J. Basic. Appl. Sci. Res., 2(8)8218-8229, 2012
© 2012, TextRoad Publication
ISSN 2090-4304
Journal of Basic and Applied
Scientific Research
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Evaluation of Flow Capacity and the Pattern of Water Requirement in
Irrigation Area of Lereh, Jayapura Regency of Indonesia
Pitojo Tri Juwono1*, Dwi Priyantoro1, Nimbrot Rumaropen2
1
Department of Water Resources, Faculty of Engineering, University of Brawijaya,
Malang, East Java of Indonesia
2
Master Program of Water Resources, Faculty of Engineering, University of Brawijaya,
Malang, East Java of Indonesia
ABSTRACT
This paper intended to study the suitable pattern of water requirement in irrigation area of Lereh. In addition this
study wanted to evaluate the flow capacity of bearer channel based on the water demand due to the selected
cropping pattern. The methodology consisted of analysing dependable discharge of 80% and irrigation water
balance due to the some alternative of irrigation water supply and cropping pattern. The methods which were
used in this study included Stagnant Constant Head (SCH), System of Rice Intensification (SRI), and
combination of the both system. Alternative of cropping patterns were rice-rice-second crop, rice-rice/second
crop-second crop, and rice-second crop-second crop. Design of water distribution for every cropping season due
to the Relative Second-crop Factor (FPR) and K factor was based on the balance analysis of irrigation water
requirement. Result showed that selected cropping pattern was rice-rice and second crop-second crop with
enough water supply criteria of 0.12 < FPR < 0.23, but field water demand due to the SRI method with water
stagnant of 2 cm, water distribution interval on the vegetative phase was 5-8 days and the generative phase was
7-10 days, and it was hoped to have been enough. The channel capacity was designed to be able to flow the
maximum discharge of 2,300 l/s and the minimum discharge of 300 l/s due to the available velocity control
between 0.6 and 1.5 m/s in order not to be occured sedimentation and erosion in the irrigation channel. The
results could be used as the consideration on distribution optimal water distribution and it could be known the
channel capacity of bearer channel in flowing irrigation water due to the cropping demand
Keywords: irrigation, water distribution, cropping pattern, SCH, SRI, flow capacity
INTRODUCTION
Planning of water resources is not an easy job mainly when the case is as national wide [1][2]. It becomes
complex when an area is unstable or some events are unpredictably [3]. The main objective of water resources
management is to make balance of the demand and supply of water resource for a specific area taking into
account various dimensions like time, space, politics, economy, environment, and other aspects. Regional
decision making is considered to a variety of technical aspects which is needed for being decided [4]. Water
resources development in Indonesia was targeted to supply some kinds of water needs. The kinds of water needs
include for irrigation,industry, hydro electrical power, recreation, and daily human needs. Indonesia is as a
agricultural country. Therefore the important aspect of water resources development is used for irrigation.
One of the Indonesian government efforts for implementating food suffering especially in outside of Java
island was carried out in Papua Province. Indonesian government has opened the potential area of Lereh
irrigation area that is located in Yapsi District of Jayapura Regency. The irrigation area of Lereh used the water
source from Nawa river through the Lereh Weir as water capturing with flowing the water by gravitation
system. The system was planned for supplying the agricultural area of 2,119.36 ha. The planned cropping
included rice and second crop. There were some efforts had to be carried out for obtaining the maximal
agricultural production like the usage of well rice varietas, optimal distribution of irrigation water, regular
vertilizing, and wiping out the plant disease accurately.
Irrigation scheme was generally designed by using design flood as the maximum discharge which could
be flowed through the intake gate of weir. This maximum discharge could only be reached if the water supply in
river was sufficient. Whereas in dry season, water supply in river was decreased so that would decrease the
flowed discharge through intake gate. If the channel which is designed by high design flood being flowed with
low actual discharge so the flow velocity will decrease. If the actual flow velocity is under the arrangements of
minimum velocity, the water is not able flowing to the farest structure and if the irrigation water contents
sediment, it will occur sedimentation.
Based on the reason as above, it was nacessary to make a special study about the pattern of optimal water use
in order to function the irrigation channel well and it also important to evaluate the flowing capacity of existing
bearer channel. It was hoped the maximal and increasing agricultural production due to this special study.
*Corresponding Author: Pitojo Tri Juwono, Department of Water Resources, Faculty of Engineering, University of Brawijaya, Malang,
East Java of Indonesia. Email: pitojo_tj@ub.ac.id; pidiaa@yahoo.com
Juwono et al., 2012
MATERIALS AND METHODS
The irrigation area of Lereh is located in Yapsi District, Jayapura Regency, Papua Province of Indonesia.
Map of location is as in Figure 1. This area is fall between south latitude of di 2o49’23,53” and east longitude
140o06’59.46” .
Lereh
Figure 1 Map of location
Lereh irrigation area is as a potential agricultural area with well soil fertilizing. The water source comes
from Nawa river with Lereh weir as the water capturing. Lereh weir included two intakes such as the left one for
supplying the irrigation area of 1414.76 ha and the right one for supplying of 704.60 ha.
Data collecting in this study used surey approach. The data was collected indirectly from the related
institution as secondary data. This secondary data included data of hydrology, climate, topography, geology, and
agriculture. The steps of analysing data were as follow:
1. To analyze the design flood using Log Pearson Type III and Unit Synthetic Hydrograph of Nakayasu
for controlling the main structure.
2. To analyze water supply using the method of dependable discharge due to the ouput data of Mock
method.
3. To analyze irrigation water requirement based on the some alternative of cropping pattern and crop
type using Design Criteria Method of General Working, Stagnant Constant Head Method (SCH), and
System of Rice Intensification Method (SRI).
4. To analyze water balance between water supply and demand in the irrigation area of Lereh.
5. To design the pattern of water requirement using the method of Relative Second crop Factor (FPR) and
K for every cropping season by dividing the Lereh irrigation area into some blocks.
6. To analyze the cropping rotation time based on the pattern of water supply.
7. To evaluate the channel design based on the water demand during the preparation of area, maintenance
of crop, and cropping time of second crop.
Water balance
Water balance in an irrigation area is nacessary to be made for dectecting the condition of irrigation water
demand and dependable discharge in the intake. Analysis of water balance is based on the irrigation water
demand of used cropping pattern compared with dependable discharge. If the river discharge overflows, the
irrigation water demand will be fulfilled and if the river discharge does not overflow, it indicates the lack of
discharge.
Evapotranspiration
Evapotranspiration is the process union of evaporation and transpiration, This study used the method of
Penman Modification for analyzing the potencial evaporation (ETO) with the formula as follow [5]
ETo = c ETo* ......................................................................................... (1)
ETo* = w (0,75 Rs – Rn1) + (1-w) f (U) (ea-ed) ......................................
(2)
Note:
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J. Basic. Appl. Sci. Res., 2(8)8218-8229, 2012
w = factor that related to the area temperature and elevation; Rs = radiation of short wave; Rγ = radiation of
short wave in the limitation of atmosphere outside ( ≈ angot number); Rn = net radiation of long wave; Rn1 =
f(t) f(ed) f(n/N ); f(t) = temperature function; f(ed) = vapour pressure function; ed = ed* RH; RH = relative
humidity; f(n/N) = sunshine function; f(U) = wind velocity function in the height of 2 m; (ea – ed) = the
difference between satiated and really vapour pressure; and c = corecction factor
Analysis of dependable and effective rainfall
Dependable rainfall is as the rainfall along year with failure risk has been calculated. This study used the
method of basic month. Effective rainfall is rainfall dropping in an area and it can be used by the crop for
growing. The effective rainfall can be used to supply water demand in order to decrease the discharge which
was needed from intake. The formula of effective rainfall for rice and second crop is as follow [6]:
Reff for rice
= 70% x R80 ........................................................
(3)
Reff for second crop
= R50 ....................................................................
(4)
Note:
R80 = dependable rainfall with the probability of 80%
R50 = dependable rainfall with the probability of 50%
Cropping arrangement
The factors which influence water demand in wet rice field included crop water demand, percolation,
water demand for preparation work, water demand for cultivation, water demand for water layer change, and
efficiency of irrigation. Some important things related to cropping arrangement are as follow:
1. Cropping pattern
Cropping pattern is intended to use irrigation water supply efficiently so that the crop can well grow.
Two important things related to cropping pattern are the limitation of water supply during dry season
and every tertiary block is nacessary to receive enough water due to the demand. There were four
things being arranged in design of cropping pattern such as the cropping schedule, the cropping
location, the arrangement of crop type, and the arrangement of cropping number area.
2. Cropping schedule
The arrangement of cropping schedule is intended to use the water supply in river for irrigation
effectively due to the demand of every area.
3. The form and type of cropping pattern
There are two times cropping schedule in one year such as in rainy season (October to March) and dry
season (April to September). The restriction of time is used to determine the begnning schedule of rice
cropping in rainy season as well as the other type of crop. The alternative of cropping pattern that is
generally used is rice-rice-second crop, rice-rice-second crop-second crop, or rice-second crop-second
crop.
Irrigation water requirement
There are some methods for analysis irrigation water requirement as follow:
1. Design Criteria Method of Public General Work (PU)
This method is as standard method which is used in Indonesia for design of irrigation. The formula of
this method is as follow [7]:
- Water demand in wet rice field:
NFR = LP + ETc + P – Reff + WLR
- Water demand in intake for rice:
IRrice =
-
NFR
Eff
Water demand in intake for second crop:
IRsecond crop =
ETc  Re ff
Eff
Note:
LP = water demand for area preperation and cultivation; Etc = crop water demand; P = percolation;
WLR = water demand for water layer change; Reff – effective rainfall; Eff = efficiency of irrigation
2.
Stagnant Constant Head Method (SCH)
SCH method is the method of irrigation water distribution by irrigating the wet rice field with the
certain height for soil preparation as well as the crop maintenance. Water demand in wet rice field for
the phase of area preparation as well as crop maintenance is based on the Relative Second crop Area
(LPR). LPR is the comparation between base area to the second crop which is based on the water
demand to the other crop. Analysis of crop water demand used Relative Second crop Factor (FPR).
8220
Juwono et al., 2012
FPR is the minimum allowed water distribution which the second crop can grow without considering
water loss in channel as well as in wet rice field. The formula of FPR due to the agricultural soil type is
as follow:
FPR =
Q
LPR
Note: Q = flow discharge in river and LPR = number area of relative second crop
If FPR has been designed, water demand in intake is formulated as follow:
Q = FPR x LPR
Note: FPR = factor of designed relative second crop and LPR = number area of relative second crop in
the submerged wet rice field.
3.
System of Rice Intensification (SRI) method
SRI method principally is as the method of intermittent water distribution. At the SRI plantation, the
condition of water supply in area is arranged so that the area is dry enough but it remain fulfills the
crop water demand. Distribution of irrigation water is carried out by giving submerged height of 2 cm
during 5-10 days depends on the growth phase. Irrigation water demand with SRI method is formulated
as follow [8]:
Q1
Q2
HxA
x 10.000
T
Q1
1
=
x
86.400 1  L
=
Note: Q1 = daily water demand in the field; Q2 = daily water demand in intake; H = submerged height;
A = number area of wet rice field; T = interval of water distribution; L = water loss in the filed and
channel
The pattern of water requirement
Based on the distribution method, water distribution for rice crop is divided as follow: continuous flow,
continous submergence, and intermittent. Water distribution can be based on the comparison between
irrigation water supply and demand or the water distribution by K factor which is formulated as follow:
Factor of K
=
Qi
Qd
Note: Qi = supply discharge in intake; Qd = demand discharge
Water distribution due to block system is a water distribution method regularly and concentrated in the
area of technical irrigation and based on the area by area which the irrigation area is divided into some
blocks.
Capacity of bearer channel
Bearer channel in the irrigation scheme is designed to be able to flow water discharge as follow [7]:
Q
=
c NFR A
e
Note: Q = design discharge; c = decreasing coefficient because of the block system;
NFR = fresh
water demand in wet rice field; A = number area of irrigated wet rice field; e = total efficiency of
irrigation.
Bearer channel in irrigation scheme included as follow:
1. Soil channel without lining
Parameter that has to be determined in hydraulic design of channel is the comparison between
water depth and tight base width of long slope. The channel flow is assumed as steady flow by
applying Strickler formula with the assumption that longitudinal section of channel as trapezoid
shape as in Figure 2 below [9].
Figure 2 channel longitudinal section
J. Basic. Appl. Sci. Res., 2(8)8218-8229, 2012
The general equation of discharge which flows in trapezoid opened channel is as follow:
Q= vA
v = k R 2/3 I1/2
R=
A
P
A = (b + m h) h
P = b  2h m2  1
b= nh
Note: Q = channel discharge; v = flow velocity; A = longitudinal section; R = hydraulic radius; P =
wet periphery; b = base width; h = water depth; I = energy slope (= channel slope); k = coefficient
of Strickler; m = talud slope (1 vertical : m horizontal)
Research of Lim and Kim [10] presented that minimum velocity which is allowed to decrease
sedimentation and the growth of wild grass in the channel without lining is 0.45 m/s for small
channel and 0.60 m/s for bog channel.
2.
Channel with lining
The giving lining in irrigation channel is intended to prevent water loss due to the seepage,
scouring and erosion, and act violently and arbitrarilly of water vegetation; to decrease
maintenance cost, to give loose for the more bend and little of soil releasing. The
allowed
minimum velocity in lining channel is minimum velocity which does not cause sedimentation and
wild grass growing and the minimum velocity is 0.45 m/s for small channel and 0.60 m/s for big
channel [10].
RESULTS AND DISCUSSION
Design flood
Flood hydrograph of a river is generally used for analysing design flood. There was not Automatic Water
Level Recorder (AWLR) in the location of study, so that was used the synthetic unit hydrograph of Nakayasu.
Analysis result of design flood is presented as in Table 1.
Table 1 Recapitulation of design flood
No
1
2
3
4
5
6
7
8
Periode
(year)
1.01
2
5
10
20
25
50
100
Q
(m3 /s)
35.84
189.51
276.50
329.79
370.69
392.64
436.61
478.27
H
(m)
0.69
1.80
2.32
2,61
2,82
2,93
3.14
3.34
Elevation
water level
69.74
70.95
71.47
71.76
71.97
72.08
72.29
72.49
of
Dependable discharge
Transformation from rainfall to discharge in this study used Mock method. Dependable discharge of 80%
was based on basic month method. The result is presented as in Figure 3.
r
a
i
n
f
a
l
l
d
i
c
h
a
r
g
e
(mm)
(m3
/s)
Rainfall
Q80
Month - period
Figure 3 Illustration result of dependable discharge of 80% and rainfall
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Juwono et al., 2012
Evapotranspiration
Analysis of potential evaporation in this study used the method of Penman Modification. Climate data
was collected from Meteorology and Climatology Station of Sentani which is located at the height of 99 m
above sea water level with south latitude of di 2o30’ and east longitude 140o28’48”. Climate data used in this
study was in the year of 2000 until 2010. Analysis result of potential evaporation is presented as in Table 2.
Table 2 Potential evaporation for Sentani Station using Penman Modification Method
Item
Etp
Unit
mm/day
Jan
4.33
Feb
4.08
Mar
4.13
Apr
4.35
May
3.87
June
3.59
Jul
3.66
Aug
4.00
Sep
4.46
Oct
4.55
Nov
4.25
Dec
4.06
Effective rainfall
Based on the analysis of average monthly rainfall during 11 years, the coefficient of average effective
rainfall was 0.3 until 0.6. Therefore if it was remained due to the design standard of 0.7, it will give the high risk
of failure.
Percolation
Soil type in location of study is dominated by loam-sandy loam, so the percolation rate when soil
preparation was estimated as 10 mm/day and after soil preparation (during the crop maintenance) was estimated
as 3 mm/day.
Water demand for area preparation
Area preparation was carried out together with cultivation during 30-45 days before rice cropping time as
shown in Table 2.
Table 2 Water demand for area preparation
Month
Jan
Feb
Mar
Apr
May
June
July
Aug
Sep
Oct
Nov
Dec
I
II
I
II
I
II
I
II
I
II
I
II
I
II
I
II
I
II
I
II
I
II
I
II
Eo
(mm/day)
4.76
4.76
4.49
4.49
4.54
4.54
4.79
4.79
4.25
4.25
3.95
3.95
4.03
4.03
4.40
4.40
4.91
4.91
5.00
5.00
4.68
4.68
4.47
4.47
P
(mm/day)
3.00
3.00
3.00
3.00
3.00
3.00
10.00
10.00
10.00
10.00
3.00
3.00
3.00
3.00
3.00
0.00
0.00
0.00
0.00
0.00
10.00
10.00
10.00
10.00
M
(mm/day)
7.76
7.76
7.49
7.49
7.54
7.54
14.79
14.79
14.25
7.25
6.95
6.95
7.03
7.03
7.40
4.40
4.91
4.91
5.00
5.00
14.68
14.68
14.47
14.47
K=
M.(T/S)
1.40
1.40
1.35
1.35
1.36
1.36
2.66
2.66
2.57
1.31
1.25
1.25
1.27
1.27
1.33
1.33
0.88
0.88
0.90
0.90
2.64
2.64
2.60
2.60
IR
(mm/day)
10.31
10.31
10.12
10.12
10.15
10.15
15.90
15.90
15.44
9.95
9.74
9.74
9.79
9.79
10.05
8.04
8.36
8.36
8.43
8.43
15.80
15.80
15.62
15.62
Water layer changing
Water layer changing was carried out for one time when the vegetation age was 20-30 days after
vegetation moving. The design depth of water layer was 50 mm during 30 days. The calculation of water layer
changing was as follow:
WLR = 50 mm = 1,667 mm/days
30 days
Efficiency of irrigation
The average of irrigation efficiency in the location of study with new channel condition included ± 90%
of primary channel, ± 90% of secondary channel, and ± 65% of tertiary channel. Therefore, the total efficiency
was 65%.
Irrigation water requirement
Analysis of irrigation water requirement in this using Design Criteria Method of Public Work Department
(PU), Stagnant Constant Head (SCH) Method, System of Rice Intensification (SRI) Method, and the
8223
J. Basic. Appl. Sci. Res., 2(8)8218-8229, 2012
combination of SRI, SCH. The alternatives of cropping pattern were rice-rice-second crop as alternative-1; ricerice & second crop-second crop as alternative-2; and rice-second crop-second crop as alternative-3. The
calculation of irrigation water requirement for Lereh irrigation area was as follow:
1. Design Criteria of Public Work Department (PU):
- Water demand in wet rice field
NFR
= LP + ETc + P – Reff + WLR
- Water demand in intake for rice
IRrice =
-
NFR
Eff
Water demand in intake for second crop
IRsecond crop =
ETc  Re ff
Eff
Result of irrigation water demand for the three alternatives of cropping pattern was presented as in Figure 4.
GRAFIK HUBUNGAN ANTARA KEBUTUHAN AIR DAN KETERSEDIAAN AIR Q80%
Relation
curve between water demand and water supply of Q80%
4,0
3,5
Q Andal an 80%
Q80%
Q (m 3 /dt)
3,0
Q
m3/s
Q kebAlternative-1
Alt. 1
2,5
Alternative-2
Q keb.
A lt. 2
2,0
Q kebAlternative-3
Alt. 3
1,5
1,0
0,5
0,0
I
II
Nop
I
II
I
Des
II
Jan
I
II
Feb
I
II
I
Mar
II
Apr
I
II
Mei
I
II
Jun
I
II
Jul
I
II
I
Agust
II
Sep
I
II
Okt
Bulan
month
Figure 4 Water balance curve due to Public Work Method (MU) of Q80%
2. Stagnant Constant Head (SCH) Method
Analysis of irrigation water demand by using Stagnant Constant Head (SCH) was based on the criteria of
Relative second crop factor (FPR). Table 3 presented the value of FPR by using the method of Public General
Work (PU) that was compared to water supply based on the Mock Method
Table 3 Analysis of LPR-FPR by using Q80%
No
1
Item
Unit
CP-1
CP-2
Number area of rice
ha
2,119.4
2,119.4
Number area of second crop
ha
0
0
2
Water supply average for cultiation
l/s/ha
2,56
1,84
Water supply average for crop maintenance
l/s/ha
1,03
0,73
3
Q dependable (80%)
l/s
1,409
856
4
LPR for cultivation
ha.pol
9
6,1
LPR for crop maintenance
ha.pol
3,4
2,4
5
FPR
l/s/ha.pol
0,2
0,2
Note: LPR = Relative number area of second crop, FPR = Relative second crop factor, CP = cropping pattern
CP-3
0
2,119.4
0,00
0,30
164
1,0
0,1
In addition, the value of FPR was also determined based on the soil type of Latosol as shown in Table 4
below.
Table 4 The value of FPR in study location based on the soil type
Item
Water distribution
CP-1
CP-2
CP-3
Turning
FPR (l/s/ha.pol)
Less water
< 0.12
Nacessary
Enough water
0.12-0.23
0.20
0.20
0.15
possible
Available water
>0.23
no
Source: General Public Work Department Level 1 of East Java (1977)
One of the irrigation water demand using SCH method based on the FPR criteria was presented as in
Figure 5.
Juwono et al., 2012
Grafik Hubungan Antara Kebutuhan Air Blok Golongan 1 - 3 dengan Q 80%
Alternatif 2 : Padi - Padi+Palawija - Palawija
Q (lt/dt)
3500
Lereh Kanan
3000
Lereh Kiri 1
2500
Lereh Kiri 2
Q 80%
2000
1500
1000
500
0
I
II
I
Nop
II
I
Des
II
I
Jan
MT 3
II
I
Feb
II
I
Mar
II
I
Apr
II
I
Mei
II
I
Jun
MT 1
II
Jul
I
II
Agust
MT 2
I
II
Sep
I
II
Okt
MT 3
Periode
Period
Figure 5 Water balance curve using SCH method for alternative-2 of rice-rice & second crop-second crop with Q80%
3.
System of Rice Intensification (SRI) Method [11]
The pattern of irrigation water distribution in every approaching location is different and it is
depended on the agro-ecology and irrigation water supply. In this study, there was designed the
water distribution when crop maintenance on vegetative phase of cropping pattern-1 and it was 2
cm for 8 days and generative phase of 10 days, but for vegetative phase of cropping pattern-2 was
2 cm for 5 days and generative phase of 7 days. One of the irrigation water demand using SRI
method was presented as in Figure 6.
GRAFIK PEMBERIAN AIR METODE SRI/ INTERMITTENT DI. LEREH MT. II (ALTERNATIF 2)
Relation Curve between water demand block 1 to 3 with Q80%
Alternative-2: rice-rice+second crop-second crop
2500
DEBIT (m3/ dt))
2000
Q
(m3/s)
1500
1000
500
Lereh Kanan
0
Lereh kanan
Lereh kiri-1
Lereh kiri-2
Q-80%
Lereh Kiri 1
1
4
7
10
13
16
19
22
II
25
28
1
4
I
Mar
7
10
13
16
19
22
II
25
Lereh Kiri 2
28
31
34
37
I
40
43
46
II
Apr
Awal
52
55
58
61
64
I
Mei
Pengolahan tanah
49
67
70
73
76
79
82
II
85
88
Q 80%
91
94
97
I
Jun
II
Jul
Vegetatif anakan
Pembungaan
100 103 106 109 112 115 118
121 124 127 130
I
II
Agust
Pengisian bulir masak - susu
Pematangan
MT II
Figure 6 Water balance curve using SRI method for alternative-2 of rice-rice & second crop-second
crop with Q80%
4.
Combination of SCH and SRI Method
The other alternative of irrigation water distribution was carried out by combining between SRI
and SCH method. This combination is intended to find the optimal water demand based on the
available dependable discharge. The SRI method was applied in the right side of Lereh Block and
the first left side of Lereh Block, but SCH method was applied in the second left side of Lereh
Block. One of the irrigation water demand using the combination of SCH and SRI method was
presented as in Figure 7.
GRAFIK PEMBERIAN AIR KOMBINASI METODE SRI - SCH DI. LEREH MT. II (ALTERNATIF 2)
Relation Curve between water demand block 1 to 3 with Q80%
Alternative-2: rice-rice+second crop-second crop
2500
DEBIT (m3/dt))
2000
Q
(m3/s)
1500
1000
500
Lereh Ka nan
0
Lereh kanan
Lereh kiri-1
Lereh kiri-2
Q-80%
Lereh Ki ri 1
1
4
7
10
13
16
19
II
22
25
I
Mar
28
1
4
II
Apr
Pengolahan tanah
7
10
13
16
19
22
25
Lereh Ki ri 2
28
31
I
37
40
II
Mei
Awal
34
43
46
49
52
55
58
61
64
I
67
II
Jun
70
73
76
79
82
85
88
I
Jul
Vegetatif anakan
Pembungaan
Pengisian bulir masak - susu
Q 80%
91
94
97
II
100 103 106 109 112 115 118
121 124 127 130
I
II
Agust
Pematangan
MT II
Figure 7 Water balance curve using the combination of SCH and SRI method for alternative-2
of rice-rice & second crop-second crop with Q80%
J. Basic. Appl. Sci. Res., 2(8)8218-8229, 2012
The recapitulation of water balance based on the methods of PU, SCH, SRI, and the combination of SCH and
SRI by using K factor for determining Turn Criteria (KG) as follow:
1. KG > 0,8
: Continuous
2. 0,6 < KG ≤ 0,8 : Turn of Blok C
3. 0,4 < KG ≤ 0,6 : Turn of Blok B and C
4. KG ≤ 0,4
: Turn of Blok A, B, and C
The recapitulation result of water balance was presented as in Table 5 and the recapitulation of turn level
in every cropping season for the four methods was presented as in Table 6.
Item
Nov
Unit
I
Dec
II
I
Jan
II
I
Feb
II
I
Mar
Apr
II
I
May
II
I
II
Jun
I
Jul
II
I
Aug
II
I
S ep
II
I
Oct
II
I
II
I
II
0,20 0,72 0,48 1,32 1,11 0,97 1,03
2,41
2,09
2,33 1,02 1,25 1,38
0,86 0,70 0,72
0,42 0,36
0,33 0,19 0,33 0,20
0,39 0,16
0,34 1,39 2,63 3,40 2,84 2,19 2,19
2,19
2,19
1,51 1,86 2,10 2,87
2,43 1,92 1,92
1,92 1,92
1,53 1,17 0,75 0,75
0,75 0,75
0,34 1,39 2,63 3,40 2,84 2,19 2,19
2,19
2,19
1,48 1,27 0,78 1,18
1,04 1,12 1,12
1,12 0,82
0,73 0,56 0,75 0,75
0,75 0,75
0,34 1,39 2,63 3,40 2,84 2,19 2,19
2,19
2,19
1,46 0,79 0,20 0,38
0,47 0,47 0,47
0,47 0,27
0,33 0,48 0,75 0,75
0,75 0,75
a. Alternative-1
0,6
0,5
0,2
0,4
0,4
0,4
0,5
1,1
1,0
1,5
0,5
0,4
0,4
0,4
0,2
0,2
0,2
0,2
0,4
0,3
0,5
0,2
Note
gilir
gilir
gilir
gilir
gilir
gilir
gilir continucontinucontinu gilir
gilir gilir
gilir
gilir
gilir
gilir
gilir
gilir
gilir
gilir
gilir
gilir
gilir
1,6
0,8
Water supply
Qdependable 80%
m3/s
Water demand
1. PU Method
a. Alternative-1
b. Alternative-2
m3/s
c. Alternative-3
Factor of K
1,1
0,6
0,5
0,2
0,4
0,4
0,4
0,5
0,6
0,6
0,4
0,4
0,5
0,3
0,4
0,3
0,5
0,2
Note
gilir
gilir
gilir
gilir
gilir
gilir
gilir continucontinucontinucontinu
continu
continucontinu gilir
gilir
gilir
gilir
gilir
gilir
gilir
gilir
gilir
gilir
1,5
0,9
1,4
1,0
1,0
1,6
1,6
0,8
0,6
b. Alternative-2
1,1
1,0
0,5
1,3
6,3
1,2
c. Alternative-3
0,6
0,5
0,2
0,4
0,4
0,4
0,5
0,4
0,4
0,3
0,5
0,2
Note
gilir
gilir
gilir
gilir
gilir
gilir
gilir continucontinucontinucontinu
continu
continucontinucontinu
continucontinucontinucontinu gilir
3,6
1,8
1,5
gilir
gilir
gilir
gilir
2. S CH Method
a. Alternative-1
0,28 1,52 2,65 3,18 2,40 1,48 1,48
1,48
1,48
1,06 1,94 2,65 3,18
1,48 1,48 1,48
1,48 1,48
1,10 0,85 0,32 0,32
0,32 0,32
0,28 1,52 2,65 3,18 2,40 1,48 1,48
1,48
1,48
1,02 1,10 0,78 1,08
0,77 0,77 0,77
0,77 0,57
0,44 0,32 0,32 0,32
0,32 0,32
0,28 1,52 2,65 3,18 2,40 1,48 1,48
1,48
1,48
0,99 0,54 0,14 0,27
0,42 0,42 0,42
0,42 0,28
0,26 0,32 0,32 0,32
0,32 0,32
a. Alternative-1
0,7
0,5
0,2
0,4
0,5
0,7
0,7
1,6
1,4
2,2
0,4
0,6
0,5
0,5
0,3
0,2
0,3
0,2
1,2
Note
gilir
gilir
gilir
gilir
gilir
gilir
gilir continucontinucontinu gilir
gilir gilir
gilir
gilir
gilir
gilir
gilir
gilir
gilir continu gilir continu gilir
1,6
1,1
0,9
0,9
b. Alternative-2
m3/s
c. Alternative-3
Factor of K
1,6
0,5
0,2
0,4
0,5
0,7
0,7
0,5
0,6
0,8
0,6
gilir
gilir
gilir
gilir
gilir
gilir continucontinucontinucontinu
continu
continucontinucontinu
continu gilir
gilir
gilir
gilir continu gilir continu gilir
1,3
1,3
0,6
8,9
5,1
2,0
1,7
1,7
1,0
1,0
1,0
0,6
0,6
1,2
0,5
0,7
1,9
1,3
0,6
gilir
2,4
0,9
1,0
Note
1,4
2,3
0,5
b. Alternative-2
1,6
1,4
0,5
1,2
0,5
c. Alternative-3
0,7
0,5
0,2
0,4
0,5
0,7
0,7
Note
gilir
gilir
gilir
gilir
gilir
gilir
gilir continucontinucontinucontinu
continu
continucontinucontinu
continucontinucontinucontinu gilir continu gilir continu gilir
0,5
3. S RI Method
a. Alternative-1
0,31 1,44 1,54 1,89 0,88 0,82 0,76
0,70
0,70
0,58 1,58 1,72 2,23
1,40 1,27 1,15
1,00 0,67
0,46 0,30 0,30 0,30
0,30 0,30
0,31 1,44 1,54 1,89 0,88 0,82 0,76
0,70
0,70
0,51 0,79 0,69 0,95
0,67 0,69 0,64
0,58 0,45
0,36 0,25 0,30 0,30
0,30 0,30
0,31 1,44 1,54 1,89 0,88 0,82 0,76
0,70
0,70
0,47 0,25 0,10 0,19
0,30 0,30 0,30
0,30 0,30
0,30 0,30 0,30 0,30
0,30 0,30
a. Alternative-1
0,6
0,5
0,3
0,7
3,4
3,0
4,0
0,6
0,6
0,6
0,6
0,4
0,5
0,7
0,6
1,3
Note
gilir
gilir
gilir
gilir continucontinucontinucontinucontinucontinu gilir
gilir gilir
gilir
gilir
gilir
gilir
gilir
gilir
gilir continu gilir continu gilir
1,8
1,3
1,0
1,1
0,7
0,8
0,9
0,7
b. Alternative-2
m3/s
c. Alternative-3
Factor of K
1,3
1,3
1,2
0,5
0,3
0,7
gilir
gilir continucontinucontinucontinucontinucontinucontinu
continu
continucontinucontinu
continu gilir continucontinu gilir continu gilir continu gilir
5,0
1,3
4,0
1,5
12,7 7,3
2,9
2,4
2,4
1,4
1,2
1,1
0,6
1,1
1,1
0,7
0,7
1,3
0,6
gilir
3,0
4,5
0,7
0,6
3,4
3,0
1,1
gilir
1,3
3,4
0,7
Note
1,2
1,3
0,6
b. Alternative-2
1,3
1,2
1,3
1,3
0,6
c. Alternative-3
0,6
0,5
0,3
0,7
Note
gilir
gilir
gilir
gilir continucontinucontinucontinucontinucontinucontinu
continu
continucontinucontinu
continucontinucontinucontinu gilir continu gilir continu gilir
0,6
4. S CH-S RI Method'
a. Alternative-1
0,43 1,66 1,78 2,02 1,10 1,04 0,98
0,98
0,98
0,98 2,09 1,95 2,35
1,43 1,30 1,18
1,18 0,84
0,64 0,30 0,30 0,30
0,30 0,30
0,43 1,66 1,78 2,02 1,10 1,04 0,98
0,98
0,98
0,84 1,16 0,78 1,00
0,69 0,70 0,65
0,65 0,52
0,43 0,25 0,30 0,30
0,30 0,30
0,43 1,66 1,78 2,02 1,10 1,04 0,98
0,98
0,98
0,75 0,54 0,10 0,19
0,30 0,30 0,30
0,30 0,30
0,30 0,30 0,30 0,30
0,30 0,30
a. Alternative-1
0,5
0,4
0,3
0,7
2,5
2,1
2,4
0,6
0,6
0,5
0,6
0,4
0,4
0,5
0,6
1,3
Note
gilir
gilir
gilir
gilir continucontinucontinucontinucontinucontinu gilir
gilir gilir
gilir
gilir
gilir
gilir
gilir
gilir
gilir continu gilir continu gilir
1,6
1,2
1,0
1,1
b. Alternative-2
c. Alternative-3
m3/s
Factor of K
1,0
1,0
0,9
0,4
0,3
0,7
0,7
0,7
0,8
0,7
gilir
gilir continucontinucontinucontinucontinucontinucontinu
continu
continucontinucontinu
continu gilir
gilir
gilir
gilir continu gilir continu gilir
1,2
1,1
0,6
3,1
0,9
1,9
1,4
12,7 7,3
2,9
2,4
2,4
1,4
1,1
1,1
0,7
0,7
1,3
0,6
gilir
2,1
2,8
0,7
0,5
2,5
2,1
1,1
gilir
1,0
2,5
0,6
Note
0,9
1,0
0,5
b. Alternative-2
1,0
0,9
1,0
1,3
0,6
c. Alternative-3
0,5
0,4
0,3
0,7
Note
gilir
gilir
gilir
gilir continucontinucontinucontinucontinucontinucontinu
continu
continucontinucontinu
continucontinucontinucontinu gilir continu gilir continu gilir
0,6
Juwono et al., 2012
Table 6 Recapitulation of Turn Level
PU Method
Cropping Dependable
ppattern discharge
Alt. 1
Alt. 2
SCH Method
Alt. 3
Alt. 1
Alt. 2
SRI Method
Alt. 3
Alt. 1
Alt. 2
SCH_SRI Method
Alt. 3
Alt. 1
Alt. 2
Alt. 3
MT 1
Q 80%
7
x 7
x
7
x
7
x
7
x
7
x
4
x
4
x
4
x
5
x 5
x
5
x
MT 2
Q 80%
8
x 4
x
1
x
8
x
3
x
0
x
7
x
1
x
0
x
7
x 3
x
0
x
MT 3
Q 80%
4
x 4
x
4
x
4
x
3
x
3
x
3
x
3
x
3
x
3
x 3
x
3
x
Total
Q 80%
19
x 15
x 12
x 8
x
7
x 15
x 11
x
8
x
x 19
x 13
x 10
x 14
Schedule of turn in Lereh Irrigation Area
Schedule of turn was made based on the evaluation result of water distribution from each method. The
aim of turn schedule is to regulate the rotation time in determined each block. Based on the water supply, it was
made the pattern of turn operation with the alternative of maximum discharge was 2,00 l/s; the average
discharge was 1,150 l/s; and the minimum discharge was 300 l/s as in Table 7 below.
Table 7 Operation pattern of turn discharge
Irrigation water demand of rice
Water demand for second crop
Name of DI
Water
supply
Irrigation
Area
(Block)
(lt/s)
(ha)
(lt/s)
(A) Lereh Kanan
Q min
705
1268,28
0,05
14
493,22
0,02
5
(B) Lereh Kiri 1
300,00
Preparation Area
Debit
Maintenance
water depth supply Discharge water depth supply discharge
day
(day)
(m)
(lt/s)
(m)
(lt/s)
Water depth
(m)
Supply
day
105,69
0,00
0
648
1165,97
0,05
12
453,43
0,02
5
97,16
0,00
0
(C) Lereh Kiri 2
767
1380,60
0,05
15
536,90
0,02
6
115,05
0,00
0
(A) Lereh Kanan Q average
705
1268,28
0,05
4
493,22
0,02
1
105,69
0,00
0
(B) Lereh Kiri 1
1150,00
648
1165,97
0,05
3
453,43
0,02
1
97,16
0,00
0
767
1380,60
0,05
4
536,90
0,02
2
115,05
0,00
0
Q max
705
1268,28
0,05
2
493,22
0,02
1
105,69
0,00
0
2300,00
648
1165,97
0,05
2
453,43
0,02
1
97,16
0,00
0
0,05
2
536,90
0,02
1
115,05
0,00
0
(C) Lereh Kiri 2
(A) Lereh Kanan
(B) Lereh Kiri 1
(C) Lereh Kiri 2
767
1380,60
Evaluation of channel design
Evaluation of channel design was carried out by considering the flow velocity during the phase of area
preparation, rice crop maintenance, and second crop demand. Design velocity was fitted to the soil type where
the channel was build. Bearer channel in Lereh Irrigation area was as masonry channel so that according to the
Criteria of Irrigation Design [3], it was said that the minimum velocity which did not cause sedimentation and
wild grass growing in channel was 0.45 m/s for small channel and 0.6 m/s for big channel.
To evaluate the design of bearer channel, permitted range of velocity was 0.6 m/s until 1.5 m/s. The
channel was evaluated based onthe demand discharge during the phase of area preparation, rice crop
maintenance, and second crop demand. The evaluation result showed that some channels were safe to the
problem of sedimentation and erosion but in some section there was possible to occur sedimentation because the
flow velocity was under the permitted range. The recapitulation on design evaluation of bearer channel was
presented as in Table 8 below.
Table 8 Evaluation result of bearer channel design in Lereh irrigation area
Phase of area preparation
Block
Lereh-right
sedimentation section
BLA.5 - BMLA.5
2 sec
BLA.7 - BMLA.7
Phase of maintenance
safe section
BLA.0 - BLA. 6
sedimentation section
8 sec
BLA.0 - BLA.8 8 sec
Phase of second crop
the same section
BLA.5 - BLA. 7
2 sec
sedimentation safe
section
section
all of section
-
all of section
-
all of section
-
BLA.6 - BLA. 7
BLI.4 - BLI.8
Lereh-left-1
6 sec
BLI.0 - BLI.4
2 sec
BLI.0 - BLI.11
4 sec
all of section
13 sec
BLI.0 - BLI.3
10 sec
BLI.2 - BMLI.2.1
BLI.9 - BMLI.9.1
Lereh-left-2
BLI.11 - BMLI.11.2
9 sec
BLI.9 - BMLI.11.2
BLI.3 - BLI.9
6 sec
J. Basic. Appl. Sci. Res., 2(8)8218-8229, 2012
CONCLUSION
The conclusion of this study was as follow:
1. Design of cropping pattern
If there was shown from the function of water supply through irrigation system based on the rice crop,
it was hoped the reaching of minimum crop intensity was 180% (alternative I and II). But if there was
based on the rice crop and second crop, the reaching of minimum crop intensity (government
allowance) was 225% (alternative I, II, and III). Design of cropping pattern in Lereh irrigation area was
presented as in Table 9.
Table 9 Design of cropping pattern in Lereh irrigation area
Alternative
I
II
III
Crop intensity reaching
base of rice crop base of rice crop and second crop
rice 100% - rice 100% - second crop 100%
200%
300%
rice 100% - rice 40% and second crop 60% - second crop 100%
140%
300%
rice 100% - second crop 100% - second crop 100%
100%
300%
Cropping pattern
2.
The pattern of water distribution and division
- The pattern of water distribution
Irrigation water distribution for SCH method due to the FPR criteria for enough water was: 0,12 <
FPR < 0,23; but for SRI method by using 2 cm of water depth and the interval of water distribution
was 5 to 8 days for vegetative phase and 7 to 10 days for generative phase.
- The pattern of irrigation water division
Based on the operation pattern of turn discharge, the preparation area phase needed the maximum
discharge of 2,300 l/s so that was not occur a long time in the turn level. The maintenance phase
and second crop needed the average discharge of 1,150 l/s until the minimum discharge of 300 l/s.
3.
Design evaluation of bearer channel
Based on the evaluation of bearer channel design, it was shown that during the phase of area
preparation, the velocity in channel was not more than 1.5 m/s and not less than 0.6 m/s, and the
sedimentation was only occured in the farest section of channel. Sedimentation was occured in almost
the whole section during the phase of maintenance and second crop. For the farest tertiary block, it was
nacessary to be added the travel time of irrigation water until to the block of tertiary block. Whereas the
addition of turn time based on the travel time to each block was presented as in Table 9 below.
Table 9 Recapitulation of travel time
Phase of area preparation Phase of maintenance Phase of second crop
travel time
travel time
travel time
Block
(hour)
(day)
(hour)
(day)
(hour)
(day)
Lereh-right
Lereh-left-1
Lereh-left-2
17,72
14,88
28,30
1,12
0,93
1,77
22,88
19,67
37,98
1,43
1,23
2,37
36,26
33,18
72,34
2,27
2,07
4,52
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