Spatio‐Temporal Dynamics of River Water Quality in Response to Cumulative Industrial Land Expansion; the Case Study of Balok River, Malaysia

ABSTRACT Rapid industrial expansion in developing regions has intensified pressure on river systems, raising concerns regarding cumulative water quality degradation. While previous research has established associations between industrial activity and surface water pollution, quantitative evidence linking the scale of industrial land use expansion to river water quality remains limited. This study investigates the relationship between the accumulated scale of industrial land use expansion and river water quality in the Balok River, Kuantan, Pahang. Water Quality Index (WQI) data from 2000 to 2020 were obtained from the Department of Environment at upstream, midstream and downstream of Balok River. The WQI were analyzed with scale area of two major industrial parks which are Gebeng Industrial Estate and Malaysia China Kuantan Industrial Park. Person's correlation, Spearman's rank correlation and simple linear regression analyses were applied to identify the relationship of accumulated scale area and water quality at upstream, midstream and downstream sections. Results shows upstream remained non‐significant ( r = −0.436, p = 0.208) validating its location above the major industrial discharge point, while midstream and downstream sections showed declining WQI values corresponding with higher industrial development intensity ( p < 0.05). The simple regression shows the upstream model was not statistically significant ((R^2 = 0.190), adjusted (R^2 = 0.089), (B = −0.002), ( p = 0.208)). The midstream model showed negative relationship ((R^2 = 0.517), adjusted (R^2 = 0.457), (B = −0.003), ( p = 0.024)) and the downstream is statistically significant negative relationship ((R^2 = 0.473), adjusted (R^2 = 0.407), (B = −0.003), ( p = 0.032)). These findings highlight the limitations of individual industry discharge compliance and emphasize the need to transition toward watershed‐scale cumulative load management. The findings emphasize the importance of integrating land use planning with watershed‐scale environmental monitoring and adaptive green buffer infrastructure in rapid industrial area.