Chapter-3 Bena Hydrology IND

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Review Design on Bena Irrigation Extension Hydrology

CHAPTER III

HYDROLOGY

3.1. THE HYDROLOGY DATA

The hydrological data that was available are as follows:

(1) Daily rainfall data at Noilmina catchment area:

Station of rainfallrecorder

No. Sta Elevation Long of data

ebobo !1" TTS # $ years (1$%& ' 1$$ )

*etalan !!+ TTS # 1% years (1$,, ' 1$$ )

Nif*-ani !! TTS # 1% years (1$,, ' 1$$ )

Source : Data 1994 up to 1999 taken from Climatological Station, Lasiana-Kupang

(") limatological data

Data ty/e 0eteorology Sta eriod

0onthly solar radiation ebobo "! years (1$,& 2 1$$&)

0onthly wind velocity ebobo "! years (1$,& 2 1$$&)

0onthly h*midity ebobo "! years (1$,& 2 1$$&)

0onthly tem/erat*re ebobo "! years (1$,& 2 1$$&)

Source : Hidrological eport, !"# $asapatria %unatama, 1999&'(((

This data is *sed for calc*lation of eva/otrans/iration with enman 0ethod.

(3) 4ct*al Discharge

4ct*al discharge got by co*nting discharge which overflow of Linamn*t* 5eir6 /assing

of sco*ring gate and inta-e gate at the time of field visit. alc*lation of discharge based

on water level at the */stream of weir6 geometry of sco*ring gate and geometry of inta-e

gate.

NIPPON KOEI DISIMPIII - 1


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4s for the discharge data7s shall be as follows:

Date "'8*li'"!!3

1!'4*g*st'"!!3

",'4*g*st'"!!3

" 'Se/tm'"!!3

1,' ctbr '"!!3

11'Nov'"!!3

Discharge(m3/s)

3.+" 1. 1. , 1.+, ".33 3.+&

(+) 9*/ab*mi 0a/

9*/a *mi 0a/ by a-os*rtanal6 Scale 1 : " !!!

Descri/tions N*mber of sheet Ty/e of ma/

atchment 4rea Noilmina 13 sheets ard co/y and Digital file

ena D1 ;rrigation Scheme 3 sheets rint and Digital file

( ) atchment area

Data of catchment area Noilmina 9iver on Linamn*t* 5eir are as follows:

9iver : Noilmina

5idth of catchment area : 1&1%63, -m "

Length of main river : ,$.!! -m


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LUAS CATCHMENT AREA

- INTAKE LINAMNUTU = 1618 Km2

INTAKETAEKOLA

LINAMNUTUINTAKE

1.618 Km

LEGENDA

STASIUN HUJAN

JALAN

SUNGAI

U

Figur 3.1 . atchment 4rea Noilmina 9iver in Linamn*t* 5eir


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3.2. WATER REQUIREMENT

5ater re=*irement for /addy is determined ta-ing into acco*nt several factors mentioned

bellow: Land /re/aration ons*m/tive *se ercolation and infiltration 5ater layer re/lacement Effective rainfall ;rrigation efficiency ro//ing /attern

a) La ! "re"ara#i$

;n ena irrigation scheme6 water layer re=*irement for land /re/aration is ass*med to be

" ! mm in total6 incl*ding "!! mm for sat*ration and /lo*ghing and ! mm for standing

water immediately after trans/lanting.

%) C$ &u'"#i(e u&e

ons*m/tive *se was calc*lated by the modified enman method

) Per $*a#i$ a ! i +i*#ra#i$

ercolation rate in general de/ends on soil characteristic> normally /ercolation rate after

in*ndated is aro*nd 1'3 mm?day. @or ena irrigation scheme6 the val*e of /ercolation

ass*med to be " mm?day.

!) Wa#er *a,er re"*a e'e #

5ater layer re/lacement is ! mm (or 3.3 mm?day for half month) at one month and two

month after the trans/lantation res/ectively.

e) E++e #i(e Rai +a**

The calc*lation of effective rainfall for /addy is based on ,!A from a half'month rainfall

with "! A no f*lfilled /ossibility (9 %!)6 while /alawiBa ,!A from a half'month rainfallwith !A no f*lfilled /ossibility (9 !). 9ainfall data that is *sed for ena irrigation area is



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9ainfall data ebobo station6 beca*se that is nearest station and re/resented rainfall

condition in ena irrigation area.

9ainfall data ebobo station from 1$%& *ntil 1$$ are ta-en from CLa/oran idrologi 6T. 8asa/atria *natama6 1$$$?"!!!.

Effective rainfall for ebobo station as fallows:

Descripti1on Sat Jan Peb ar !pr ei J"nR#$% mm &'#% $' '$#' %#' & #' *3#% 1 #% %#% %#% '#% %#%R#'% mm 1&3# 1'$#% $% +1# $+#% *#% &*#' % #' #% %#%%# % x R#$% (Pa,,-) mm 31#' '+#* &1#% &*#& 33#3 1 #1 11#+ %#% %#% 3#' %#%%# % x R#'% (Pa.awi a) mm 1%%# 11%# '$#$ *#3 &3#& *+#$ *#$ + %

Sat J". !gt Sep 0 t 2op DesR#$% mm %#% %#% %#% %#% %#% %#% %#% %#% %#% +#%R#'% mm 1#% %#% %#% %#% %#% %#% %#% %#% %#% $#*%# % x R#$% (Pa,,-) mm %#% %#% %#% %#% %#% %#% %#% %#% %#% #3%# % x R#'% (Pa.awi a) mm %# %#% %#% %#% %#% %#% %#% %#% %#% &

+) Irriga#i$ e++i ie ,

efore irrigation water reaches /addy field thro*gh canal systems6 a =*arter */ to one'

third of water in general is lost d*e to /ercolation6 management losses6 and illegal *se.

;rrigation efficiency eF/resses as ratio between water reach to /addy fields and water

inta-e.

Loss of irrigation water by canal system is generally considered as follows:

1 2 "". A at tertiary system

,. 2 1". A at secondary canal

,. 2 1". A at /rimary canal

Th*s6 total efficiency is:

G Eff. Tertiary system F Eff. Secondary system F Eff. rimary canal.

Hal*e of totally efficiency is aro*nd !. $ 2 !.,3. @or ena irrigation scheme6 losses in

each canal system are considered as follows:

%!A at tertiary system

$!A at secondary canal

$!A at /rimary canal

Th*s6 total efficiency is !.& .



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g) Cr$""i g "a##er

ro/osed cro//ing /attern for ena irrigation scheme is C addy ;2 addy ;; and alawiBa

starting from the firs half of November 1.

3.3. WATER A-AILA ILITY

The water availability for farming is *s*ally *sed on de/endable discharge %!A6 or failed

level "!A. The analyse res*lt of water availability of Noimina 9iver which based on the

calc*lation res*lt from Ni//on Ioei6 is shown on Ta%*e 3.1.

Ta%*e 3.1. De/endable Discharge %!A

Unit : m 3 /sec

8an*ary @ebr*ary 0arch 4/ril 0ay 8*ne

; ;; ; ;; ; ;; ; ;; ; ;; ; ;;

$#+% 13# $# % **#1% 11# % +#*% $# % $#*% #3% #1% '#$% +%

8*ly 4*g*st*s Se/tember ctober November December

; ;; ; ;; ; ;; ; ;; ; ;; ; ;;

&% 3# % 3#'% *#+% *#$% *#'% *#*% 1#$% 1#+% 1#$% 3#3% 3#'% Source: Analysis by Nippon Koei

3./. WATER ALANCE

;rrigation area is determined based on the water balance analysis6 *sing the following

form*la:

A 0 Q DR

5here:

4 G 4rea to irrigated ( a)

J G De/endable discharge (m 3?sec)

D9 G Diversion 9e=*irement (l?sec?ha)

n ena irrigation scheme6 cro//ing /attern addy ; 2 addy ;; 2 alawiBa is done with

calc*lation of irrigation water diversion needed with fo*r alternatives /lanting starting Nov'16



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Nov'"6 Des'16 Des'". The detail calc*lation can be seen on A##a 'e #& 6 and the calc*lation

res*lt is shown on Ta%*e 3.2 */ to Ta%*e 3. .

Ta%*e 3.2. 5ater alance for Nov'1



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Ta%*e 3.3. 5ater alance for Nov'"



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Ta%*e 3./. 5ater alance for Dec'1



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Ta%*e 3. . 5ater alance for Dec'"



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ase on the calc*lation res*lt6 that is choose alternative the first /lanting on Dec'1 with water

diversion needed ena irrigation scheme is 1.+1 lt?sec?ha ( Ta%*e 3./ ). 5idth of the irrigation

area that will be design is 36 !! ha6 so that will get the cro/ intensity is "$1A. The gra/hic of water balance ena 5eir is shown on Figure 3.2 .

3. . DRAINAGE MODUL

The drainage of ena irrigation scheme will be /rovided by a system which incor/orates a

collector drain and an internal drainage net wor- discharging to the nat*ral water co*rsescrossing the irrigation area. The drainage re=*irements are estimated for two -inds of area6 i.e.

the rice field area and the non'rice field area.

a. Ri e Fie*! Area

;n order to assess the drainage re=*irement in rice field6 the D 59D7s Design riteria was

ado/ted. The drainage water re=*irement for rice field area is estimated base on the maFim*m



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3'day rainfall with a ret*rn /eriod of years. Drainage water re=*irement of &.!! l?sec?ha was

*sed for designing drainage canal.

b. N$ Ri e Fie*! Area

The drainage water re=*irement for non'rice area is divided into two drainage re=*irements6

namely6 the /ea- drainage re=*irement and the design drainage re=*irement. The /ea-

drainage water re=*irement is estimated by the Der 5ed*wen or 9ational @orm*la7s by *sing

maFim*m daily rainfall with a years ret*rn /eriod.

The design drainage re=*irement is estimated by the following form*la *sing the maFim*m

one day rainfall with a 'years ret*rn /eriod.

Q! 0 4.115 a R6 ) A 4.72

Jd : Design drainage re=*irement (l?se)

4 : 9*noff coefficient

9( ) : 0aFim*m one day rainfall with a 'years ret*rn /eriod

4 : Drainage area (ha)

The design drainage discharge with a 'years ret*rn /eriod is:

Q! 0 1.52 8 .3 8 A 4.72

3.5. PEA9 DI:CHARGE

There are many nat*ral drains ? river from hill at the left side of irrigation area. The nat*ral

drain crossing with main canal6 so that need crossing str*ct*re i.e. a=*ed*ct6 cross drain6 andover ch*te. a/acity of its str*ct*re was designed with /ea- discharge. The catchment area

fig*re of nat*ral drain ? river is shown on A##a 'e #&.

4nalysis /ea- discharge for the eFternal drainage *se 9ational method6 that is method of

5ed*wen6 as/er6 and 0ononobe. ;n general method of 9ational can be written down as

follows:

Jn G K . ; . 4 or Jn G K . . = n . 4



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5here :

Jn G flood discharge for ret*rn /eriod n (m 3?s)>

M G catchment area (-m ")>

; G rainfall intensity (mm?ho*r)>

K G r*noff coefficient (')>

G red*ction coefficient of rainfall area>

=n G rainfall in m 3?s.-m " for ret*rn /eriod n

L G length of river (-m)

4ccording to 0ononobe7s method6 rainfall intensity can be calc*lated by the form*la as

follows :

; G ( 9n ? "+ ) ("+ ? t) "?3

5here :

t G L ? (," slo/e !.&)

4ccording to 5ed*wen and as/er6 r*noff coefficient can be eF/ressed:

' 5ed*wen : K G 1 2 (+.1?( . = n # ,))

' as/er : K G (1#!.!1".4 !., ) ? ( 1# !.!, 4 !., )

9*noff coefficient of the methods corres/onding to r*noff coefficient in the /roBect area that

re/resenting res*lt of the calibration and sim*lation rainfall'r*noff model (1$,,'1$$ ) from

the Tan- and Nreca model li-e as follows:

' on the ena basin : K G !." 2 !.+ >' on the 0ala-a basin : K G !.+%, 2 !.&>

Data of eFternal drainage on the ena irrigation area co*ld be seen on the Ta%*e 3.5 . and

9eca/it*lation for design of eFternal /ea- discharge co*ld be seen on the Ta%*e 3.; .



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Ta%*e 3.5. atchment 4rea data for eFternal drain

No. of .4

5idth of .4

(-m ")

Length of 9iver (-m)

Elevation


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eneraliOation of eFternal drainage flood discharge on ena ;rrigation area based on the

com/*tation flood discharge by 9ational method for vario*s ret*rn /eriod as the following

4=*etion.

J " G %.""!$ 4!. $,

6 9 "

G !.$%!&J G 1!.1%$ 4 !.&"&" 6 9 " G !.$%+!

J 1! G 11.""$ 4 !.&3, 6 9 " G !.$% "

J " G 1".3!3 4 !.&+%1 6 9 " G !.$%&3

J ! G 1".$,+ 4 !.& +! 6 9 " G !.$%&%

J 1!! G 13. &! 4 !.& %+ 6 9 " G !.$%,"5here J is flood discharge in m 3?s and 4 is atchment area in -m " .


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Chapter-3 Bena Hydrology IND