cover map was developed containing different classes. Saline areas mapped from remote sensing (58.118 square kilometers (km²) and field data (highly saline 61 km²) were compared, which showed 65% similarity between these two methods. The same was applied on Landsat Images of 1992 and 2000 to calculate the change in the saline area over this time. The results showed an increasing trend (from 43.743 km² in 1992 to 58.118 km² in 2011) in saline area. A water table map of this area was generated from water table data and correlation (R²) between soil salinity and water table depth was calculated, which was fairly negative (R² = 0.7273 and R² = 0.6436) in moderately and highly saline categories based on electrical conductivity levels. It was concluded that remote sensing data are helpful only for detection and mapping highly saline areas (having salts on surface) and less suitable to detect where there is even slight vegetation cover.
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