Canal blocking strategies for hydrological restoration of degraded tropical peatlands in Central Kalimantan, Indonesia

Background

In the 1990s, the Government of Indonesia sponsored the construction of thousands of km of canals in 1 million Ha of peatlands of Central Kalimantan to drain the peatlands for conversion to agriculture. The project over-drained the peatlands, leaving it unusable agriculturally and subject to fires and subsidence. Existing efforts to dam the canals to return the water table to previous levels have failed.

Research Goals & Methods

The paper suggests a new method for dams to re-saturate peatlands. The authors constructed six cofferdams of low height out of local materials, monitoring them for three years. Local materials of compressed peat and wooden poles enable native vegetation to gradually establish on the dam, reducing erosion over time, while the wooden slowly decompose.

Conclusions & takeaways

The study found that the dams resulted in an increase in upstream water levels and in the groundwater table, with variation based on El Nino cycles. The study also suggests that dam type should be dependent on hydrology, with larger dams built in canal sections that run parallel to the contour lines that have more gentle flows and multiple smaller dams without extended sides built in sections perpendicular to contour which experience more extreme stormwater flows.