1.4 Waterlogging

Water logging

An agricultural land is said to be water logged when its productivity gets affected by high water table. The root zone of plants gets flooded with water and thus become ill aerated affecting productivity.

Problems caused by water logging

· Normal cultivation operation like tilling, ploughing becomes difficult.

· Certain water loving plants like grasses, weeds etc grow profusely in water logged lands thus affecting and interfering growth of crops.

· Water logging also leads to salinity

Causes of water logging

· Over and intensive irrigation – intensive irrigation results in heavy percolation and subsequent rise of water table.

· Seepage of water from adjoining high lands – Water may seep from adjoining high land into subsoil of affected land and may raise water table.

· Impervious obstruction – Due to impervious obstruction water table may rise on upstream side.

· Inadequate natural drainage – less permeable substratum below top levels of pervious soils may not facilitate to drain water deep into ground resulting water logging.

· Inadequate surface drainage- Storm water will constantly percolate and raise the water table if not removed by surface drainage.

· Excessive rains – creates temporary water logging and continues if good drainage facility is not available.

· Submergence due to floods – in flood submerged lands grass; weeds etc will grow obstructing natural drainage of soil increasing chances of water logging.

· Irregular or flat topography – In steep terrain water is drainage drained out quickly while on flat terrain drainage is very poor.

Control of water logging

· Lining of canal and water courses – this is very effective method where water logging is caused due to seepage from canals.

· Reducing intensity of irrigation

· By introducing crop rotation- High water requiring crops should be followed by less or no water requiring crops.

· Optimum use of water – Cultivators have a notion that use of more water increase crop of yield hence tend to use more & more water causing water logging. This can be checked by educating cultivators for optimum use of water.

· Providing intercepting drains – intercepting drains can prevent seeping canal water from reaching area likely to be water logged.

· Providing efficient drainage system – A good drainage system consists of surface drains as well as subsurface drains will drain excess storm water & irrigation water giving freedom from water logging.

· Improving natural drainage of area – To reduce percolation water should not be allowed to stand for longer period. If obstructions in one natural flow are removed and slopes of the drainage lines are maintained, water logging can be avoided.

· Introduction of lift irrigation – lift irrigation utilizes underground water, lowering water table.

· Use of sprinkler method of irrigation – This method effectively reduces percolation through water courses & helps in lowering GWT.