The design of a low-lift irrigation pump pilot project: improving the availability of affordable pumpsets to african farmers

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HIPPO InfoService

vanthof1998a

Feb 9, 2003

Van 't Hof, S. (1998) The design of a low-lift irrigation pump pilot project: improving the availability of affordable pumpsets to african farmers . Atelier sur le transfert de technologies en irrigation en support à la sécurité alimentaire, Ouagadougou, 30/11 au 4/12/1998 vanthof1998a.pdf, 223k

Abstract: In 1998, the HIPPO Foundation carried out a desk study of about 20 low-lift pumpsets, mostly of Asian origin, for which information had been collected from 1994 to 1997. The aim was to identify a small number of pumpsets for field-testing under the conditions along the Niger River near Timbuktu, Mali. Only commercially available, industrial products were considered. Most of the pumps were of the mixed-flow, volute type and powered by 8-15 hp diesel engines. Some centrifugal and axial-flow pumps were also included. It was demonstrated that as a result of improved overall water-lifting efficiency and Asian provenance it may be possible to reduce specific pumping costs of a total water volume of 15.000 m3/ha/season for the production of wet rice from the current level of 250 to 300 US$ to about 120 US$/ha/season. Specific costs included: fuel cost, interest cost (10%), repair and maintenance cost (10% of initial system cost) and depreciation. The following subjects were dealt with: design principles, selection criteria, preselection of equipment, comparison with existing equipment and the proposed testing programme. Recommendations for improving the economic, financial, social and mechanical sustainability of introduced pumpsets and the about 250 village irrigation schemes in the region of Timbuktu that depend on these pumpsets, were formulated. The establishment of a small local pump rental organization (GIE Hari Goumo & Machines Agricoles) is suggested.

Contact: HIPPO Foundation, De Verwondering 27, 3823HA Amersfoort, the Netherlands, e-mail [email protected], www.hipponet.nl

Key words: irrigation equipment, mechanical engineering, efficiency, costs, pumps, diesel engines, irrigation schemes, small farms

Mots clés: matériel d'irrigation, génie mécanique, consommation d'énergie, rendement, cout, pompe, moteur diesel, périmètre irrigué, petite exploitation Annotation1: (S. van ’t Hof, [email protected]) This document of mid-1998 explains how cost and energy efficiency of community-based irrigation schemes in the region of Timbuktu, Mali, and elsewhere in the northen Sahel could be improved. New information on Asian pumps and engines has been gathered since that time. The HIPPO Foundation hopes to finalize its main database in the course of 2003, after which this article could be updated. Test results of some of the new equipment mentioned in table 6 have been gathered over the past few years. Some of these results have been published by the HIPPO Foundation.

1 The annotation serves to highlight aspects that are related to the mission or work of the HIPPO Foundation (http://www.hipponet.nl/mission).

Design of a low-lift irrigation pump pilot project

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The design of a low-lift irrigation pump pilot project: improving the availability of affordable pump-sets to African farmers2

Sjon van 't Hof3, 1998 Résumé [Etude d’un projet pilote d’irrigation par pompage à basse pression: amélioration de la disponibilité de groupes motopompe à prix abordables aux paysans africains] Les résultats d’une étude d’environ 20 groupes motopompe (GMPs) à basse pression, la plupart d’origine asiatique, sont présentés. Cette étude avait comme but d’identifier un nombre restreint de GMPs pour tester sous des conditions pratiques le long du cours moyen du fleuve Niger près de Tombouctou, Mali. Seulement des produits industriels ont été considérés. La plupart des pompes est du type hélico-centrifuge, monocellulaire et actionnée par des moteurs à gasoil de 8-15 cv. Quelques pompes centrifuges et axiales ont été considérées également. Il est montré qu’il est possible de doubler le rendement global de GMPs à basse pression sous des conditions de pompage à hauteurs géométriques de 1 à 4 mètres. La forte amélioration de rendement et la provenance d’Asie pourraient permettre de réduire les coûts spécifiques de pompage pour 15.000 m3/ha/saison (riz dressé) du niveau actuel de 250 à 300 US$ à un niveau d’environ 120 US$. Dans les coûts spécifiques sont comprises: coût de carburant, frais d’intérêt (10%), frais de réparation et d’entretien, et amortissement. Les sujets suivants ont été discuté: principes de conception, critères de sélection, présélection de l’équipement, comparaison avec équipement existant et propositions concrètes pour une programme de test. Des recommandations pour améliorer la durabilité économique, financière, sociale et mécanique des GMPs et des 250 périmètres irrigués villageois dans la Région de Tombouctou à travers une structure de location de GMPs locale (GIE Hari Goumo & Machines Agricoles) sont inclues.

1. Introduction Since the mid-1970s the drought-affected region of Timbuktu, Mali, has been the scene of many efforts of development agencies to develop community-based irrigation (CBI), more or less in the image of CBI along the middle course of the Senegal River. Each of these agencies introduced its own choice of pumpsets. Equipment selection was always based on the least favorable pumping conditions. In practice, most pumpsets operated under much more favourable conditions, for which they were not designed. It was found that for static heads in the 1-4 meter range, overall water-lifting efficiencies (OWEs) were 20-25% only. Most of these inefficient pumpsets were procured from Europe, where equipment prices are very high compared to those in Asia, the region where most of the world’s output of irrigation pumps is produced. It is the purpose of this paper to describe how high-efficiency, low-cost irrigation equipment of Asian origin could be identified and tested for possible subsequent introduction in Africa. The rationale for a rather narrow pumpset-oriented development programme can be described as follows: (1) regional cereal self-sufficiency has been in the order of 40% for decades, leading to serious nutrition and poverty problems; (2) one cannot expect any grain market policy to redress this problem; (3) most of the village irrigation development programmes of

2 Presented at the Atelier sur le transfert de technologies en irrigation en support à la sécurité alimentaire, Ouagadougou, 30/11 au 4/12/1998. 3 De Verwondering 27, 3823HA Amersfoort, the Netherlands, e-mail [email protected], www.hipponet.nl.


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the 1980s and early 1990s were effective in achieving cereal self-sufficiency at a village level; and (4) farmers have demonstrated adequate technical ability in spontaneously creating irrigation schemes themselves once they have irrigation pumps. Improving the availability of affordable pumpsets is expected to kickstart autonomous, self-financing village irrigation development. In addition, a low-lift irrigation pump testing project may contribute to improving the availbility of more appropriate equipment in other parts of West-Africa. For reasons of inherent energy-efficiency low-lift pumping in Africa should receive more attention if irrigation development is really a top-priority.

2. Pumping Conditions

2.1 The Niger River

The Niger River is the largest river of West Africa. It has an annual discharge of about 30,000 million m3. From Koulikoro, near Bamako, the river bed is fairly free from impediments for about 1,300 km. This is the Niger's middle course, which remains navigable during high water as far downstream as the rapids of Labbezanga, where the river enters the Republic of Niger. About 250 km upstream of Mopti the Niger branches out into a maze of distributaries to form a 600 km long, flood-prone labyrinth of lakes, creeks and backwaters, which is better known as the "internal delta", an area of about 20,000 km2 with many opportunities for small-scale and community-based lift irrigation. A few km before Koryoume, since 1991 the perennial quay of Timbuktu, the Niger retrenches again into a fairly narrow valley. The irrigation potential of this vast surface source is only partially exploited, mostly in the form of highly subsidized, relatively inefficient and ineffectual, large-scale, gravity-fed systems.

2.2 Climate and agriculture

The Niger traverses virtually all the vegetation zones of West-Africa, but flows for most of its northern tracts through flood plains that are mostly devoid of plant life as a result of the dry climate that is typical of the northern Sahel and the southern Sahara. Most of the annual precipitatin falls in about 3 or 4 events during the 3 months of July, August and September. During the decade of 1980-1990 average annual rainfall in Timbuktu was only 150 mm. Because of relatively low temperatures from mid-November to February flowering must take place before the 10th of November to ensure a good crop of rice. The best period for irrigation pumping is between 15 August and 5 March when the static head is between 0,8 and 3,5 meter (80% probability). Combining these hydrological facts with the above-mentioned agro-climatological constraints, it appears that a 150-day modern rice, like IR-15, is best sown on 15 July, transplanted 15 August and harvested 15 December. This corresponds exactly with the experience of Unicef project ZL-805 during 1989-1992, with average yields of more than 5,5 t/ha (paddy).

Fig. 1: low-lift conditions along Fara Bangou, a branch of the Niger


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2.3 Hydrology

At Diré, one of the most reliable measuring stations on the middle course of the Niger, situated 70 km upstream from Koryoume (Timbuktu), the river shows the following characteristics: Table 1: Characteristics of the Niger River river width at low water (June) 250 m highest peak flow ever (1955) 2 900 m3/s mean annual peak discharge (1925-1985) 2 430 m3/s mean annual low water discharge (1925-1985) 61 m3/s lowest discharge ever (1980) 5 m3/s typical flow speed 0.3 m/s level indicative of severe flooding (1925-1985) 262.59 m a.s.l. mean annual peak water level (1925-1985) 262.45 m a.s.l. mean annual minimum water level (1925-1985) 257.42 m a.s.l. lowest water level ever recorded (1980) 256.74 m a.s.l. Since 1970 widespread flooding has not taken place anymore, whereas it occurred once every 2 years before that. The combined effect of reduced rainfall and decreased flooding has led to a strong reduction in the productivity of traditional agriculture that was based on river-related crops such as floating rice and post-inundation sorghum. The 80% and 90% probability levels are depicted in below graph because they are more in agreement with the realities of the 1980s and 1990s. Fig. 2: Hydrograph of the Niger River at Diré, 70 km upstream of Timbuktu, Mali

2.4 Irrigation requirements

From August to December potential evaporation of rice decreases from 9 mm/day to 5.7 mm/day. Percolation losses may vary a lot but generally seem to be situated between 5.5 and 7 mm/day. So, peak irrigation requirements are estimated at 13 to 14.7 mm/day. Based on 11 to 12 hours of pumping per day (no pumping at night) the discharge per hectare is between 3


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and 3.8 liters/second. To allow for transport losses and a small margin, the discharge norm of 4 liters/second/hectare seems well adapted to local circumstances.

2.5 Community-based irrigation

Of the about 250 pumpsets used in the Timbuktu region in 1992, about 150 had a discharge of 55 liters/second for serving irrigation systems of 15 hectares each, and 70 had a discharge of just over 80 liters/second for irrigating community-based irrigation systems (CBIS, locally known as "Périmètres Irrigués Villagois or PIVs) of 20 hectares each. Typically, a CBIS is composed of basins of identical size. In most cases each farmer is attributed with one basin. The average basin size is 0.25 ha, so a 20 hectare CBIS has about 80 farmers. The water distribution system usually involves simple, earthen canals and field ditches and small concrete distribution boxes. It is generally considered that the flow of an earthen field ditch should be between 15 and 60 liters/second. If it is less, irrigation is too time-consuming, if it is more it may be too difficult for 1 person to keep the ditch in good repair.

2.6 Pressure-line length

The mobile pumpsets are placed on the bottom end of the slope of the natural, unamended riverbank, just next to the water. They are often trolley-mounted and are moved up and down the slope by hand to stay just out of the rising river water: this is normally achieved in 5-10 steps per season. On the suction end the pumps are provided with a 4-6 meter suction hose with a more or less appropriately dimensioned foot valve. The pressure line may consist of galvanized iron pipes or lay-flat irrigation hoses. The length and diameter of the pressure line are major determinants of system friction losses. The following table provides detailed information on the length of the pressure lines at the time when the first rice plants were being transplanted as observed on 15 Unicef sites in 1990 and in 1991: Table 2: Maximum length of discharge hose, Unicef sites Village Date of 1st pumping Type of site Length of hose Static head (m) Kondi 25 Aug river branch 20 2.75 Douékiré I 20 Aug river branch 20 2.8 Douékiré II 20 Aug river branch 20 2.8 Tin Teloud 19 Aug river branch 30 3.5 Koura 20 Aug main river 40 3.1 Tinam 15 July "bas-fond" 40 5 Bani I 17 Aug river branch 50 3.2 Sakoyra 20 Aug main river 40 3.5 Issafay 19 Aug river branch 30 3.1 Dangha 20 Aug main river 40 2.9 Koyratao 20 Aug main river 30 2.6 Tassakan 15 Aug river branch 40 2.95 Garbakoyra 15 Aug river branch 50 4.5 Bani II 5 Aug "bas-fond" 40 5.1 Fondoboro 1 Aug "bas-fond" 40 3.65 Average 14.6 Aug 35.3 3.43


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3. Preselection

3.1 Design requirements of low-lift pumpsets

The ideal HELP pump is one that can be speed-regulated in such a way that it is capable of a discharge in the entire range of 60-80 liters/second with static heads in the entire range of 1-4 meters. In terms of potential energy this means a range variation of 60x1 to 80x4 or 1:51/3. The desk-study demonstrates that several of the preselected pumpsets fit the bill. The main requirements for HELP pumps in the Timbuktu area are tabulated below. Some of the values (1, 2 and 3) follow from the pumping conditions described in section 2. Others (6 and 7) could be considered industry standards. The remaining ones are additional considerations to improve overall performance or user-friendliness. The tabulated values, apart from those for requirements 1-3, should not be adhered to under all circumstances. Appropriateness is a complex concept. The ultimate goal is to find the most appropriate solution for low-lift irrigation in the area. Table 3: Design requirements of low-lift pumpsets Main requirements 1 Discharge (Q): 60-80 liters/second 2 Static head (Hs): 1-4 meters 3 Pressure line length: 10-40 meters 4 Overall water-lifting efficiency (OWE): close to 50% Other requirements 5 Pumpset weight preferably less than 400 kg 6 Engine power output (EPO) 40% < EPO < 90% 7 Maximum discharge (Qmax,n) < 120% of Qn at BEPn 8 Hs-Q regulation engine speed variation 9 Specific speed (nq in rotodynamic pumps) 60 < nq < 150 (indicative) 10 Hs-Q characteristics a smooth curve with relatively high

efficiency over a wide range of Q

3.2 Pump, discharge hose and foot valve dimensions

Table 4: discharge-orifice relationship Diameter of discharge orifice "Design" discharge

3 inches 18 l/sec 5 inches 50 l/sec 6 inches 70 l/sec 8 inches 125 l/sec

10 inches 200 l/sec The mixed-flow pumps in below desk studies are all of the volute-type because they have to be used in mobile pumpsets. As a rule the diameters of orifices of volute-type housings correspond to standard pipe sizes. A common range of irrigation pipe diameters is 3, 4, 5, 6, 8 and 10 inches or their metrical proxi-equivalent of 75, 100, 125, 150, 200 and 250 mm internal diameter. Manufactured to suit these sizes, many pumps are designed for a discharge


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orifice exit velocity of about 4 m/s, which provides us with a clue to the discharge of the pumps (see table 4). The table shows that both 6-inch and 8-inch pumps may fit the bill for the full 60-80 liter/second range. In order to check main design requirement nr. 4 in the previous paragraph it is assumed here that pump efficiency will be around 75%. Engine output is based on 7% derating, 5% transmission losses and 6% margin, or a total "margin" of 18%. The preselection results for the dimensions of the discharge hose, suction tube and foot valve with discharges between 20 and 120 liters/second are tabulated below. These values will be used in the desk studies of section 4. Table 5: preliminary power requirements for a range of optimized pumping units

Discharge discharge hose Ø (inches)

suction tube Ø (inches)

foot valve Ø (inches)

OWE (%) required engine output

20 l/sec 5 5 8 47% 2,73 HP 30 l/sec 6 6 8 48% 3,97 HP 40 l/sec 6 8 8 55% 4,63 HP 50 l/sec 6 8 8 48% 6,66 HP 60 l/sec 8 8 10 49% 7,74 HP 70 l/sec 10 8 10 55% 8,06 HP 80 l/sec 10 8 10 51% 9,96 HP 90 l/sec 10 10 12 52% 10,93 HP 100 l/sec 10 10 12 49% 13,00 HP 110 l/sec 10 10 12 46% 15,35 HP 120 l/sec 10 10 12 42% 17,99 HP

3.3 The preselection of the 60-80 l/sec systems

Both in India and in China hundreds of manufacturers produce the same diesel engines. In India mainly licence-free Lister engines and in China mainly licence-free Yanmar engines: the TS-engines in fig. 1 (section 4). The HW-series of mixed-flow pumps, too, is widely manufactured in China. Clearly, the quality standards to which these products are made vary from one manufacturer to another and not all products in each series are produced by every manufacturer. Clearly, the 60-80 l/sec systems will all normally be equipped with 10 inch discharge hoses, an 8 inch suction tube and a 10 inch foot valve and strainer. The Indian Lister copy AV-2 and the Chinese Yanmar copy TF-160 are capable of producing the required output of 9,96 bhp in the table above. The following main pumping systems are proposed for consideration:

Unit 1: 6 inch Indian ATE-Stork CN150-125/AV-2 (reverse rotation) direct-drive

arrangement Unit 2: 6 inch Indian Kirloskar 6-inch low pressure, direct drive (normal rotation) Unit 3: 8 inch Indian Kirloskar MF200/AV-2 V-belt arrangement Unit 4: 6 inch Chinese (150HW-5) "Yanmar" TF-160 direct drive Unit 5: 8 inch Chinese (200HW-5) "Yanmar" TF-160 V-belt arrangement


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3.4 Preselection of other pumpsets

In addition to the preselection of 60-80 l/sec pumpsets it seems of interest to consider adding both larger and smaller pumpsets. Larger ones, because there seems to be a certain demand for pumpsets of 90-110 l/sec; smaller ones, because they are cheaper and may be useful in improving the accessability of pumpsets for private farmers and starting farmers' associations. In addition, there may also be tremendous scope for the application of dedicated, low-lift systems for static lifts of about 1 meter (see also paragraph 3.4.2). It is emphasized that below list of suggestions is not exhaustive.

3.4.1 Additional preselected Indian pumpsets

Unit 6: A very common and relatively inexpensive indian engine is the 7.5 HP 1500 rpm single-cylinder, water-cooled engine, such as the Kirloskar TV-1. It is used in many of Kirloskar's standard pump sets of which the direct-coupled TV-1/NW9ME is the one operating at the lowest pressure: Hd 5-10 m, Q 33-60 l/sec. This will be the smaller Indian pump set in the pilot project. Unit 7: For a large discharge in the order of 90-110 l/sec it will be necessary to use a 15 HP, 1500 rpm, double-cylinder water cooled engine like the Kirloskar TV-2. A reverse-rotation (footnote d) TV-2 could be direct-coupled to the Kirloskar MF 17,5-20 mixed flow pump. Including a reverse-rotation engine will provide information on the limitations and potential of the reverse-rotation option.

3.4.2 Additional preselected Chinese pumpsets

Unit 8: Probably 3-inch and 4-inch pumps are the most widespread in the tropics. The main reason for such small sizes to be more common is the fact that the manometric head is often 10 meters or more and the engine power output required corresponds to the smaller engine sizes commonly available. Many of the smaller engines have speeds in the 1500-3000 rpm range. To allow direct coupling preference is given to a mixed-flow high-speed 4-inch pump, the 100HW-8. Such a pump could be driven by a Yanmar L40AE or a similar engine for discharges in the 16-22 l/sec range. The use of other cheap engines (2-stroke and 4-stroke petrol and paraffin engines) that are already available in Mali could also be considered. Units 9 and 10: For extremely low-pressure conditions such as those prevailing in "irrigation d'appoint" in Gao it may be interesting to have a small axial-flow pump (Van ‘t Hof, 1992) such as the 8YZ and the 8YZ-2A. It is assumed that a standard fitted engine will suffice for testing purposes. Equipping the pump with other engines already available in Mali could also be considered. For reasons of comparison 2 DA-IRRI pumps (Aban, 1985) have been included, too.

4. Desk study

4.1 Introduction

The purpose of the desk-study is to compare the performance of the preselected pump sets. In sub-section 4.3 a tabular overview of all pumping systems described in section 3 is presented. The HELP pumpsets that seem of interest for practical tests are printed in bold. A number of asian, european and japanese systems is printed in italic to show the difference with "real"


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HELP pumps preselected above. The main reason for their presence here is to to emphasize that from a performance point of view there is no reason to prefer equipment from one place or another. Also they may provide a price/quality benchmark for the HELP equipment. In bold type the 7 pumpsets that seem to be most suited for a low-lift irrigation pump pilot project. The ones typed in italic are introduced "from the blue" (see sub-section 4.1). Some of the assumptions in above calculations are: (1) 5-10% efficiency loss in v-belt transmissions; (2) the pumpsets are equipped as set out in the table of subsection 3.2; and (3) fuel consumption is corrected for engine load. Specific cost includes: fuel cost, interest cost (10%), repair and maintenance cost (10% of initial system cost) and depreciation. Table 6: overview of pumpsets and desk-study results

Hs = 1 m Hs= 2,5m Hs = 4 m Hs = 6 m Pumpsystem drive* price BKO (FF)

lifespan (hrs) Q

l/sec fuel liters

Qmin Q fuel Q fuel Qmax Q fuel

Average fuel

cons. l/hr

Spec. Cost/

100 m3 (FF)

Spec. Cost

/ha ($)

60-80 liter/second systems

ATE-Stork CN150-125/AV-2 direct 27000 7000 80 1,43 63 80 1,79 80 2,15 80 70 2,2 1,70 5,7 142

Kirloskar 6-inch low pressure/AV-2

direct 26000 7000 80 1,43 63 80 1,79 80 2,15 80 70 2,2 1,70 5,6 139

Kirloskar MF200/AV-2 v-belt 33000 7000 80 0,95 65 80 1,48 80 1,7 95 80 2,2 1,27 5,78 145

150HW-5/TS-160 direct 18000 6000 80 1,44 65 80 1,74 80 2,03 83 72 2,1 1,66 4,7 118

150HW-5/TS-140 direct 18000 6000 80 1,39 63 80 1,74 78 1,94 78 69 1,95 1,61 4,6 116

200HW-5/TS-160 v-belt 24000 6000 80 0,9 75 80 1,43 80 1,67 95 72 1,67 1,23 4,84 121

Stork CN150-125/Yanmar TF-160

direct 60000 8000 80 1,43 63 80 1,79 80 2,15 80 70 2,2 1,70 9,3 231

Caprari BHR200/Lister-Petter TS-2

v-belt 60000 8000 80 1,1 74 80 1,57 80 1,96 83 61 1,8 1,43 8,86 221

Kirloskar MF200/TV-1 v-belt 30000 7000 80 0,95 80 80 1,47 80 1,91 80 0 N/A 1,32 5,5 137

Kirloskar MF200/TV-1 v-belt 90000 7000 80 0,95 80 80 1,47 80 1,91 80 0 N/A 1,32 5,5 137

<60 liters/second

Kirloskar NW9ME/TV-1 direct 24000 7000 60 1,16 45 60 1,42 59 1,62 59 52 1,62 1,34 6,4 160

100HW-8/"L40AE" direct 9000 2000 25 0,35 20 25 0,45 25 0,6 25 21 0,6 0,44 9,0 226

>80 liters/second

Kirloskar MF 17½ -20/TV-2 direct 33000 7000 107 2,03 80 107 2,40 107 3,00 107 80 2,36 5,5 138

Stork CN200-200/Lister-Petter TR3

direct 69000 8000 110 3,00 60 110 3,00 110 3,00 N/A 95 3,00 8,8 221

Axial-flow systems

8YZ Axial-flow Pump (China)

direct 9000 2000 72 1,00 N/A N/A N/A N/A N/A N/A N/A N/A 1,00 4,05 101

8YZ-2A Axial-flow Pump direct 9000 2000 75 1,60 N/A 50 1,6 N/A N/A N/A N/A N/A 1,60 7,23 181

DA-IRRI single-stage direct 9000 2000 80 1,30 55 50 1,9 N/A N/A N/A N/A N/A 1,60 7,23 181

DA-IRRI two-stage direct 9000 2000 80 1,35 75 80 2,16 80 2,81 80 50 N/A 1,92 4,99 125

Previously introduced systems

Cooper CVR, CUB or SVC?? (india)

direct 5000 5000 15 1 10 15 1 15 1 15 15 1 1,00 11,5 287

Deutz (2-cilinder 14.4 hp) direct 60000 8000 55 2 40 80 2,25 55 2,5 55 55 2,5 2,19 10,0 249

Caprari BHR200/Lister-Petter HR-3

direct 100000 8000 134 3,9 120 134 4 134 4,2 134 120 4,2 4,00 10,2 255

Stork CN160-200/Lister-Petter HR-2

direct 69000 8000 80 2,8 60 80 3 80 3,2 90 75 3,4 2,95 12,1 302


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4.2 Desk-study outline

The performance of the pumpsets will be calculated on the basis of documents provided by the manufacturers. Typically the dimensions suggested in table 6 for the hoses, tubes and foot valve and strainer will be used with the pumping conditions found in subsection 2.6, i.e. a maximum length of 40 meters at a static head of 4 meters. The performance under average pumping conditions will be calculated in terms of HE, OWE, OWSE, fuel consumption and the cost of water in $/100 m3 for pressure line lengths of 40, 25 and 10 meters and corresponding static heads of 4, 2.5 and 1 meter. In addition, system discharge at a static head of 6 meters will be approximated. These results will be presented in a tabular overview in Fig. 1 (see next page). Some of the assumptions related to interest rates, depreciation periods etc. will also be mentioned there.

5. Testing and evaluation On the basis of the deskstudy results it is possible to make a selection of suitable pumpsets for practical testing. We emphasize that no funding agency has as yet approved the testing programme. Possibly, the funding agency would like some say in the preliminary selection (see also table of sub-section 5.1: providers of finance).

5.1 Evaluation criteria

It is recommended that the following items are evaluated: (1) technical performance, especially overall water-lifting efficiency; (2) costs and benefits, including economics of operation; (3) user friendliness, especially with regard to system mobility, ease of installation and pump priming; (4) importing and procurement aspects, including spare-part availability; and (5) machine quality, especially with regard to average technical lifespan under normal maintenance conditions. Table 7: Evaluation and selection criteria Technical evaluation criteria Efficiencies HE, OWE, OWSE, fuel efficiency Life-span & reliability difficult to assess on the basis of a single

pumpset during a relatively short period of time, so: initial appreciation only

Procurement-related evaluation criteria Price (Asia, ex-factory) indicates bottom price limit Price (Mali, incl. transport, taxes etc.) initially on the basis of a single unit only Enhancement of supplier competition to ensure lowest possible price to end-users Supplier communication and reliability important to permit transfer of all

responsibilities to Malian partners Availability of various items with 1 supplier in particular of the large-diameter, low-

pressure, low-cost discharge hose Availability of spare-parts e.g. existing availability of spare-parts Possibility or necessity to complete or assemble pumpsets in Mali

this may be interesting for a variety of reasons: (1) increasing the use of local labour or products; (2) reducing costs; (3) increasing flexibility


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(Table 7 ctd.) Acceptability Farmers suitable discharge at low cost and easy pump

priming Hari Goumo & HIPPO suitability for pump rental programme, system

mobility, ease of installation Providers of finance should normally be based on lowest

anticipated specific irrigation costs Economic evaluation Specific irrigation cost e.g. US$/100 m3 of irrigation water taking

into account all costs including maintenance, depreciation, interest and fuel costs.

5.2 Evaluation procedure outline

The selected units will be procured for delivery in Bamako to provide a standard price for Mali. During the ordering procedure notes will be made of various procurement-related issues. The pumpsets will be received by a predetermined recipient. Pumpset completion or assembly work will also be carried out in Bamako. Ideally, the work supervisor is the same as the recipient. Attention should be paid to the possibility of involving a Hari Goumo representative in all stages of procurement, completion, supervision and transport. During an initial 1-day test run the various efficiencies will be determined and estimates will be made of irrigation cost parameters. From there the units will be transported to Timbuktu to be subjected toa practical test by Hari Goumo for one or more years. It seems very useful if a single supllier could supply the whole lot, i.e. pump, engine, mounted on frame, hoses, foot-valve etc. It may be interesting to have a slight compromise (in efficiency or price) to allow this.

5.3 Additional technical issues

The following issues should be taken into account when testing the selected pumpsets. These are general issues, that do not apply to one pumpset or collection of pumpsets in particular. However, they are important to ensure practical relevance of the testing results. Some might affect the choice of pumpsets to be tested. They are: (1) the maximum normal operation speed of pumps, especially in the case of the 6-inch pumps, since they may have to operate at speeds of 1900-2100 rpm; perhaps other bearings will have to be fitted; (2) in case the pump is driven by a v-belt, care should be taken that both the pump and the engine are capable of a lateral load; (3) in case of v-belts the system for maintaining the tension should be simple, reliable and rugged; also, the v-belt should be designed for maximum efficiency; (4) ideally the foot valve-cum-strainer should be capable of operating in very shallow water of no deeper than 30-40 cm; a suitable design will have to be agreed upon and probably manufactured locally; (5) similarly, in the absence of a stilling basin, a bubbler or other type of arrangement may be needed at the discharge end of the pressure hose.


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6. Proposed methods of introduction

6.1 Hari Goumo

Once the testing is over, the subsequent matter of introduction of the pumping equipment is the responsibility of Hari Goumo. The latter will have to produce a business plan in order to obtain a loan through a small business development programme. The G.I.E.-Hari Goumo & Machines Agricoles, P.O. Box 94, Timbuktu, was created by Mr. Dramane Arby on the 16th of September 1996 with the aim to improve the availability of high-performance farm machinery, including pumping equipment, to allow farmers’ associations to increase their productivity. Mr. Arby was born in Timbuktu in 1958, married with 3 children, and a graduate of the Petrochemical Institute of Baku (USSR). He has 12 years of experience in community-based irrigation development in the region of Timbuktu. Actitivities of Hari Goumo include: renting out pumpsets on a seasonal basis and providing maintenance & repair services. Special attention is paid to the method of payment by the farmers. This involves the principle of "co-exploitation", which means that to ensure viability of the enterprise it is considered necessary to demand payment by the farmers at the right time and in the right form, i.e. payment in kind at harvest time. In 1997 2 pumpsets were rented out and 150 tons of paddy were produced. Hari Goumo is expecting to expand to 30 pumpsets for rent while improving its repair and maintenance services. It will also attempt to sell pumpsets, either directly or at the end of hire-purchase agreements.

6.2 Willingness-to-pay (WTP) vs. Cost-Benefit Analysis (CBA)

It is crucial that the introduction of pumpsets is both financially self-sustaining and financially attractive to Hari Goumo. The farmers in the area are notorious for attempting not to pay. For their own benefit, as well as for the benefit of their fellow farmers, Hari Goumo and the provider of finance, the risk of not-paying has to be minimalized. Such unwillingness to pay is difficult to understand if one carries out a CBA: the cost of irrigation, even with the current, less suitable equipment is normally in the order of 10-25% of the value of the harvest. It is easier to understand if one is acquainted with the poverty of most of the farmers. The below WTP-approach is proposed as a necessary supplement to CBA-logic. It is considered that the willingness-to-pay is an important measure of the self-sustaining financial capacity of any project. WTP is affected by a number of so-called biases, such as the "not used to money" bias, the payment vehicle bias, the interpreter bias, the "culture" bias and the researcher bias. In one study of a vegetable irrigation project in Zimbabwe the average WTP corresponded with 2.4% of the average income. Post-survey results suggested that the real WTP was not likely to exceed 60% of that value, i.e. 1.5% of average income. Applying these Zimbabwean results to village pumpsets near Timbuktu we get the following situation: GDP per head (rural, Mali) is probably less than US$ 150. The average village has 800 inhabitants, or the WTP of the entire village may be estimated at: 800 x US$ 150 x 1,5% = US$ 1800. This is a rather small amount considering that a european pumpset of average size may cost as much as 10 000 to 15 000 US$. Clearly, the first step is to reduce the cost of the pumpsets. Secondly, the various biases have to be used wisely to obtain a WTP that corresponds with the cost of the pumpsets. Such an approach will have consequences for the organizational set-up of both the farmers’ organizations and the local pump rental operation (see 6.3 below).


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6.3 Organizational aspects

Accountability is a crucial element in "co-operative" farmer organization. Literacy rates among farmers are very, very low and the co-operative "movement" has met with very little success. To achieve maximum accountability the number of monetary operations by any farmers association should be limited to the absolute minimum for the members to be able to check the "books" in their heads. Also, experience has shown that the introduction of revolving funds, large enough to depreciate the relatively expensive pumping equipment, further acerbates the accountability problems. Therefore, the pump units should be rented out on a seasonal basis with suitable incentives to pay the entire sum at once prior to first pumping. The rental sum will include a pump maintenance & repair contract. The "not used to money bias" could be used by allowing starting groups to pay in kind after the harvest. The rental organization will then transport and process the paddy for an additional profit. Since 1997 Hari Goumo has used this approach successfully in the village of Kakondji, not far from Timbuktu.

6.4 Renting, selling, hire-purchase

It is obvious that a pump rental operation is complicated compared to the straightforward selling of pumpsets. Therefore the pump rental organization should also allow the possiblity of direct sales. It is not clear what the effective demand for pumpsets will be. Potential demand for pumpsets in grain-deficit north-eastern Mali may well be in excess of 1000 units. Because 30 pumpsets may already represent an organizational ceiling for Hari Goumo, it seems worthwhile to try and sell pumpsets by way of a kind of hire-purchase system. This will also reduce the dependence of farmers and farmers’ organizations on a small pump rental organization. Increasingly the pump rental organizational should become a pump sales, maintenance and repair business.

6.5 Suggestions for future technological development

A small number of alternatives to and variations of diesel-powered, mobile pumpset equipped with a long, flexible pressure hose will be briefly reviewed below. At a convenient time, they could be used to supplement the simple testing programme proposed above. These supplements are by no means crucial to the present pilot programme. No attempt is made to consider other aspects than those that are directly related to the testing of mobile pumpsets. (a) Suppression of the long pressure hose: The main reasons for suppressing long pressure hoses are: (1) their often relatively high cost, although cheap ones also exist; (2) the friction losses they incur. There are 2 simple methods for suppressing their use: (1) an adduction canal; (2) extending the main irrigation canal towards the riverside using supports or an embankment. Simple, concrete pipe- and well-like structures could also be used to make a more conventional pumping station; (b) Night-pumping: For a given command area the pump discharge, and therefore the pump and its initial cost, could be halved in size if night-pumping would be resorted to. This would lead to a more intensive use of the equipment, which reduces the specific irrigaton costs. Night-pumping could be achieved by irrigating at night or by discharging into a night reservoir. Perhaps such a night reservoir would not have to be lined, thus making it very cheap indeed. Also, its applicability is easily tested at a small scale.


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(c) Bio-fuel: In the slightly or non-monetarized village economies along the Niger River the use of locally cultivated bio-fuel could be very desirable. The experience of the IFAD/UNIDO project in Mopti shows that the oil of Jatropha curcas nuts, readily available in Mali, can be used to fuel small diesel engines (IFAD/UNIDO, 1996). (d) Locally manufactured pumps: It is possible to locally manufacture certain types of pumps, such as the SIPA/DA-IRRI axial-flow pump, archimedean screws, and an array of simple positive displacement pumps. In fact, a small number of axial-flow pumps was manufactured in Niono, Mali, in the late 1980s. Although they were not used intensively, they have been in use for at least several years, especially for emptying fish ponds (personal observation).

Acknowledgements The contribution of the following people is gratefully acknowledged: Mr. Gert-Jan Bom of Solartec, Papendrecht, the Netherlands; Mr. Bert Nouwen, Schalkhaar, the Netherlands; Maurice Onderdonk of Ile de Paix, Belgium; Mr. Dramane Arby of Hari Goumo, Timbuktu, Mali; Mr. Jean Coursimault, Unicef, Mali; Michael Bate of Batescrew Pumps and Valves, Tocumwal, Australia; Mr. Celal Sahin and Mrs. Inge Heetveld of BSC, Utrecht, the Netherlands; Mr. Peter van der Sman, Kommanet B.V., the Netherlands; Mr. Jayant Kirloskar, Frankfurt, Germany; Vraag en Aanbod Internationaal; and Mr. Nico Kroes of the Amsterdam Polytechnic.

References Aban M.M. (1985) Design parameters affecting the performance of the IRRI-designed axial-flow pump Arby D. (1996) Projet de location et de maintenance de machines agricoles en 6e région (Tombouctou-Mali) Arby, D. (1997a) Projet de co-exploitation de 3 périmètres irrigués par des motopompes louées pour la campagne de riz 97/98 Arby, D. (1997b) Demande de financement pour le montage d’un atelier de maintenance agricole et hydraulique à Tombouctou Bom, G.J. and Van Steenbergen, F. (1997) Fuel efficiency and inefficiency in private tubewell development DNHE (1986) Actualisation de l’étude hydrologique du bief Akka - Koryoumé: hauteurs moyennes décadaires El Hadji Sene (1991) Périmètres irrigués: un apprentissage qui s’inscrit dans la durée" in: "La lettre du réseau Recherche Développement FAO (1996) Irrigation technology transfer in support of food security Gujarat Forgings Ltd. (1994) Performance curve of Field Marshal high-speed diesel engine IFAD/UNIDO (1996) West Africa’s rural communities launch their industrial revolution, Joint Press Release IDO/1642, Rome-Vienna, 15 Oct. 1996. Jensen, M.E. (ed.) (1983) Design and operation of farm irrigation systems PCARRD (1986) The SIPA/DA-IRRI low-cost axial-flow pump Steffen, Philip N. (1995) The roles and limits of the grain market in assuring household food security in northeastern Mali: implications for public policy, PhD thesis, pp. 721. Van 't Hof, S. (1990) Proposition essai pompe helice de l'IRRI (unpublished) Van 't Hof, S. (1991) Perimètre de Garangassou, avant projet detaillé: memoire explicatif (unpublished)


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Van 't Hof, S. (1994) Economical low-lift pumps for village irrigation along the Niger River (unpublished) Van 't Hof, S. (1992) Irrigation d'appoint a Bourem: rapport de mission 18-25 mars 1992 (unpublished) Wallace D.E. (1987) Belt selection and application for engineers Wuxi Pump Works (1991) Type HW mixed-flow pumps: instructions Note: copies of the above-mentioned unpublished documents written by Van ‘t Hof, Coursimault, Arby and Bom can be obtained from the secretary of the HIPPO Foundation, De Verwondering 27, 3823 HA Amersfoort, the Netherlands, e-mail: [email protected]. If time permits, copies will also be uploaded to the HIPPO website: http://www.inter.NL.net/hcc/HIPPOMP.

Glossary of terms, acronyms & abbreviations Bas-fond Used in north Mali to indicate a trough in the channel of a river branch that

runs dry from February to July; such troughs are useful sources of surface water during the dry season and well into the next wet season.

BEP Best efficiency point CBI Community-based irrigation (in french: irrigation villageoise, from where

"périmètre irrigué villageois" or PIV) the name used in Mali and other french-speaking countreis for community-based irrigation schemes or CBISs)

FENU/UNCDF Fonds d’Equipement des Nations Unies or United Nations Capital Develop Fund

GIE Groupement d’intérêts économique, a form of private enterprise in which a group of individuals pool certain resources; such a group could consist of only 2 persons, but also an entire farmers’ association.

HELP pumps Short for "high-efficiency low-pressure pumping systems" HIPPO High-efficiency Irrigation Pumps, Procurement & Organization. The HIPPO

Foundation is registered with the Chamber of Commerce of Amersfoort, the Netherlands. For more information visit the website: http://www.inter.NL.net/hcc/HIPPOMP

HE Hydraulic efficiency = Hs / Hd OWE Overall water-lifting efficiency = Epump x HE OWSE Overall water-lifting system efficiency = OWE x Eengine x Etransmission UNICEF United Nations Children’s Fund (formerly: UN International Children’s

Emergency Fund

Documents

The design of a low-lift irrigation pump pilot project: improving the availability of affordable pumpsets to african farmers