water logging

Water losses in Canals: 

Water losses in Canals Evaporation loss : In most of cases evaporation loss is 0.25 to 1 % of the total discharge. The rate of loss of water by the process of evaporation depends up on following factors: Temp. of the region Wind velocity in the region Humidity Area of water surface exposed to the atmosphere. Seepage loss : It is the most significant loss from canals. It depends up on the following factors: Under ground water table conditions Porosity of soil Physical properties of canal water ( Temp., turbidity etc.) Condition of canal system The seepage loss may occur in two characteristics: Absorption: When the under ground water table is at a considerable depth, the water which is entered the soil is unable to join the saturated zone and wets the subsoil locally immediately below the canal bed. The soil layer which is in immediate contact with the channel section is completely saturated due to absorbed water. Thus the extent of saturation goes on decreasing from the ground level. There is no chance of continued and constant flow from the canal to the ground water table reservoir. Percolation When the under ground water table in nearer to the natural surface, the water which has entered the subsoil may join the under ground reservoir to maintain a continuous direct flow. In such conditions water directly flows from the canal to under ground reservoir through the soil pores. Since there is a direct flow this type of loss is more serious than the loss due to evaporation.

Slide 2: 

Water logging:- It may be defined as the soil becomes unproductive and infertile due to the presence of excessive moisture &creation of anaerobic conditions . Causes of water logging:- Inadequate drainage of soil Uncontrolled flood water from the rivers Seepage of water from the canals Irrigation water used in excess Sometimes sub soil does not permit free flow of subsoil water Ill effects of water logging :- Creation of anaerobic conditions in the crop root zone Growth of water logging wild plants Impossibility of tillage operations Accumulation of harmful salts in soil Lowering the temp. of soil

Slide 3: 

Water logging may be a result of both natural and man-made factors. Natural factors may include poor natural drainage as a consequence of unfavorable 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 man made 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; inadequate drainage and poor maintenance of existing drainage systems and outlets

Slide 4: 

Prevention and remedial measures :- Controlling the seepage from the canals By lining the canals By lowering the full supply level of the canal Introducing intercepting drains Preventing the loss of water due to percolation from the field channel Quick disposal of rain water Remedial measures: Installation of lift irrigation system Implementation of drainage schemes

Drainage of soil:- : 

Drainage of soil:- When irrigation canal run , large quantity of water enters the soil layers . After some time soil layer become saturated . It makes the soil water logged . also decease like malaria spread in the region ,drainage of cultivable lands equally essential for humid and arid regions Drains:- drains are the devices both natural and artificial , which remove the surplus water from any particular area. Consequently their functions are diverse . Thus drains are required to:- relieve water logged area Remove flood water Benefits of drainage: Facilitated early ploughing , early sowing Maintains higher soil temperature Proper aeration of upper soil Harmful salt are leached off Improves sanitary conditions

Slide 6: 

Classification of drains :- Artificial drains Natural drains Artificial drains :- These drains are generally constructed to dispose off surplus water quickly before it gets absorbed deep into the soil . Artificial drains are further classified into two types : Surface drains :- which are provided on the surface Sub-surface drains :- which are constructed underground Surface drains and their alignment:- They are open to atmosphere while aligning surface drains following points are given due considerations :- So far as possible drain should follow lowest contour in a valley or a natural drainage line. Alignment should be straight to reduce the length and cost of a drain Alignment should not pass through ponds and marshes Alignment should not cross irrigations canals The drains are designed to carry maximum anticipated flood .

Types of surface drains: 

Types of surface drains Storm water drains : to drain off excess rain water Seepage drains : To collect subsoil water Storm cum seepage drains Subsurface drains: Aim of subsurface drainage is to lower the under ground water table sufficiently below the natural ground level. Relief drains : They relieve the saturated soil of its excess water content. Carrier drains : They carry water from relief drains towards an outfall. Intercepting drains : When the canal carries irrigation water seepage water goes to the adjoining low land. These drains check and collect the seepage flow and finally collected water is taken out of the land. Layout of drains Natural system Herring bone system Grid iron system Double main system Intercepting main system

Slide 8: 

Advantages of tile drainage :- Yield related benefits: Earlier planting Better stand establishment Reduced plant stress, so more vigorous, competitive plants Better ability to compete against weeds Reduction in plant diseases that require saturated soil conditions Reduced soil compaction Improves ability to harvest in adverse conditions Better utilization of water (a wheat crop that yields 10bu/A more uses 3 inches more water

Slide 9: 

Reduced cost related benefits: Reduced wear and tear on equipment – not operating in the mud Less power required for field operations (tillage equipment pulls easier and tractor slippage is reduced) More predictable, consistent yields allow more efficient use of resources (you are more likely to hit your yield targets, so you can plan inputs accordingly) Other benefits: Reduced weather risk reduces stress to the farmer – you can sleep better A more stable production system provides more potential to produce higher value crops More stable yields enhance the ability to contract and forward pric Economics of Tile Drainage Investment 1) Drainage is installed on the entire 500 acres 2) The life of investment is 15 years 3) Production is continuous wheat (not a rotation) 4) Wheat yield increases (and selling price) are assumed to be constant over the investment period 5) Returns are calculated before taxes 6) No additional expenses or benefits (due to drainage) are considered—in reality, there

Slide 10: 

Maintenance of tile drains:- it involves cleaning of the drain section .this can be done through the vertical holes which are sunk from ground level up to the drain. The holes are sunk at 75 m spacing approximately. A strong bag filled with straw and fastened at both ends by puller ropes is used for cleaning . The ropes can pass through the vertical holes and the straw cleaner can be operated to push all the silt deposits towards the holes . Here it is bailed out . Specially prepared flexible sewer rods give most satisfactory results .