Theoretical and Empirical Contributions to Understanding Cumulative Environmental Impacts of Mining in the Benue Trough, North Central Nigeria

Cumulative environmental impact assessment (CEIA) addresses the aggregate effects of multiple mining operations on shared environmental systems, yet the theoretical and methodological tools for CEIA remain underdeveloped in the Nigerian regulatory context. This dissertation makes theoretical and empirical contributions to understanding cumulative environmental impacts of mining in the Benue Trough, North Central Nigeria, where coal, limestone, and artisanal mineral extraction coexist in a shared fluvial catchment system. The research develops an original Benue Trough mining catchment cumulative impact assessment framework, integrating spatial analysis, ecosystem services valuation, cumulative metals loading modelling, and community-reported environmental change documentation. A 10-year remote sensing change detection analysis quantifies the cumulative extent of land disturbance from all mining activities across the study catchment. River water quality monitoring data from 18 stations spanning 2019 to 2024 were synthesised into cumulative metal loading time series. Ecosystem services valuation applying a benefits transfer methodology estimates the monetary value of provisioning and regulating services lost to mining-related degradation. Interviews with 160 farming and fishing households document perceptions of cumulative environmental decline. Results demonstrate that the cumulative suspended sediment loading from all mining operations in the Benue Trough exceeds the assimilative capacity of the river system during the dry season, with downstream consequences for fisheries and irrigation agriculture. The dissertation proposes a CEIA protocol and catchment-level mining activity ceiling for the Benue Trough. Keywords: cumulative environmental impact, Benue Trough, mining, catchment assessment, ecosystem services.