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Mapping and Monitoring Saline and sodic Soil Reclamation in Semi-arid and Arid Environments of India Using Geo-information Tools

Mapping and Monitoring Saline and sodic Soil Reclamation in Semi-arid and Arid Environments of India Using Geo-information Tools

Dr. A.N. Singh
Ex. Director, Remote Sensing Applications Center,  India. 

About 57 per cent of land area in India is reported to be degraded, of which the lands under cultivation are the most degraded, followed by the grazing lands and the forests. Soil salinity and sodicity has degraded 6.73 M ha in the semi-arid and arid climatic regions of the country, significantly affecting its productivity and in several cases turning it completely barren. It is estimated that due to the intensive use of natural resources in view of the population pressure, and climate change effects, these lands may further increase to 16.2 M ha by the year 2050 (ICAR-CSSRI Vision 2050). To counter their further increase, large scale sodic land reclamation has been taken up in the states of Punjab, Haryana, Uttar Pradesh, Rajasthan, and Bihar. In Uttar Pradesh, which has the largest sodic land area, about 0.40 M ha area has been reclaimed under the Uttar Pradesh Sodic Land Reclamation Project. The project, supported through a World Bank loan, was carried out during 1993- 2018 in three phases. An important aspect of the project has been the extensive use of geo-informatics in project planning, implementation, and monitoring which included initially the use of aerial photographs and subsequently the multi-date, multi-sensor, multi-spectral data from Landsat and IRS satellites. A multi-stage remote sensing approach was adopted to cater to the requirement of reclamation programme. While the large reclamation sites in different districts were selected based on the Landsat TM derived map, the field plots for reclamation were selected based on 1:15,000 scale aerial photographs in the first phase, IRS LISS III (23 m) and high-resolution Pan (6 m) merged data in the second phase, and IRS LISS-IV data (multi-spectral, 6m) in the third phase. Land levelling, field bunding, provision of adequate drainage, use of Gypsum as a reclaiming agent, and keeping the land under rice-wheat crop rotation with a green manuring crop in the summer season, were the important components of the reclamation technology. In order to assess the success of reclamation, land use change was monitored after a period of five years using high resolution IRS data. The land use change monitoring at field plot level showed that between 73 to 91% of the severely sodic barren plots had been converted to rice- wheat cropping, indicating that reclamation had a significant positive impact on increasing cropping intensity and long-term sustainability. The increase in average cropping intensity from the pre-reclamation period of 124% to nearly 200% during post-reclamation has led to higher total farm production, helping the small farm holders not only achieve self-sufficiency in the availability of food grains for their family consumption, but also additional income. Environmental impact assessment has been carried out by studying pre- and post- project soil quality, ground water level and its quality, surface water quality, as well as floral and faunal biodiversity. These studies, involving the use of Geographical Information System (GIS), have shown positive improvements in soil quality, floral and faunal biodiversity, whereas no adverse impact was found on the quality of ground and surface water. The project has thus been able to not only achieve food self-sufficiency for the farm families, but has also helped in national food security and environmental sustainability.