Environmental Determinants of Peatland Degradation in Central Kalimantan: A GIS-Based Remote Sensing Analysis

Abstract

Tropical peatlands in Central Kalimantan, Indonesia, represent important terrestrial carbon stores and support highly diverse tropical rainforest ecosystems with significant ecological, hydrological, and climatic functions. However, decades of drainage development, deforestation, plantation expansion, land-use change, and recurrent fire have contributed to extensive peatland degradation across the region. Large-scale hydrological disturbance following the Mega Rice Project initiated in the 1990s further accelerated peat drying, vegetation degradation, forest loss, and increased fire vulnerability.

This study analysed peatland degradation in south-eastern Central Kalimantan between 2017 and 2025 using remote sensing and GIS-based spatial analysis. Satellite-derived indicators including the Normalized Difference Vegetation Index (NDVI), Normalized Difference Water Index (NDWI), VIIRS active fire detections, annual forest loss data, and supplementary Land Surface Temperature (LST) information were integrated with environmental variables related to hydrology, terrain, drainage infrastructure, and land use. Particular emphasis was placed on NDWI as a proxy indicator of peatland moisture conditions associated with hydrological disturbance. Spatial and statistical analyses were performed using Pearson correlation, hotspot analysis, Ordinary Least Squares (OLS), Geographically Weighted Regression (GWR), Random Forest (RF), and weighted spatial overlay techniques.

The results demonstrated that peatland degradation is spatially heterogeneous, with major degradation hotspots concentrated in the southern and central peatland regions where vegetation loss, moisture reduction, forest loss, and fire occurrence overlapped. Areas located near drainage canals generally exhibited stronger drying trends and higher levels of disturbance than areas located further from drainage infrastructure. Pearson correlation, regression analyses, and Random Forest modelling consistently identified distance to drainage canals as one of the most influential variables associated with peatland degradation, whereas Topographic Wetness Index (TWI) showed weaker and less consistent relationships. GWR further revealed substantial spatial variation in the environmental controls of degradation, indicating that peatland responses differ across the landscape. Although vegetation and moisture indicators showed relatively strong relationships, fire occurrence appeared to be influenced by additional climatic and anthropogenic factors beyond those included in the analysis.

Overall, the study highlights the critical role of hydrological disturbance in tropical peatland degradation and emphasises the importance of long-term hydrological restoration and sustainable peatland management, particularly in heavily drained peatland areas. The integration of remote sensing, GIS, and spatial modelling techniques provides a useful framework for identifying degradation hotspots and supporting future peatland restoration and conservation strategies in tropical regions.

Abstract (Uncoded languages)

Lahan gambut tropis di Kalimantan Tengah, Indonesia, merupakan penyimpan karbon daratan yang penting serta mendukung ekosistem hutan hujan tropis dengan fungsi ekologis, hidrologis, dan klimatologis yang signifikan. Namun, pembangunan jaringan drainase, deforestasi, ekspansi perkebunan, perubahan penggunaan lahan, dan kebakaran berulang telah menyebabkan degradasi lahan gambut secara luas di wilayah tersebut. Gangguan hidrologis akibat Proyek Lahan Gambut Sejuta Hektar (Mega Rice Project) sejak tahun 1990-an semakin mempercepat pengeringan gambut, degradasi vegetasi, kehilangan hutan, dan meningkatnya kerentanan terhadap kebakaran. Penelitian ini menganalisis degradasi lahan gambut di bagian tenggara Kalimantan Tengah selama periode 2017–2025 menggunakan penginderaan jauh dan analisis spasial berbasis GIS. Indikator berbasis satelit, termasuk Normalized Difference Vegetation Index (NDVI), Normalized Difference Water Index (NDWI), deteksi titik api aktif VIIRS, data kehilangan hutan tahunan, serta informasi Suhu Permukaan Lahan (LST) yang digunakan sebagai indikator pendukung, diintegrasikan dengan variabel lingkungan yang berkaitan dengan hidrologi, topografi, drainase, dan penggunaan lahan. Penelitian ini menempatkan NDWI sebagai indikator proksi kondisi kelembapan gambut yang berkaitan dengan gangguan hidrologis. Analisis dilakukan menggunakan korelasi Pearson, analisis hotspot, Ordinary Least Squares (OLS), Geographically Weighted Regression (GWR), Random Forest (RF), dan teknik weighted spatial overlay. Hasil penelitian menunjukkan bahwa degradasi lahan gambut bersifat heterogen secara spasial, dengan hotspot utama erkonsentrasi di wilayah gambut bagian selatan dan tengah area penelitian. Wilayah tersebut menunjukkan tumpang tindih antara penurunan vegetasi, pengurangan kelembapan, kehilangan hutan, dan kejadian kebakaran. Variabel drainase, terutama kedekatan terhadap kanal drainase, secara konsisten menjadi faktor dominan yang memengaruhi dinamika kelembapan gambut dan pola degradasi, sementara Topographic Wetness Index (TWI) menunjukkan hubungan yang lebih lemah dan kurang konsisten. Hasil penelitian juga menunjukkan bahwa proses degradasi bervariasi sesuai kondisi lingkungan lokal dan intensitas gangguan. Meskipun indikator vegetasi dan kelembapan menunjukkan hubungan yang relatif kuat, kejadian kebakaran tampaknya dipengaruhi oleh faktor iklim dan aktivitas manusia lainnya di luar variabel yang dianalisis. Secara keseluruhan, penelitian ini menyoroti pentingnya gangguan hidrologis dalam degradasi lahan gambut tropis serta menekankan perlunya restorasi hidrologis jangka panjang dan pengelolaan lahan gambut berkelanjutan, terutama pada wilayah dengan drainase intensif. Integrasi penginderaan jauh, GIS, dan pemodelan spasial memberikan kerangka kerja yang berguna untuk mengidentifikasi hotspot degradasi dan mendukung strategi restorasi serta konservasi lahan gambut tropis di masa mendatang.

Popular Abstract

Tropical peatlands are among the world's most important natural carbon stores and play a crucial role in regulating climate, water resources, and biodiversity. Indonesia contains some of the largest tropical peatland areas, but many of these ecosystems have been heavily affected by deforestation over recent decades due to agricultural expansion. In Central Kalimantan, the large-scale Mega Rice Project of the mid-1990s caused substantial damage to peatland ecosystems. Deforestation and land clearing increased to meet the growing demand for palm oil, timber, and agricultural land. Extensive drainage canals were constructed, and fire was often used as a cheap method of land clearing. These activities altered natural water systems and increased the vulnerability of peatlands to degradation.
This study investigated peatland degradation in south-eastern Central Kalimantan, Indonesia, between 2017 and 2025 using satellite imagery and Geographic Information Systems (GIS). The aim was to identify where degradation is occurring and to better understand the environmental factors contributing to these changes.
The results showed that peatland degradation is not evenly distributed across the landscape. The most severely affected areas were concentrated in the southern and central peatland regions, where loss of vegetation, drying conditions, forest loss, and fire activity frequently occurred together. Areas located close to drainage canals generally showed stronger signs of drying and degradation than areas located further away. These findings indicate that changes to the natural water system are an important driver of peatland degradation.
The study also found that peatland conditions vary considerably across the region, suggesting that local environmental factors and land-use practices influence how degradation develops. While vegetation and moisture changes were closely related, fire occurrence appeared to be influenced by additional climatic and human factors.
The findings highlight the importance of protecting and restoring peatland hydrology through measures such as canal blocking, rewetting, and sustainable land management. Improved management of tropical peatlands can help reduce greenhouse gas emissions, decrease fire risk, and support biodiversity conservation.

• author: Hägglund, Reneé
• supervisor: Torbern Tagesson
• organization: Department of Earth and Environmental Sciences (MGeo); Dept of Physical Geography and Ecosystem Science
• course: GISM01 20261
• year: 2026
• type: H2 - Master's Degree (Two Years)
• subject: Earth and Environmental Sciences
• keywords: Geography, GIS, Physical Geography, remote sensing, tropical peatlands, tropical peatland degradation, peatland degradation, hydrological disturbance, drainage canals, Central Kalimantan.
• publication/series: Master Thesis in Geographic Information Science
• report number: 217
• language: English
• id: 9243823
• date added to LUP: 2026-06-25 12:02:24
• date last changed: 2026-06-25 12:02:24