Waterlogging and Salinisation
About half the proposed command area of the SSP is prone to waterlogging and salinisation. A preliminary study called "Regionalisation of Narmada Command" (ORG 1982) divided the command area of the SSP into 13 agroclimatic zones, and classified them into irrigability classes as shown in Map 3. The Soil Survey Manual of the Indian Agricultural Research Institute recognizes six irrigability classes:
However, the ORG (1982) report used somewhat different nomenclature. Class II areas are called "suitable for rice", Class IV areas are called Class IVA ("partly suitable for rice"), Class VI areas are called Class IVB ("partly unsuitable for rice"), and Class V areas are called "unclassified". The inventiveness of calling an area that is marginal for irrigation as "partly suitable for rice" is impressive!
It is clear that areas classified as Class III are moderately prone to waterlogging, whereas Class IV-VI have severe waterlogging problems under sustained irrigation. It is possible to calculate the areas under different irrigability classifications from Map 3. The results are shown in Table 7 and 8.
Less than half the command area can be called "suitable" for irrigation. 25.61% of the command area has severe limitations for sustained irrigation (Class III), and 26.5% of the command area is not suitable for sustained irrigation at all. In other words, 52% of the command area faces high to very high probability of waterlogging and salinisation if the SSP is completed. (It should be reemphasized here that the preliminary land classification done by ORG (1982) is for the gross command area, and not the culturable command area.)