Rivers are fundamental components of natural ecosystems, playing a vital role in maintaining environmental balance, recharging groundwater resources, supporting biodiversity, and fulfilling a wide range of human needs. They serve as dynamic systems that connect terrestrial and aquatic environments, regulate hydrological cycles, and provide essential services such as water supply, flood control, and habitat for diverse species. However, in recent decades, the rapid expansion of urbanization, uncontrolled development of residential areas, and unsustainable exploitation of natural resources have led to significant changes in the structure and function of river systems worldwide.The Alvand River, a prominent watercourse in western Iran, originates from the Zagros Mountains and flows through Sarpol-e Zahab County. In recent years, this river has undergone considerable transformations due to both anthropogenic and natural pressures. Key threats include encroachment on the riverbed and floodplain, land-use changes, excessive extraction of sand and gravel, and the construction of engineering structures along the river channel. These activities have disrupted the river’s natural morphology, reduced its ecological resilience, and imposed serious damage on its hydrogeomorphological integrity.

This study aims to assess the hydrogeomorphological quality of the Alvand River within the urban stretch of Sarpol-e Zahab, specifically from the point where the river enters the city to the village of Qareh-Bolagh. To achieve this, the Hydrogeomorphological Quality Index (IHG) was employed—a multi-criteria assessment tool designed to evaluate the ecological and physical condition of river systems. The main channel was divided into seven distinct segments, and the IHG index was calculated for each segment using field observations, satellite imagery, and GIS-based spatial analysis.

The IHG index evaluates nine parameters grouped into three main categories: (1) river functionality (including flow continuity, interaction with groundwater, and flow dynamics), (2) channel morphology (including cross-sectional shape, meandering patterns, and bed diversity), and (3) riparian vegetation (including density, diversity, and connectivity of plant cover). Each parameter is scored from 1 to 10, with higher scores indicating more natural conditions and better ecological performance. The total score for each segment reflects its overall hydrogeomorphological quality and provides a basis for comparison across different parts of the river.

The results revealed that segments 1, 6, and 7 exhibit relatively favorable conditions. These areas are located outside the urban core and have experienced limited human interference. Natural riparian vegetation is largely intact, meandering patterns are preserved, and hydrological connectivity remains functional. In contrast, segments 3 and 4—located within the urban center—show very poor quality due to extensive human interventions. These include channelization, construction of engineering structures within the riverbed, disruption of flow continuity, and conversion of the floodplain into residential and agricultural land uses. Additionally, uncontrolled extraction of riverbed materials such as sand and gravel has led to bed degradation, loss of habitat diversity, and reduced ecological stability.

Segments 2 and 5 fall into an intermediate category. Situated on the urban fringe, these segments show signs of disturbance but still retain some natural features. The river in these areas is semi-stable, and without proper management, they risk degradation similar to segments 3 and 4. Therefore, these transitional zones are critical for conservation planning and can serve as priority areas for restoration and protection efforts. Their current condition offers an opportunity for proactive intervention before irreversible damage occurs.

From a practical standpoint, the findings of this study provide a valuable foundation for decision-making in water resource management, river ecosystem conservation, and sustainable urban development. The IHG index, with its multi-dimensional approach, enables comparative analysis across different river segments and can be adapted for use in similar studies on other rivers in Iran and beyond. Moreover, the integration of GIS tools enhances the precision and interpretability of spatial data, supporting more informed environmental planning and policy-making.

To improve the condition of the Alvand River within Sarpol-e Zahab’s urban stretch, the following measures are recommended: (1) legally define and enforce the river’s buffer zone to prevent construction within the floodplain, (2) regulate and reduce in-stream material extraction, replacing it with alternative sources outside the river corridor, (3) restore natural riparian vegetation and establish protective green belts, (4) redesign engineering structures to minimize disruption to natural flow patterns, and (5) engage and educate local communities in river stewardship and water conservation.

In conclusion, this study demonstrates that the hydrogeomorphological quality of rivers is highly influenced by human activities. Without targeted management and conservation interventions, degradation will likely continue, leading to long-term ecological and social consequences. The Alvand River serves as a case study illustrating the challenges of balancing urban development with the preservation of natural resources. Therefore, adopting scientific, participatory, and data-driven approaches is essential for maintaining the ecological integrity of river systems and ensuring their long-term sustainability.