Causes of Water-logging:
(1) Over and Intensive Irrigation: When a policy of intensive irrigation is adopted, then, the maximum irrigable area of a small region is irrigated. This leads to, too much of irrigation, in that region, resulting in heavy percolation and subsequent rise of water table. For this reason, to avoid water-logging, a policy of extensive irrigation (i.e. irrigation spread over wider regions) should supersede the policy of intensive irrigation.
(2) Seepage of Water from the Adjoining High Lands: Water from the adjoining high lands may seep into the sub-soil of the affected land and may raise the water table.
(3) Seepage of Water through the Canals: Water may seep through the beds and sides of the adjoining canals, reservoirs, etc., situated at a higher level than the affected land; resulting in high water table. This seepage is excessive, when soil at the site of canals, reservoirs, etc. is very pervious.
(4) Impervious Obstruction: Water seeping below the soil moves horizontally (i.e. laterally) but may find an impervious obstruction, causing the rise of water table on the upstream side of the obstruction. Similarly, an impervious stratum may occur below the top layers of pervious soils. In such cases, water scoping through the pervious soils will not be able to go deep, and hence, quickly resulting in high water table.
(5) Inadequate Natural Drainage: Soils having less permeable sub-stratum (such as clay) below the top layers of pervious soils, will not be able to drain the water deep into the ground, and hence, resulting in high water level in the affected soil.
(6) Inadequate Surface Drainage: Storm water falling over the land and the excess irrigation water should be removed and should not be allowed to percolate below. If proper drainage is not provided, the water will constantly percolate and will raise the level of the underground reservoir.
(7) Excessive Rains: Excessive rainfall may create temporary water-logging, and in the absence of good drainage, it may lead to continued water-logging.
(8) Submergence due to Floods: If a land continuously remains submerged by floods, water loving plants like grasses, weeds, etc. may grow, which obstruct the natural surface drainage of the soil, and thus, increasing the chances of water-logging.
(9) Irregular or Flat Topography: In steep terrain, the water is drained out quickly. On flat or irregular terrain having depressions, etc., the drainage is very poor. All these factors lead to greater detention of water on the land, causing more percolation and raised watertable.
