Delineation and Characterization of Waterlogged Salt Affected Soils in IGNP Using Remote Sensing and GIS

The India Remote Sensing data on 1:50,000 scale revealed the occurrence of permanent waterlogging in low-lying flats and depressions of the Indira Gandhi Nahar Pariyojona (IGNP) command area. Such data also indicated seasonal dynamics of waterlogging and soil salinization (Salt efflorescence/crusting) in irrigated areas. Mixed spectral signatures of high moisture content and poor crop stand indicated the presence of shallow aquifers close to the main canal. Digital analysis facilitated some indicators for segregating such land uses, limited to optical range. Ground truth study found patchy crop stand, moist soil profile and subsurface soil salinization indicating the presence of high water table (<1.5 m). It also found fluctuating (1.5–6.0 m) water table with poor vegetative growth indicating areas sensitive to waterlogging These were classified as potential waterlogging. Moderate to high soil salinity was found at surface and at the control section (0.2–0.8 m) of soil profiles indicating initiation of secondary salinization. Coarse to medium soil texture facilitated capillary rise of salts with the advancing water table in irrigated zone. The presence of fine textured and impermeable calcium carbonate layers at a depth below the surface enhanced waterlogging and rise of water table. The preponderance of chlorides and sulfates of sodium, calcium and magnesium was found in the salinized areas. The quality of ponded water was extremely poor and unfit for its reuse. The ground water was saline in some areas but normally lies within the prescribed limit. The quality of drainage water was poor in saline depression and unsuitable for reuse. These were moderate in other areas suggesting its safe reuse if mixed with good quality water. Suitable soil and water management practices are necessary for sustainable crop production in the irrigated areas