AUTHOR=Jati Stevanus Nalendra , Irawan Dasapta Erwin , Wijaya Dudy Darmawan , Puradimaja Deny Juanda 
  
TITLE=Declining volume development index precedes basin infilling in Mahakam Lakes, Indonesia
  
JOURNAL=Frontiers in Earth Science
  
VOLUME=Volume 14 - 2026
  
YEAR=2026
  
URL=https://www.frontiersin.org/journals/earth-science/articles/10.3389/feart.2026.1818351
  
DOI=10.3389/feart.2026.1818351
  
ISSN=2296-6463
  
ABSTRACT=IntroductionIndonesia has designated 15 National Priority Lakes (Presidential Regulation No. 60/2021), yet quantitative baselines to assess sedimentation threats remain insufficient for most watersheds. This study evaluates Volume Development (VD) trajectories as early warning indicators of basin infilling in the Three Mahakam Lakes (Jempang, Melintang, Semayang)—a flood-pulsed tropical lake complex supporting the new capital city, Ibu Kota Nusantara (IKN).MethodsWe analyzed Landsat-derived shorelines (1990–2020) and calculated VD from bathymetric data obtained in 2010 and 2020.ResultsResults reveal starkly contrasting lake trends. Lake Melintang exhibited a marked VD decline from 0.94 to 0.52 (ΔVD = –0.42) with 80% volumetric loss (∼463 million m³)—among the higher infilling signals reported for an Indonesian priority lake. Conversely, Lake Semayang showed VD recovery from 0.06 to 0.24 (ΔVD = +0.18) despite surface area reduction, suggesting that hydrological reversibility may be possible under certain conditions. Lake Jempang remained mostly stable (ΔVD = –0.08).DiscussionWe propose a preliminary decadal ΔVD threshold of –0.2 as a potential emergency trigger for intervention prioritization under the regulation. By this criterion, Lake Melintang qualifies for immediate dredging and catchment restoration, while Semayang’s positive trajectory indicates that current flow management through the Pela River should be sustained. This study illustrates the potential of low-cost geospatial monitoring using publicly available satellite and bathymetric data as a replicable tool for Indonesia’s 15 National Priority Lakes, offering a quantitative benchmark for assessing sedimentation impacts in tropical flood-pulsed lake systems.