Assessing Groundwater Sustainability in BumiTech Mining Operations, Kalimantan, Indonesia

Thesis Abstract

This study investigates groundwater sustainability within the operational footprint of BumiTech mining activities in Kalimantan, Indonesia, addressing concerns about aquifer depletion, quality degradation, and long-term ecological and community resilience. The problem centers on balancing mineral extraction with the preservation of groundwater resources in a tropical peat–alluvial context characterized by variable rainfall, fracture-enhanced flow, and complex hydrological connectivity to surface water systems. The aim is to evaluate current groundwater stock and quality, identify drivers of unsustainable use, and propose a management framework that aligns mining operations with regional groundwater governance. Specific objectives are (i) to quantify groundwater availability and storage changes over the past decade using time-series data; (ii) to assess spatial and temporal variations in groundwater quality and salinity intrusion risk; (iii) to identify hydrogeochemical processes affecting aquifer sustainability via multivariate statistics and isotope tracing; (iv) to evaluate the impacts of dewatering, rainfall recharge, and mine water management on aquifer dynamics; and (v) to develop a decision-support model integrating hydrological, geochemical, and socio-economic indicators for sustainable water management in mining operations. Methodologically, a mixed-methods approach will be employed within a realist research design to capture measurable hydrological responses and stakeholder perceptions. The population comprises groundwater wells within a 25-kilometer radius of BumiTech operations, aquifer units in the Kalimantan deposit region, and mining engineers and local community water users. A stratified random sample of 60 groundwater wells will be selected for monitoring and sampling, complemented by semi-structured interviews with 20 mine hydrologists and 15 community representatives. Data collection instruments include automated loggers for continuous groundwater level monitoring, multi-parameter water quality sondes, grab samples for laboratory analysis (major ions, trace metals, stable isotopes 18O/2H, and microbial indicators), and a structured questionnaire for stakeholder perspectives. Analytical techniques will comprise time-series analyses to detect trends and seasonal patterns, regression modeling to attribute causality (e.g., dewatering rates vs. drawdown), ANOVA to compare pre- and post-operational periods, principal component analysis and cluster analysis to identify hydrogeochemical facies, and isotope hydrology to elucidate recharge sources and groundwater–surface water interactions. A conceptual groundwater sustainability index will be constructed, integrating hydrological balance, quality thresholds, and governance indicators, validated through expert elicitation. The theoretical framework will draw on the Thermodynamics of Aquifer Systems and Water-Food-Energy Nexus concepts, supplemented by the Theory of Planned Behavior to account for stakeholder behavior in water use and management. Ethical considerations include informed consent for interview participants, data anonymization, and compliance with national environmental reporting standards. Expected findings indicate a net decline in aquifer storage in proximity to active pumping zones, with variability driven by monsoonal rainfall, recharge disruptions, and mine dewatering schedules. Groundwater quality is anticipated to show episodic chloride and sulfate increases associated with mining fluids and mobilized secondary minerals, alongside localized microbial indicators linked to surface infiltration events. Isotope data are expected to reveal partial isolation of mine-influenced waters from regional recharge, necessitating targeted recharge enhancement and improved mine-water mitigation. The study will generate a spatially explicit sustainability index map and a decision-support tool that integrates hydrogeochemical indicators, operational constraints, and community water-demand scenarios to guide adaptive management. The contribution to knowledge lies in developing an integrative, context-specific groundwater sustainability framework for high-depth mining in tropical Southeast Asia, combining empirical hydrology with governance and stakeholder analyses to inform policy and operational best practices. The study will inform enhanced water budgeting, optimized dewatering regimes, improved monitoring networks, and transparent reporting mechanisms aligned with Indonesian regulatory standards. Conclusions will advocate a precautionary, evidence-based approach to groundwater management in mining, emphasizing precautionary water reuse, targeted aquifer recharge, and collaborative governance with local communities. Recommendations include redesigning dewatering schedules to minimize aquifer drawdown, expanding monitoring to inland and downstream receptors, deploying real-time data dashboards for stakeholders, and institutionalizing a mining–community water-sharing agreement to ensure equitable access and long-term groundwater resilience.