p–ISSN: 2723 - 6609 e-ISSN: 2745-5254

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

Jurnal Indonesia Sosial Teknologi, Vol. 5, No. 5, Mei 2024 2066

Calculation Analysis of Erosion Rates and Sedimentation

Transport in the Liliba Watershed

Sri Santi L M F Seran

, Agustinus H Patiraja

, Krisantos Ria Bela

, Azarya Bees

Muritius I R Naikofi

Universitas Katolik Widya Mandira, Indonesia

Email: [email protected]

*Correspondence

ABSTRACT

Keywords: USLE, SDR,

Erosion, Sedimentation.

Erosion is the loss or erosion of land or parts of land from a

place by water or wind. Erosion causes the loss of fertile soil

layers good for plant growth and reduces the soil's ability to

absorb and retain water. The Liliba watershed area in

Kupang City includes Maulafa District, Oebobo District, and

Kelapa Lima District. The Liliba River Watershed (DAS) is

part of the development of the Noelmina River area, which

flows into Oesapa Beach. The Liliba watershed has an area

of 4,534 hectares with a central river length of 20,176.22 m.

Using the USLE Method and SDR Transport Analysis, it

was found that the erosion that occurred was 3.72 tonnes per

year, and the amount of sediment transport that occurred was

2.73 tonnes per year.

Introduction

The biggest challenge in managing natural resources is to create and then maintain

a balance between fulfilling the needs of human life and the sustainability of the use and

existence of natural resources (Asdak, 2023). The primary natural resources, namely land

and water, are renewable but easily damaged or degraded. Soil damage can occur by (1)

loss of soil elements and organic material in the root area, (2) accumulation of salt in the

root area, (3) saturation of the soil with water, and (4) erosion. This soil damage causes a

reduction in the soil's ability to support plant growth (Anasiru, 2015).

According to (Neolaka et al., 2022), erosion is the loss or erosion of land or parts

of land from a place by water or wind. Erosion causes the loss of fertile soil layers good

for plant growth and reduces the soil's ability to absorb and retain water. A river basin

(DAS) is a land area topographically limited by mountain ridges that collect and store

rainwater. It becomes a water catchment area to channel it to the sea via the main river

(Asdak, 2023). A water catchment area is an ecosystem whose main elements consist of

natural resources, including land, water, and vegetation, as well as human resources as

users of natural resources (Soetedjo, n.d.).

The Liliba river basin (DAS) is administratively located in 2 (two) administrative

areas, namely Kupang City and Kupang Regency. The Liliba watershed area in Kupang

Regency includes Nekamese District and Taebenu District. The Liliba watershed area in

Calculation Analysis of Erosion Rates and Sedimentation Transport in the Liliba Watershed

Jurnal Indonesia Sosial Teknologi, Vol. 5, No. 5, Mei 2024 2067

Kupang City includes Maulafa District, Oebobo District, and Kelapa Lima District. The

Liliba River Watershed (DAS) is part of the development of the Noelmina River area,

which flows into Oesapa Beach (Seran, 2022). The Liliba watershed has an area of 4,534

hectares with a central river length of 20,176.22 m. The Liliba watershed serves the

community's agricultural needs, flood control, and tourism activities (Kupang et al.

Number 12 of 2011). Currently, there are many social activities along the banks of the

Liliba River. This can be seen in many residential developments, even those on the river's

edge. It can also be seen that a lot of rubbish is thrown into the river basin. This, of course,

also influences the emergence of sedimentation in river basins (Sudira et al., 2013). This

research aims to obtain initial data so that it can be compared again with analyses that

will be carried out in the next 5 or 10 years. This research aims to determine the rate of

erosion in the Liliba watershed using the Usle method.

Research Methods

The research was conducted in the Liliba River Watershed, Kupang City

Figure 1

Location of the Liliba watershed

The first analysis is erosion analysis using the USLE method.

The research method used in erosion analysis is the USLE (Universal et al.

Equation) method, which involves several essential steps. First, primary data on the study

location, including soil type, topographic characteristics, rainfall patterns, and land use,

were carefully collected. Furthermore, these parameters will be used to calculate erosion

using the USLE formula. The next step is to apply the USLE formula, which includes soil

erosion, slope, land cover, and land management factors. The data that has been collected

Sri Santi L M F Seran, Agustinus H Patiraja, Krisantos Ria Bela, Azarya Bees, Muritius I R

Naikofi

Jurnal Indonesia Sosial Teknologi, Vol. 5, No. 5, Mei 2024 2068

will be processed and analysed using this method to produce an estimate of the level of

soil erosion at the study location. Subsequent analysis will compare these results with

existing erosion standards and identify the main factors contributing to soil erosion in the

area (Sujatmoko & Hirvan, 2022). This approach is hoped to provide an in-depth

understanding of the level of soil erosion and the factors that influence it, which can be

used for more sustainable land management and environmental protection.

Figure 2 Research Flow Diagram

Results and Discussion

The Liliba watershed is in Kupang Regency (upstream) and Kupang City (middle

and downstream). Taebenu sub-district, Kupang Regency on the east side, and two sub-

districts in Kupang City, namely Maulafa sub-district and Oebobo sub-district.

Meanwhile, the downstream part is the Kelapa Lima sub-district in Kupang City (Fathan,

Conclution

Discussion

Analysis Using the

USLE Method

Data sekunder

Data Primer

Study Literature

Calculation of

Sediment Transport

Using SDR

Start

Calculation Analysis of Erosion Rates and Sedimentation Transport in the Liliba Watershed

Jurnal Indonesia Sosial Teknologi, Vol. 5, No. 5, Mei 2024 2069

2022). The dominant soil type in the Liliba watershed area is Alluvial, with an Erodibility

Value (K) of 0.315 (Rizkia & Putri, 2019).

Erosion Analysis Using the USLE Method

When analysing rainfall data, erosion analysis was used to obtain the R-value.

Rainfall calculations use Rain Data from El Tari Kupang Station.

Table 1

Rainfall Calculation for 1998 – 2008

Based on the rainfall data above, the erosivity value that can be calculated is seen

in Table 2.

Table 2

Erosivity values for the Liliba watershed

Soil Erodibility Value (K) is obtained from secondary data collection through

digital maps of the distribution of soil types in the Noemina watershed obtained from

BWS NTT II. The soil type in the Liliba watershed area is an alluvial soil type with a soil

erodibility (K) value of 0.315 (Upadani, 2017). The Liliba watershed area has a diverse

topography using GIS tools. The average LS factor value obtained in the Liliba watershed

can be seen in Table 3:

Sri Santi L M F Seran, Agustinus H Patiraja, Krisantos Ria Bela, Azarya Bees, Muritius I R

Naikofi

Jurnal Indonesia Sosial Teknologi, Vol. 5, No. 5, Mei 2024 2070

Table 3

Table of Slope Slope and S Factor Values in the Liliba Watershed

Calculation of Slope Length (LS)

Slope length-slope factor:

LS = (L/22) z (0.006541S2 + 0.0456S + 0.065)

Is known:

Slope Length (L) = 20,167 m

z = 0.3

S = 0.24

So, LS = (20167/22)0.3 (0.006541(0.24)^2 + 0.0456(0.24) + 0.065)

LS = 0.18 m

Next, calculations are carried out to find the value of the Land Cover Factor (C) and

Soil Conservation (P), which can be seen in Table 4 below:

Table 4

Determining the Average CP in the Liliba Watershed

So the estimated amount of erosion per area (ha) is:

A = R x K

= 415.41 x 0.315 x 0.18 x 0.16 x 1

= 3.72 Tons/Ha/Year

So, the amount of sediment transported per year is

Calculation Analysis of Erosion Rates and Sedimentation Transport in the Liliba Watershed

Jurnal Indonesia Sosial Teknologi, Vol. 5, No. 5, Mei 2024 2071

SDR : 0.5656 x Atot ^-0.11

:0.5656 x 33.58^-0.11

:0.64

So, the annual sediment transport obtained is:

Ae = Total Erosion per Year x SDR Value

= 3.72 x 0.64

= 2.73 Tons/Ha

Conclusion

From the research results, it is known that the average rainfall in ten years is

1567.42 mm, Rain Erosivity value (R) = 415.41, with the most dominant slope being 5-

10% with a value of S = 0.24, the dominant soil type is alluvial with a value of K = 0.315.

From the values above, it is known that the amount of erosion that occurs is 3.72 tons per

year, and the amount of sediment transport that occurs is 2.73 tons per year.

Sri Santi L M F Seran, Agustinus H Patiraja, Krisantos Ria Bela, Azarya Bees, Muritius I R

Naikofi

Jurnal Indonesia Sosial Teknologi, Vol. 5, No. 5, Mei 2024 2072

Bibliography

Anasiru, Rahmat Hanif. (2015). Perhitungan laju erosi metode USLE untuk pengukuran

nilai ekonomi ekologi di Sub DAS Langge, Gorontalo. Jurnal Pengkajian Dan

Pengembangan Teknologi Pertanian, 18(3), 273–289.

https://doi.org/10.21082/jpptp.v18n3.2015.p%p

Asdak, Chay. (2023). Hidrologi dan pengelolaan daerah aliran sungai. UGM PRESS.

Fathan, F. (2022). Analisis Perubahan Luas Daerah Resapan Daerah Aliran Sungai

Jeneberang= Analysis of changes in the area of water infiltration area of the

Jeneberang watershed. Universitas Hasanuddin.

Neolaka, Elsa Yovanka, Tanesib, J. L., & Bernandus, Bernandus. (2022). Pemetaan

Daerah Rawan Erosi dengan Menngunakan Metode Universal Soil Loss Equation

(Usle) di Kota Kupang. Jurnal Fisika: Fisika Sains Dan Aplikasinya, 7(1), 29–36.

Rizkia, Riza, & Putri, Nanda Melyadi. (2019). Analisis Perhitungan Laju Erosi

Permukaan Dan Angkutan Sedimen Melayang (Suspended Load) Pada Aliran

Sungai Cisanggarung. University Technology Yogyakarta.

Seran, Sri Santi L. M. F. (2022). Analisis Erosi Pada Das Noelmina Menggunakan

Metode Usle. Eternitas: Jurnal Teknik Sipil, 2(1), 33–39.

Soetedjo, I. N. P. (n.d.). Rozari. DP, Leo, NM (2021). Studi Penutupan Lahan Hulu dan

Hilir Dareah Aliran Sungai Liliba Terhadap Kuantitas Air. Jurnal Ilmu Lingkungan,

19(3), 630–637.

Sudira, I. Wayan, Mananoma, Tiny, & Manalip, Hierico. (2013). Analisis Angkutan

Sedimen pada Sungai Mansahan. Jurnal Ilmiah Media Engineering, 3(1).

Sujatmoko, Bambang, & Hirvan, Zikron. (2022). Analisis laju erosi dan sedimentasi

lahan pada DAS Batang Kuranji Kota Padang. Jurnal Teknik, 16(1), 1–8.

Upadani, I. (2017). Model Pemanfaatan Modal Sosial Dalam Pemberdayaan Masyarakat

Pedesaan Mengelola Daerah Aliran Sungai (Das) Di Bali. WICAKSANA: Jurnal

Lingkungan Dan Pembangunan, 1(1), 11–22.