A scenario-based approach to valuation of the Erosion Prevention Service in the Himalayan region

Soil erosion poses a critical environmental challenge, particularly in mountainous regions like the Indian Himalayas, where steep slopes, intense rainfall, and fragile ecosystems, along with anthropogenic land use change, exacerbate erosion rates. This leads to increased sediment loads in rivers and reservoirs, adversely affecting agricultural yield, water resources, and ecosystem health. Erosion prevention, a crucial ecosystem service, is vital for mitigating these effects. The diverse forest cover of the Indian Himalayan region plays a key role in erosion prevention. This study focuses on quantifying the erosion prevention service using the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) Sediment Delivery Ratio (SDR) model in the Giri watershed in the Himalayan region. The SDR model was used in two scenarios: with forest (F1) and without forest (F0). The role of forests was identified based on forest cover density, categorised as very dense, moderately dense, and open forests. Results revealed that the avoided erosion under scenario F1 is approximately 85% higher than under F0. On the contrary, sediment export and deposition were higher in the F0 scenario. The economic value of erosion prevention service in the Giri watershed is estimated at 1.22 billion US$ annually. The study concluded that forest cover plays a significant role in reducing sediment export and in supporting erosion prevention. The study also suggested that erosion prevention service is an important indicator for understanding the diverse and challenging ecosystem of the Himalayas.