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TIfE GlWIDL\N,MoOOaJMay14,2012

For The Record owmJ]l'lj;JIJ~r;I:'II;m,t;\iI!1Q;Jlt1:W11't~

Irrigation development and practices:

The good, the bad and the ugly (3) Being text of an inauguraf lecture series 7 delivered by Prof. Jeremiah Oludele Ojediran of Ladoke Akintola Universtly ofTechnology, Ogbomoso recenHy. 'T"HEfull bene..iu of IrrigatJonan: not onlycap1 tum! by famK"1'S, butan: also spll.'ad t:o wider sections of society; These externality effeen all.' the unintended inwme(alsoempfo,yTnent) equivalent of welfitre changes brought about by tile Irdjtiltion project.lhe I!Ktent of such lnigauon Induad p'JSIl1Ve externalities, orspilioVer impactS ofimratlon ~ts, Is much wider In scope in largMcale imgauon profect,s, conoibutlngsi),'iliflCanuyto Iheregional and nadonal dewliJplllent pace of a country. Wilha dearunderstandlnsand In agreement of Ihe pmiti~ I mpact of irrigation tkvelOI'" ment and Pr.K1 ice, our ll.'Search 'Mlrk, OjtdJr.m and5.tnJ{Odavi~ (loOO}.was published 105ensitiz.e the J(ebbf Stilte and' !.he Frderal Govern. mrntsofNlger ato the neo::s.sltyofhames.slng the imrnensea.ld untapoed potential oflhe main Zauro Polder Pilot Irrigatlon SCheme and me probable plJsltivr: Impact of this scheme on the food produuion effon oflhe counlIy. 'Ne sta[t'd .tSSe1tM 1y. uslnganon-g Ol ngsuccess.fuJ project. that tho' success of the [hrre ~ar mal cane plotS whk It led to the estabU.5hment of a large sale co mmerclalSugar prnltctat Badta, Nigeria In 1961 : hould lta~sriY«Jasan impetus tothe Sokol o Rima RiVl'T Basin ~Iopment Authorities, (SP RIIDA)which estabUshed (he Zauro Pokier Pllo[ Project (ZPPP) In 1980 at Bimin-Kebbi. NtgCria to quJckty-commence me full scaleschell 'e [0 boost the food and fibll.' production drl1rt.5 oftheCoun~Sadl~ thllt¥one yearsafter he commellO!'mt'nlOlthe plrot scheme,lht' m;-In Zauro PolderProject (ZPP} had not takdl ( ff. Impaasof lnitatlon -THE 8M> Mr_\lice Oldntellor,sir, mo~ than ~rbefo~ we live in rurbulenttimeswith myriad of problems, ~gingt-om u nemplO}'!Ilem tosG!IViItion and as if lO aggr.avate an aJ.1l!~ bad situation. ctlensl~ degradation of the environment has becolne rampanL Whaherweare in ag~~nt witil this or nOt, the survtval of thl.5 generation and lhat of the future depends on iheenvironmentl l The Il.'aiitiesall.'alll.'ady unroldingbefo~t)urown vt:ryeyes-with poilution,arought. roods,soll rrosion,dlmate changeanCl incll.'ilSInglybarrm and unproducti~ lands. So..u I have: stilred eanler, me need to Identlfyand prn'l!ntOT ameJIOl'ilte the PrniliJIng nega~ Of ddverse environmental .5ltuations shouk! ~ the compelling or driving force

The impoupdment of water upstream of dam also leads 10 loss of natural

foresl (deloreS1a~on), wild life and grazing larids. That is, the flora and fauna are also adversely affected. In Nigeria, NEST (1991) noted that much needed vegetation, such as

woodlands, forests, and grazing lands have been wiped out in areas where irrigation has been intro-


Inall areas,lrrlgation InclU.5l~ Irrigation has condnut'd to contribute slgnlficantlyand posItivdy lD ~nyaIImation, food 2CUrity: and improVed qualityorufeforrural and urban populations worldwlde..lhese con, tJibutions, I hiM!!descrlbed,iustlfiably as lllE GOOD. However,despiU! Ihese positiV'eeffecr:s, Irrigauon development and practlces havr been iI.5.SOdated with seYeral negatlvt: ImpactS. both during Inframucturaf construction and operational stages. Hener, the SU.5talnabllity of Irrigated agrlcultu~ Is being questioned, both «onomlca lIy and environmemally since the posi~ impilctsofirrig<llion 111 theexeansloll and Imenslfication of agricultull.' haW' ba!n oJ>. served t:o ha~ thepottnlial for causing nega~ side effects.. Thfell.' existS evidmcfe thal following Irrigatlon,large tracts of land have become unsuitable for agrlcul~ and srudles havt: also shown ad~rse environmental effects on publJc healm, soil and wa£er Il.'gimes, water quality and In someasessocio-economlcconmdons of the pet?p1e..5pedfiGlUy; In the laf8e and medium scale Irrigation projectS, lhell! ex· Ists the potentia] of major environmental disrurbances posing srresses. dlsOlient..tlon, polludon and health hazards- Thesedlsturbances have had serious deleterious effects on both man, animals and the environmwt. The negative impacts of Irrisation appear to occur in rwophases viz: dunngdevl!lopmenl and pl'ilcdce Which can be G1~orized as: (I) I~as duling construction stag~ (devl!lopmem and (Ii) en schemr becomesoperationaJ.(prac· tice). (AfOl and Slngh.1987 and 1991;otedlran, 2004a) As I have earlier reponed on case studies of IrrI~tion schemes In thTff River8.Jslns In Nigeria (Qied lran, 1004a ~ the d~lopment of InMlum - largescale irrigation schemes qui£eoften In· YOMs the construction of damsand ~Irs and In cases wherfe surface methodsofirrig<!tion all.' to be employnl, canals all.' also constructed These constructions oftw lead to Il.'moval of \oegeL1l ct7'o'ers displact:mem of human and animal population and submer· gence of large uamiof a~rulrural and grazing lands. Theconstruction of dams leads to tile impoundment of large body of water, with conse-

Prof. Jeremiah Oludele Ojediran

quenl submetKence of land areas upstream of tile enVIronment. When Irrigatkm schemes become operaIhe dams..lnhabltanu of such lands all.' usudonal, problems wtJich werfe COVttt during !.he ally evacuated before me consuucdon complannln3 and col1$OUction stages are soon nomences and resettled In totallynew ticed Th1s Is bec.ause, thl.5 phase of irrigation environment.Exampll.':'i of these abound development involvei me application of one 'Mlndwide. In Ind1a,.lBoo peoplewell.' displaced from the or mo~ of rhe irrigation methods (le.. the practlce) desaibed earllerin this kaure_The canal sl£e of Mahl-Kadana Irrigation projea problems which emanateareWt':1l captured in (M~and Purohlt.I98S~ l n~igeria,K1riand FIg-9 most of which havt: both soon and long. badln-Kowa reserwln on the RJver Gongola tenn effects.. ma)orpoLentlai It'd to lht' displacemen[ofis,OOO and 26,000 people respectivtMAdams,1995);44,OOO peas- negi'ltiveenVlronmental impac:tsob$erved on larxe and medium Irrtgation projects Include: imt fanners well.'diSplaced byKalnJi Soil degradation, crustTormation_ wa£erlogiaU.l2,OOO bvllga la"ke: In Kano,anomer ging and Sillinisallon of soils,groundwater 40,000 byotherre;rfWirs in Kano; 14,000 ""'ele WHe dlsplilct'd bv the Bakolori scheme, and downstream pollution, inCll'ased Inddence of water- bOrne and water- mated diswhi eGoronYOdi~crd20'ooO prople(NESTJ99I~ In nstate, priOrto the 1m,""'~radatlon of .soils (5011 crusting) poundmentof the n~r,anumbuof Soli crust.lngon agrlculrui.l.llands bec.ame an villages existed on bOth banks scattered O'o'er Issue when pooT seedling emergence and sigan area of 42km2 _These villages well.' evacunificant dectNSC' In crop yield Wt':rfe observed ated and resenJed In 169 housing units in a on some fields as earlyas 191-4 (Carnes, 1934 ~ new-environment. The stress ani) disorientation causm by such dlsplattmems, dispossess- Soil crust'i wtJkh all.' fonned by the Impact of falling walerdror on the soil calISe medlam· Ing farmefS of their wmlands and cal desnucdono aggregates, washlng--in of unsatisfactory Il.'SC'ttlements have worsened fine partiCles Into tfii Infrr a~tr pores the situation of evacuees and have In some cases led toourrigh[ rnoohs_ ThI.5 l.5considered and mpture of the soil aggregates byalrentrapped In the pl'l."VlouslY(lry.solL Upon drybad and unheallhy. The Impoundment of warer upstream of dam Ing. the layerof soil thus funned haidens to also leads [0 loss of narura.l forest (defoll.'SLlprOduce crust. Several studies(Hanks and Thorp, 19S6; Edwilrds, 1977;~I,lm and tion). wild lifeandgnzlng lands.'that 1.5, tht' 1980; Bilbro e[ al~ 1981) Il.'ponai poor seffiling DOCiIand raunaa~alsoad~rselyaffected In emergence and Inadequa£eCtOpstands in Nlgerla, NEST(199t) nol'OO that much needed cap~.solls- as a result of the Impactor water ~doJl,suchaswoodlands foll.'Sts,and drops from rainfall and sprinklers duringOYH&l!Izlnslands him!! been wiped out In areas wh~ Irrigation has been introduced In Kane heaCi irrigation. Also, due to th~ surface sealing stilte alone some 3.000 kml of what Will fOlnt thatocrurs In thrCtust fonnlng process.lnfllrese~ and fannlallds now lie underartlfidal nation 1.5~ly reduced Jeadlngto Increased surfat:r runoff and lM!r1and flow and conseJake.. Similarly: in Kabini project of Kamataka quently loss of topsoil due to emsiOIl. SClle,lndla,a totiil oC6400 hKGIll.'SoCland was submerged, but the COll.'Sldeared fOTreha- Thl.5lssue oC .soil crustin~ppm&, or great concern In the t980 sin the 'cultural bllit-ation was almost thrre times theactual sa:tofoftheUnited K1ngdom (UK. Thlscularea submerged The dispute in Ihls d~lop­ mlnatt'd Into my researCh al M5c 1f'Ve~ al SI}menta:! phase Is the dls\EirtiOn bet'nftn soeCoilegeofCranfield Instlru£eor rneaaualarea.5tJbme ~lheschemeand the forest area deared orrdiabllitadon of!.he Technology (now Cranfield Unfvtorsttyl 11«1. submerged tJilhltat. The lauer-area sometimes ford, U_K Which wasan wlnvt'StiJrltlon ntoSoil amounts to three or four times the submerged Cmsting underdiffell.'nt Irriganon Intensities and Durations· (Oiediran.1934 ~ area. These losses constlrure some of the ad~ Impacts of Irrigation devclopment on