Distribution
Of these two issues, distribution is the most complex, for several reasons. First, whereas the system for collecting water at the main delivery chamber makes use of pumps, the distribution system is typically completely gravity-based, and have to be designed solely on the basis of the available hydraulic head. In addition, the area to be irrigated is scattered and has varying topography, and each farm is of a different size, so it can be a challenge to design a gravity-based system that allots each farmer a fair amount of water. Several mechanisms have been developed to meet these challenges.
In the most prevalent system. system, the area under irrigation is divided into different blocks according to typography determined by contour plan. The water requirement for each block is determined, and pipe lines are designed for these blocks depending on the available head and required discharge. Field delivery chambers are then constructed on the distribution pipe lines, and valves are fitted to control the flow of the pipe lines, with flow from the main delivery chamber controlled by these valves. In this system, lines for lower fields have more discharge, because the force of gravity is greater, so water distribution can be unequal.
In other systems, the area is divided into three or four equal parts, and each part is given the entire discharge for one day. This means each part gets rotation of the full design discharge on the fourth or fifth day. Again, however, water distribution can be unequal, and alternate methods of distribution have been proposed to deal with this problem.
EQUAL AND PROPORTIONATE DISTRIBUTION This ia invented and developed Nashik by Yashpal Morey, agricultural Engineer. It is a system having principle of equal and/or proportionate distribution. The salient features of this system are: Every farmer gets precisely equal or proportionate water at the same time. For example, if the discharge of the scheme is 100 LPS and 20 members in the scheme, every farmer precisely gets 5 LPS discharge as long as the pump is running. OR Every farmers gets precisely proportionate water to his area under irrigation and investment, at the same time. If the scheme is on the basis of area, and if a farmer has invested for two hectare area, he will precisely get double the water of the farmer investing for one hectare. A farmer investing for six hectare will get three times as much water; and so on. As long as the pump is running, all the farmers will get PROPORTIONATE discharge. There is no scheduling or time table such as so many hours or so many days in a week for farmers or their groups. As per the availability of electricity, as long as the pump is running, all the farmers will get EQUAL or PROPORTIONATE discharge. No need of control valves: Control valves are NOT needed in this system. The problems of malfunctioning of valves and unauthorized operating of the same do not arise. The cost of the valves also saved. The dependability or reliability of the scheme is increased among the farmers. No need of an operator: Since there are no valves, valve operator is not needed, thereby saving the expenses for the same. As the total discharge is delivered at a time, distribution pipe diameter required is less with saving in the cost of the distribution system. Since equal or proportionate distribution is foolproof, certain and doubtless; farmers willingly and happily share the capital expenses (loan and investment) and recurring expenses in that proportion. The repayment of the loan is in time and recurring expenses like electric bill, water charges, maintenance cost are shared in time. The principle used in this system is very simple and commonly observed. ‘Water maintains its level in a closed container’ is that principle. In main delivery chamber, pipes are fitted at precisely on the same level. The number of pipes depends on the number of farmers or groups. The pipes deliver water in to a distribution tray. They are grouped for further conveyance through a common pipe line. At the further delivery point, the same type of field distribution chamber is constructed, and so on. While designing new schemes, we give water on the basis of units rather than based on crop and area to be irrigated. We therefore decide a unit of water and farmer decides how many units he wants, and shares capital and recurring expenses accordingly. He has then freedom to take any crop and to irrigate any amount of area by using water saving techniques like micro irrigation and mulching etc.
Applications For the new irrigation schemes For the rehabilitation of the schemes which are closed up due to improper distribution, thereby reutilizing the vast amount of funds blocked in these schemes. Applicable to any size of scheme from two farmers to thousands of farmers or from a few hectares to thousands of hectares.
Application to canal distribution system
This type of distribution system is applicable for distribution from canals also. From all the dams, irrigation water is distributed through canals and distributaries. There are many water distribution co-op. societies on these canals. Since the key point in equal and proportionate distribution is the delivery chamber, it can be used in canal systems also with equal effect. The farmers at the tail point will also get their share of water without any doubt. And all the benefits described above can be reaped by the member farmers. We have successfully implemented many small and large LIS in this way. The satisfaction level of the beneficiary farmers is very high.
Comparative chart Conventional System Equal and Proportionate System Water is distributed in unequal quantity, either more or less than design, depending on the available gravity and diameter of the pipe line Every farmer gets PRECISELY equal or proportionate water at the same time Valves are needed. There arise differences on operation of valves. Expenses for valves, their operation and maintenance are additional Valves are not needed. Expenses towards the same are saved. There is no question of differences There is scheduling or time table for distribution. This time table is disturbed when the pumps do not run due to power failure or maintenance. There is no scheduling or time table. All farmers get their precise share of water as long as the pumps are running The cost of the scheme is comparatively more The cost of the scheme is comparatively less The share of investment is not equal or proportionate. Individual loan account cannot be maintained. Insincerity towards loan repayment increases The share of investment is equal or proportionate. Individual loan account can be maintained. Loan repayment is proper and in time Planning is based on area or crop which leads to complications. Planning based on UNITS of water. The farmer has freedom to take any crop and irrigate any amount of area
Read more about this topic: Lift Irrigation
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