Here is an essay on ‘Water Logging’ for class 9, 10, 11 and 12. Find paragraphs, long and short essays on ‘Water Logging’ especially written for school and college students.
Essay # 1. Introduction and the Effects of Water Logging:
An agricultural land is said to be water-logged, when its productivity gets affected by the high water table. The productivity of land in fact, gets affected when the root zone of the plants gets flooded with water, and thus become ill aerated. Inadequate aeration reduces crop yield.
Effect of Water Logging:
(a) Hampering the Nitrification:
The life of a plant, in fact, depends upon the nutrients like nitrates, and the form in which the nitrates are consumed by the plants is produced by the bacteria, under a process called nitrification. These bacteria need oxygen for their survival. The supply of oxygen gets cutoff when the land becomes ill aerated, resulting in the death of these bacteria, and fall in the production of plant’s food (i.e., nitrates) and consequent reduction in the plant growth, which reduces the crop yield. Apart from ill aeration of the plants, water logging creates many other problems.
(b) Delayed Cultural Practices:
The normal cultivation operations, such as tilling, ploughing, etc., cannot be easily carried out in wet soils. In extreme cases, the free water may rise above the surface of the land, making the cultivation operations impossible. In ordinary language, such a land is called a swampy land. In general, this leads to excessive delay in cultural practices and delayed sowing of crop, less or very poor yield.
(c) Overgrowth of Weeds:
Certain water loving plants like grasses, weeds, etc., grow profusely and luxuriantly in waterlogged lands, thus affecting and interfering with the growth of the crops.
(d) A Major Cause of Salinity:
With the rise of the water table, the plant roots happen to come within the capillary fringe, and water get continuously evaporated by capillarity. Thus, a continuous upward flow of water from the water table to the land-surface gets established. Due to this upward flow of water, the salts, present in the water, also rise towards the surface, resulting in the deposition of salts in the root zone of the crops.
The concentration of these alkali salts in the root zone of the crops has a corroding effect on the roots, which reduces the osmotic activity of the plants and checks the plant growth. The plant ultimately fades away. Such soils are called saline soils. Thus, water logging ultimately leads to salinity, resulting into reduced crop yield. Salinity and water logging are treated as a twin problem as salinity and water logging occurs together. Water logging is followed by salinity.
Essay # 2. Causes of Water Logging:
Basically, water logging is the rise of water table unto root zone level leading to various problem to crop growth.
This may occur due to the following reasons:
(a) Over and Intensive Irrigation:
Under the practice of intensive irrigation, the maximum irritable 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. ‘This can be overcome by a policy of extensive irrigation, i.e., irrigation spread over wider regions. Thus, to avoid water logging extensive irrigation should supersede the policy of intensive irrigation.
(b) Seepage of Water from Nearby Areas:
Water from the adjoining high lands may seep into the sub-soil of the affected land and may raise the water table. This occurs generally when land surface is not flat and adjoining area is moisture rich.
(c) Seepage of Water through the Canals/Reservoirs:
This is major cause of water logging in canal command areas. This has reached an arming stage in many areas. Water may seep through the beds and sides of the adjoining canals, reservoirs, situated at a higher level than the affected land. This results into high water table in the affected area. This seepage is many a times excessive particularly when soil at the site of canals and reservoirs is very pervious.
(d) Encounter of Impervious Obstruction:
We know that water seeping below the soil moves horizontally or laterally. This may encounter an impervious obstruction, causing the rise of water table on the upstream side of the obstruction. This may lead to water logging. Similarly, in certain cases it is possible that an impervious stratum may occur below the top layers of pervious soils. In this case also, water seeping through the pervious soils will not be able to go deep, and hence, quickly results in high water table rise.
(e) Lack of Natural Drainage System:
If sufficient availability of natural drainage is not there in form of slope, soils having less permeable sub-stratum such as clay lying below the top layers of pervious soils, will not be able to drain the water deep into the ground. This may lead to rise in water level to the extent that it can affect the root zone and the crop cultivation.
(f) Inadequate Surface Drainage:
Surface drainage system is common passage way for run off water. It becomes necessary to ensure that storm water falling over the land and the excess irrigation water should be removed from the area. It should not be allowed to percolate below. In absence of proper surface drainage, the water will constantly percolate and will raise the level of the water table leading to water logging.
(g) Excessively High Rain Fall:
This is common source water logging is cities. Even in farm land heavy down pouring may cause water logging. However, excessive rainfall may create temporary water logging, but in the absence of good drainage, it may lead to continued water logging over the area.
(h) Overgrowth of Weeds and Aquatic Plant:
During rainy seasons weeds and grasses grow excessively obstructing the passage of water in natural waterways. If a land is continuously submerged by floods, aquatic plants like hyacinths, grasses and weed may grow. They may obstruct the natural surface drainage of the soil, and thus, increasing the chances of water logging.
(i) Irregular or Flat Topography:
Topography also affects natural drainage and thus lead to water logging. In steep terrain, the water is drained out quickly. On flat or irregular terrain having depressions, the drainage is very poor. These factors lead to greater detention of water on the land, causing more percolation and water logging, if infiltration of soil is not proper.
Essay # 3. Control Measures of Water Logging:
It is evident that water logging can be controlled only if the passage and quantity of water into the sub soil below the surface is controlled and reduced. For this first of all, the inflow of water into the underground reservoir should be reduced and the outflow from this reservoir should be increased simultaneously. It is necessary to keep the highest position of water-table at least about 3 m below the ground surface.
The various measures adopted for controlling water logging are given below:
(а) Lining of Canals and Water Courses:
Control measures must try to check the causes of water logging. As seepage is one of the main culprits of rise of water table, attempts should be made to reduce the seepage of water from the canals and watercourses. This can be achieved by lining them. It is a very effective method of controlling water logging.
(b) Reduced Intensity of Irrigation:
The areas where there is a possibility of water logging, intensity of irrigation should be reduced. Efficient water supply should be ensured. Only a specific portion of irritable land should receive canal water in one particular season.
The remaining areas can receive water in the next season, by rotation. This can be achieved by crop rotation. This would help controlling water logging in the region.
Crop rotation is also an effective means of controlling water supply to sub surface zone. As certain crops require more water and others require less water. If a field is always sown with a crop requiring more water, the chances of water logging are more. In order to avoid this, a high water requiring crop should be followed by one requiring less water. We may choose next crop one requiring almost no water. For example, rice may be followed by wheat and a dry crop such as cotton may follow wheat. This will ensure break in continuous excess irrigation.
(c) Optimum Use of Water:
Excess of anything is harmful. We know that only a certain fixed amount of irrigation water is required for best productivity. Any major deviation k reduces the yield and empties the pocket of the farmer. But there is ignorance in some areas that using more water can increase crop yield.
This happens more in the areas where water charges are less or where there is uncertain supply of canal water and electricity in case of tube well irrigation. Educating the farmers by proper extension method can bring improvement. As a policy matter, the revenue should not be charged on the basis of irrigated area but should be charged on the basis of the quantity of water utilized.
(d) Intercepting Drains:
These drains are to check the canal water seepage. Intercepting drains along the canals should be constructed, wherever necessary. They would help intercepting seepage water and prevent the water from reaching the area and thus water logging may be prevented.
(e) Improved Natural Drainage:
The worn out natural drainage systems in the cropped area should be revived. This would reduce the percolation by, not allowing water to stand for a longer period. At community level, some relief in this direction can be obtained by removing the obstructions from the path of natural flow. This can be achieved by removing bushes and other obstructions and improving the slopes of the natural drainage lines.
(f) Efficient Drainage System:
An efficient drainage system should be provided in order to drain away the storm water and the excess irrigation water. A good drainage system consists of surface drains as well as sub-surface drains.
(g) Consumptive Use of Surface and Subsurface Water:
Conjunctive use is a combined use of sub-surface water or ground water and the surface water or canal water in a judicious manner to derive maximum benefits. The introduction of lift irrigation to utilize ground water helps in lowering the water table in a canal irrigated area, where water table tends to go up.
This system ensures use of the ground water in conjunction with canal water for irrigation. The continuous use of ground water will not allow any appreciable rise in the level of water table, even due to continuous seepage of canal water. Thus, consumptive use should be adopted to control water logging.