ANALISIS KONDISI RESAPAN AIR TERHADAP PERUBAHAN KAWASAN TERBANGUN MENGGUNAKAN METODE INDEX-BASED BUILT-UP INDEX (IBI) DAN URBAN INDEX (UI) KOTA PEKALONGAN

Abstract

ABSTRAK

Pertumbuhan penduduk di Indonesia mengalami peningkatan terutama di kota-kota besar setiap tahunnya. Hal ini menyebabkan lahan kosong yang ada di lingkungan perkotaan berubah menjadi bangunan sebagai bentuk dinamika pertumbuhan kota. Kota Pekalongan merupakan salah satu kota besar yang memiliki potensi perubahan penggunaan kawasan terbangun yang pesat. Kawasan terbangun dengan intensitas yang semakin tinggi dapat menimbulkan terganggunya kondisi sumber daya air karena berkurangnya daerah resapan air. Menurut BPBD Kota Pekalongan, hampir seluruh daerah yang ada di Kota Pekalongan merupakan wilayah daerah rawan banjir. Kawasan resapan air memiliki peran penting dalam menjaga lingkungan perkotaan karena menjaga kestabilan siklus air.

Penelitian ini menggunakan metode Index-based Built-up Index (IBI) dan Urban Index (UI) untuk mendapatkan informasi kawasan terbangun. Daerah resapan air didapatkan menggunakan metode scoring  dari beberapa parameter, antara lain kelerengan, curah hujan, jenis tanah,  jarak sungai dan tutupan lahan. Data yang digunakan adalah citra Landsat 8 OLI. Analisis kondisi resapan air dilakukan secara spasial dan deskriptif kemudian dilakukan analisis persebaran kawasan terbangun, persebaran kondisi resapan air, korelasi spasial terhadap kawasan terbangun.

Hasil penelitian ini adalah peta kondisi resapan air Kota Pekalongan. Pengolahan kawasan terbangun metode IBI tahun 2019 menghasilkan luas sebesar 2.673,855 ha dan metode UI seluas 2.503,603 ha dengan akurasi yaitu 89,39% dan 87,88%. Kondisi resapan air dibagi dalam 5 kelas antara lain baik, normal alami, mulai kritis, cukup kritis dan kritis.  Kondisi resapan air kelas baik memiliki luas 64,854 ha (1,40%), normal alami seluas 435,753 ha (9,41%), mulai kritis seluas 1.944,726 (42,01%), cukup kritis seluas 1.453,620 ha (31,40%) dan kritis seluas 730,701 ha (15,78%) yang memiliki tingkat kesesuaian sebesar 77,27% dari data survei lapangan. Korelasi spasial kondisi resapan air terhadap perubahan kawasan terbangun tahun 2017-2019 memiliki kelas tingkat korelasi sangat rendah seluas 75,420 ha (2,82%), korelasi rendah seluas 48,600 ha (1,82%), korelasi sedang seluas 1.578,830 ha (59,35 %), korelasi tinggi seluas 738,540 ha (27,62%) dan korelasi sangat tinggi seluas 224,460 ha (8,39%). Korelasi kondisi resapan air terhadap perubahan kawasan terbangun yang dominan yaitu kelas sedang. Sehingga dapat disimpulkan perubahan kondisi resapan air memiliki korelasi terhadap pertumbuhan kawasan terbangun.

Kata Kunci   : Index-based Built-up Index, Kawasan Terbangun, Kondisi Resapan Air, Urban Index, Scoring

ABSTRACT

Population growth in Indonesia continues to increase, especially in big cities. This causes the vacant land in the urban environment to change into buildings as a form of city growth dynamics. Pekalongan City is one of the big cities that has the potential to rapidly change the use of the built area. The built area with higher intensity can result in disruption of water resource conditions due to reduced water catchment areas. According to BPBD of Pekalongan City, almost all areas in Pekalongan City are flood-prone areas. Water catchment areas have an important role in protecting the urban environment because they maintain the stability of the water cycle.

This research uses Index-based Built-up Index (IBI) and Urban Index (UI) methods to obtain information on the built area. The water catchment area is obtained using the scoring method of several parameters, including slope, rainfall, soil type, river distance and land cover. The data used is Landsat 8 OLI imagery. Analysis of water catchment conditions is carried out spatially and descriptively then an analysis of the distribution of built up areas, distribution of water catchment conditions, spatial correlation with the built up area.

The results of this study are maps water catchment conditions  of Pekalongan City. The processing area built by the IBI method in 2019 has an area of 2,673,855 ha and the UI method is 2,503,603 ha with an accuracy of 89.39% and 87.88%. Water catchment conditions is divided into 5 classes, including good, natural normal, getting critical, quite critical and critical. Good grade water catchment condition has an area of 64,854 ha (1.40%), natural normal area of 435.753 ha (9.41%), getting critical area of 1,944.726 (42.01%), quite critical of 1,453.620 ha (31.40%) and critical area of 730.701 ha (15.78%) which has a suitability level of 77.27% from data survey. Spatial correlation of water catchment conditions on changes in the built area in 2017-2019 has a class of very low correlation level of 75,420 ha (2.82%), low correlation of 48,600 ha (1.82%), moderate correlation of 1,578.830 ha (59.35%), high correlation area of 738,540 ha (27.62%) and very high correlation area of 224.460 ha (8.39%). The dominant correlation of water catchment conditions to changes in the built area is moderate class. So it can be concluded that changes in water catchment conditions have a correlation to the growth of the built area.

Keywords       : Index-based Built-up Index, Built Area, Urban Index, Scoring, Water Infiltration Conditions