Jurnal

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THE DEVELOPMENT OF EQUALIZATION MODEL OF
WATER ALLOCATION
Anang M. Farriansyah1
, Galuh Rizqi Novelia2
* and Budi Husnan3
1
Water Resources, Civil Engineering, Brawijaya University, HATHI NTB
2
Youth Professional Engineer, HATHI NTB
3
Youth Professional Engineer
*e-mail: grnovelia@gmail.com
Abstract
The water allocation of inter-sectoral, inter-similar users and inter-regional
should be optimal from time to time because the limited sources, uncertainty
and unbalanced due to condition of the world today. Model is a decision support
system to optimize the issue. Existing models cannot calculate the equity of water
allocation in each headwork that hydraulically connected in the river, because of
concept and computation system problems. Model as the pillar of water allocation
management, in addition to the institution and infrastructure, should achieve the
common goal of maximum volumetric reliability index, minimum gap of deficit
upstream-downstream index and minimum spillout. The “Equalization Model of
Water Allocation” (EMWA) with the concept of “equal for equity”, will simulate
the water balance synergy, aided by Excel-Visual Basic forApplication (VBA). This
tools is the “search engine” of maximum-equal K-factor, based on the scheme of the
system, inflow and demand. EMWA is a competent generic model that applicable,
despite with complex configuration of headwork. The development of EMWA’s
prototype with synthetic data results the equity of water allocation on various
system. EMWA is helpful to establish strategic plans, annual water allocation plan
(irrigation cropping pattern plan), real-time instruction, and water use permits.
Keywords: equal for equity, K-factor, generic, model, system.
INTRODUCTION
Background
Hatmoko (2012:71), water allocation of inter-sectoral, inter-similar users and
inter-regional from time to time, must be oriented of “equal for equity”. The water
allocation volumetric reliability index (K-factor) in irrigation areas (IA) expected
to be equal to similar users (Hatmoko, 2012:81) in order to reach fairness in the
system (Gorantiwar, 2005:21 and Subagyono, 2007:39). This K-factor method is
the indicator of water allocation equity inter-headwork (HW) on the river.

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To knowing the achievement of volumetric equity, exemplified by Lombok river
basin (RB) which has deficit of irrigation water caused by the distribution and
continuity of water available (Rohmat, 2010). Survey results on 25-27 March 2016
for 115 IA which receives water from HW in main rivers at 15 watershed, indicates
the inequity of trend in upstream-downstream (K-factor gap) which should be able
to equalize. Water surplus does not increase productivity (Gorantiwar, 2005:17). If
the system occurs equity then the productivity will increase thoroughly.
In addition, application of the model such as: a) HLD (high level diversion)
models in Lombok RB (Puslitbang Pengairan, 1994), b) RIBASIM and c) WRMM,
was challenged by the holders of water allocation because the import status and
unpractical (Hatmoko, 2012:83). From that time until the publication of Technical
Guidelines of Water Balance and Implementations of Water Allocation (Ditjen
SDA - 2012), still cannot compile the strategic plans, annual water allocation plan
(irrigation cropping pattern plan), real-time instruction, and water use permits that
oriented of “equal for equity” in one system. Based on models performance, as
written in Hatmoko, 2006 and 2012, and Yulistiyanto, 2008, the summaries are:
a) The model has not actualize the regulation of “highly water utilized, in equity” on
systems, except as the calculation tools of local water balance in each HW.
b) The model needs a longstanding trial-error thus pursued a compromise.
c) The model has limited number of nodes in the systems, therefore an expensive water
district approach has done using a difficult and unmodifiable programming language.
Model as a decision support system of planning (Hatmoko, 2012:74), is an
abandoned pillar, besides institution and infrastructure. The solution is to develop
an alternative model in common, a practical and general model to every system
called “Equalization Model of Water Allocation” (EMWA). This computation
model is to support the manager of water resources in watershed to build an optimal
water allocation. First of all is to develop the EMWA’s prototype with the output of
water release that depend on maximum-equal K-factor of inter-user, according to
the input of the system scheme, water availability and water demand.
METHODOLOGY
Water Balance and K-Factor in System
Eriyanto (2012:8), system is a unitary combination of a synergic and organized
components that working for one common goal. To learning the system needs

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quantitative model and technic with simulation (Eriyanto, 2012:51). Kodoatie
(2010:128), system must be controlled by the manager of water resources in
river basin involving the stakeholders, so the surplus water in upstream can be
transferred to other areas that receive less water, in order to reach overall increase
of productivity in the system (Gorantiwar, 2005:17).
Wurbs version of system with the
following configuration:
- Reservoir: 1,2,3
- Weir: 4,5,7,9,11,12
- Junction: 6, 10
- Node config. of
1,2,3,4,5,6,7,8,9,10,11,12
(Resources: Wurbs, 2005: 43)
Figure 1. Figure 1.The illustration of water allocation system scheme
The flow control in the system using water balance approach according to the law
of conservation of mass (Wurbs, 2005:46). In Hadisusanto (2011:5), inflow (I),
outflow (O) and volume changes (ΔV) in each headwork (HW), by water balance:
I – O = ΔV.................................................................................................... (1)
with local inflow inter HW (QL), spill (QS), release
(QR) and demand (QD). The water loss is ignored
(Wurbs, 2005: 46-49).
In the weir scheme beside, QL – QR – QS = 0 (ΔV=0). If the
elements above divided by QD (Farriansyah, 2015: 282) then,
K = QR/QD.......................................................................... (2)
with 0 ≤ K ≤ 00% due to constraint 0 ≤QR≤QD. The K-factor equation (2) is
according to Wurbs (2005:56), Gorantiwar (2005:16), Fagi (2007:4) and Hatmoko
(2012:81) as the volumetric reliability index. If the water is less, it has to be rotated
to stabilize the crop area, save water ± 40% and crop productivity is not declining
(Fagi, 2007:10).

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Table 1. The scenario of water distribution pattern of irrigation with K-factor
Class
K-factor
(%)
Level of water
shortage
Water distribution inside irrigation
areas
Interlude duration
(days)
K1* 100 - Continuous -
K1 80 - 99 Extremely low Continuous (limited) -
K2 60 - 79 Low Light rotation ≤ 3
K3 40 - 59 Medium Medium rotation 3.01 – 5
K4 20 - 39 High Heavy rotation 5.01 – 7
- <20 Emergency Rotation of Inter-segment of IA 7.01 - 10
Resource: Fagi, 2007:10; Tongangor, 2008:478; Permen PU-PR No.12/PRT/M/2015, and survey result of Pengamat Pengairan in
Lombok river basin (2016).
Model and Optimization Concept
Mathematical model in water resources system using linear programming (Wurbs,
2005:66). Still Wurbs (2005:46-57 and 79), in the case of optimization it is more
effectively solved by simulation method, because simulation methods (ad hoc)
commonly provides excellence, as it imitates the complex system in detail and
realistic also applicable to special computing strategy. The generic model is a model
that flexibly developed to follow the form of system scheme, is in contrast with
specific model that valid in one particular system (Wurbs, 2005:2).
EMWA bring concepts of: “if water available can flow along with gravitation, to
be highly utilized in equity to fulfill the demands, then each HW that hydraulically
connected in river as unitary system that must be controlled (equalization), so the
common goal of maximum-equal K-factor of inter-user, include: 1) maximum
volumetric reliability index, 2) minimum gap of deficit upstream-downstream index,
and 3) minimum spillout. To actualize the concept (Figure 1), with the objective
function of maximum (K1.QD1 + K2.QD2), minimum (K1 - K2) and minimum QS,
as well as the constraint of water balance, water rationing and spill.
Figure 2. Water balance sketch in two similar weirs

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Computation and Generic Model Concept
The ad hoc simulation model can be developed for operational engineering system,
according to the calculation arrangement of the most upstream HW in tributary
to main rivers, by adding the local inflow (Wurbs, 2005:56). In a complex system
with some arithmetic equation, then the calculation must be solved by simulation
model (ad hoc), by iterating the K-factor of each HW, example gradient step of 0.1
% (Farriansyah, 2014:226 and 2015:282 ; Yulistiyanto, 2015:25). Gap condition
on step tolerance called termination status, is an optimal/almost optimal result
(Manonama, 2008:184) or not optimal because the water is unqualified to share.
Computing in EMWA solved with the assistance of Microsoft Excel – Visual Basic
for Applications (VBA) (Farriansyah, 2015:283). The Excel – VBA is popular and
practical to non-professional programmers to develop a decision support system in
water resources sector, with relatively few of syntax code to run a larger program
(Wurbs, 2005:88-91) also to fasten calculation process (Yulistiyanto, 2015:101).
EMWAisflexibleforvarioussystems,ithasautomationinformulationsofarithmetic
function in every node of HW on the river. The concept of generic model is: 1)
tracking node of HW and river junction in system scheme on Excel’s worksheet,
2) deciding configuration of node and 3) connecting node upstream-downstream in
the river.
Figure 3. The illustration of system scheme tracking in EMWA
In figure 2, the calculation is performed by the configurations of nodes 1, 2, 3, 4, 5,
6, 7, 8, 9, 10, 11, 12 (first) or with nodes 3, 4, 5, 8, 9, 1, 2, 6, 7, 10, 11, 12 (second).
The first configuration is similar with the node orders in EMWA (Figure 3).

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EMWA Development
EMWA prototype using symmetrical data such as system scheme with HW
configuration, local inflow and irrigation demands. In assumed intake capacity is
adequate with demands and river maintenance is 5% of available water in HW.
Figure 4. Flowchart of EMWA development
In the following stage, verification and validation is to determine the model
feasibility of behavior appeared (Mays & Tung, 1992:20). Verification is to ensure
the correctness of mathematic model transformation to generic-computation model,
while validation is to prove the model application in system appropriate preparation
purposes (Sargent, 2014:118).
Figure 5. Flowchart of work procedures of EMWA

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RESULT AND DISCUSSION
EMWA Prototype for Dependent System
QA 1712 QA 856
BU1 BU6
QS 1396 QD 519 QS 410 QD 734
QM 36 QC 1000 QM 38 QC 1000
QR 316 QR 446
K 61% K 61%
QA 2099 QA 1214
BU2 BU7
QS 1637 QD 760 QS 755 QD 755
QM 49 QC 1000 QM 40 QC 1000
QR 462 QR 459
K 61% K 61%
QA 3268 QA 811
BU3 BU8
QS 1158 QD 3470 QS 418 QD 645
QM 44 QC 3500 QM 37 QC 1000
QR 2110 QR 393
K 61% K 61%
QA 1847 QA 1289
BU4 BU9
QS 530 QD 2159 QS 890 QD 653
QM 96 QC 3500 QM 46 QC 1000
QR 1317 QR 398
K 61% K 61%
QA 1981 NERACA AIR GLOBAL
BU5 DAR 163%
QS 54 QD 3177 RDR 61%
QM 54 QC 3500 RAR 99%
QR 1927 FALSE
K 61%
DI FFF
DI EEE
SUNGAI ZZ
DI CCC
DI AAA
CAB SUNGAI YY
DI HHH
CAB SUNGAI XX
DI GGGDI BBB
DI DDD DI III
CLEARDEBIT
MEQAA
WADUK EL_BEG
Figure 6. Prototype of dependent system with weir
Figure 7. Prototype of dependent system with weir and reservoir

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EMWA Prototype for Independent System
QA 446 QA 667
HW 2 HW 1
QS 239 QS 430
QM 22 QD 307 QM 33 QD 351
QC 800 QC 800
QR 207 QR 237
K 68% K 68%
QA 1081 QC = 1500 QA 974 QA 522
HW 3 HW 7 HW 6
QS 313 QS 439 QS 322
QM 31 QD 448 QM 39 QD 793 QM 26 QD 296
QC 800 QC 1000 QC 1000
QR 302 QR 535 QR 200
QR SUP 465 K 68% K 68%
K 68%
QA 510 QA 929
HW 4 HW 8
QS 247 QS 44
QM 26 QD 391 QM 46 QD 669
QC 800 QC 1000
QR 264 QR 455
K 68% K 68%
QA 631 QA 658
HW 5 TRUE 1 HW 9
QS 32 QS 33
QM 32 QD 892 QM 33 QD 925
QC 800 QC 1000
QR 599 QR 625
K 67% K 68%
GGG IRR. AREA FFF IRR. AREA
YYY RIVER
HHH IRR. AREA
III IRR. AREA
ZZZ RIVER
XXX RIVERWWW RIVER
EEE IRR. AREA
BBB IRR. AREA AAA IRR. AREA
CCC IRR. AREA
DDD IRR. AREA
DATA RUN
DELETE
SUPPLY
Figure 8. Prototype of independent system of wet – dry watershed
Discussion
If water release as in the scheme (figure 6, 7, 8) is calculated with the existing
methods (without equalization), then it can be ascertained that the water allocation is
unequal and causing inequity between similar users (as written in the background).
With efforts to control the system, it is obtained as follows:
1. The value of K-factor is equal in each HW, although the water balance is deficit
indicated by demand-available ratio (DAR) > 100%, unless in case if local
water availability in most upstream HW not qualified to share to downstream.
2. Use of the available water can reach the maximum indicated by the spill in the
most upstream HW that always has same value with QM, except that HW has
a larger local inflow than QD.
3. The value of K-factor in system with weirs reaches 61% and the efficiency
of water utility in system indicated by release-available ratio (RAR) is 99%
(figure 6). Whereas if there is a reservoir with particular initial storage, the
K-factor becomes 91% and RAR reaches 66% due to the storage (figure 7).
4. In the scheme of interconnection of wet-dry watershed (figure 8), it can be
regulated so that the value of K-factor is similar or with specific gap (according
to agreement). The results of K-factor is 67% - 68%.

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CONCLUSION AND RECOMMENDATION
Conclusion
Based on the performance of the prototype, the conclusions are:
1. The model are competent to give equal result in various scheme with various
number of inflow and demands.
2. Ageneral EMWAcan formulate several schematic shape of a system with HW
configuration to use in equalization process, either dependent or independent
system.
3. EMWA can give result of highly utilized water in equity, it is the achievement
of maximum-equal K-factor value in each HW, with the requirements of
available water must flow hydraulically.
Recommendation
1. Optimization concept of “equal for equity” and general model in EMQA
can be proved with mathematical model so that EMWA is applicable in real
system although in complex HW configuration.
2. This prototype can be applied in a various levels of system with complex
configuration of HW between similar users (irrigation), including Lombok
RB.
3. A test of EMWA prototype in utility watershed is necessary (such as on the
Lombok RB with interconnection system), in order to discover the reliability
of the computation-generic model inter upstream-downstream and inter wet-
dry watershed.
4. For the application of the model should be supported by setting tools,
measuring tools and operator in each HW, including network communication
system to the operations control center.

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