Agriculture:- Model Bankable Projects in India | Minor Irrigation : Small Lift Irrigation Schemes --- www.nabard.org

Agriculture:- Model Bankable Projects in India | Minor Irrigation : Small Lift Irrigation Schemes --- www.nabard.org

Small Lifts

Small Lift Irrigation Schemes - Guidelines

1.0. Introduction For small river lift irrigation schemes whose culturable command varies between 10 and 40 ha and which do not require conventional civil works like intake well, intake pipe, jack well, pump house, etc., the following guidelines are prepared which would facilitate in designing as well as appraisal of such schemes. These guidelines are only indicative and could be modified to suit the local conditions. 2.0. Size and Location The culturable command area should be restricted up to 40 ha only under small lift irrigation schemes. Lift irrigation schemes on surface water source with command area more than 40 ha may be considered as medium / large schemes and the technical and financial appraisal may be carried as per the guidelines pertaining to lift irrigation schemes. The scheme area should be as close to source of water as possible and land holdings are contiguous as far as possible from design optimisation point of view. 3.0. Water Availability It is necessary to ascertain the availability position of water from sources like river, canal, ponds, tanks or any other surface water body. It should preferably be perennial in nature and should have adequate flow to support the quantity of water to be pumped for the proposed scheme. 4.0. Design Discharge The design discharge for small lift irrigation scheme should be assessed based on peak water requirements for envisaged cropping pattern and area of crops during kharif, rabi and summer seasons based on usual norms. 5.0. Water Lifting Permission Water lifting permission should be obtained on the usual lines indicating the period, area and percentage of different crops in each season. It should be issued by the competent State Government Authority which is authorised to issue such permission. Long duration water lifting permission to cover loan repayment period is required to assure uninterrupted water supply. 6.0. Soil Characteristics As a part of appraisal, the soil characteristic is to be studied for considering its suitability for various crops proposed in the scheme. 7.0. Command Area / Cropping Pattern The command area of each small lift irrigation scheme should not exceed 40 ha and the cropping pattern adopted in the scheme should be duly approved by State Agriculture Department / Zila Parishad as the same mandatorily adopted and invariably mentioned in the water lifting permission issued by the competent authority. 8.0. Power Normally the power availability for large schemes is considered to be 16 hours per day but in case of small lift irrigation scheme up to 40 ha command area, power availability may be considered at maximum of 12 hours. If the command area is less than 10 ha then 8 hours of power supply can be considered on economic considerations. 9.0. Intake Well This is a civil structure required for guiding the water in the sump well / jack well. In some cases, this structure is necessary even for small schemes to take care of water level fluctuations in the river. It also provides silt free water for the pumping operations. However, for small lift schemes, this need not be insisted upon. 10.0. Intake Pipe This structure is not necessary for small schemes. 11.0. Jack Well and Pump House This is also not necessary. 12.0. Groundwater based small lift irrigation schemes If the lift irrigation scheme is proposed on the sub surface flow in a given alluvial formation then the intake well has to be designed as per the design criteria adopted for a dug well determined on the basis of aquifer characteristics. If the source of water is an existing irrigation well, the well discharge and command area to be adopted under small lift irrigation scheme could be similar to one that is as usually considered under a dugwell scheme. For schemes, contemplating well discharge of more than 6 lps in hard rock and 10 lps in alluvial areas, the availability of groundwater from such dugwells has to be ascertained from local groundwater department including stiputaltions of spacing criteria and clearance of scheme based on categorization of blocks/watersheds etc..

13.0. Suction Pipes for Pumpset   The following table may be followed in determining the diameter of suction and delivery pipes for various discharge ranges:

Discharge (lps) Diameter of Suction pipe (mm) 5 65 10 80 15 100 20 125 30 150 50 200 100 300

14.0. Rising Main Rising main should be designed based on discharge and total pumping head. It is expected that the total pumping head in normal cases will not exceed 50m. The total length of the rising main should not exceed 3000m. The diameter of rising main recommended for RCC pipes and Rigid PVC pipes for various discharges are given below: (a) RCC Pipes

Discharge (lps) Dia (mm) Discharge (lps)* Dia (mm) 5 100 55 300 10 150 60 300 15 200 65 300 20 200 70 300 25 225 75 300 30 225 80 300 35 250 85 350 40 250 90 350 45 250 95 350 50 250 100 350

*(lps = litre per second) (b) Rigid PVC Pipes

Discharge (lps) Dia (mm) Discharge (lps) Dia (mm) 5 90 45 225 10 125 50 250 15 150 55 250 20 150 60 250 25 200 65 250 30 200 70 300 35 200 75 300 40 225 80 300

If direct tapping on the rising main is proposed for drawing partial discharge then such tapping should not exceed 2 numbers. Water hammer control devices in case of large schemes are necessary but in case of small lift irrigation schemes, it may not be required. However, the accessories like air valve, drain valve may be provided as per the topographic conditions. Apart from the PVC and RCC pipes, HDPE and AC pipes of equivalent class and diameter can also be allowed. Cast Iron (CI) and Mild Seel (MS) pipes are not recommended except for road crossing and nala crossing. 15.0. Pumping Machinery Most of the small lift irrigation schemes require centrifugal pumpsets for pumping surface water / groundwater. In case the fluctuations between low water level and high flood level is less than 4.5 m, then the pumpets can be placed in the pump house subject to suitability of site conditions. If the pumpsets are to be operated with shifting arrangements then it should not exceed 20 HP per unit. The permanent pump house can be provided if the water level in the river is more or less constant throughout the year. This may vary from site to site depending upon the stream hydrology. The centrifugal pumpsets selected should conform to BIS standard i.e., IS:10804-94 for Complete Pumping System. The usual formulae that may be applied for calculating the horse power of the centrifugal pumpsets and discharge required to be pumped are given as under: (a) Break Horse Power BHP = (Q x H) / (75 x e) Where, BHP = Break Horse Power of the Centrifugal Pumpset Q = Discharge in litres per second H = Total Head in meters (including friction losses) e = Overall efficiency of Pumpset (as percentage) (b) Discharge required to be pumped: The discharge required for the envisaged command area may be calculated from the following formula: Qr = (28 x A x I ) / (R x t) Where, Qr = Required discharge in litres per second (lps) A = Crop area in ha I = Depth of irrigation in cm R = Rotation period in days t = Working hours per day The discharge required to be pumped during different crop seasons can be calculated for kharif, rabi and summer seasons and the peak discharge i.e., maximum discharge should be adopted as the required discharge (Qr). 16.0. Number of Stages From the management point of view, the number of stages should not exceed two. 17.0. Delivery Chambers The delivery chamber of one minute retention capacity can be provided for release of water in the command area. 18.0. Distribution System Generally a chak size of 8 ha may be considered while designing the distribution system. If scheme economics does not permit use of underground pipes then open channels can be provided. For schemes up to 8 ha. command area only open channels need be provided. 19.0. Project cost The project cost of the scheme should be based on the schedule of rates prevailing in the area. 20.0. Technical appraisal by financing banks The financing banks should carry out the technical appraisal for all schemes. The details on the technical appraisal should be furnished to NABARD in the format shown in Annexure I. The technical appraisal should include the comment on the reasonableness of the cost of pipes, excavation of trenches, laying pipe lines and availability of power for operating the scheme. A map of the command area showing layout drawing of civil works should be attached to the scheme along with a longitudinal section(L Section) for rising main indicating the Low Water Level (LWL), High Flood Level (HFL) position of fixed foundations, pumpset, etc. Number of small lift points in the same area having similar topography could be clubbed as one scheme. The civil works in small lift irrigation scheme generally involve a pumpset and pipeline, hence instead of detailed project report, a proforma information for lift irrigation scheme could be considered which is given in Annexure I.