PEMBUATAN PETA KERAWANAN POTENSI GENANGAN BANJIR DENGAN METODE WEIGHTED OVERLAY (Studi Kasus: Kawasan Industri Hijau Desa Mangkupadi, Kec. Tanjung Palas Timur, Kab. Bulungan, Prov. Kalimantan Utara)
Enggar Saputro, Hidayat Panuntun, S. T., M. Eng., D. Sc
2024 | Tugas Akhir | D4 TEKNOLOGI SURVEI DAN PEMETAAN DASAR
Kawasan Industri Hijau yang dibangun di Desa Mangkupadi, Kecamatan
Tanjung Palas Timur, Kabupaten Bulungan, Provinsi Kalimantan Utara, merupakan
salah satu wilayah di Indonesia yang memiliki kerawanan potensi genangan banjir.
Hal ini dikarenakan keadaan topografi yang didominasi oleh dataran rendah,
jenis tanah yang kurang baik dalam hal drainase, dan intensitas hujan yang tinggi.
Adanya rencana pembangunan Kawasan Industri Hijau akan mengurangi area resapan
air. Oleh karena itu perlu upaya preventif penanggulangan masalah banjir. Dengan belum adanya peta kerawanan potensi
genangan banjir yang dibuat, penentuan prioritas dalam mengurangi risiko
genangan banjir menjadi kurang terarah. Oleh karena itu, perlu dilakukan pembuatan
peta kerawanan potensi genangan banjir. Tujuan dari pembuatan peta tersebut
ialah untuk mengetahui sebaran kerentanan spasial sebagai langkah awal
pengurangan risiko genangan banjir.
Pembuatan peta kerawanan
potensi genangan banjir disusun menggunakan sebelas parameter antara lain curah
hujan, tutupan lahan (block plan), elevasi, kemiringan lereng, Stream
Power Index (SPI), Topographic Weatness Index (TWI), Topographic
Position Index (TPI), Normalized Difference Vegetation Index (NDVI),
kerapatan aliran, jarak ke sungai, dan jarak ke jalan. Data curah hujan
diperoleh dari mengombinasikan data stasiun BMKG dan citra satelit Climate
Hazard Group Infrared Precipitation with Station (CHIRPS). Data elevasi dan
kemiringan lereng diperoleh dan diekstraksi dari data LiDAR. Data SPI, TWI, dan
TPI didapatkan dari proses pengolahan DTM hasil ekstraksi data LiDAR. Data NDVI
didapatkan dari pengolahan Sentinel 2A. Data tutupan lahan diperoleh
berdasarkan data rencana block plan Kawasan Industri Hijau. Data
kerapatan aliran diperoleh dari operasi line density terhadap jaringan
sungai. Data jarak ke sungai dan jalan didapatkan dari .shp jaringan sungai dan
jalan kawasan. Setiap parameter diklasifikasi dan di-scoring berdasarkan
kelas kerentanan potensi genangan banjir. Setiap parameter yang ditelah di-scoring
dibobotkan dan dilakukan overlay menggunakan operasi map algebra
atau disebut weighted overlay. Hasil overlay dilakukan
klasifikasi menjadi tiga kelas kerentanan dengan interval yang sama setiap kelasnya,
yaitu rendah, sedang, dan tinggi dengan nilai indeks kerentanan 272 sampai dengan 460.
Peta
kerawanan potensi genangan banjir di Kawasan Industri Hijau Kabupaten Bulungan
berhasil dibuat berdasarkan sebelas parameter kerentanan lingkungan yang mempengaruhi.
Berdasarkan peta kerawanan potensi genangan banjir yang telah dibuat, Kawasan
Industri Hijau memiliki tiga tingkat kerawanan potensi genangan banjir,
meliputi rendah, sedang, dan tinggi. Kerawanan potensi genangan banjir Kawasan
Industri Hijau didominasi tingkat kerawanan sedang dengan persentase 67% atau 8.875,66 ha. Area
sekitar pantai memiliki kelas kerawanan tinggi terjadinya genangan banjir.
Kelas kerawanan tinggi didominasi oleh area yang akan digunakan sebagai area industri
dengan persentase 61% atau 1924,62 ha.
The Green Industrial Estate built in
Mangkupadi Village, East Tanjung Palas Sub-district, Bulungan Regency, North
Kalimantan Province, is one of the areas in Indonesia that is prone to
potential flooding. This is due to the topography which is dominated by
lowlands, poor soil types in terms of drainage, and high rainfall intensity.
The planned development of the Green Industrial Estate will reduce the water
catchment area. Therefore, preventive efforts to overcome flooding problems are
needed. With the absence of a map of the
vulnerability of potential flood inundation, prioritization in reducing the
risk of flood inundation is less directed. Therefore, it is necessary to make a
map of the vulnerability of potential flood inundation. The purpose of the map
is to determine the spatial distribution of vulnerability as a first step in
reducing the risk of flood inundation.
The flood inundation
vulnerability map was prepared using eleven parameters, including rainfall,
land cover (block plan), elevation, slope, Stream Power Index (SPI),
Topographic Weatness Index (TWI), Topographic Position Index (TPI), Normalized
Difference Vegetation Index (NDVI), stream density, distance to river, and
distance to road. Rainfall data was obtained from combining BMKG station data
and Climate Hazard Group Infrared Precipitation with Station (CHIRPS) satellite
images. Elevation and slope data were obtained and extracted from LiDAR data.
SPI, TWI and TPI data were obtained from DTM processing of LiDAR data extraction
results. NDVI data was obtained from Sentinel 2A processing. Land cover data
was obtained based on the Green Industrial Area block plan data. Flow density
data is obtained from line density operation on river network. Distance to
river and road data is obtained from .shp river and road network of the area.
Each parameter is classified and scored based on the vulnerability class of
potential flood inundation. Each parameter that has been scored is weighted and
overlaid using map algebra operations or called weighted overlay. The overlay
results were classified into three vulnerability classes with equal intervals
for each class, namely low, medium and high with a vulnerability index value of
272 to 460.
The vulnerability map of potential flood inundation in the Green Industrial Area of Bulungan Regency was successfully created based on eleven influencing environmental vulnerability parameters. Based on the map of potential flood inundation vulnerability that has been made, the Green Industrial Estate has three levels of potential flood inundation vulnerability, including low, medium and high. The vulnerability of potential flood inundation in the Green Industrial Area is dominated by the medium vulnerability level with a percentage of 67% or 8,875.66 ha. Areas around the coast have a high vulnerability class for flood inundation. The high vulnerability class is dominated by areas that will be used as industrial areas with a percentage of 61% or 1924.62 ha.
Kata Kunci : Kerentanan, Banjir, AHP, Weighted Overlay, Parameter Banjir