IJERD ± International Journal of Environmental and Rural Development (2018) 9-2

Research article
erd

An Evaluation of Water Demand and Supply for a Smallscale Irrigation Scheme in Zimbabwe
EDIMUS MASONA
Graduate School of Agriculture, Tottori University, Tottori, JapanKATSUYUKI SHIMIZU*
Faculty of Agriculture, Tottori University, Tottori, Japan.
Email: shimizu@tottori-u.ac.jp

YUMI YOSHIOKA
Faculty of Agriculture, Tottori University, Tottori, Japan
Received 20 February 2018

Accepted 20 October 2018(*Corresponding Author)

Abstract Previous studies have shown that most smallholder irrigation schemes indeveloping countries in Africa, have proved to be unsustainable beyond external assistance.
The low performance of most smallholder irrigation schemes is largely attributable tounreliable and inadequate water delivery. This research assessed the on-farm water
management performance for Fuve-Panganai irrigation scheme in Zaka District ofZimbabwe. The objective of this study is to assess the on-farm water management
performance for the irrigation scheme in terms of water demand and supply. The irrigationwater demand for 204 ha of dry beans for the winter irrigation season (April to August) wasestimated using the FAO CROPWAT. The seasonal water supply was calculated using the2012 to 2016 recorded canal water depths. The Relative Water Supply (RWS) index wascalculated from the water demand and supply. 38 randomly selected farmers, members of
he a eea ocia ion and ele an agenciee e in e ie ed o nde and hedecision-making process and the overall performance of the scheme. The results showed astable water supply for the five years with a coefficient of variation of 0.2. The watersupply was greater than water demand during the winter mid-irrigation period (May to July)
with an average RWS of 1.59. The results correspond with results from the interview
survey in which more than 90 percent of the farmers were satisfied with the irrigation
management performance. However, 37 percent reported to have experienced water
shortages. This is due to the heavy distribution losses by damaged pipes and leaking water
valves. The irrigation system is in dire need for rehabilitation to minimize water losses.
Keywords performance assessment, water demand, water supply, relative water supply

INTRODUCTION
Irrigated agriculture is the most effective way of reducing crop failure, hunger and malnutrition inAfrica and has the potential to increase the competitiveness of smallholder farming in most parts ofAfrica (World Bank, 2008). Despite these potential benefits of irrigation, smallholder irrigation
schemes in most developing countries, including Zimbabwe have proved to be unsustainablebeyond external assistance (Mutambara and Munodawafa, 2014). They showed that thesustainability of small-holder irrigation schemes in Zimbabwe was being affected by a complex
interaction of a variety of factors which include; limited access to agricultural inputs, low
educational level and/or lack of training in appropriate farming skills, lack of collateral whichenables farmers to access loans or working capital and erratic irrigation water supply.
To achieve higher crop yields from irrigated agriculture it is necessary to supply the amount ofwater required by the crops. The amount of water required by the crops is determined by the area
under cultivation, the crop water requirements and any inevitable losses incurred during theapplication of the water to the field (DFID, 1997).
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IJERD ± International Journal of Environmental and Rural Development (2018) 9-2

According to Sakthivadivel et al., (1993), the two most crucial factors in irrigation planning,
design and operation are the available water supply and the water demand. The two authors defined
Relative Water Supply (RWS) as the ratio of water supply to the water demand associated withcrops grown with the cultural practices used, and for the actual irrigated area. They underscored theusefulness of the RWS as a tool for understanding the performance of irrigation systems.
OBJECTIVESThe objective of this study is quantitatively and qualitatively assess the on-farm water management
performance to identify the current problems for the small irrigation scheme, Fuve-Panganai
Irrigation Scheme, Zimbabwe.
METHODOLOGY
Study Site
Fuve-Panganai irrigation scheme is in ward 15 of Zaka district, 131 km south of Masvingo City,
Zimbabwe. The nearest meteorological station; Buffalo Range Airport, records a minimum temp of
8.7 oC in July and a maximum of 32.9 oC in January. Average annual rainfall received is 584 mm.
The irrigation Scheme is 283 hectares in extent comprising of four blocks, designated, A, B, Cand D each with 9; 70; 54 and 150 hectares respectively. Irrigation water is conveyed by gravity
from Siya dam by a 14.5 km conveyance canal that discharges into Murerezi stream and ultimately
to Chiredzi River and Manjirenji Dam through a water catchment transfer. The design capacity ofthe main canal is 3.5 m3/s. There is an off-take to blocks C and D at 11.5 km from the dam and it isfrom this off-take that a branch canal with a design capacity of 0.25 m3/s supplies water to blocks Cand D. Both the main and branch canals are lined in concrete. The off-take to block C regulation
pond is 3.5 km along the branch canal. The branch canal eventually discharges into block D
regulation pond at 7.5 km from the main off-take and there other two regulation ponds for the othersubsections of block D. Figure 1 shows the layout of the irrigation system.
The regulation ponds receive water from the branch canal for 24 hours and store it overnight,
since irrigation is practiced during the day time. Water is conveyed from the regulation pond to thefield by an underground pipeline system. Farmers take water from the field hydrants using hose
pipes and direct it into furrows. Each farmer is entitled to one hectare of irrigated land.

Fig. 1 Layout map of blocks C and D of Fuve Panganai Irrigation SchemeⒸ ISERD

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IJERD ± International Journal of Environmental and Rural Development (2018) 9-2

Sections C and D with a total area of 204 ha were purposely selected as the study site because
they share the same branch canal. Maize, groundnuts and sugar beans are the main crops grown.
Maize and groundnuts are grown in the summer whilst sugar beans is grown in winter. It wastherefore assumed that sugar beans was continuously grown in winter for the period underconsideration.
Water Demand and Supply
The irrigation water demand for 204 ha of dry beans for the winter irrigation season was calculatedusing the FAO CROPWAT 8.0 for Windows which is a computer program for the calculation ofcrop water requirements and irrigation requirements based on soil, climate and crop data.
The average monthly climate data for Buffalo Range Airport was accessed from FAO
CLIMWAT 2.0 which is a climatic database to be used in combination with the computer program
CROPWAT. The average monthly water supply for April to August which is the winter/dry season
was calculated from daily irrigation water supply data for 5 years (2012-2016). The Relative Water
Supply (RWS) index was calculated for dry season using the formula;
RWS＝S/D(1)

Where, S is an amount of water supply and D is an amount of water demand
Quessionaire Survey
A sample of 38 randomly selected farmers were interviewed to get their perception on the watermanagement performance with 80 percent confidence interval and 10 percent margin error. Theaee a ocia ion membe and ke info man f om Zimbab e Na ional Wa e A ho i(ZINWA), Department of Irrigation (DOI) and Agricultural Research and Extension Services(AGRITEX) department were also interviewed to understand the decision-making and water
allocation process.
RESULTS AND DISCUSSION
Stakeholders
There are five key stakeholders in the irrigation scheme; the farmers, the Water Users Association(WUA), ZINWA, DOI and the AGRITEX department. Their roles and responsibilities are in shownin Table 1.
The Water Allocation and Irrigation Practice
The water allocation process is in three stages; the planning stage, the negotiation stage and theimplementation stage.
During the planning stage the farmers make the irrigation season plan; i.e. they come out withcrop(s), the total hectarage, the planting dates, the tentative water requirements and amount ofmoney needed to buy the water from ZINWA, etc. The WUA coordinates this process and they
may also consult the AGRITEX and or the DOI officers for technical advice.
The WUA on behalf of the farmers engage the ZINWA in the negotiation stage to agree on thewater contract. The water contract includes the crop, the total hectarage, the irrigation season, theamount of water needed and the payment plan amongst other factors.
During the implementation stage ZINWA supplies irrigation water to the farmers throughout
the irrigation season as per the agreement in the water contract. The farmers order water as per
demand by calling the ZINWA offices, the ZINWA through its resident technician, who stays inⒸ ISERD43IJERD ± International Journal of Environmental and Rural Development (2018) 9-2

the farm, supplies a canal water depth for a certain number of hours and or days to meet the farmers
water requirements. The process of ordering and receiving water is 24 hours.
Table 1 The roles and responsibilities of key stakeholders
Name ofstakeholder

Roles and responsibilities

Farmers

The main beneficiaries of the irrigation scheme. They are autonomous, and run thescheme independently. They are responsible for the operation and maintenance of thebranch canal and other farm level irrigation facilities

WUA

The farmers committee which coordinates the irrigation activities on behalf of thefarmers e.g. making contract with ZINWA, collecting water fees from the farmers andholding meetings.

ZINWA

A quasi-government body managing irrigation facilities such as dams and the main
canal. They supply the farmers with water based on the contract with WUAs.

DOI

A government department responsible for the supervision of irrigation projects
including the operation and maintenance of the irrigation structures.

AGRITEXThe government department responsible for extension services; such as advising
farmers on the best agronomic practices including irrigation scheduling

The farmers are charged by ZINWA 4.36 USD/hectare/month. Of the 4.36, 1 USD is taken by
the Save Water Catchment Council and the remaining 3.36 USD is for ZINWA. This means thateach farmer on average pays 22 USD per irrigation season per hectare.
As seen from the water allocation process ZINWA water supply is not limiting; the farmers
can order as much as they need and since this can be done within 24 hours there is less risk ofwater shortage. The farmers can irrigate during the day from 0800 hours to 1600 hours, there is nostrict time table hence all the farmers can irrigate whenever they need but in practice in sections
where the water pressure is low, they follow a flexible irrigation time table.
The Water Supply and DemandFig. 2 shows the annual branch canal water discharge for the five years. The highest amount ofwater supply was observed in 2013 and the least amount in 2014. There is a relatively stable waterppl
i h a coefficien of a ia ion (CV) of 0.2. Thi mean he ZINWA
aeppl o hefarmers is reliable.
The RWS for the mid-irrigation period (May, June and July) was shown in Fig. 3. It ranges
from 1.28 to 2.12 with an average of 1.59. Although the irrigation season is five months from April
to August, the first and last months of the irrigation season were not included in the analysis toavoid the error margin.
The RWS values at different locations of a system are closely linked to the management
behavior of water managers and farmers (Sakthivadivel and Merry, 1993). Levine (1991) gave
general recommendations (based on observations) that for a RWS of approximately 2.0, monitoring
and control to secondary channels, daytime monitoring, limited communication between the systemmanagers and farmers would still permit relatively high yields. Levine recommended that for a
RWS of 2.5 or greater, minimal operational control at the main distribution level is enough toensure that water will not be the limiting factor in crop production. However, considering the pipeline system is installed in the study scheme, this RWS is very high since the conveyance anddistribution efficiency is theoretically very low under pipe line system.

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IJERD ± International Journal of Environmental and Rural Development (2018) 9-2Fig. 2 Annual canal water discharge

Fig. 3 Water demand and supply during mid-irrigation period
Farmers Perceptions on Irrigation PerformanceFig. 4 shows the farmers perceptions as far as irrigation performance is concerned. Over 90 percentof the farmers are generally satisfied with the water delivery service by ZINWA. Although most of
the farmers are satisfied, about 37 percent of the farmers have experienced periodical water
shortages. Field observations revealed water leakages from damaged hydrants and pipes whichmight be the major reason for the water shortage. The high value of RWS are caused by thedamaged hydrants and pipes in the study irrigation scheme. The rehabilitation of these will go along way in improving the availability of water to all farmers.

Fig. 4 Farmers perception on irrigation performanceⒸ ISERD

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IJERD ± International Journal of Environmental and Rural Development (2018) 9-2

CONCLUSIONS
The analysis of water demand and supply revealed that the water supply from ZINWA is reliably
stable as shown by a CV of 0.2. The scheme received more water than the IWR as shown by theRWS of 1.6. The water allocation system is efficient with the farmers being able to order andreceive water within 24 hours. Although more than 90 percent of the farmers are generally satisfied
with the water delivery performance, 37 percent are experiencing some water shortages. There arewater losses due to damaged hydrants and pipes. The results of this study can contribute to theoverall evaluation of the performance of the irrigation scheme and therefore help in making thenecessary recommendations for improvement e.g. increasing the water supply and or rehabilitation.
ACKNOWLEDGEMENTS
Thida cond c ed nde he De elopmen of c op h band echnolog in ma ginal ain
fed environment ing d land plan e o ce P ojec b To o i Uni e i and a pa iall
supported by International Platform for Dryland Research and Education, Tottori University.
REFERENCESDFID (Department for International Development). 1997. Smallholder irrigation: Ways forward. Guidelines
for Achieving Appropriate Scheme Design, Volume 2, Summary of Case Studies, Chancellor, F.M. andHide, J.M., Report OD 136, August 1997.
Mutambara, S. and Munodawafa, A. 2014. Production challenges and sustainability of smallholder irrigationschemes in Zimbabwe. Journal of Biology, Agriculture and Healthcare, 4, 15.
Sakthivadivel, R. and Merry, D.T. 1993. Cumulative relative water supply: A methodology for assessing
irrigation system performance. Irrigation and Drainage Systems, 7, 43-67.
World Bank. 2008. Mobilizing public-private partnerships to finance infrastructure amid crisis is the focus ofthe World Bank Conference. World Bank Press Release, No: 2008/175/WBL.

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