Understanding the three-dimensional flow turbulence generated by the combined presence of a bridge abutment and adjacent piers is essential for accurately predicting local scour, a primary cause of hydraulic-structure failure. Although the vortical fields associated with piers and abutments have been studied extensively in isolation, their coupled effect on coherent turbulence and sediment entrainment remains insufficiently clarified. This study evaluates the predictive capability of turbulence diagnostics obtained under rigid-bed conditions, prepared after prior mobile-bed experiments, by organizing all results along four longitudinal transects (Rows 1–4) to ensure direct comparability between hydrodynamic parameters and scour patterns. High-resolution Acoustic Doppler Velocimeter (ADV) measurements collected across multiple depths and cross-sections were used to quantify turbulence intensities, Reynolds shear stress (RSS), quadrant events, and sweep-to-ejection (STE) dynamics around a rectangular abutment and two circular bridge piers. The results demonstrate that the narrow interaction zone between the abutment and the upstream pier constitutes the dominant source of three-dimensional turbulence. Elevated near-bed RSS and strongly dominant sweep (Q4) events in this region represent the principal drivers of sediment entrainment, while the vertical concentration of turbulent energy close to the bed is shown to be more decisive for scour initiation than the magnitude of vertical velocity alone. This critical zone corresponds directly with the deepest scour measured in the mobile-bed tests. Downstream, turbulence progressively weakens, ejection (Q2) events become more prominent, and reductions in RSS and STE coincide with decreasing scour potential toward the second pier and the flow-recovery region. The unified presentation of results along four longitudinal transects confirms that RSS distributions, Q4–Q2 bursting behaviour, and STE profiles obtained under fixed-bed conditions provide robust, physically consistent predictors of scour in compound pier–abutment systems. These findings also strengthen recent hydrodynamic frameworks by confirming that pier–abutment spacing fundamentally governs vortex interaction and near-bed momentum transfer. The insights gained here offer improved guidance for scour prediction and the resilient hydraulic design of bridge foundations in fluvial and coastal environments.

Local scour around bridge foundations remains a major threat to structural stability, particularly when bridge piers and abutments are placed within the same contracted flow region. This study experimentally investigates the temporal evolution and final morphology of clear-water scour around coupled pier-abutment configurations, with emphasis on the combined effects of pier-abutment spacing and blockage ratio. The experiments were conducted in a recirculating laboratory flume using a rectangular vertical-wall abutment and single and double-pier arrangements. The results show that pier-abutment spacing has a non-monotonic effect on abutment scour. At the closest spacing ( $$x/{D}_{\text{p}}=1.5$$ x / D p = 1.5 ), the pier partially shields the abutment by reducing the direct erosive action of the approach flow. In contrast, the intermediate spacing ( $$x/{D}_{\text{p}}=3$$ x / D p = 3 ) produces the most severe abutment scour because of constructive interaction between pier-induced and abutment-induced flow structures. Under this condition, the maximum abutment scour depth increases by 10.9% compared with the close-spacing configuration and by up to 55% compared with the far-spacing ( $$x/{D}_{\text{p}}=6$$ x / D p = 6 ). Increasing the blockage ratio further intensifies scour, raising the maximum scour depth by approximately 7.4% at the abutment and 10% at the first pier. The temporal scour response follows a clear biphasic pattern, with 65–75% of the maximum scour depth developing during the initial 10–15% of the test duration, followed by a slower asymptotic approach toward equilibrium. The final scour morphology reveals pronounced upstream–downstream asymmetry, with deeper upstream scour holes controlled by downflow and horseshoe-vortex action and shallower downstream depressions associated with wake vortices and sediment redistribution. These findings demonstrate that pier-abutment spacing and blockage ratio jointly control both the rate and magnitude of scour development, highlighting the need to consider their combined effects in bridge-foundation design and scour-risk mitigation.

Water quality management is a growing global priority due to increasing pressures from climate change, population growth, urbanisation, industrialisation, agricultural intensification, and emerging contaminants. These challenges threaten freshwater ecosystems, public health, economic development, and progress towards Sustainable Development Goal 6 (SDG 6). This critical review employed a PRISMA-guided systematic literature review to evaluate future directions in water quality management from sustainability, resilience, and social equity perspectives. A total of 11,485 records were identified, with 3632 duplicates removed. Following the screening of 7853 records and assessment of 1441 full-text articles, 117 studies met the inclusion criteria for qualitative synthesis. Geographical analysis showed that 88 studies (75.2%) adopted a global perspective encompassing both developed and developing countries, while 24 studies (20.5%) focused on developing countries and 5 studies (4.3%) on developed countries. The review identified notable progress in water quality monitoring, wastewater treatment, pollution control, and integrated water resources management. Emerging technologies such as smart monitoring systems, artificial intelligence, advanced treatment processes, and resource recovery approaches were consistently highlighted as promising tools for improving water quality and enhancing adaptive capacity. Despite these advances, significant barriers remain, including fragmented governance systems, climate-related risks, emerging contaminants, and persistent inequalities in access to safe water resources. The findings underscore the importance of integrating sustainability, resilience, and social equity within water governance frameworks. Achieving long-term water security will require coordinated and transformative approaches that strengthen links between science, policy, and practice while promoting inclusive, resilient, and sustainable water management.