MODEL PENATAAN LAHAN KOMODITAS SIRTU DI AREA RAWAN BENCANA (Studi Kasus: Tambang di Aliran Sungai Apu Hulu Gunung Merapi)

GUNAWAN, RISAL (2023) MODEL PENATAAN LAHAN KOMODITAS SIRTU DI AREA RAWAN BENCANA (Studi Kasus: Tambang di Aliran Sungai Apu Hulu Gunung Merapi). Masters thesis, UPN "Veteran" Yogyajarta.

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Abstract

v
RINGKASAN
Kegiatan penambangan pasir dan batu akan menimbulkan dampak negatif dari
lahan bekas galian tambang. Oleh karena itu, perlu dilakukan perencanaan
pascatambang untuk mewujudkan pembangunan yang berkelanjutan sebagai acuan
pada rencana pascatambang. PT. Hasta Mulya Energy, salah satu perusahaan
tambang pasir dan batu yang terletak di Kabupaten Boyolali Provinsi Jawa Tengah
melakukan aktivitas penambangan dengan metode tambang quarry dan memiliki
IUP tambang seluas 12,45 Ha.
Tujuan penelitian yakni merekontruksi saluran sungai, merancang rencana desain
penataan lahan di daerah rawan bencana, merencanakan biaya rencana pengerjaan
sipil. Hasil pengamatan aktifitas penambangan dikawasan Sungai Apu terjadi
luapan air sungai, maka perlu dilakukan perancangan normalisasi sungai dan desain
pembuatan jenjang untuk tidak terjadi longsoran, yang mana daerah penelitian
merupakan rawan bencana masuk dalam kategori VII (sangat kuat) berdasarkan
skala Mercalli.
Analisis curah hujan rencana yang digunakan dalam penelitian ini menggunakan
metode distribusi Gumbbel selama 10 tahun (2013-2022). Hasil prediksi
menghasilkan curah hujan rencana sebesar 20,51 mm/hari, intensitas hujan sebesar
2,43 mm/jam menggunakan Mononobe dikategorikan hujan ringan. Lokasi
penelitian memiliki daerah tangkapan hujan seluas 4.56 km2, memiliki kondisi
wilayah di daerah tambang tanpa vegetasi sehingga nilai koefisien 0,9, hasil analisis
debit total 4,45m3/detik pada periode ulang lima tahun.
Pengukuran langsung di lapangan menggunakan current meter flowatch FL-03
didapatkan lebih tinggi debit airnya sebesar 0,57m3/detik dibandingkan dengan
analisis curah hujan 10 tahun terakhir sebesar 4,45 m3/detik, sehingga dalam
perbaikan penampang menggunakan debit air yang lebih tinggi. Metode perbaikan
penampang sungai yakni metode saluran terbuka bentuk trapesium, dimensi saluran
terbuka dirancang menggunakan kekasaran manning 0,30. Kedalaman rancangan
awal saluran 1,35 m ditambah 0,60 m untuk menghindari terjadinya luapan banjir,
sehingga kedalaman saluran menjadi 1,95 m.
Berdasarkan rekomendasi kestabilan lereng maka hasil penataan lahan berupa
pembuatan jenjang (benching), diperlukan pemotongan lereng sebesar 41.242 m3
sedangkan penimbungan sebanyak 24.924 m3 untuk jenjang timur laut, pada
jenjang barat daya diperlukan pemotongan 25.981 m3 dan penimbungan di barat
daya sebanyak 33.015 m3, sedangkan perbaikan penampang saluran sungai
diperlukan penggalian sebesar 4.544 m3. Hasil perhitungan biaya perencanaan
pengerjaan sipil sebesar Rp 608.657.085.
Kata kunci: desain jenjang, normalisasi sungai, pascatambang
vi
SUMMARY
Sand and stone mining activities will have a negative impact on ex-mining land.
Therefore, it is necessary to carry out post-mining planning to realize sustainable
development as a reference for post-mining plans. PT. Hasta Mulya Energy, a sand
and stone mining company located in Boyolali Regency, Central Java Province,
conducts mining activities using the quarry mining method and has a mining IUP
covering an area of 12.45 hectares.
The aims of the research are to reconstruct river channels, to design plans for land
management in disaster-prone areas, to plan the cost of civil works plans. Based
on observations of mining activities in the Apu River area, there was an overflow
of river water, so it is necessary to design a river normalization and a ladder design
to avoid landslides, which is a disaster-prone research area included in category
VII (very strong) based on the Mercalli scale.
The planned rainfall analysis used in this study uses the Gumbbel distribution
method for 10 years (2013-2022). The prediction results produce a planned rainfall
of 20.51 mm/day, a rain intensity of 2.43 mm/hour using Mononobe is categorized
as light rain. The research location has a rain catchment area of 4.56km2, has a
condition in the mine area without vegetation so that the coefficient value is 0.9,
the results of the total discharge analysis are 4.45m3/second at the five-year return
period.
Direct measurements in the field using the current meter flowatch FL-03 found a
higher water discharge of 0.57 m3/second compared to the analysis of rainfall in
the last 10 years of 4,45 m3/second, so that in cross section repairs using a higher
water discharge. The river cross section improvement method is the trapezoidal
open channel method, the dimensions of the open channel are designed using a
manning roughness of 0.30. The initial design depth of the channel was 1.35 m plus
0.60 m to avoid flooding, so that the channel depth became 1.95 m.
Based on the recommendations for slope stability, the result of land arrangement
is in the form of benching, 41,242 m3 of slope cutting is required while 24,924 m3
of balancing is required for the northeastern level, 25,981 m3 of cutting for the
southwest level is required and 33,015 m3 for the southwest level, while repairs
cross section of the river channel required excavation of 4.544 m3. The results of
the calculation of the cost of planning civil works amounted to IDR 608.657.085.
Keywords: ladder design, river normalization, post-mining

Item Type:	Thesis (Masters)
Uncontrolled Keywords:	ladder design, river normalization, post-mining
Subjects:	T Technology > T Technology (General)
Divisions:	Faculty of Engineering, Science and Mathematics > School of Engineering Sciences
Depositing User:	Eko Yuli
Date Deposited:	03 Jul 2023 07:06
Last Modified:	07 Jul 2023 06:39
URI:	http://eprints.upnyk.ac.id/id/eprint/36259

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