Impacts of Civil Infrastructure and Dam Structures on Aquatic Ecosystems: A Comprehensive Survey of Hydrological, Geomorphological, and Biodiversity Responses

Abstract

Civil-construction activities and hydraulic structures such as dams, reservoirs, embankments, bridges, culverts, river-training works, and water-diversion systems are essential for urban development, flood management, irrigation, navigation, and energy production; however, their construction and operation can substantially modify the physical, chemical, and biological processes governing aquatic ecosystems. The principal ecological consequences arise from alteration of natural flow regimes, sediment transport, channel morphology, water temperature, nutrient dynamics, habitat connectivity, and pollutant pathways. Dams are particularly influential because they transform flowing riverine environments into comparatively lentic reservoir systems while simultaneously disrupting longitudinal connectivity between upstream and downstream habitats. Global assessments indicate that dams and reservoirs are among the dominant anthropogenic pressures responsible for river fragmentation, with major implications for freshwater biodiversity. This review synthesizes major scientific findings concerning the effects of civil-construction and dam structures on aquatic ecosystems, with particular emphasis on hydrological modification, sediment retention, habitat fragmentation, water-quality deterioration, fish migration, and biodiversity. The discussion further considers ecological-flow management, fish passage, sediment-management strategies, environmentally sensitive construction practices, and removal or modification of obsolete structures as potential mitigation measures. The review demonstrates that sustainable hydraulic infrastructure requires an integrated engineering–ecological framework in which structural functionality and ecosystem integrity are considered simultaneously during planning, design, construction, and operation.