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Irrigation and Flood Control

Irrigation and Flood Control

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402 views114 pages

Irrigation and Flood Control

Irrigation and Flood Control

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reyadniit
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CE 4161 Irrigation and Flood Control Course Teacher. Dr. Kh. Mahbub Hassan Dr. S.M. Moniruzzaman | eauey eye Rete Ohya Md.Nahid Hasan Io) eACE aOera E-mail. nahid5959°email.com Dept. of Civil Engineering KUET, Khulna 9203 A Techniques and Quality of Irrigation Water 3 2 Water Requerments of Crops 14 3 Canal Irrigation System 35 4 Design of Irrigation Channels 39 5 Irrigation Pumps. 41 6 Headworks 52 7__|__ Irrigation Institutions of Bangladesh: Some Lessons 63, 8 Flood, Flood Estimation 71 9 Reservoir 87 10 Levees and Flood Walls 96 11 Supplied Sheets 99 Exam Question’2016 113 * we e101 racer ee eet // E464 r y : Honirieeaman Shy Frigation and Flood _Condyol re chapler i. Sc ail Sa Ht Define. Srigehion . Explain ifr necessity in a ropicad coun {ike Gangledesh « Toigation: — Erigation mney, be Aefned on ka scithee & erparal agplicahion & ach +o de land , in accordance vif Hr * cop requirmand” Heroughout Ma "crop period ' fox full edged nourishmede craps Grigahion is macessary th Tropico county liber Gangladesh because § Hs ogcul}urad bared for growing super(ov crops. > for grosing a numb 4- ops using a year. & whet ane To Bjediva, § Jeigadion } -> Ensure onoagh moisture for plank Me a > frovide oP imsutance agains} choi teth rough: > Cod Aix sd] and afmosphene dv provide a suifable sunoun dans - lao dilute hanmpal seth . chemicals in the sail. _5 Reduce harards §& sal Piping . > SoFfen Hilage pan. # define fw Gadion Bygineniing + Ont Eygimetrs have fo fwhevack 7 Trigation enginacring ts an applied cubject dealin site. : raves Tgation ; planning A sein, axtcution ,contyo| & sexvicing &§ Iavigahion and Wied Aorks Inigation Enginests have to infevach- Totlae > Ha ricwl sis ay, Galeri} hon iigation } v Planners > Sel seiendist > Mefcoroligis|— uy Farmers © Hydrologist yD Pawan Cs # Scape & Bicarbonafe concentration an reladed + Me concen ration $F colerum 2 magnesium. MY Backevial confanigation g te do Te flosmyy imparition male adhe enhit for fraigatin 7 Q_Sedimmb—in_weler: The feet F-sedimual prenent in Mas iwrigation wader ckpends pon Px type § waigaded Jand. When fina sediment from waher fs deposited on sandy soifs , tox fertility is improved OW oitey hand fF He sediment han bern derived from eroded areas ik may reduce Hn futility or decrease Ite ze permen- Aig for Amos all typo 4 craps, SAE =, 07 10, Mediam sodium odey | tarardow in Hine HFK / Joruved sls | (sr) sahich maz neqwive gypsum efe. | SAR = 10-18 Ruf — mag be wed on coarse -dextured | ov ovqanic 501] wi}, ged pomecbilily. lars F a4 ev | Be in jrigation 2 High sodium datey | Nay prove has rfl on almost al? (Ss) SAR= E16 | g | be leachin j | gt c 4 1 Bars addition prélem sodium acder A neprvcnh by Seer I Again , Elechyica} conduchviy i 26> micro mhos fem ab ste lich bitin fox vanga__ loo~ 260 $0, low selivily, wafer (2957 Seb fckoy Clamiffestion + GS, Wadley. ® An Fim -torduved soils the medium sodium wader (2) meq cree fa Follocsing. proms 3 > Soil becom lew permeadle w Sf start cating vffan, dy wy St becomes plastic and sticky Shey oe > SK ph imcnearen Araacds jak & alkoling sof). © Gapsam (ea604) addition , etter fo sel ov te Daker Is suggerted te overcome sodium baravds pod by Ms given ohey. z B2© varia wilh je results Fo gt hat ane ta considerations py we & sufface Waler oy 0 sousce § jnvigation ) y lower} available water WigBer|- (ost involved (trafiol , Operation 2 maintenance of) > Ewivonmenfol appeots # Wht ane He consideralfons for ux - Ground water wa sourer rigation ? 1 Safe eld §- ground gates: May” wuonhity & Water that can be exinacted undey spectied apetating condifons wifhouk producing undksivable nesubls . Such an — > Reduction §- wakey resourcer. 2s Develepmant &¢ uneconomic planning. > Bualitg degradation. > Tterference wif (prior oftier) wade right — land subsidence . Wy Water vigil Wy Wodey quality - wy cost involved , vy Envirvonmentol a@opects . H hat ana Ha ech Ff wing Gaifqer Ave Ground weber in ocon qHanht Results Using axcen Surface Water > Frensases artificial recharge = Ground eatery Tabi yo Pe — Wofey legging as leaching Is Inadequafe = Salinity Mensasey, Rea of wiley econ Grvound Weft: => Reduction & water nesoureen . > Development d- uneconomic planning . cae Quality degredaffon. > Milexference si}, Wager vig = land shsidence #& Ghok fs conjunchve we ¥ f inigation aohey 7? Ghat ana fe advantage 2 disadvantasen g conjuncive wr . Conjunctive use? Combined use & suvface oatey 8 ground water , so Hhak fhens is a balance betwen Racharse ond idd sound Oates . : j ERE Natural — (Rainfadt ) PT he it CDoigation ) Advantages dh Conjunchive ust cleapey storage G& Vey. i ey ee eS aii g storage shuhure. wy A sevien & drougtys can be Control &§ GWT js eanier. "> leaching can be effeck vely don by incorporating undey dvoinage & salinity can Abu be handled properly. i> Less ime involving prjcck, vy Strom dvain Site reduced on infilmation increased and suvfoce runoft deceased , W land area saved due len area ne and didvibubon ate Ds Adventoye ge Conjunctive tees D Consumplion gf fuel is excessive > Production ¢ hydraulic poou ned read W> Cost allvcation is difficutP- > Project operation is move cemplex 4 tthe} ane Aa factors governing Ake rack percentage shaving G sw a D Natural recharge Wt) ArhificfoA recharge Wy Aquifer charackeuishis , jlakifi sw oy GW : gail ity fe aint % Operation & mainfenann éF mackmary & strachies, WD Economic B environmental wpects , 8 Explain ophimum uliliaation 4- irvigation waher que quantity & afer a ubich 4 Ne yield is maximum is called dd ophimam dep) , : é 4 Therefore _ opm ufiliaation of inigation dade posal meas, qting max” geld oft a arnouj— G ache . quired by shorage Wake Required ff Soops Cwp period: Tr fime period dha elapses from fhe ins}ant § th sowing to Me instant of th harvesting is cobled crop period. Bore peried: es Fim bohween Are fies} aefering fa crop af the time & th sowing jo if love wedeving— before havvesting.. ‘ Sup paved Z Gare period . data la) Te tefal dep db aafer Cin om) nequived by a cp fo come 4o maturity js Med th delfa (4), Avaage Appsoximale Vahuy ba far cerfdin. rps iw Indio. vy sugarcane = [20cm v Vegetobler = 45 om vy Rie Sirs vy whet = 40 om Melescce i ee Barley 2 30 cm Garden fruik = Go om ire: Soar ies aU Foddw = 225m — Fear = is om Dag: buhy may be defined a she number & hechorey & land rigated for fl growth Goa given coup by stepply G 1 cumee (1 WL) 6 wader commuousle during the enhie bare period (6) F that crop. H derive o eedfation bfwan Defy 2 Delt. lef , Agnes be a crop g bare period = days and $ came § Wofer be supplied qo Mis crop on dhe field for B dogs. Now, Vue J acter supplied fo pris crop , Ure 1x(0x 24 *¢0 #60) = $6400% w’ o by dirahion duty WD) 3 w? supplied jr © days lilies, vB hectanielia taal 1 hectare 2 tolm Weta > Delotm™ | Galenvey MOS oy FC ee. 3 ee Fe gt oe D aco What ane A factors om Shidh pty depends ? D> Tepe & cop © Climofe @ Season ty Useful vainfal . Ww ee 4-sofl : YD Eiiciency & culfivation metro . 4 Injgatiom Eticiencion: 1 Waker convigense ficiency, ia Viator dativered fo te field via © oder supplied Gwh the canal ofA head Wy Water Bile oheameg , __dater stored in Ihe vob} tone duviny iwigahon an ce Vahey dalivered fe Wor field i uw Wofer shiege Hichency , Wadey stored in ke vob} tone duving ini jAToy J SieaNiod Gg? meled im He reek cone ‘prion fe in WM Wodew dishibuion Widency , eae 4) where, pa Mean depl fe water doves during iy”, d= Average 4 absoluke valuer df deviations from Me mean. % 1% kor Daderng: The first aedeving which is quen ba crap , when the crop is a feo cenkimetres righ , called kor aaheing - kor periods The kor wadeving mut be applied within o fixed limited period called’ or period # Belem crop volation with examples , What are the benififs Increare He Fertility se. > Reduce te disearen and warteger dur to insects. > Encreare the overall Cop yield, 4 Consumphive vse Ce) on Evay ofnans pivation Consumplive use for a particular crop may be defined an te tofal amount ¢ woty used by bs plant in transpiration and evaporation from adjacent Roilwon feorn plant leaves fn ang specified time. a _ Blfective Rainfall, Re Pacipitadion falling daring oa growing period Ga ciop hak is available te mad fra evapo- dnamspiration weeds f fe crep , is called effective rainfall, aL _Consumplhive Inigotion Requivment (eta): af is the arnount & Inigotion wodey required in order qv reek The evapodranspiradion mead S te cvep daring i Ru Foo pci 2 4 Ne} _Inigalion Raquirmant (N08): Ah is Ma amount & inigahon oder required fo meek fra Vapotranspivation needs 4 the cep ar wean Ofte weeds such an leaching NERS Cu-@e + Waders (Rercelobion / teaching )] tt Fackrs affecting Cu ee = Hur ditty a Sunlight — Wind movemen}— + Bslimation cu © Bang - eo Sm ee Where, cas Moth Consasnphive use in om, ‘& Crop fachor P Hontbls pera annual dag light hours Jhat occurs during dhe period. f= mean monttly Jemperahite mn °c Yow © bargneaver Clam # pan epoyodion nedrod . Cus kEp whim, €,2 fn evaporation, | k= eu coefficient, | oO fenman's Equation : Al te AMntEaY when, E> Daily potential cvapotranspivari aay A= Slope Aus saturation vapor vs. Temp. curve ot fe mean aiy deme. My = Net Incoming slay Yadiation. | Gp Glender Soro Aus AMAN = Fall i = Sostially BU Tw = staple fog HW — Protection from a suplinentag- tw" — fev monsoon pre monsoon foo ds pvotecko: — Droinage — Monsoon flood flood protection prolection ~ Embaqkmeat— define field capacity - Devive the sof. ttatshure - Srigation relation equation. field capacity: “Tha field capacity ts the water content ha sol after free dvamage hon Fala place fora sufficient period - a dh & waadey refoined ina cerfain vAM A soi eas af & same vol” § dey sotl Z 00 % A, soi] area = Le dept cf rool Rone = dm Density 4 soll = % KN/w? 2 vol" §— soil = dais d wn” 2b & dw sil = ed = Vad UN ey Fea F wh & aater nafained iy unit ans de sal (5D OF sama amount & ayy sof sad 2 ah. d woder rafained iy unk nea dsol] 2 Yyd +f kN fw ees einstein ed) =e Mee atce a Tg Deh Gunter . UE E Yo | he ‘ Z oe fe chy 5 , od copay a ce fol A Redity available eee eared ne a cape at oe ee moisture moistare emai i WS Temes Mle Zp mois ha ee cot Bete ance Frapervioun strauen f Rael Salty pik— slag natliee Tis & Rady avellabla_woihe = 70-407. & Avod| abla_moisre_ % Permaneni- cfftig psn (rap) pup is Arat aaher content at ahich plawk can no longer extract suficient wale fy ils grooth. Available wmoishure Peer Cesanwep Redily available meshes Apts that potion & He available ynoishiye which is conily otnacted by Me plank. sol_motshave deficiency: The water naquived fp bring. Kar sol mmoistuve covfeni- a given sol to ifs field capacity. 4h tigation Melted (Chz01) | dt sha do you maan by sutface 8 sub-surface iwigodion, Sxplain vAlamificaion 6 Irrigoken : > surface vig ation. > Sub-sunfacs. fnigation Surface _iwigahon : The fvigotion procon ™ ahich ater ovailable at a highsy (evel or mechanically oy een lifted matey os dhe soil surface | This (ype § ivsigation ay be domified o When tie wah {s available of a higher Flow _irvigagio level and ik ts supplied do [ower level by action fF gnavily - Lift icvigation When wahey fs oy manual rmxans , such a pumps 2 Aten supplied for wvigalion. Sub-surface imigaion: the ivigation proeem in whidk water doo wot oc Hee soil surface The under ground aghey nourish Hu plant Yools Wy capillag. 3+ may be divided info the following 40 Hyper: Nafural swh-imigahion: Leakage fromm channels, de. ae undeground and during fom age Frrough flee sub-seil iF mag tnigade craps by capillary sx, then underground iwigation is adived - simply by natural proce), aifrowt any additonal extra effort: iF fs called Mahal sub- ivnigation ; Avbificiad sub iwigahion: when a syston ef open joined drains is arhficialty laid beloo the soil, so a dw up Wffed_ by some mashanicol supply ader tu dha crops by capill axilg , then Th is known a avhficial sub- Wrrigation 4 Bplom Ha fillowing oder dishibuiton dechniquer wif, igee Tn this mathrod, ditches tein Sry Std. an oraveded in the field, and oy 4 meq be cifker on Hee confor or up \ and down fue slope. Wafer from. | Mais ditches, flows accross Ku freld Since fe movement G wafer fs né-— restricted, fs sometimes caked vild Flooding. Minow —_ Faitial cot 4 land prepavodion is low . = labour requivmenfs ana wally highs - Wate application ficiency is low. ~ Most suitable for fase growing reps. pastures fe . D > Te land is divided inte a numb 4 ships sepasoded by low Lewes cole borders. = Land arear confined i cach strip is G- w-20m in width 2 tao-qoom im Lengit, . > Ridger beheen bordeys shouwtd be sufficiently. highs to preven overtopping during inigation. ba leven borders (Wha Flooding + St is similar do ordinary flooding excep} flay Moe aafey js confrolled bq surrounding New check area iif, Joo and flak levees. The confined plot anea vorier from 0:2 4 og heolaven Spel. Aig Laveen connen @wain flooding, Ti; matted is special ype F check flooding and is adopted specially for erchavd tree. One or move tees ane generally placed mM He borin B He surface Is Flooded % in check ween ies fit] = ce Ft Hain ditt. 7 Genie Farvows ane narrow field ditches excavaded befween vows ff plank and cry inrigation uotes Asougl May « spacing 4- furrows is defamined by Me propes spacing G Yow plants - Fuxvouws vary from g~ 30 em deap and mat be. much or 400 m long. Wafey is applied do Me soil im Me form GF a sptag Abvough o nedwork & pipes 2 pumps. Sh is a kind dan arhificfal rain and AMsrefere, Biv very good result. Abts a costls proceso and widely used jn USA pose §— pete F SEPT Take epply- ‘Pipe Abis He lafevt field nigahion dechnique and % retart— for adoption at places ohene Mane exish acute scarcity F inigatton wafer and oftay salt problems. In Ahi method water is foray and dinely applied do te roo} Zone F fre plants , thereby Wend ising Ma loser by evaporation & percolation. (Gn eB Sat ‘i : BH Negative Pressure Difference B ation CNPDE Mechanism NPDL system a land sw sudeace invigadion and is composed Fa wader reservoir and a porous pipe jastalted in sol, ‘Te aahey rayervoix is placed at a lower elevation then the porous pipe. geurde negative pressuve, Pre Water moves towards fhe porous pipe From ha reservoir in a woke supply conduit linking hese 420 oben dhe absolte value f matric polewtiad II ic longer Ahan absolute value & Py , \Pal . The supplied water vate is proportion qo negative — pressuve difference (opp); [¥] -|fal ee supply Sle: Gary, Example 2. If rice requires about 10 cm depth of water at an average interval of about 10 days, and the crop period for rice is 120 days, find out the delta for rice. Solution. Water is required at an interval of 10 days for a period of 120 days. It evidently means that 12 no. of waterings are required, and each time, 10 cm depth of water is required. Therefore, total depth of water required 4=12x 10 cm=120cm. Hence A for rice = 120 cm. Ans. cm Example 2/2. If wheat requires about 7.5 cm of water after every 28 days, and the base period for wheat is 140 days, find out the value of delta for wheat. Solution. Assuming the base period to be representing the crop period, as per us practice, we can easily infer that the water is required at an average interval of 28 days up to a total period of 140 days. This means that Was no. of waterings are required. ual ‘The depth of water required each time = 7.5 cm. - Total depth of water reqd. in 140 days = 5 x 7.5 cm = 37.5 cm Hence, A for wheat = 37.5 cm. Ans. Example 24. Find the delta for a crop when its duty is 864 field, the base period of this crop is 120 days. Solution. hectares/cumec A(cm)= 50h 8 where B is in days and D is in hectares/cumec In this question, B = 120 days and D = 864 hectares/cumec 864 x 120 OS ghGOr Example 240 One cumec of water is pumped into a farm distribution system. 0.8 cumec is delivered to a turn-out, 0.9 kilometre from the well. Compute the conveyance =120cm. Ans. efficiency. ‘ Solution. By definition, Output ieee 100= 7-5 100=80% Ans. Example 9S. 10 cumecs of water is delivered to a 32 hectare field, for 4 hours. Soil probing after the irrigation indicates that 0.3 metre of water has been stored in the Toot zone. Compute the water application efficiency. a Solution. Volume of water supplied by 10 cumecs of water applied for 4 hours = (10 x 4 x 60 x 60) m® = 1,44,000m? = 14.4x 10* m3 = 14.4m x 10* m?= 14.4 ham. si Co 10*m?=1 we Input = 14.4 ha.m is a Output = 32 hectares land is storing water upto 0.3 m depth. i Output = 32 x 0.3 ha.m = 9.6 ham ) application efficiency (n.,) Queer 100 = 3 x 100= 66.67% Ans. Example 2.6. The depths of penetrations along the length of a boarder strip at Points 30 metres apart were probed. Their observed values are 2.0, 1.9, 1.8, 1.6 and 1.5 metres. Compute the water distribution efficiency. Solution. The observed depths at five stations are 2.0, 1.9, 1.8, 1.6 and 1.5 metres, respectively Mean depth =D = 2. O+19+ Les 16+1.5 _ 8.8 _ 1 76 metres 5 Values of deviations from the mean are (2.0— 1.76), (1.9 — 1.76), (1.8~ 1.76), (1.6 ~ 1.76), (15 ~ 1.76) ice. 0.24, 0.14, 0.04, —0.16 and — 0.26. The absolute values of these deviations from the mean, are 0.24, 0.14, 0. “and 0:26: Prk 0s ¥ The average of these absolute values’of deviations from the 0.24 + 0.14 + 0.04+0.16+0.26 5 0.168 metre mean =d= 0.84 _ == The water distribution efficiency d 0.168 ={1-“|=| 1-722 |=1-0.095=0.905 -{t-d)e[1-248] 1-00 Hence, the water distribution efficiency =0.905. Ans. A stream of 130 litres per second was diverted from a canal and 100 ered to the field. An area of 1.6 hectares was irrigated in 8 i ir id was 420 . The fective depth of root zone was 1.7 m. The runoff loss in the fie! ee The oo of water penetration varied linearly from 1.7 m at the headend of the ral to 1.1 mat the tail end. Available moisture holding capacity of the soil is 20 cm metre depth of soil. It is required to determine the water conveyance efficiency, cae application efficiericy, water storage efficiency, and water distribution efficiency. Irrigation was started at a moisture extraction level of 50% of the available moisture. Example 2.7. n litres per second were deliv ". oO Wafer conve, an ce of feng MW) Acdey delivered b tea fields ) wale applied info de canal Shite SEE Poe \so a y WV () Water app! _AWeiemeye wend 6) Bade _stoved in Mea voot roe duving _falgeHon hake lived Rocoheld 100 Water, supplied te Me ffeld daring & lows Zin Vite, = (OFS COED Uhr = 2EEO chim Runde los mW te field ~ Te wate shred fy dic tosf tone = 2860- 170 es = 2460 ane 420 eis 2460 - = —§<— _ *(0 Me 2860 See Bo? teas (WH _Water_slorege elfen Co.) Wed stored ty fe veot one duvi Boter needed tn Vook gone prioy te Hota helding capacity, sof tocm per m depih + NFm depts § sof} tone 24 em v " Mofshere Aneady ovediable in veot aone a A ti, Steck = gettin = ey S Foo = Addrtfonal ade nel in vost am = 34-17 ee tee Wot naded in vost sore pricy h ‘enygation Worn iO. Be 2 I ore = 27420 CH ot actual Aw shoved dn act zone a 24¢9 sae eee —X (| = 90 ¥ © Woke _ anita eG Ce IS Alene , = Mean dept, A weder stored ‘im dhe voot zone Ee) ea eal z aie Neola a. Ocoee [uletaje o> dn oy. fe fee absolute valine cevintions from mean CEOS 2 OS = = \aee , a C 1 5) 0 286 as 6 7, Example 2.8. The following table gives the values of consumptive uses and effective rainfalls for the periods shown against them, for a Jowar crop sown at Bellary in Karnataka State. The period of growth is from 16th October to 2nd Feb., i.e. (110 days). Determine the net irrigation requirement of this crop, assuming that water is not required for any other purpose except that of fulfilling the evapotranspiration needs of the crop. 6 = aie? Give Gen ae ae ee Dales Cu. comm) Recomm) eb i equine Odo bey Ue DL 37-0 30.6 6a November %l- 90 4 204

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