E on the upstream side of Ulin, about 50–100 m from the canal. In addition, the
location also experienced fire during the dry season on the 29th of September 2018
to 6th of October 2018. Based on bulk density measurement, both Jajangkit and Ulin
canals have average value of 0.45 and 0.46, respectively. The bulk density values of
the study site are given in Table 20.2.
Microtopographic field measurement also shows that Ulin canal area has higher
elevation compared to Jajangkit canal area (Fig. 20.9). Ulin is situated at an altitude
of 5–7 amsl, the slope of Ulin study area has lower tendency towards the southwest
(area E in Fig. 20.10) which is opposite to the flow direction in the canal that is
moving from Southwest to Northeast. Meanwhile, Jajangkit study area is located at
4–7 amsl, which has lower tendency to the southwest (area D in Fig. 20.9) and in line
with the water flow direction in the canal.
20.4.3.2 Groundwater Dynamics at the Restored and Unrestored
Peatlands
During drought, GWL in both Jajangkit and Ulin canals fell below the peat surface.
Meanwhile, during rainy season, GWL was near and even above the peat surface. In
the dry period (24th of September 2018 to 5th of October 2018) with the precipitation of 48 mm, GWL at Jajangkit area dropped to 44–89 cm below the peat surface,
whereas GWL at Ulin area declined to 53–81 cm below the peat surface (Figs. 20.11
and 20.12). It should be noted, however, that the lowest GWL in Ulin area could not
be recorded due to wildfire occurred in the area rendering the field measurement to
stop temporarily. Furthermore, in the transition from dry to rainy season (8th of October
2018 to 7th of November 2018, with the precipitation of 300 mm), GWL in Jajangkit
area varied between 20 and 44 cm below the peat surface, whereas in Ulin, GWL
ranged between 44 and 65 cm below the peat surface. Finally, during the rainy season
(9th of November 2018 to 20th of December 2018, with the precipitation of 700 mm),
GWL in Jajangkit area ranged from 19 cm below up to 12 cm above the peat surface,
whereas in Ulin, GWL varied from 41 cm below up to 5 cm above the soil surface.
20.4.3.3 Surface Water Level Dynamics at the Restored and Unrestored
Peatlands
Results from field measurement conducted on 24th of September 2018 to 20th of
December 2018 show that both canals had similar range of water decrease
(Fig. 20.13). At Ulin canal (the depth of the canal was 120 cm), for instance, the
surface water level declined around 45 cm down the bank surface during the rainy
season, and even the canal itself was often dried out completely during the dry
season. Meanwhile, at Jajangkit canal, the canal surface water level was about 35 cm
below the canal bank surface during the rainy and dry season, it could drop up to
110 cm below the canal bank surface. It should be noted, however, that Jajangkit
canal could still retain water in its canal body and it received additional water inflow
resulted from high tide backwater.
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A. Dohong and L. Tanika
location also experienced fire during the dry season on the 29th of September 2018
to 6th of October 2018. Based on bulk density measurement, both Jajangkit and Ulin
canals have average value of 0.45 and 0.46, respectively. The bulk density values of
the study site are given in Table 20.2.
Microtopographic field measurement also shows that Ulin canal area has higher
elevation compared to Jajangkit canal area (Fig. 20.9). Ulin is situated at an altitude
of 5–7 amsl, the slope of Ulin study area has lower tendency towards the southwest
(area E in Fig. 20.10) which is opposite to the flow direction in the canal that is
moving from Southwest to Northeast. Meanwhile, Jajangkit study area is located at
4–7 amsl, which has lower tendency to the southwest (area D in Fig. 20.9) and in line
with the water flow direction in the canal.
20.4.3.2 Groundwater Dynamics at the Restored and Unrestored
Peatlands
During drought, GWL in both Jajangkit and Ulin canals fell below the peat surface.
Meanwhile, during rainy season, GWL was near and even above the peat surface. In
the dry period (24th of September 2018 to 5th of October 2018) with the precipitation of 48 mm, GWL at Jajangkit area dropped to 44–89 cm below the peat surface,
whereas GWL at Ulin area declined to 53–81 cm below the peat surface (Figs. 20.11
and 20.12). It should be noted, however, that the lowest GWL in Ulin area could not
be recorded due to wildfire occurred in the area rendering the field measurement to
stop temporarily. Furthermore, in the transition from dry to rainy season (8th of October
2018 to 7th of November 2018, with the precipitation of 300 mm), GWL in Jajangkit
area varied between 20 and 44 cm below the peat surface, whereas in Ulin, GWL
ranged between 44 and 65 cm below the peat surface. Finally, during the rainy season
(9th of November 2018 to 20th of December 2018, with the precipitation of 700 mm),
GWL in Jajangkit area ranged from 19 cm below up to 12 cm above the peat surface,
whereas in Ulin, GWL varied from 41 cm below up to 5 cm above the soil surface.
20.4.3.3 Surface Water Level Dynamics at the Restored and Unrestored
Peatlands
Results from field measurement conducted on 24th of September 2018 to 20th of
December 2018 show that both canals had similar range of water decrease
(Fig. 20.13). At Ulin canal (the depth of the canal was 120 cm), for instance, the
surface water level declined around 45 cm down the bank surface during the rainy
season, and even the canal itself was often dried out completely during the dry
season. Meanwhile, at Jajangkit canal, the canal surface water level was about 35 cm
below the canal bank surface during the rainy and dry season, it could drop up to
110 cm below the canal bank surface. It should be noted, however, that Jajangkit
canal could still retain water in its canal body and it received additional water inflow
resulted from high tide backwater.
580
A. Dohong and L. Tanika