Analysis of Nusa Dua Estuary Dam Operations

for Clean Water Supply South Badung Tourism Area

I Gusti Lanang Made Parwita, I Made Tapayasa, I Wayan Wiraga and I Nyoman Anom P. W.

Department of Civil Engineering Bali Sate Polytechnic, South Kuta, Bali, Indonesia

Keywords: Nusa Dua Estuary Dam, Water Supply, Operating System, Tourism, South Badung.

Abstract: The southern part of Badung is a very rapidly developing tourist area. Several areas have become world

tourism icons such as Kuta Beach, Nusa Dua Area and other supporting areas such as Seminyak and Legian

Beaches, Benoa Water sports area, Pandawa Beach, Jimbaran area, Uluwatu Temple and several other beaches

in Pecatu, Kutuh and Ungasan. . With such rapid development causing an increase in the need for clean water

Various breakthroughs have been made to support the availability of sufficient water in this area, one of which

is through the construction of the Nusa Dua Estuary Dam in 1994 with capacity 350 liters/second. This

capacity is enlarged to 500 liters/second. To maintain water supply by the reservoir in 2019, new buildings

have been added in the form of pneumatic crest gates, diversion channels and trash racks. With the new

building, of course there will be changes in the operating system, but until now there is no operating system

guide. Therefore, it is necessary to analyze the operating system according to the current building. This

research was conducted by observing and analyzing the operating system of the Muara Nusa Dua Dam which

has been running so far after the addition of new buildings as well. The problem to be conveyed in this

research is the need for a new operating system according to the current building conditions. The results

showed that the operating system was distinguished in three conditions, namely normal water, flood water

and low water with the operation of the trash rack, radial gate, pneumatic crest gate and rubber dam set by

taking into account the normal water elevation at 1.7 sea above level.

1 INTRODUCTION

The development of tourism in Bali, especially in the

southern part, greatly affects the increase in the

amount of water needed. The increase in water

demand is seen from its quality, quantity and

continuity (Yamamoto at al 2021),(Sunarta, Rahman,

and Syakur 2015). Therefore, a good arrangement is

needed so that the availability of water and the

carrying capacity of the environment can be

maintained. It is necessary to regulate the existing

clean water infrastructure so that it produces water as

expected (Cole 2012)

Nusa Dua Dam is a single purpose reservoir in the

form of providing clean water for the South Badung

area, this reservoir utilizes water in the Badung River

estuary in Benoa Bay. At the beginning of its

construction, this reservoir provided water of 300

liters/second but at this time the capacity has been

increased to 500 liters/second (Bali river council

2020). Judging from the initial construction in 1994,

the Nusa Dua Estuary Dam has undergone changes

and additions to buildings. In 2019-2020, additional

buildings in the form of diversion channels equipped

pneumatic crest gates and a trash rack located to the

west of the reservoir.

The development of the Nusa Dua Estuary Dam

with several new buildings aims to provide greater

raw water in the southern area of Badung Regency

which has experienced very rapid development. The

rapid development of tourism in southern Badung

cannot be separated from well-known tourism

destinations both nationally and internationally which

are the center of tourism activities such as the Nusa

Dua area, Kuta Beach, Tanjung Benoa water sport

area, Uluwatu Temple and several supporting tourist

areas in the vicinity such as Legian Beach, Seminyak

Beach, Pandawa Beach, Dream Land and other areas

(Badung Tourism Board 2020)

The increase in water demand is related to the

systematic operation of the reservoir system. The

reservoir operating system is closely related to several

factors, namely: sedimentation that enters the

reservoir, water needs, water conservation needs,

552

Parwita, I., Tapayasa, I., Wiraga, I. and W., I.

Analysis of Nusa Dua Estuary Dam Operations for Clean Water Supply South Badung Tourism Area.

DOI: 10.5220/0010949000003260

In Proceedings of the 4th International Conference on Applied Science and Technology on Engineering Science (iCAST-ES 2021), pages 552-557

ISBN: 978-989-758-615-6; ISSN: 2975-8246

 2023 by SCITEPRESS – Science and Technology Publications, Lda. Under CC license (CC BY-NC-ND 4.0)

flood control and as a water quality controller

(Wulandari. at al 2014) (Fang et al. 2014).With a very

vital role as a provider of clean water and the addition

of several new buildings, it requires a good operating

system so that the water supply can still be maintained

at 500 liters/second. However, until now the latest

operating and maintenance patterns do not exist, so an

analysis is needed that can be a guide in the operation

and maintenance system for water supply. This

research aims to design the right operating system

according to the current building conditions

2 METHOD

2.1 Research Design

This research was conducted for six months by

conducting in-depth observations related to the

operation and maintenance activities of the Nusa Dua

estuary Dam. The data were taken based on

interviews and direct measurements in the field as

well as by conducting an audience at the Bali Penida

River Council. The activity begins with an analysis

of the discharge of the Badung river to obtain

reservoir inflow, continued with population

projections to obtain water needs and finally an

analysis of current operations is carried out to

determine operating system policies in accordance

with the latest existing buildings. In more detail the

research methods carried out can be seen in figure 1.

Figure 1: Research flow.

2.2 Data Collections Activities

Data collection was carried out by taking secondary

data from the Bali Penida River Council, Badung

statistic agency and primary data through direct

measurements.

2.3 Analysis

The analytical work carried out includes: discharge

analysis, water demand analysis, simulation analysis

of water in reservoirs, analysis of building functions

in reservoirs, analysis of current operating systems,

analysis of operating development systems.

The hypothesis that can be conveyed in this study

is that the addition of new buildings, especially in the

diversion channel equipped with pneumatic crest

gates and trash racks, has an effect on the operation

and maintenance system that is easier to divert water

from the reservoir during the rainy season.

3 DISCUSSION

3.1 General Description

Nusa Dua Estuary Dam is located at the Badung

River estuary, precisely at the downstream of the By

Pass Ngurah Rai road bridge, Suwung is the border

between Denpasar City and Badung Regency which

is the main road to the Sanur–Kuta–Nusa Dua tourist

area. The area of the Nusa Dua Estuary Dam area is

35 Ha, with an inundation/reservoir area of 3 km

(Bali river council 2020). The watersheds that affect

the flow conditions of the Nusa Dua Estuary Dam are

the Badung river watershed and the Ayung river

tributary. The Badung river stream originates in

Cemenggaon Village which flows through the heart

of Denpasar City to the south with a total length of 22

km. The Ayung river drainage area from the Oongan

Weir until its meeting with Badung river on

Dipenogoro street is a 3.20 km long urban drainage.

General technical data as follows: catchment area

Badung river: 37.70 km

, reservoir inundation area:

35 Ha, deposition zone area: 1.6 Ha, total reservoir

storage: 770,000 m

, Total effective reservoir

reservoir : 595,000 m

, Normal water level elevation

(NWL): 1.70 m, Elevation minimum water level

(LWL): 0.50 m, maximum water level (HWL): 2.10

m, rubber dam lighthouse elevation: 1.70 m, reservoir

embankment elevation: +2.85 Installed capacity of

raw water supply: 500 litres/second, Output average

discharge of raw water drawn: 500 litres/second,

length of dam: 3.10 km, maximum tidal elevation:

0.90 m Design flood discharge (Q50): 234 m

/second.

In 2019, new buildings were added to the Nusa

Dua estuary Dam in the form of making a 20 m wide

diversion channel equipped with a pneumatic crest

gate and trash rack, adding a pneumatic crest gate to

the active reservoir section, adding a bar screen and

structuring the area in some parts of the estuary dam.

Analysis of Nusa Dua Estuary Dam Operations for Clean Water Supply South Badung Tourism Area

553

The addition of this new building of course creates a

new operation system that must be made to suit the

existing building.

3.2 Hydrological Analysis

Hydrological analysis is carried out to obtain the

amount of water that enters the reservoir as inflow

(Fang et al. 2014) (Iqbal et al. 2020). Hydrological

analysis was carried out downstream of Badung river

because the water became inflow into the Nusa Dua

estuary dam. Inflow and outflow data of 500

litres/second that enters the Nusa Dua estuary dam

with 50% reliability is then seen in Figure 2.

Figure 2: Fluctuations inflow and outflow the nusa dua

estuary dam with 50% reliability.

On the other hand, the calculation of water

reliability in reservoirs for drinking water is

calculated with 90% reliability in accordance with the

provisions of the minister of public works where this

discharge has a 90% chance of occurring. Simulation

of inflow and outflow the reservoir with 90%

reliability shows that there are 10 months with inflow

discharge conditions below the outflow taken at 500

liters/second. Of the existing 10 months, there are

four months with very small inflows that cause the

reservoir elevation below 1 m, namely in June, July,

August, September. More details can be seen in

Figure 3 and Table 1 below.

Figure 3: Discharge simulation with 90% reability.

Table 1: Inflow and outflow Nusa Dua Estuary Dam with

reability 90%.

Source: analysis, 2021

3.3 South Bali Area Water Needs

The need for clean water is closely related to

population growth and other non-domestic needs. For

the South Badung area (South Kuta Sub District) the

largest non-domestic water needs are needed for

tourism purposes where in this area there are many

tourist destinations that are spread evenly in almost

all areas. Based on data analysis in 2020, the

population in South Kuta District is 176,950 people.

Based on the projected population and the

increase in

the amount of water demand, in 2030 the need for

clean water has reached 514.02 litres/second,

exceeding the 500 liters per second that can be

prepared by the Nusa Dua estuary dam. Completely

projected population and water needs in South Kuta

District can be seen in Table 2 below.

Table 3: Projection of water demand in the south Badung

area.

Source: analysis, 2021

3.4 Operating System

The addition of new buildings in the Nusa Dua

Estuary Dam makes it necessary to change the new

operating pattern which is emphasized on three

conditions, namely low water conditions, normal

water conditions and high/flood water conditions.

(Vincenzo and Molino 2013)(Navas et al. 2009)(Iqbal

et al. 2020)(Vugteveen and Lenders 2009). The

No. Month Inflow Outflow Elevation

/second) (m

/second) (m)

1 January 0,50 0,50 1,70

2 February 0,54 0,50 1,70

3 March 0,43 0,50 1,65

4 April 0,41 0,50 1,61

5 May 0,25 0,50 1,13

6 June 0,20 0,50 0,41

7 July 0,44 0,50 0,35

8 August 0,38 0,50 0,28

9 September 0,35 0,50 0,01

10 October 0,09 0,50 1,23

11 November 0,50 0,50 1,22

12 December 0,44 0,50 1,25

Population Domestic use Non domestic use Total Use

P e ople lite rs/second lite rs/second lite rs/second

1 2020 176.950 245.76 61.44 307.20

2 2025 206.905 287.37 71.84 359.21

3 2030 236.860 411.22 102.80 514.02

4 2035 266.815 463.22 115.81 579.03

5 2040 296.770 515.23 128.81 644.03

YearNo.

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operating system on the estuary Nusa Dua dam is as

follows:

a. Equipment Operating System.

The radial gate is operated open when there is a flood

and closed when the water is normal level and the

water is low. This is done because the radial gate has

a very large influence in reducing water. There are 7

radial gates located in the southern part of the

reservoir. Rubber dam are opened when there is a

flood and closed when the water is normal level and

the water is low. The pneumatic crest gate in the bar

screen is closed when there is a flood but is opened

when the water is normal water level and the water is

low. The bar screen is always closed at various water

conditions to prevent debris from entering the

reservoir. More details equipment and new operating

system proposalof Nusa Dua estuary dam can be seen

in figure 4 table 4 below:

Figure 4: Equipment of Nusa Dua Estuary Dam.

Table 4: Operating System.

Source: analysis, 2021

The gate radial and rubber dam operating systems are

operated as before. Door opening can be done

manually or automatically. The complete condition of

the gate radial, rubber, and pneumatic crest gate and

bar screen can be seen in figure 5 and figure 6.

Figure 5: Radian Gate and Rubber Dam.

Figure 6: Pneumatic Crest Gate.

Figure 7: Bar Screen and Groundsill.

b. Trash Rack and Pneumatic Crest Gate Operation

The trash rack operating system is carried out on the

diversion channel which aims to control waste and

maintain water elevation in the reservoir. Trash racks

are always operated under various conditions to

prevent waste from entering the reservoir. The

pneumatic crest gate is opened when there is a flood

but is closed when the water is normal level and the

low water level. More details can be seen in table 5.

Table 5: Trash rack and pneumatic crest gate operation.

Source: analysis, 2021

Condition high water level normal water level low water level

Equipment

1 Radial Gate Open Close Close

2 Rubber dam Open Close Close

3 Penumatic crest gate di groudsill Close Open Open

4 Bar Screen pada groundsill Close Close Close

No.

Condition high water level normal water level low water level

Equipment

1 Trashrack Operation Operation Operation

2 Penumatic crest gate Open Close Close

No.

Radial Gate

Rubber Da

Pneumatic Crest Gate

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c. Flow System and Sediment Dredging

Flow system and sediment dredging are very

important, especially during floods condition.

(Wulandari, Legono, and Darsono 2014) (Heydari,

Othman, and Qaderi 2015) (Fang et al. 2014) At the

time of flood water, the flow system is directed to the

diversion channel, when normal water is directed to

the diversion channel and utilization zone and at low

water level flow is directed to the utilization zone.

Sediment dredging is an effort to prevent sediment

from entering the reservoir. In the reservoir operating

system, dredging is carried out only when low water

conditions are carried out in the deposition zone area.

The deposition zone is in the downstream of the

Badung River where mechanical dredging is carried

out which is operated periodically. More details can

be seen in table 6.

Table 6: Flow System and Sediment Dredging.

3.5 Flood Problems in the Badung River

The problem of flooding in the Badung river

downstream often causes inundation problems in the

southern Denpasar area around the estuary reservoir.

The flooding that occurred was caused by the

blockage of garbage that clogs the equipment on the

trash rack of the estuary reservoir, causing the water

level to rise which could potentially inundate the

surrounding area. So that the most important

operation of the estuary reservoir during the rainy

season is controlling waste so that it does not enter the

reservoir. Waste management must be carried out

with various approaches, both technically through

building infrastructure and non-technically through

guidance to the community. The people around the

river are mostly Balinese who are very obedient to the

values of nature conservation through traditional and

cultural approaches. Therefore, in the waste

management system, it is very effective to approach

the community through the customary and cultural

systems that already exist in the study area.

Customary and cultural regulations in the form of

customary regulations can be adopted to encourage

the community to actively participate in handling

waste. Three approaches that are very familiar in Bali

are environmental conservation systems with the

concept of a harmonious relationship between

humans and God, humans and humans and humans

and their natural surroundings. This concept is widely

known as the Tri Hita Karana concept. (Kristinayanti

et al. 2020)(Sukarma 2016)

4 CONCLUSION

Based on what was described in the previous section,

it can be concluded several things as follows:

1. The addition of a new building in the Nusa Dua

estuary dam creates a new operating system

2. The results of the hydrological analysis show that

with 90% reliability there is an inflow that is 10

months smaller than the outflow. Based on this, it

is recommended that at the peak of the dry

months, namely June, July, August and

September does not take 500 liters/second.

3. Based on the projected water demand in the South

Kuta District in 2040, there is an excess of

demand compared to the discharge provided by

the Nusa Dua estuary dam. Therefore, it is

necessary to take steps to develop raw water

sources through development from other sources

4. The operating system of the estuary dam is

regulated in three conditions, namely flood water

conditions, normal water conditions and low

water conditions.

ACKNOWLEDGMENT

On this occasion we would like to thank all those who

have helped, namely the Bali Penida River Council,

the Civil Engineering Department of the Bali State

Polytechnic, and I Gusti Ngurah Agung's colleague

REFERENCES

Badung Tourism Board. 2020. Badung Regency Tourism

Statistics.

Bali river council. 2020. Nusa Dua Estuary Dam Project.

Denpasar Bali.

Cole, Stroma. 2012. “A Political Ecology of Water Equity

and Tourism. A Case Study From Bali.” Annals of

Tourism Research 39(2): 1221–41.

Fang, Hong Bin, Tie Song Hu, Xiang Zeng, and Feng Yan

Wu. 2014. “Simulation-Optimization Model of

Reservoir Operation Based on Target Storage Curves.”

Water Science and Engineering 7(4): 433–45.

http://dx.doi.org/10.3882/j.issn.1674-

2370.2014.04.008.

Heydari, Mohammad, Faridah Othman, and Kourosh

Qaderi. 2015. “Developing Optimal Reservoir

Operation for Multiple and Multipurpose Reservoirs

Kondisi high water level normal water level low water level

Operation

1 Flow System Directed ti diversion channel Directed to utilization zone Directed to utilization zone

and diversion channel

2 Sediment Dredging No operation No operation Operation

No.

iCAST-ES 2021 - International Conference on Applied Science and Technology on Engineering Science

556

Using Mathematical Programming.” Mathematical

Problems in Engineering 2015.

Iqbal, Khairul, Lily M. Limantara, Widandi Soetopo, and

Ussy Andawayanti. 2020. “Multi-Reservoirs with Inter-

Reservoir Water Transfer Operation Rules.” IOP

Conference Series: Earth and Environmental Science

437(1).

Kristinayanti, W. S., I. G.A.I. Mas Pertiwi, M. A. Santiana,

and I. G.M.O. Aryawan. 2020. “Tri Hita Karana-Based

Green Environment Building Management Model.”

Journal of Physics: Conference Series 1450(1).

Navas, Ana, Blas Valero-Garcés, Leticia Gaspar, and Javier

MacHín. 2009. “Reconstructing the History of

Sediment Accumulation in the Yesa Reservoir: An

Approach for Management of Mountain Reservoirs.”

Lake and Reservoir Management 25(1): 15–27.

Sukarma, I Wayan. 2016. “Tri Hita Karana: Theoretical

Basic of Moral Hindu.” International Journal of

Linguistics, Literature and Culture 2(3): 84.

Sunarta, I Nyoman, Abd. Rahman, and As- Syakur. 2015.

“Study on the Development of Water Crisis in Bali

Island in 2009 and 2013.” E-Journal of Tourism 2(1):

33–42.

Vincenzo, Annamaria De, and Bruno Molino. 2013. “The

Rehabilitation of a Reservoir: A New Methodological

Approach for Calculating the Sustainable Useful

Storage Capacity.” Agricultural Sciences 04(08): 46–

50.

Vugteveen, Pim, and H. J.R. Lenders. 2009. “The Duality

of Integrated Water Management: Science, Policy or

Both?” Journal of Integrative Environmental Sciences

6(1): 51–67.

Wulandari. at al. 2014. “Reservoir Operation to Minimize

Sedimentation.” International Journal of Science and

Engineering 6(1): 16–23.

Wulandari, Dyah Ari, Djoko Legono, and Suseno Darsono.

2014. “Reservoir Operation to Minimize

Sedimentation.” International Journal of Science and

Engineering 6(1): 16–23.

Yamamoto at al. 2021. “Impact of Rapid Tourism Growth

on Water Scarcity in Bali, Indonesia.” Indonesian

Journal of Limnology 2(1): 1–16.

Analysis of Nusa Dua Estuary Dam Operations for Clean Water Supply South Badung Tourism Area

557