Most of the canals run in open surface in irrigation engineering. There will be many losses of water while transmitting in the canal. There may be a loss from seepage to the subsoil and intensity of seepage depends to the type of subsoil of the canal. There will be loss due to evaporation occured by the temparature in the atmosphere which may varie from region to regio where the irrigation canal is running. The seepage water from the irrigation canal first fills the pores of the soil around the canal, but subsequentlu the loss is balanced partly by the evaporation and transpiration of seepage water which reemerges at the ground surfave by capillary action. The absorption loss is more when canal is in deep cutting reach. The seepage losses will be more in initial discharges of water in to canal but gradually reduces as a impervious layer is formed by the deposits of fine silt. There will be perculation losses in some zones where subsoil has reached the saturation. The seepage losses due to perculation will be high compared to normal absorption of water in canal sub surface. These losses in irrigation canal due to perculation is possible mostly in those zones of canal where the ground water table is well below the sub surface of the canal. There may be loss of water in irrigation canals due to transpiration which occurs through vegetation and weeds along canal bed. But these losses due to transpiration are negligible compared to other losses. To avoid these transpiration losses in irrigation canals the canal surface need to be clear from vegetation and weeds.
No Comments | Tagged : canal, irrigation | read more...In major irrigation projects, the main canals are generally aligned as contour canals to give the benefits to the maximum extent possible. These contour canals have to necessary to cross number of ridges and valleys depending upon magnitude of the project. In general, it is noticed that canal alignments are finalized following the shorter routes available to minimize the ultimate length of canal. This would naturally result in the crossing of the canal over major ridges by means of deep cut flumes or tunnels and the negotiation of major valleys by means of level crossings, very high aqueducts or pressure aqueducts. Generally the authorities are hesitant to adopt detour alignments.
No Comments | Tagged : alignment, canal, irrigation, tunnel | read more...Irrigation is defined as the artificial application of water to arid land for growing crops. It is a profession as well as a science. A crop requires certain amount of water at certain fixed intervals throughout its period of growth. Irrigation is not required if this requirement is met with from sufficient rainfall as in England. In tropical countries like India the first two or three essential requirements of plant growth, that is, heat and light are available in abundance, but the third, that is, moisture needs to be supplemented frequently by artificial application of water. Thus, irrigation is supplementary to rainfall when it is either deficient or comes irregularly or at unreasonable times.
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