Bathymetric survey of lakes Maninjau and Diatas (West Sumatra), and lake Kerinci (Jambi)

Determining the bathymetry of lakes is important to assess the potential and the vulnerability of this valuable resource. The dilution and circulation of nutrients or pollutants is largely dependant on the volume of water and the incoming and outgoing fluxes, while the degree and frequency of mixing depends on the water depth. The bathymetry of lakes is also important to understand the spatial distribution of sediments, which in turn are valuable archives of natural hazards and environmental change. We thus conducted a bathymetric survey of lakes Maninjau and Diatas in West Sumatra and lake Kerinci in Jambi (Indonesia) using a sonar. We found maximum water depths of 168 m, 55 m, and 105 m and minimum volumes of 9.79 km3, 0.32 km3, and 1.57 km3 for lakes Maninjau, Diatas and Kerinci respectively. Although lake Maninjau is the largest, it is vulnerable due to the low water fluxes in and out of it, and is thus currently threatened by increasing levels of cultural eutrophication. Lake Diatas is smaller but surrounded by less human settlements and is thus less impacted by related human activities. Lake Kerinci is relatively voluminous, has larger incoming and outgoing water fluxes, and doesn't appear to be suffering greatly from surrounding human activities. Given the sizes and inlets of these lakes, Maninjau and Diatas likely have the highest potential for hosting a long-term sediment record built from low sedimentation rates.