Water table variations on different land use units in a drained tropical peatland island of Indonesia

Abstract

Restoration and water table control on peatlands to limit fire risk are national priorities in Indonesia. The present study was initiated at Padang Island, Sumatra, to increase understanding on peatland hydrology in the tropic. At the pilot site, water table and precipitation were monitored at different stations. The results show variation in water table depths (WTDs) over time and space due to spatial and temporal variability in rain intensity and drainage networks. In part of the island, large-scale drainage for plantations led to deep WTD (−1.8 m) and high WTD recession rates (up to 3.5 cm/day). Around villages, farm-scale drainages had a smaller impact with a lower recession rate (up to 1.8 cm/day) and shallow WTD, typically below −0.4 m, the threshold for sustainable peatland management in Indonesia. The recession rates levelled off at 1.0 cm/day near the drained forest/plantation and at 0.5 cm/day near the farm. Deeper layers had much lower specific yield (Sy), 0.1 at −1.5 m depth, compared with top peat soils with Sy up to 0.3. Proximity to drainages extended discharge flow to deeper layers. The results highlighted the severity of peatland drainage impact on most coastal zones of Padang Island, which have intensive drainage networks.

Modelling the performance of bunds and ditch dams in the hydrological restoration of tropical peatlands

“…In a place where more than 3 months of inundation on the bunded area is unacceptable, it is suggested to drain the storage of the bunded area in the wet period but allow it to fill fully at the beginning of the Early Dry period. Keeping the peatland sufficiently wet (Evers et al, 2017; Ismail et al, 2021) and maintaining peatland water tables near to the surface should reduce fire risk (Page et al, 2009; Wösten et al, 2006).…”

Applying Field Research in Tropical Peatlands and Managing Ground Data: A Challenging Approach

“…Padang Island's topography is generally flat, with a maximum elevation of 15 m above mean sea level (MSL), and nearly all settlements are situated at altitudes lower than 6 m above MSL. Several researchers have conducted their study here [9,10].…”

“…Figure 2a and b illustrates the traditional methods of reaching the location. Nevertheless, several researchers have conducted studies there, as indicated by the following references [9,11]. The Indonesian government, through Peatland Restoration Agency-Badan Restorasi Gambut (BRG), now known as Peatland and Mangrove Restoration Agency-Badan Restorasi Gambut dan Mangrove (BRGM) -of the Republic of Indonesia, has selected it as a pilot project for monitoring.…”

“…Observation intervals can range from 10 minutes to 24 hours, so the way to present depends on the data provided. Researchers have utilized intervals of 10 minutes, 15 minutes, 30 minutes, and 1 hour [9,10,16,18]. Different intervals have also been used, such as 3 hours [16], daily [2,19], weekly and monthly [14,15], and three times a month [19].…”

Diversity in characteristics of tropical peatlands varying in land uses leads to differences in methane and carbon dioxide emissions

“…Changes in land uses of tropical peatlands result in diversity in peatland characteristics. Generally, agricultural development is always accompanied by the construction of drainage channels, causing a decrease in the water table of tropical peatlands (Ismail et al 2021). Changes in the water table ultimately cause a shift in the biochemical reactions of peat decomposition, which initially occurred in anoxic conditions to become oxic conditions (Marwanto et al 2019).…”