Spatiotemporal Investigation of Soil Salinity Using Geospatial Techniques: A Case Study of Tehsil Toba Tek Singh

ABSTRACT

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.

KEYWORDS:

• GIS
• image analysis
• mapping
• remote sensing
• soil salinity

Acknowledgments

We acknowledge the following Institutions and individuals for financial and logistics support and providing free data for this research:

1. National University of Sciences and Technology (NUST), H-12, Islamabad (Financial Support in the form of bill payments to conduct field survey for collection of soil samples and laboratory analysis of these samples).

2. International Water Logging and Salinity Research Institute (IWASRI), Lahore (Provision of free data of saline areas in the study area in vector format).

3. International Water Management Institute (IWMI), Lahore (Provision of free data of saline areas in the study area in ssssvector format).

4. District Soil and Fertility Laboratory, Toba Tek Singh (Provision of laboratory facility to check EC and pH in soil samples).

5. Soil Survey of Pakistan Lahore Office (Provision of free data of saline areas in the study area in Raster format).

6. Mr Rauf Sabiq, Masood Tahir Hameed and Dr Abid Hussain, Toba Tek Singh (Provision of logistic support, help in collection of soil samples and preparation of sample results report).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

Authors did not receive any funding grant for this study. National University of Sciences and Technology (NUST) partially supported for field survey, collection of soil samples and payment of bills of laboratory analysis.