Water logging is one of the major problems of land degradation in India. Unscientific management of soil, water and crops in irrigated lands and obstruction of natural drainage systems by various developmental activities are the main factors responsible for disrupting the balance of inflow and outflow of water, leading to water logging. While irrigation has increased by leaps and bounds, its attendant problem of water logging is now plaguing substantial area of agricultural lands.
An irrigated area is said to be waterlogged when the surplus water stagnates due to poor drainage or when the shallow water table rises to an extent that soil pores in the root zone of a crop become saturated, resulting in restriction of the normal circulation of the air, decline in the level of oxygen and increase in the level of carbon dioxide. The actual depth of water table, when it starts affecting the yield of the crops adversely, may vary over a wide range from zero for rice to about 1.5 meters for other crops. A Working Group constituted by the Ministry of Water Resources to identify the problem areas affected by water logging/ salinity/ alkalinity in existing irrigation projects in the country and to suggest suitable remedial measures for their reclamation adopted in 1991 the following norms for identification of waterlogged areas:
|Water logged Areas |
(Due to rise in water Table)
|Water table within 2 meters of the land surface|
|Potential Areas for water-logging||Water table between 2 to 3 meters below land surface|
|Safe Areas||Water table below 3 meters of land surface|
Some States, however, have adopted different norms for defining waterlogged areas in their States according to their own conditions and perceptions.
Causes of Water Logging
Water logging may be a result of both natural and man-made factors. Natural factors may include poor natural drainage as a consequence of unfavourable sub-soil geology like existence of hardpan at shallow depths; spilling of rivers resulting in submergence of agricultural lands; heavy storm rainfall coupled with poor natural drainage etc. Water-logging is, however, caused mainly because of manmade factors like deforestation and poor upkeep of watersheds; developmental activities such as construction of roads, bridges, railway lines and buildings resulting in choking of natural drainage; hydraulic pressure of water from upper irrigated areas resulting in seepage outcrop in low lying areas; introduction of irrigation without taking into account characteristics of soils and sub-soils for their irritability; seepage from canals, distributaries and watercourses; excess application of irrigation water particularly in the initial years when the command is not fully developed; poor “On Farm Water Management” resulting in poor water-application efficiencies; unrealistic cropping patterns tilted in favour of water intensive crops; lack of night irrigation in some commands; inadequate drainage and poor maintenance of existing drainage systems and outlets; lack of conjunctive use of surface and ground water etc.