Development pfcrystalUQ&lîaseinpntaquifers HÏ£ *isemi-arid a i ^ ^ ^

Lack of water is the main constraint on agricultural production in south-east Zimbabwe

This booklet provides a brief overview of an ODA-fundedprogramme in south-east Zimbabwe which has the widerobjective of reducing environmental degradation andimproving agricultural sustainability in semi-arid areas.The programme comprises several research and technicalcooperation projects carried out by the Institute ofHydrology, the British Geological Survey and severaldifferent departments of the Zimbabwean Ministry ofLands, Agriculture and Water Development.

Gardening is a keyagricultural activitytraditionally practisedby women in much ofAfrica. In semi-aridareas vegetables aregrown both for sale andJor home consumption ifsufficient water isavailable.

Background

Many conventions and initiativesthat resulted from the UN Conference onthe Environment and Development inRio de Janeiro in 1992 recognised thatthe links between poverty, highpopulation growth and environmentaldegradation are circular and mutuallyreinforcing. Consequently, targetingprojects to benefit poor ruralcommunities, and women in particular,has become an accepted strategy forreducing poverty, protecting theenvironment and promoting sustainabledevelopment.

The programme of research andtechnology transfer described here isevaluating innovative ways of providingrural communities in semi-arid areaswith more reliable and safer watersupplies. These improved watersupplies can be used for domesticpurposes and for garden-scaleproduction of vegetables for homeconsumption and sale. The programme,which is being carried out with theparticipation of local institutions and

communities, is also evaluating thefeasibility of using community orallotment-type gardens as an initial steptowards improved environmentalmanagement at the village andcatchment levels.

The rationale behind theprogramme is that access to morereliable water supplies for domestic andgarden use can lead to improvements inhealth, household incomes and areduction in poverty. As part of astrategy of integrated resourcemanagement, gardening may alsoreduce the need of rural communities torely on unsustainable agriculturalpractices such as the cultivation ofmarginal areas. Furthermore,organisational experience and theconfidence gained from implementingand managing community gardens canbe used effectively in other community-based activities aimed at reducingenvironmental degradation andpromoting sustainable development.

200

Crystalline basement

Mean annual precipitation (mm)

1000 km

Location and extent of crystalline basement geologies in Africa

Basement aquifers

Widespreadimplementation of gardenirrigation in semi-arid areas isconstrained by the availabilityof water resources. Theweathered surface zone ofhardrock (or basement) areas,which are present over much ofAfrica, provide a limited butvery extensive water resourcewhich has the potential forgreater use.

Development of thesecrystalline basement aquifers isnormally carried out either bydigging traditional wells in theweathered overburden orregolith, or by drilling deeperboreholes into the fracturedrock beneath.

LIBRARY IRCPO Box 93190, 2509 AD THE HAGUE

Fax: +31 70 35 899 64BARCODE: || Q C, ^ (

Collector wellsA collector well is a shallow hand-dug

well of large diameter with horizontalboreholes drilled radially from the base to adistance of approximately 30 m, typically infour directions. Research during the lasttwelve years has shown that collector wellscan be used to maximise and optimisegroundwater abstraction from basementaquifers. This work has demonstrated thefeasibility of obtaining substantially largeryields from collector wells than slimboreholes and with the addedadvantage of low drawdowns. Meansafe yields from eightcollector wells inZimbabwe and 20 in SriLanka have beencalculated at 2.7 Is-1 withdraw downs of 2-3m.These can be comparedwith typical yields in the %range 0.1 - 0.7 Is ' for slimboreholes with drawdownsin excess of 30m.

As collector wells are shallow —typically 5-15m depth to water — andhave a low drawdown, handpumpingwater from the wells is less arduousthan is the case for boreholes. Thewide diameter vertical shaft ofcollector wells also providesincreased volume of storage andallows two or more handpumps to beinstalled. This ensures that therequired pumping capacity can bemet and reduces the risks of watershortages when a pump breaks downand repairs are being carried out.

I

A vertical shaft for acollector well being dugby members of the local

community under theguidance and super-vision of a projectjorcmun

Horizontal drilling rigbeing lowered down a well

shaft

Using a chart recorder to monitor depth, to waterin a project collect well

Casing

fr*1" '~" '•"""Weaihered rock

with fissures oCM

i ~ '——---_ • "̂f -——.?• ' •

Raterais,, up to 30m long

* // " "

= r J- Pumps

* Soí| ' • aWater table í

/

"~ . v/.:"?t

2mBedrock

Schematic diagram of a collector well

"the garden putslife into people and

promotes self-reliance during

drought "- Siphelani Dhohani

Programme objectiveis

1 To assess the feasibility of usingshallow aquifers as a source of waterfor irrigated gardens of up to onehectare in area. In particular, theproject is assessing the potential ofusing collector wells to abstractsufficient waLcr from shallow basementaquifers for both domestic and stockwater requirements and yet stillprovide enough water to meet therequirements of an irrigated garden.

2 To compare and develop methods oflow-cost, high-efficiency irrigationwhich are suitable for use on irrigatedgardens. LimiLed water supplies andavailability of labour are the principalconstraints on the size of irrigatedgardens in most semi-arid areas. Thereis merit, therefore, in adoptingirrigation practices that increaseirrigation efficiency and lead to acombination of reduced labourrequirements, expansion in gardensize, increased yields and/or improvedcrop quality.

3 To study the effects of landmanagement on groundwater rechargeand to improve the criteria used for

Ploughing in one ofthe instrumentedsubcatchmenls of theRornwe catchment

siting wells and for selecting the mostappropriate well design for a givenlocation. The environmentalconsequences of increased exploitationof groundwater in semi-arid areas arealso being assessed.

To assess the physical, socio-economicand institutional feasibility of usingintegrated catchment resourcemanagement (ICRM) to halt, and,possibly, reverse land degradation insemi-arid areas. The long-term aim isto demonstrate that agriculturalsustainability can be achieved byadoption of community gardening aspart of a package of improved resourcemanagement practices which includeimproved livestock and forestrymanagement.

Project staffing

Romwe Collector Well Garden during the 1991/92 drought

Extensive collaboration betweenagriculturalists, hydrologists,hydrogeologists, economists and socialscientists has been a key component of theprogramme. With the exception of theirrigation trials, Lhe work has been carriedout away from the research station atlocations representing a number ofdifferent physical, institutional and socialsettings. The emphasis has also been onworking with and encouraging theparticipation of local people in evaluatingresearch recommendations at the villagelevel. It was recognised from the outset.that the many human, institutional andeconomic factors that influence adoption ofresearch recommendations would be asimportant as the viability of therecommendations themselves.

Programme chronology

In 1989 a collector well and associa-ted irrigated garden were installed at theChiredzi Research Station. These wereused for demonstration purposes and alsoas the location for a series of replicatedirrigation trials. Recommendations fromthese trials have been disseminated

il

actively by Agritex extension workers andby field staff of the IntermediateTechnology Development Group.

In 1990, the first off-station collectorwell garden was constructed in the RomweCatchment with the participation ofmembers of Tamwa, Sihambe andDhobarii Kraals. Since construction,around 98 families have used the well as aprimary source of drinking water and 46families have grown vegetables onallotments on the 0.5ha garden. Afterinitial social and institutional "teething"problems this garden has flourished, mostnotably through the 1991/92 droughtwhen all irrigation schemes using damwater failed and when the garden was theonly source of vegetables in the area.

The success of this first off-stationscheme led to an ODA-funded Pilot Projectthat constructed a further six collector wellgardens that are providing domestic waterfor around 1319 families and allotmentsfor 577 families. Valuable lessons werelearnt during the siting andimplementation of earlier schemes whichled to significant improvements incommunity involvement and sense ofownership on later schemes.

In 1992 work started in the RomweCatchment on a project studying theprocesses and mechanisms that controlgroundwatcr recharge. In 1994, additionalmonitoring equipment was installed tomonitor the effects of land use andmanagement on groundwater recharge. Atthe time of writing this pamphlet, effortsare being made to secure funding so thatthis project can become a long term

assessment of the physical and socio-economic benefits of taking an integratedapproach to community management ofresources in semi arid areas.

In 1994, two community gardenswere funded by and constructed incollaboration with Plan International insouth-east Zimbabwe in an area underlainby basalt geology. Several NGOs inZimbabwe have now indicated awillingness to fund further communitygardens in their programme areas.Preparations are also well advanced for asecond phase of the ongoing ODA-fundedprogramme. There is considerable interestin the programme by NGOs and researchgroups working in other parts of the SADCregion.

to Ndanga

B AlluviumYounger granites

'*!?¥ Older gneiss complex•,.i Undifferentiated gneisses

Beitbridge paragneissesKaroo sandstoneKaroo basaltGranite (¡urassic)Cretaceous sandstone

f Collector well gardensLVRS Lowveld Research Station A

to Masvi

10 20 30 40 50km

Romwe catchment's mainflume and sédimentsampling station

"The project issustainable

because the localcommunity and

researchers haveworked together as

a team"- Mai Stoko Ziwawa.

N to Beitbridge

Geology of area roundChiredzi and location ofcollector well gardens

IHbllf,;

Low-cost, high-efficiency irrigationExperimental DesignA series of replicated (rials were carried out on thecollector well garden at the Lowvcld ResearchStation during the period 1989 to 1994. The trialswere designed to compare and quantify thebenefits of several simple low-cost irrigationmethods that included: pitcher irrigation,improved flood irrigation, low-head drip irrigation,subsurface irrigation using slotted PVC or bamboopipes and subsurface irrigation using clay pipes.The monitoring equipment used included:tensiometers, neutron probes and small and largelysimeters. Crops grown in the trials includedmaize, beans, tomato, okra, covo, cabbage andrape.

The principal findings from the trials were:

• There is enormous scope for improving •water use effectiveness on irrigatedgardens. For example, measurementsduring a flood-irrigated maize crop showedthat 54% of irrigation water and rainfallwas lost as soil evaporation;

•• Subsurface irrigation using clay pipes had

advantages over the other improvedirrigation methods in terms of irrigationefficiency, ease of use and cost;

• Compared with traditional flood irrigation, •subsurface irrigation led to improvementsin yield, water use effectiveness and cropquality. However, these advantages aremost apparent when irrigation regimes arematched to crop water requirements;

Subsurface irrigation using clay pipes

It was shown that there is a low risk inadopting subsurface irrigation in that thismethod does not require particularmanagement skills nor does it increasepest and disease problems;

Large yield advantages were recorded infavour of subsurface irrigation ascompared with traditional flood irrigationunder summer drought conditions whenevaporative demands were very high;

Subsurface irrigation gave good resultswith relatively saline groundwater. Thiscan be explained by soil water movementand distribution being similar undersubsurface pipe irrigation to that achievedunder subsurface drip irrigation;

14

12

10

§ 8

WUE = water use effectiveness

.Mu0

-10 0 10 20 30 40 50 60 70 80 90 100% WUE improvement

14

12

10

| 6

III.-10 0 10 20 30 40 50 60 70 80 90 100

% Yield improvement

Comparison of analogous subsurface and flood irrigated treatments (1989-1994)

5

Clay pipes for subsurfaceirrigation can be made with asimple mould by villagers withskills in pot. or brick making;

Subsurface irrigation should beadopted by gardeners as part ofa package of measures toimprove water use efficiency andreduce risk of crop failure.Other measures should includelandforming to improve effectiveuse of rainfall and improvedirrigation scheduling, varietalselection, crop husbandry andpest management.

600- Total Evaporation(lysimeter)

Total Evaporation(neutron probe)

21 49 77Days after planting

T05

Cumulative water use of a flood-irrigated maize crop

Aerial view of experimental collector well garden at ChiredziResearch Station

Developing community gardens using groundwater

Experience gained to date in Zimbabwehas led to guidelines being drawn upthat distinguish key steps in identifyinggroundwater resources and ensuringactive participation of all stakeholders.The critical considerations during thedevelopment phase include:

• Close liaison with district councils isvital in identifying ongoing andproposed water development projectsand thereby avoiding duplication orconflicts of interest.

• Although there can be no substitute

for genuine community interest,undertaking schemes on a ward-by-ward basis improves logistics andenables communities to learn fromeach other more effectively.

The importance of comiminitymeetings cannot be overstated. Nowork should be: done in an area untillocal leaders have: been consulted.Meetings provide opportunities fordetailed discussion, for clarifyingmisconceptions, confirmingcommunity commitment and agreeingcommunity action.

6

Discussions takingplace at a typicalcommunity meeting

When possible, hydrogeologiealevaluations of potential sites shouldbe carried out. during diy seasonswhen groundwater levels are likely tobe at their lowest, using a range oftechniques including localknowledge.

In most semi-arid areas it is rare thata community will not have a need foror express an interest in acommunity garden particularly asthis will also offer a source of cleandrinking water. Thus at the firstcommunity meeting it is importantnot to raise hopes too high. It shouldbe explained from the outset that thescheme will only be possible if all thephysical, technical and economiccriteria arc satisfied.

The consideration, signing anddistribution of copies of an informalcontract (translated into the locallanguage) before schemeconstruction is a potent means ofensuring that communities knowtheir obligations. This is also animportant, stage in promotingparticipation and creating a sense ofcommunity ownership of the scheme.

<#••• J ^ , ,

SIMPLIFIED GARDENIMPLEMENTATION

FLOW CHARTcDiscussions with district organisations

(eg. representing area of S00km2) 3Discussions with ward organisations

(eg. representing area of S0km2) J"The project

scheme is now thecentre of thecommunity"

- Mr Patrick Manhiwe.

KEY STEPS INIDENTIFYING

GROUNDWATERRESOURCES FOR A

COMMUNITY GARDENNO

Process initiated by feedbackfrom village level that includesrequests for technical advice,

assistance and resources

Discussions at community level(eg. representing area of 1 -5 kmZ)

Tr^ Preliminary. XI Institutional, social and II economic criteria satisfied J

If social and Institutional criteria satisfied,evaluation of hydrogeologieal and

agricultural potential JT

Í(DoeDoes a borehole^ YES

well exist? I '

\

If physical and technical criteriasatisfied, further community meetings J

NO IEvaluate groundwater potential

using a range of techniques.Groundwater available? (Are yields/pumping ^ \

capacity sufficient to Isupport garden? J

NO

Use range of techniquesto evaluate most costeffective well design.

Any design cost effective?

f No garden atV this site

YES

Can yield ofexisting well

be enhanced?

When discussions with all stakeholderscompleted and informal contract signed,construction of well and garden can start J

^Proceed to second phaseI of social, institutional andI economic evaluation

Constructing wells and gardens

Once an informal contract has beenagreed and signed there are a number ofimportan I points that should berecognised during the constructionphase. These include:

• Experience has shown that monetarypayment for work done should beavoided whether this be payment byproject staff or by other communitymembers. In the former case,payment promotes neither sense ofownership nor good progress. In thelatter case payment causesdifficulties because the problemspoor communities have in findingcash. Automatic membership of theproject for those who do work is tobe preferred, others paying a cashjoining fee at a later date.

• In terms of community participationand sense of ownership, collectorwells have an advantage over otherwell designs in that, the communitiesare directly involved in digging thewells.

• Both women and men from thecommunity should be given trainingin pump maintenance and repair. Aset of tools should be supplied withpumps and be kept by a reliablescheme member.

• Official openings of schemes areenjoyed by all as well as providinganother important opportunity forthe community ownership ofschemes to be confirmed by all theoutside agencies that might haveassisted during scheme developmentand construction.

Garden Management

Regardless of the level of communityparticipation during schemedevelopment and construction, it seemsthat most gardens experience a numberof institutional and social problemsduring the first cropping seasons.However, production figures from theprogramme gardens show that once

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these are overcome garden outputstabilises at an acceptably high level.Some points worth noting are:

• Trained facilitators can helpenormously in resolving difficulties ifa scheme is experiencing social andinstitutional "teething" problems.

• Garden committees experience arapid change of personnel during thefirst cropping seasons.

• Members of new gardens benefitenormously from visiting longestablished gardens and discussinggarden management and crophusbandry with more experiencedgardeners.

• Good extension advice is vital forinexperienced gardeners as is theavailability of seeds, fertilisers,sprays and sprayers.

• It takes time for new gardeners tobecome aware of the marketrequirements and value of differentvegetables.

Average non-availability ofvegetables beforeand afterimplementation ofODA-fundedcollector wellgardens

"The collector well-is life for us and

our children"- Mai Never Mhlanga

Official opening of theMawadze Collector WellGarden

8

Socio-economic research findingsThe socio-economic aspects of lhe schemesfunded by ODA have received considerableattention. Baseline surveys and routinemonitoring show that:

• The schemes are economically viable, withan average IRR of 19% and total grossmargins per ha per year averaging at.Z$ 25 000 per scheme.

• Price increases for plots within the gardenindicate the degree of welfare improvementthe scheme is bringing its members. Manypeople, originally disinterested in thescheme now wish to join, to the extentthat at one site there is a willingness toforfeit 16% of a. year's income from rainfedcrops as a joining fee.

• The schemes provide extensive marketingopportunities for the sale of dry seasonvegetables to surrounding communitiesand townships. Schemes also offeropportunity for wealth creation andincome diversification.

• The wells and gardens play an importantrole in improving the welfare of womenand children in the community, by makingmore efficient use of time and labour givento horticultural practices, improvingnutrition in the household and providingan important source of disposable incomefor household items, education fees, etc.

Routine monitoring and feedback from localinstitutions have also indicated that specificenvironmental benefits of the schemesinclude:

• A reduction in pressure on the cultivationof marginal lands, particularly streambanks.

• Decreased soil erosion due to a reductionin the cutting of nearby trees and bushes,used to build and repair garden fences.

• The promotion of "long term" landmanagement strategics, due to thedecreased risk and improved security oftenure the scheme supplies.

• Experience and confidence gainedimplementing and managing thecommunity garden can help theimplementation of further community-focused projects that, promote sustainableenvironmental management practices.

Financial costs of the collector wellscompared to boreholesA framework for analysing the capital cost: ofcollector wells compared to boreholes hasbeen developed. It calculates the equipment,staff and material costs for a hypotheticalprogramme to develop 25 collector wellschemes per year for ten years (discount rateof 13%).

Using this framework, the total financialcost per collector well, that, is installed by amultidisciplinary team following the approachoutlined is Z$80,584. This approach ensuresa success rate of 100% (for collector wellsyielding greater than 0.61s'1 and the costscompare favourably with the alternative ofinstalling boreholes. For example, if twoboreholes yielding 0.3 1 s 1 each were drilled toallow two handpumps to be fitted, the realcost of each (considering a national drillingsuccess rate figure of 51%) would beZ$60,784. If a single borehole yielding 0.61 S"1

were drilled (at a national drilling successrate of 35%) and were fitted with a motorisedpump, the real cost would be Z$ 108,000.These figures translate to average costs perm3 of water of Z$3.36 for a collector well,Z$3.61 for a motorised-pump borehole andZ$4.06 for two handpump boreholes.

TO***»

Community members keeping a record of gardenproduction and water use

"During the 1991-92 droughtwe relied on the water and the

garden to survive "- Mr Tamwa, Headman of Tamwa

village.

Conclusions

Although there is still much workto do, the programme of work inZimbabwe is an excellent exampleof the transfer of technicalresearch findings from theresearch station to the real world.It has demonstrated, yet again,that technical solutions alonerarely solve practical problems.Attention must be given Lo lheneeds and aspirations of the endusers and to the institutional,socio-economic andenvironmental adjustmentsnecessary for any innovation to besuccessful.

The programme describedhere shows that there aretechnologies that can bedeveloped and used to

substantially reduce poverty andimprove the quality of life for poorrural communities living in semi-arid areas. There are large areasof the drier regions of Africa thatarc underlain by basement rocksthat could benefit from theapproaches that are beingadopted in south-east Zimbabwe.

Perhaps most exciting ofall, a first water developmentproject such as a collector wellgarden has the added benefit thatit provides an ideal initial step toother community-based activitiesthat are aimed at improvingresource management, reducingenvironmental degradation andpromoting sustainabledevelopment.

:¡¡'. il-. 'aré-"ív.'£iiinblo or.'i ' tflC ioiiüYvH.'.U

VI. R:i¡ HorIn .si itute of HydrologyIvallingford

•••|ü¡i¿..United

Hea¿ of Sl.al.ii ••;Attii: Dr C.J. LovellLowveld R o s c jP.O.Box 97, ChinZimbabwe

Mr P.J. Chillón :

British Geological SurveyWallingfordOxon OX10 SEEUnited Kingdom

MINISTRY OF LANDSAGRICULTURE ANDWATER DEVELOPMENT

ZIMBABWE

BritishGeologicalSurvey

Members of a collector well garden taking their excess produce to a local market.

Institute ofHydrology