The Least Square Adjustment for Estimating the Tropical Peat Depth Using LiDAR Data

Abstract

High-accuracy peat maps are essential for peatland restoration management, but costly, labor-intensive, and require an extensive amount of peat drilling data. This study offers a new method to create an accurate peat depth map while reducing field drilling data up to 75%. Ordinary least square (OLS) adjustments were used to estimate the elevation of the mineral soil surface based on the surrounding soil parameters. Orthophoto and Digital Terrain Models (DTMs) from LiDAR data of Tebing Tinggi Island, Riau, were used to determine morphology, topography, and spatial position parameters to define the DTM and its coefficients. Peat depth prediction models involving 100%, 50%, and 25% of the field points were developed using the OLS computations, and compared against the field survey data. Raster operations in a GIS were used in processing the DTM, to produce peat depth estimations. The results show that the soil map produced from OLS provided peat depth estimations with no significant difference from the field depth data at a mean absolute error of ±1 meter. The use of LiDAR data and the OLS method provides a cost-effective methodology for estimating peat depth and mapping for the purpose of supporting peat restoration.

The Determination of Priority Areas for the Restoration of Degraded Tropical Peatland Using Hydrological, Topographical, and Remote Sensing Approaches

“…The hydrological flow analysis involved identifying depression-less DTMs and determining the flow direction of each pixel. The following stages defined the accumulation of water flow, the structure of flow patterns, and the order of surface water flow [52,53].…”

“…Therefore, the water in the peat soil would seep out through the canal and flow along the existing canal network [35]. The direction of the water flow (i.e., streamline) of the peatland was determined by performing a hydrological flow analysis using GIS [52,53]. The results of the surface water flow patterns and the stream orders throughout the Kahayan-Sebangau PHU area based on LiDAR and WorldDEM data are presented in Figure 2 (using Universal Transverse Mercator (UTM) projective coordinate system, zone 49 South (49 S)).…”

Revealing the dominant factors of vegetation change in global ecosystems

“…It can accurately identify areas with significant changes in ecosystem (Nyamekye et al, 2021). The formula of OLS is as follows (Cahyono et al, 2020):…”

Dynamics topography monitoring in Peatland using the latest digital terrain model

“…The organic material continues to accumulate for a long time to form layers with a thickness of more than 50 cm [3], [4]. Peatlands are a type of wetlands, which are among the most valuable ecosystems on Earth, and are generally located between two major rivers [5]. They are critical for preserving global biodiversity, providing safe drinking water, minimizing flood risk, and addressing climate change as the largest natural terrestrial carbon store [2].…”

“…This location were formed during the Holocene era, along with fiery rock formations [11]. Alluvium formations are composed of clay, kaolinite, dust, sand, peat, crust, and loose chunks, which are river and swamp deposits [10], [5]. The volcanic rock formation comprises greenish-gray volcanic breccia with components consisting of andesite, basalt, and chert.…”