p–ISSN: 2723 – 6609 e-ISSN: 2745-5254

Vol. 5, No. 12, December 2024 http://jist.publikasiindonesia.id/

Indonesian Journal of Social Technology, Vol. 5, No. 12, December 2024 5609

Overview of the Influence of Land Use Change and Sediment

Control Structures on Sedimentation in Lake Sentani

Laorens Miehell Ngutra

, Mujiati

, Harmonis Rante

, Bernathius Julison

, Duha

Awaluddin

, Dewi Ana Rusim

Universitas Cenderawasih, Indonesia

Email: [email protected]

*Correspondence

ABSTRACT

Keywords: Sentani lake,

erosion, and

sedimentation, sediment

control building.

Under Presidential Decree No. 60 of 2021, on National

Priority Lakes Rescue, Lake Sentani is one of 15 priority

lakes to be rescued. In the annex to the President's regulation,

it is mentioned to date about 90 tons or ± 5 m/year of

sediment entering Lake Sentani with a total count of

62,0679.78 tonnes/year entering lake Sentani, with a storage

capacity of 1,782 billion/m3. The water supply of Lake

Sentani is obtained from the supply of 14 large and small

rivers. A slope inclination between 0% - 40% of the amount

of sediment transported during the rainy season causes a

decline in water quality and the high erosion that occurs.

This study aims to find out the impact of land-use change

and the effect of sediment control buildings on the number

of sediments that enter Lake Sentani. From the results of the

analysis, the impact of land use change before the

construction of the sediment control building based on the

analysis carried out by the Papua River Regional Hall, the

known potential sedimentation rate is 0.6 mm/th whereas the

potential sedimentation rate analyzed after the existence of

the building of the Sediment Controller is of 0.012 mm /year.

This indicates a change in the rate of potential Sedimentation

entering the lake of Sentani affected by the building

sediment operator. When it rains with repeated flooding

Q20, Q25, Q50, and Q100 years with conditions of one 1

(one) sediment control building it can be judged to be a very

heavy erosion class with land loss of more than 280

tons/ha/years with a potential sedimentation rate thickness

between 2.55 mm/years to 2.85mm/years.

Introduction

Papua is a province in Indonesia, located in the province of Papua on the western

island of New Guinea or West New Guinea. Papua Province is a province that

administratively borders directly with the State of Papua New Guinea (Asdak & Supian,

Laorens Miehell Ngutra, Mujiati, Harmonis Rante, Bernathius Julison, Duha Awaluddin, Dewi

Ana Rusim

Indonesian Journal of Social Technology, Vol. 5, No. 12, December 2024 5610

2018). This makes the Government of Indonesia continue to encourage the development

of the province of Papua which is the "home terrace" of the Indonesian State. The

Regional Government in Papua Province that is directly adjacent to and is the entrance to

Indonesia is the Jayapura City Government and the Jayapura Regency Government so the

development of Jayapura City and Regency Development continues to be spurred by the

Papua Provincial Government (Hidayat et al., 2018).

Papua is the Eastern part of Indonesia and has a huge potential for natural resources.

A vast land with dense tropical forests, abundant biodiversity, and biota. The potential of

water resources in Papua is also very large, with the number of ± rivers ± 173 or 2% of

the number of rivers in Indonesia (8,736). Papua has a coastline of ± 1,882.93 km or ±

1.98% of the coastline in Indonesia. (Rusdiyah, Dahliana, & Maulina, 2016). The

potential of swamp land ± 4.89 million hectares or ± 45% (± 10.9 million hectares) of

swamp land area in Indonesia. Papua Province has an area of 319,036.05 km2 or 16.7%

of the area of Indonesia, (Dawood, 2017).

The development of Jayapura City and Jayapura Regency continues to experience

development progress in all sectors. With the increasing development of Jayapura City

and Jayapura Regency, the need for housing and transportation facilities has also

increased, which has an impact on land use changes and the opening of new land as

residential locations. (Nurrochman, Joy, & Asdak, 2018). The land use change that

occurred had a dominant influence on the increase in surface flow discharge. Land use

change and forest encroachment around the Mount Cyloop buffer forest have resulted in

flash floods in Sentani City in 2019. The sediment material caused by flash floods has

had an impact on the accumulation of sediment in the estuaries of the river and until now

if there is rain with high intensity, the water flowing on the surface will bring sediment

into Lake Sentani (RADITYA, 2023). Lake Sentani is one of the largest lakes in

Indonesia, which is located just below the slopes of the Cyclops Mountains and stretches

between Jayapura City and Jayapura Regency. Lake Sentani also naturally functions as a

water reservoir because it receives water from 14 (fourteen) large and small rivers. Since

ancient times, Lake Sentani has been directly used by the community as a source of clean

water, aquaculture, capture fisheries, crossing transportation, and tourism. (Karim et al.,

2023).

The topography around Lake Sentani is mostly plains to undulating hills. Relatively

sloping plains are generally located at an altitude of between 50-100 meters above sea

level while undulating hills range from 100-500 meters above sea level. The morphology

of Lake Sentani includes a slightly rough relief with a slope between 0%-40%. This will

cause the problem of high erosion values and discharge fluctuations, so it is very

necessary to monitor the estimation of erosion and sedimentation values periodically.

According to BPDAS (Hidayat et al., 2017), the main factor causing flooding in the

Sentani watershed is the loss of most of the vegetation/land cover forest, as a result of

farming moving in the upstream part of the watershed so that the water absorption into

the soil becomes smaller. If land function experts continue to be left untreated and not

handled properly and appropriately, it will affect the amount of sediment transportation

Overview of the Influence of Land Use Change and Sediment Control Structures on

Sedimentation in Lake Sentani

Indonesian Journal of Social Technology, Vol. 5, No. 12, December 2024 5611

that enters Lake Sentani and will eventually cause siltation and the area of Lake Sentani

will decrease.

The accumulation of sediment carried by the water flow makes the lake shallower

which results in a reduced capacity for water volume. The siltation that occurs causes the

water area of Lake Sentani to expand in the rainy season and in the dry season to become

shallower. (Huda, Sudarsono, Sasmito, & Kahar, 2014). This exacerbates the widespread

flooding around the lake which has an impact on community activities. In addition to

siltation, changes in land use in the buffer areas of Lake Sentani will greatly affect the

occurrence of pollution.

The objectives to be proven in this study are:

1. Identify the influence of land use change on sediment control buildings.

2. Determine the influence of land use change and the influence of sediment control

buildings on the amount of sediment entering Lake Sentani.

3. Determine the strategy that must be carried out to prevent sedimentation that occurs in

Lake Sentani.

Method

Research Location

This study is located in Lake Sentani which is located in Jayapura Regency, Papua

Province at coordinates 140 23' − 140 50' LS and 2 31' − 2 41' E with a water area of

9,630 ha and the Flavouw sub-watershed which is one of the sub-watersheds located in

the Sentani-Tami Watershed with a catchment area (DTA) of 28.99 km2 and a river flow

length of 12.42 km.

Data Collection Methods

The method that will be carried out in this study uses two methods, namely: field

survey and data analysis.

1. The survey method is a method used for research by direct observation of the location

to be researched,

2. The data analysis method uses the Universal Soil Loss Equation (USLE) formula

assisted by the Geographic Information System.

In the collection of data, primary data is needed regarding the weight of the soil

content resulting from erosion in the Flavouw Sub-Basin, as a reference in converting the

value of Ton units into m3. Secondary data as inputs in the form of topographic maps,

maps of soil types, echo-sounding data, and hydrological data in the form of 10-year daily

rainfall data. The data is available from several related agencies, including:

1. Papua River Regional Center,

2. Jayapura Regency Forestry and Environment Service

Research Flow Chart

The flow chart of the stages of this research can be seen in Figure 1.

Laorens Miehell Ngutra, Mujiati, Harmonis Rante, Bernathius Julison, Duha Awaluddin, Dewi

Ana Rusim

Indonesian Journal of Social Technology, Vol. 5, No. 12, December 2024 5612

Figure 1 Research Flow Chart

Results and Discussion

Changes in Land Use of the Flavouw Watershed

Land use is an effort to plan land use in an area which includes the division of areas

to specialize in certain functions, for example, residential, trade, and industrial functions.

Land use change is the increase of land use from one side of use to another accompanied

by a decrease in other types of land use from one time to the next. At the Flavouw

watershed research location, based on the results of analysis through satellite imagery and

ArcGIS applications from 2020 to 2024, it can be found that there have been changes in

land use as follows:

Table 1

Land Cover Area in 2020-2024

Land

Cover

Land Cover Area (Km

)

Overview of the Influence of Land Use Change and Sediment Control Structures on

Sedimentation in Lake Sentani

Indonesian Journal of Social Technology, Vol. 5, No. 12, December 2024 5613

Year

2020

Year

2021

Year

2022

Year

2023

Year

2024

Jungle

Forest

18,961

18,592

18,247

18,219

Pioneer

Airport

1,290

Settlements

and

Activity

Places

4,212

4,259

4,270

4,274

Bush /

Alang

2,607

2,929

3,273

3,298

Tegalan /

Farm

0,742

0,732

Lake Water

/ Situ

0,003

Analysis of Sediment Diameter Test Results

To determine the influence of sediment control buildings in the Flavouw River,

sediment characteristics of the Flavouw River were tested at the UPTD Testing Center

and Laboratory of the Public Works, Spatial Planning, Housing, and Settlement Areas

Office of the Papua Provincial Government using filter analysis testing by taking samples

from 3 (three) different points on the flavor river which are considered to represent the

river and sediment control buildings. The data obtained in this study is primary data. From

the results of testing in the laboratory (can be seen in the attachment) it is known that:

1. The results of the test of the flavor river sand material at point-01 which is located

upstream of the river, the material is known to be included in the aggregate gradation

zone 2.3 and 4 with grain sizes ranging from 0.075 mm to 0.600 mm, which means

that the material at point-01 is included in the type of coarse-grained sand, medium-

grained sand, fine-grained sand to Silt (mud) material.

2. The results of the test of the Flavouw River sand material at point-02 which is after

the sediment control building, the material is included in the aggregate gradation zone

2.3 and 4 with grain sizes ranging from 0.075 mm to 0.600 mm which means that the

material at point-02 is included in the type of coarse-grained sand, medium-grained

sand, fine-grained sand to silt (mud) material.

3. The results of the Flavouw River sand material test at point-03, the material is included

in the aggregate gradation zone 1 and 2 which means that the material at point-03 is

included in the type of medium-grained sand, fine-grained sand, and silt (mud)

material.

Erosion Hazard Level (TBE)

Laorens Miehell Ngutra, Mujiati, Harmonis Rante, Bernathius Julison, Duha Awaluddin, Dewi

Ana Rusim

Indonesian Journal of Social Technology, Vol. 5, No. 12, December 2024 5614

Erosion calculation using the USLE method is an equation that predicts the average

erosion rate of a certain land on a slope with a certain rainfall pattern for each type of soil

and the determination of land management/land conservation actions. (Hariati, Taqwa,

Alimuddin, Salman, & Sulaeman, 2022). To determine the level of erosion hazard, the

classification of erosion levels that have been made by the Ministry of Forestry in 2008

is used.

Table 2

Classification of Erosion Hazard Levels

Based on the results of the analysis conducted by the Papua River Regional Office,

it is known that the level of erosion danger in the Flavouw Water Catchment Area is as

follows:

Table 3

Flavouw DTA Erosion Hazard Level

TBE (Erosion Hazard

Level)

Area (Ha)

Very Light

636.00

Light

352.05

Keep

1234.72

2222.77

Source: Analysis, 2019

Sediment Yield

Sedimentation is the result of an erosion process, either in the form of surface

erosion, trench erosion, or other types of soil erosion. Sediment generally settles at the

bottom of hills, in flooded areas, waterways, rivers, and reservoirs. The sediment yield

depends on the amount of total erosion in the watershed/sub-watershed and depends on

the transport of the eroded soil particles out of the watershed/sub-watershed catchment

area. (Andriyani, Wahyuningsih, & Suryaningtias, 2019). The forecast formula for the

amount of sediment yield per watershed unit per unit time (in tons/ha/year) can be

formulated as follows:

Y = E x SDR

With:

Y: Sediment Transportation

SDR: Sediment Delivery Ratio

Fennel: Watershed area or catchment area (DTA)

Overview of the Influence of Land Use Change and Sediment Control Structures on

Sedimentation in Lake Sentani

Indonesian Journal of Social Technology, Vol. 5, No. 12, December 2024 5615

The results of the sediment yield analysis on the Flavouw River DTA with river

discharge at the time of the study are as follows:

Based on the classification table of sedimentation rate with flow discharge

measured at the time of the study, it can be concluded that the sedimentation rate is still

classified as a good class because the potential sedimentation rate is < 2 mm/year.

SWOT Analysis

In determining the right and appropriate policy-making, calculations are carried out

using tools. The tools or tools used to determine decisions and policies are SWOT. The

following is the SWOT (Strength Weakness Opportunity Threat) of the effect of land use

change on erosion and sedimentation rate that enters Lake Sentani.

Table 4

Factors Influencing Decision-making

Strength

Weakness

Opportunity

Threat

The existence

of the

Jayapura

Regency

RTRW which

prohibits

deforestation

in cyclops-

protected areas

There are still

stakeholders who are

not involved in

handling land use

change.

Government

Attention through

the Ministry of

Public Works and

Housing

Regulation No.

19/KPTS/M/2024

concerning the

Determination of

Lake Boundary

Lines in the

Land conversion

occurs a lot for

agricultural land

and residential

areas.

Laorens Miehell Ngutra, Mujiati, Harmonis Rante, Bernathius Julison, Duha Awaluddin, Dewi

Ana Rusim

Indonesian Journal of Social Technology, Vol. 5, No. 12, December 2024 5616

Strength

Weakness

Opportunity

Threat

Mamberamo

Tami Apauvar

River Area

Existence of

Planning

Documents for

the

Revitalization

of Lake

Sentani

The Flavouw River

provides enough

sediment at the time

of flash floods,

making it possible

for a recurrence.

Sedimentation

control with

sediment control

buildings in the

inlet rivers of

Lake Sentani

Global climate

change that results

in high-intensity

rainfall can occur at

any time.

There is a

community of

nature lovers

who care

about the

destruction of

cyclops-

protected

forests.

The government's

program in terms of

reforestation of

protected forests

does not involve the

community.

BWS Papua's

attention to the

maintenance of

the Sediment

Control Building

Non-participatory

policymakers, the

bees of rule

enforcement

There are many

scientific studies

on land use

change, erosion,

and sedimentation

in Lake Sentani.

Land clearing by

uncontrolled

communities.

The higher the

rainfall, the greater

the rate of erosion

that occurs in the

Flavouw River

DTA

Overview of the Influence of Land Use Change and Sediment Control Structures on

Sedimentation in Lake Sentani

Indonesian Journal of Social Technology, Vol. 5, No. 12, December 2024 5617

After conducting a SWOT analysis, then a recalculation is carried out, namely the

score and weight of each SWOT. So after that, there will be which handling and direction

of recommendations need to be prioritized first.

Conclusion

From the results of the research and analysis carried out, the following conclusions

can be drawn:

1. The effect of land use change conditions that occur on sediment control buildings is

that there will be an increase in the rate of sedimentation that is carried by surface

flows and is trapped in the sediment control building so that the sediment control

building reservoir becomes full so that if maintenance is not carried out, it will cause

sediment carried by the flow of sediment-water to enter Lake Sentani.

2. The effect of land use change before the construction of the sediment control building

based on the analysis conducted by the Papua River Regional Center is known that the

potential sedimentation rate is 0.6 mm/year while the potential sedimentation rate

analyzed after the sediment control building is 0.012 mm/year. This shows that there

is a change in the potential sedimentation rate that enters Lake Sentani which is

influenced by the sediment control building.

Laorens Miehell Ngutra, Mujiati, Harmonis Rante, Bernathius Julison, Duha Awaluddin, Dewi

Ana Rusim

Indonesian Journal of Social Technology, Vol. 5, No. 12, December 2024 5618

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