Utilization of the Tukad Unda River

for the Development of Clean Water Services

Denpasar, Badung, Gianyar and Klungkung (Sarbagikung) Areas

I Nyoman Sedana Triadi, Ir. I Made Tapa Yasa, Ir. Made Mudhina, I G. L. Made Parwita,

I Nyoman Anom P. Winaya and Ketut Wiwin Andayani

Jurusan Teknik Sipil, Politeknik Negeri Bali,

Jl Kampus Bukit Jimbaran, Kuta Selatan, Kab. Bandung-Bali-8036, Indonesia

Keywords: Availability, Area, Need, Balance, Water, Development.

Abstract: The area of irrigated rice fields used by subak in the Unda River Basin is 3,891.89 ha, spread over the

Klungkung and Karangasem regencies. Specifically, the study of the discharge downstream of Tukad Unda

is in the Unda Dam, the irrigation area is called the Unda Irrigation Area, with a total area of 1,104.89 ha of

the Unda Irrigation Area. The population of Denpasar City in 2021 is 981,824 people, Badung Regency

696,850 people, Gianyar Regency 521,215 people and Klungkung Regency 181,989 people, currently trying

to fulfill clean water sourced from Tukad Unda water flow.To find out the potential of Tukad Unda

downstream in providing clean water, an analysis of its water availability and existing water needs was carried

out. Analysis of water availability with 90% reliability in the downstream Tukad Unda river was carried out

using frequency analysis based on the type of distribution of discharge data obtained in Tukad Unda. Analysis

of domestic and non-domestic water needs from 2020 to 2040 is based on the socio-economic development

conditions of the community. From the results of these calculations, an analysis of the water balance is carried

out, namely comparing the availability of water with the demand for water, so that the deficit or surplus is

known from time to time. The need for clean water in the Sarbagikung area until 2040 is 7,757 m

/s. The

planned allocation of water from Estuary of Tukad Unda Reservoir for the Sarbagikung area is 1,400

liters/second, covering 850 liters/second to meet the needs in South Denpasar District, 100 liters/second in

South Kuta District, 300 liters/second which will distributed to the Districts of Gianyar and Klungkung at 150

liters/second.

1 INTRODUCTION

1.1 Background

Provision of drinking water is a basic need and socio-

economic right of the community that must be

fulfilled by the central and local governments. The

availability of drinking water is one of the

determinants in improving people's health, welfare,

and productivity in the economic field. Therefore, the

provision of drinking water facilities and

infrastructure is one of the keys to regional economic

development. (Minister of Public Works Regulation,

2007).

Specifically, the study of the discharge

downstream of Tukad Unda is in the Unda Dam, the

irrigation area is called the Unda Irrigation Area, with

a total area of 1,104.89 ha of the Unda Irrigation Area.

The current condition of the cropping pattern in the

Unda irrigation area is Paddy Paddy Palawija.

The increasing demand for water has caused

several problems in the process of providing adequate

quantity and quality of water supply. The population

of Denpasar City in 2021 is 981,824 people, Badung

Regency 696,850 people, Gianyar Regency 521,215

people and Klungkung Regency 181,989 people,

currently trying to fulfill clean water sourced from

Tukad Unda water flow

To find out the potential of Tukad Unda

downstream in providing clean water, an analysis of

its water availability and existing water needs was

carried out. Analysis of water availability with 90%

reliability in the downstream Tukad Unda river was

carried out using frequency analysis based on the type

of distribution of discharge data obtained in Tukad

Triadi, I., Yasa, I., Mudhina, I., Parwita, I., Winaya, I. and Andayani, K.

Utilization of the Tukad Unda River for the Development of Clean Water Services Denpasar, Badung, Gianyar and Klungkung (Sarbagikung) Areas.

DOI: 10.5220/0011876400003575

In Proceedings of the 5th International Conference on Applied Science and Technology on Engineering Science (iCAST-ES 2022), pages 751-756

ISBN: 978-989-758-619-4; ISSN: 2975-8246

751

Eff

IRIR

DR 1157,0

Unda. Analysis of domestic and non-domestic water

needs from 2020 to 2040 is based on the socio-

economic development conditions of the community.

From the results of these calculations, an analysis of

the water balance is carried out, namely comparing

the availability of water with the demand for water,

so that the deficit or surplus is known from time to

time.

1.2 Problem Formulation

The formulation of the problem from the research on

Utilization of the Tukad Unda river for the

development of clean water services in the Denpasar,

Badung, Gianyar and Klumgkung (Sarbagikung)

areas is, how big the Tukad Unda river can be used

for the Sarbagikung area.

1.3 Purpose

The purpose of this study was to obtain answers to the

problems presented, is calculating how big the Tukad

Unda river can be used for the Denpasar, Badung,

Gianyar and Klungkung (Sarbagikung) areas.

2 LITERATURE REVIEW

2.1 Need for Irrigation

Taking into account the level of effectiveness and

efficiency of the water distribution pattern, the need

for irrigation water will be calculated based on a 15-

day period, this period is effective and efficient

enough to be implemented in the later operating

pattern. The methods that will be used in this analysis

are, (Kementrian Pekerjaan Umum, 2013).

 Analysis of potential evapotranspiration (ETo)

using the Modified Penman method

ETo = ETo* . C (1)

 Analysis of effective rainfall using the Basic

Year method, For Rice and For Palawija

 Crop coefficient (Kc) based on FAO . method

 Consumptive use (Etc)

Etc = Kc . Eto (2)

 Efficient irrigation based on Planning Criteria

 The need for clean water for rice is calculated

based on the formula.

IR1 = Etc1 + P + WLR + LP – Re (3)

 Water Needs for Palawija .

IR2 = Etc2 – Rep (4)

 water in the intake

(5)

2.2 Water Potential

Water potential is the amount of water contained in

water bodies, both as surface water and as

underground water. In the analysis of the amount of

water potential, it can be obtained through data series

from recording weir discharge, river or it could be

based on the mainstay discharge analysis by using

several methods of diverting the variance of rain

associated with the conditions of the existing

watershed. The method commonly used is the FJ

Mock method or the NRECA method, ( Soemarto

CD, 2011)

2.3 Strategy Management

Strategic management is defined as a way to guide

companies to achieve a number of goals, including

corporate responsibilities, managerial capabilities, to

administrative systems related to strategic decision

making, and operations.Strategic management is a

series of fundamental decisions and actions from the

highest management, which are applied by all

members of an organization, for the realization of

organizational goals. (Agrifa Masir, 2017)

2.4 Population

The calculation of the population is important,

because knowing the population of an area will be the

basis for making population policies at a certain time.

The province of Bali, which includes nine regencies

and cities, has a relatively varied population.

Population development in the province of Bali has

not been evenly distributed. As a result of the uneven

development of the region, especially related to the

development of the tourism industry sector,

community social centers, and government, which are

still in the district capital.

Calculation of the population using arithmetic,

geometric and least square formulas. To determine

the method used in each sub-district, the smallest

standard deviation value of the three approaches will

be determined. (Minister of Public Works Regulation,

2007).

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2.5 Clean Water Development System

Part of a clean water distribution network system, are

the components that exist in a series of clean water

distribution network systems. These parts consist of

pipes and their connections, valves, pumps,

reservoirs, all of which must work properly.

Based on the instructions of the Integrated City

Infrastructure Development Program regarding

Guidelines for Planning and Technical Design for the

drinking water sector, it is stated that the raw water

sources that can be treated are springs, namely water

sources that are above the ground surface, shallow

wells, namely water sources resulting from

excavations or drilling depths. less than 40 meters

deep, deep wells, namely water sources from

excavation or drilling with a depth of more than 40

meters, rivers, namely water drainage channels

formed from upstream to empties into the sea or

lakes, lakes and water reservoirs, namely deep water

storage units a certain amount of which the water

comes from streams or rainwater reservoirs.

3 METHODOLOGY

3.1 Scope of Research

The scope of the utilization of the Tukad Unda river

for the development of clean water services in the

Denpasar, Badung, Gianyar and Klungkung

(Sarbagikung) areas are:

 Conduct a literature study or review of relevant

studies related to the remaining water in the

lower reaches of Tukad Unda

 Measure the downstream Tukad Unda

instantaneous discharge

 Analyzing the Tukad Unda discharge data based

on the Unda Dam discharge recording data,

AWLR, and rain data.

 Analyzing the mainstay of the Tukad Unda debit

 Analyzing the availability of Tukad Unda water

and current irrigation water needs

 Analyzing the water balance downstream of

Tukad Unda

3.2 Data Source

The data source is a very important part related to the

validity of the data. With regard to the data to be

retrieved, the data that will be needed are as follows:

 Daily rain data for 15 years from Besakih Rain

Station, Rendang Rain Station, Duda Rain

Station, and Klungkung Rain Station.

 Data on debit recording at the Tukad Unda

AWLR Post for 15 years.

 Data on debit recording in Unda Dam for 15

years.

 Demographic data of the population, socio-

cultural facilities and infrastructure, tourism,

industry.

 Clean water supply system data

 Data on current sources of clean water

 Clean water quality and quantity data

3.3 Measurement with Current Meter

The tool used to measure the flow velocity is a current

measuring instrument, which is commonly referred to

as a current meter. The main equipment commonly

used in measuring flow is a flow meter, including all

its accessories, namely a timer and a rotation counter,

a depth gauge, a width gauge, assembly equipment

and some additional tools. The selection of the use of

equipment and equipment must be adjusted to the

physical condition of the river being measured.

3.4 Analysis of Clean Water

Availability

In calculating the mainstay discharge using the basic

year planning method. The planning base year is a

reliable debit pattern where the debit pattern has

actually happened in previous years. The mainstay

discharge calculation is intended to find the

quantitative value of the available discharge

throughout the year, in the dry season and in the rainy

season.

3.5 Population Analysis

Calculation of the population using arithmetic,

geometric and least square formulas. To determine

the method used in each sub-district, the smallest

standard deviation value of the three approaches will

be determined.(Minister of Public Works Regulation

2007).

3.6 Clean Water Needs Analysis

The Directorate General of Human Settlements has

set the water usage standard for metropolitan cities of

190 liters/person/day, standard waterrequirements for

large cities at 170 liters/person/day, medium cities at

Utilization of the Tukad Unda River for the Development of Clean Water Services Denpasar, Badung, Gianyar and Klungkung

(Sarbagikung) Areas

753

150 liters/person/day, and small cities at 130 liters

people. /day.

3.7 Water Balance

The water balance is intended to determine how much

potential is available each month, as well as how

much water is needed. The Water Balance will know

the months of surfing as well as the months that are

in deficit. Mathematically, the calculation method for

obtaining the residual water discharge in this water

balance analysis is the mainstay discharge minus the

demand discharge.

3.8 Clean Water Supply System

Strategy

The clean water supply system strategy is carried out

by means of a literature study, with the development

of the concept of sustainable water source

management, based on the condition of the current

system that has been running, taking into account the

sustainability of clean water supply in the future.

Inventory of existing clean water sources and clean

water sources that are in the process of being built.

4 DISCUSSION RESULT

4.1 Population

Calculation of population using arithmetic, geometric

and least square formulas. Determination of the

method used in each sub-district will be determined

with the smallest standard deviation value of the three

approaches. (Minister of Public Works Regulation,

2007)

Table 1: Population of the Sarbagikung Area.

Districts

Projected population (person)

2020 2025 2030 2035 2040

Denpasar 962.900 1.057.362 1.165.838 1.285.734 1.418.286

Badung 683.200 750.730 816.460 880.390 942.520

Gianyar 516.300 539.827 563.645 588.099 613.217

Klungkung 180.780 186.824 192.869 198.913 204.957

Total 2.343.180 2.534.743 2.738.812 2.953.136 3.178.980

4.2 Water Demand Projection

The sub-district's domestic water needs are

determined based on the population. In 2020 and

2021, it is assumed that the service level has reached

80%, an increase of 5% annually, until in 2025 the

service level has reached 100%. Non-domestic needs

are 20% of domestic needs, water leakage is 20% of

total domestic and non-domestic needs. The total of

water needs is the sum of domestic, non-domestic,

and water leaks.

Table 2: Average Water Demand Capacity.

Districts

Average Water Demand Capacity (liter/second)

2020 2025 2030 2035 2040

Denpasar 1.925,80 2.643,41 2.914,59 3.214,34 3.545,72

Badung 1.255,95 1.764,52 2.001,67 2.153,88 2.347,57

Gianyar 929,31 1.176,09 1.303,79 1.361,04 1.419,81

Klungkung 306,77 371,4 417,88 430,98 444,08

TOTAL 4.417,83 5.955,42 6.637,93 7.160,24 7.757,18

4.3 Mainstay Debit Analysis

Mainstay debit is the amount of discharge available

to meet water needs with a calculated risk of failure.

In planning a water supply project, a reliable

discharge must first be sought, the purpose of which

is to determine the planned discharge which is

expected to always be available in the river

(Soemarto, 1987). The mainstay discharge is intended

to find the quantitative value of the available

discharge throughout the year, both during the dry

season and in the rainy season. The mainstay debit is

the minimum debit that can be guaranteed reliability

with a probability of P% or has a failure risk level of

(1-P%).

Table 3: Mainstay debit 90% at Weir Unda.

Descri

tion

Mainstay Discharge 90% in Unda Dam (m3/s)

Jan Feb Mar Apr May Jun

AWLR Debit Data 3,84 3,88 3,66 3,59 2,76 1,57

Recording Debit

Data at Unda Dam

7,95 6,23 7,62 8,22 7,54 5,97

FJ. Mock Debit

Data

7,20 12,50 7,00 6,50 3,70 0,20

Average 6,33 7,54 6,09 6,10 4,67 2,58

Descri

tion

Mainstay Discharge 90% in Unda Dam (m3/s)

Jul Aug Sep Oct Nov Dec

AWLR Debit Data 2,74 2,21 3,34 1,40 2,11 3,60

Recording Debit

Data at Unda Dam

6,41 5,40 4,24 3,76 7,56 5,61

FJ. Mock Debit

Data

4,70 1,50 4,30 2,10 1,20 7,60

Average 4,61 3,04 3,96 2,42 3,63 5,60

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4.4 Irrigation Water Needs

The area of irrigated rice fields utilized by the Unda

Irrigation Area is 1,104.89 ha. The condition of the

existing cropping pattern in DI Unda is Paddy Paddy

Palawija, early planting of rice 1 is March 1, paddy 2

is on July 1 and palawija is on October 1st.

Table 4: Irrigation Water Needs in Unda Weir.

Descri

tion Irri

ation Water Needs in Unda Weir (m3/sec)

Jan Feb Mar Apr May Jun

Existing

Irrigation

Needs

0,04 0,68 1,46 0,59 0,56 0,77

Descri

tion Irri

ation Water Needs in Unda Weir (m3/sec)

Jul Aug Sep Oct Nov Dec

Existing

Irrigation

Needs

1,54 1,31 1,14 0,55 0,31 0,70

4.5 Water Balance

Water-balance is an analysis that describes the

utilization of water resources in a review area based

on a comparison between water demand and

availability. The calculation of the water balance is

intended to determine the remaining Tukad Unda

water after being used, which indicates a shortage or

excess of water, in the downstream part of the Tukad

Unda watershed, in terms of the availability of surface

water.

Table 5: Mainstay Discharge 90% in Unda Dam.

Description

Mainstay Discharge 90% After Use of

Irrigation in Unda Weir (m

/sec)

Jan Feb Mar Apr May Jun

AWLR Debit Data 3,80 3,20 2,20 3,00 2,20 0,80

Recording Debit

Data at Unda Dam

7,20 5,90 6,30 6,90 6,50 4,80

FJ. Mock Debit

Data

3,90 9,60 5,20 3,70 1,80 0,10

Average 4,97 6,23 4,57 4,53 3,50 1,90

Description

Mainstay Discharge 90% After Use of

Irrigation in Unda Weir (m

/sec)

Jul Aug Sep Oct Nov Dec

AWLR Debit Data 1,20 0,90 2,20 0,85 1,80 2,90

Recording Debit

Data at Unda Dam

5,80 4,10 3,50 3,60 6,20 5,20

FJ. Mock Debit

Data

4,20 1,30 2,50 2,00 0,10 5,50

Average 3,73 2,10 2,73 2,15 2,70 4,53

Figure 1: Mainstay Discharge 90% in Unda Weir

(Remaining Water downstream of the Unda Weir).

5 CONCLUSION

The conclusion of the research is :

 The average value of the residual water

discharge in Tukad Unda is 3,638 m3/sec.

 The need for clean water in the Sarbagikung

area until 2040 is 7,757 m3/s.

 The planned allocation of water from Estuary of

Tukad Unda Reservoir for the Sarbagikung area

is 1,400 liters/second, covering 850

liters/second to meet the needs in South

Denpasar District, 100 liters/second in South

Kuta District, 300 liters/second which will

distributed to the Districts of Gianyar and

Klungkung at 150 liters/second.

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