Effects Of Natural Hazards On Upper Teesta River Bank’s Ecological Bio- Biodiversity

Abstract

The upper Teesta River, flowing through the Himalayan foothills in the north-eastern Indian region, is increasingly subjected to various natural hazards, including floods, landslides, and seismic events. These hazards significantly influence the ecological biodiversity along the riverbanks, impacting both terrestrial and aquatic ecosystems. This study examines the effects of natural hazards on biodiversity in the upper Teesta River basin, comparing data from three pivotal years—1968, 2017, and 2023—to understand the changing impact over time. In 1968, the region's biodiversity was relatively stable, with minimal human interference and fewer major natural disasters. However, the ecosystem was already beginning to show signs of vulnerability to monsoonal flooding and landslides, which occasionally disrupted local habitats. At that time, the ecological composition along the riverbanks was primarily characterized by dense forest cover, native aquatic species, and a balance between river dynamics and surrounding landscapes.

By 2017, the effects of climate change, deforestation, and increased human settlements had amplified the frequency and intensity of natural hazards. Flooding became more recurrent due to altered rainfall patterns and glacier melt, causing significant erosion and loss of terrestrial habitats. The river’s aquatic biodiversity, including endemic fish species, was severely affected by siltation, habitat destruction, and water contamination caused by landslides and unregulated development along the banks. The construction of dams and roads further fragmented ecosystems, limiting wildlife movement and reducing species resilience. In 2023, the situation worsened with increasing human encroachment and ongoing climate variability. Severe floods and landslides, often triggered by extreme weather events and seismic activities, have resulted in the displacement of local communities and the degradation of critical habitats.

The upper Teesta River's ecological zones are increasingly fragmented, with fewer native species able to adapt to the altered environment. Additionally, the river’s once-diverse riparian vegetation has been replaced by invasive species, further destabilizing the local ecosystems. The loss of key ecological functions—such as flood regulation, sediment retention, and water purification—has compromised the resilience of biodiversity in the region. This study synthesizes historical data and field observations to evaluate the evolving impact of natural hazards on the upper Teesta River’s ecological biodiversity across these three distinct periods. By understanding the trends and cumulative effects over time, the study aims to inform future conservation and disaster risk reduction strategies to protect the fragile ecosystems of the upper Teesta River basin. It underscores the urgent need for integrated management,  approaches that address both the natural hazards and human-induced pressures on biodiversity in this ecologically sensitive region.