Modeling Sediment Transport and Assessing Erosion and Sedimentation Status in the HARAZ River Watershed based on the Ecosystem Services Concept.

KGROUND AND OBJECTIVES: Effective river basin management requires understanding sediment transport dynamics and their impact on ecosystem services to mitigate soil erosion and sedimentation. This study emphasizes the novel integration of the ecosystem services framework into sediment transport modeling using the Integrated Valuation Ecosystem Services and Tradeoffs Sediment Delivery Ratio model. The Haraz River basin, a critical watershed in northern Iran, faces significant erosion and sedimentation problems due to steep slopes, sporadic vegetation, and intensive land use. This study aimed to model sediment transport and assess erosion and sedimentation dynamics within the basin using the Integrated Valuation of Ecosystem Services and Tradeoffs Sediment Delivery Rate model, focusing on ecosystem services, particularly sediment retention and delivery.METHODS: The Integrated Valuation of Ecosystem Services and Tradeoffs Sediment Delivery Rate model was applied to the Haraz River Basin, using high-resolution land use maps, a Digital Elevation Model, and field-calibrated parameters. The study quantified soil erosion and sediment export at pixel and sub-watershed levels. The analysis considered key factors such as rainfall erosivity, soil erodibility, slope length, land cover, and management actions to estimate sediment dynamics and identify critical erosion hotspots.FINDINGS: The results showed considerable spatial variability in sediment transport and retention across the catchment. Subwatershed ۲ had the highest soil erosion potential (۱۳,۰۱۶,۲۶۸ tonnes) and sediment export (۱,۹۹۲,۲۷۷ tonnes), primarily due to steep slopes and limited vegetation cover. In contrast, sub-catchment ۵ had the lowest erosion potential (۶۰,۷۲۱ tonnes) and sediment export (۹,۳۲۸ tonnes) due to effective land management and favorable land cover conditions. The values for erosion control and sediment retention illustrate the crucial role of vegetation in mitigating soil loss and reducing sediment input into rivers.CONCLUSION: This study highlights the complex interplay between natural and management factors in regulating erosion and sediment dynamics. Integrating Sediment Delivery Ratio modeling with an ecosystem services framework provided actionable insights for prioritizing erosion control measures in high-risk areas and improving sediment retention. Management strategies that include vegetation restoration, land use optimization, and sediment control barriers are recommended to improve watershed sustainability in the Haraz Basin.

کلیدواژه ها:

sediment transport ، Soil erosion ، Ecosystem services ، Haraz River watershed ، InVEST DSR