Riverine Encroachment and Flood Risk Analysis: An Ecohydrological Perspective from Pakistan

Riverine floodplains are critical ecohydrological interfaces that provide natural flood mitigation,biodiversity habitats, and ecosystem services. Their uncontrolled conversion for urban and agricultural use disrupts these functions and increases societal vulnerability. This study presents a comprehensive, national-scale assessment of riverine encroachment in Pakistan and its implications for flood risk and ecohydrological integrity. Using satellite imagery and hydrological modelling from 1980 to 2020, we quantified the spatiotemporal patterns of floodplain loss and conducted a multi-faceted risk analysis. Our findings reveal that approximately 12,450 km 2 (18.7%) of natural floodplains have been converted, with acceleration in each successive decade. This encroachment has significantly altered local hydrology, increasing water velocity (15-40%), flood peaks (1.2-3.1 m), and inundation duration (18-36 hours). The consequent loss of wetland ecosystems (62% since 1980) has severely degraded the landscape’s natural water retention capacity. We identify that 6.2 million people reside directly on encroached land, with a further 12.8 million in previously inundated zones. A composite risk scoring system highlights districts in Punjab and Sindh provinces as extreme hotspots. The net economic impact is profoundly negative (-$33.4 billion), indicating that short-term development gains are vastly outweighed by long-term risk. This study underscores the critical need for policy interventions that integrate ecohydrological principles—such as nature-based solutions and strategic retreat—into flood risk management and spatial planning to enhance resilience and sustain vital ecosystem services.