Hydrological dynamics in a tropical peatland mosaic at Pulau Padang, Indonesia: influence of land-cover changes and rainfall variability

•Study Region: Pulau Padang, Riau, Indonesia, a peat dominated island.
•Study Focus: This study assessed hydrological dynamics under land-cover change and extreme rainfall variability using the coupled MIKE SHE–MIKE Hydro model. LiDAR, satellite imagery, and field measurements were used to quantify evapotranspiration, runoff, and storage change for 1972 (Past: counterfactual land-cover configuration), 2016 (Current), and 2066 (Future-policy compliance). All cases were driven by the 2015–2018 rainfall, covering the 2015 El Niño and the 2017 La Niña, to provide a representative window for evaluating interannual hydrological responses.
•New hydrological insights for the region: Evapotranspiration represented 62–98 % of annual rainfall, the dominant water loss across all land-cover types. Conversion from peat swamp forest to managed areas caused ∼1 % lower evapotranspiration, ∼6 % higher runoff, and negligible differences in storage change under same rainfall inputs. In contrast, interannual rainfall variability produced up to eightfold differences in runoff and ∼120 mm reversal in storage change between dry and wet years. Canal dams reduced groundwater drawdown to less than 5 cm within about 300 m of outermost canals, and forested peatlands buffered hydrological extremes. Inundation projections for 2066 show limited extent, with areas exceeding 1 cm depth for more than two weeks remaining below 1 % of the managed landscape, suggesting limited long-term economic implications associated with inundation risk. The study highlights the importance of responsible peatland management.