Faculty of Geoscience

The Himalayas are experiencing rapid climate change that is significantly contributing to glacier retreat, formation of new glacial lakes, and enlargement of the existing ones. The presence of glacial lakes in the Himalayan region makes it a potential threat for the downstream community, as the catastrophic failure of the lake causes the Glacial Lake Outburst Flood (GLOF), which significantly damages the low-lying areas. Devising appropriate risk reduction strategies for the downstream community to the GLOF hazard is the prime concern for the policymakers. In this study, we have assessed the social vulnerability of the downstream community of Chungthang town of Sikkim Himalaya. Many settlements at Chungthang are potentially exposed to the future GLOF of South Lohnak Lake, one of the fastest-growing glacial lakes in Sikkim, India. A sample size of 90 households have been selected and classified into migrated and permanent residents for the study. Primary data have been collected by using a semi-structured questionnaire. Results revealed that, in Chungthang migrated population are more vulnerable because of their low adaptive capacity and high exposure to the GLOF of South Lohnak lake in Sikkim. The study suggests some important mitigation measures to decrease the vulnerability of the vulnerable community by improving some of the important socioeconomic indicators.

The Ganges-Brahmaputra-Meghna delta is one of the most populous deltas in the world, threatened by diverse environmental stressors, including salinity intrusion, causing adverse consequences on livelihood adaptation. Shrimp farming has been recognized as one of the most practiced livelihoods among various livelihood opportunities. Growing global demand and higher economic returns encouraged many farmers to convert their agricultural land to shrimp farms by intruding saline water into the farmlands to produce shrimps. In this study, we investigated whether the growing trend of shrimp farming influences the migration aspirations of the vulnerable coastal communities in Bangladesh. The study employed qualitative interviews with individuals in four villages in southwest coastal Bangladesh. Satellite images were analyzed to detect land-use changes and changes in soil salinity in the last 28 years, confirming a rapid increase in shrimp farms. Results from the qualitative interviews indicate that poor people with limited resources cannot produce paddy on their land because of increased soil salinity caused by shrimp farming. Such a situation leads them to aspire to migrate. Thus, our analysis contributes to the discourse on "aspiration and capability" in environmental migration by adding the impacts of land-use changes on livelihoods. Keywords Rice to shrimp • Land use changes • Migration aspirations • Environmental degradation • Livelihoods • Remote sensing Highlights • It explains the impact of land use change on livelihoods and migration aspirations of people at risk. • Results confirm a pronounced association between soil salinity and migration aspiration. • Increment of soil salinity evolved through transformation from rice to shrimp cultivation. Communicated by Prajal Pradhan.

River Yamuna, Cowing through the National Capital Territory (NCT) of Delhi, is considered as one of the worst polluted river stretches in the world. The river is primarily polluted through untreated sewage discharge from various point and non-point pollution sources that Bnd their way through storm drains and join the river Yamuna. One of the major requirements to address urban water quality is to identify the potential sources of contamination in a large drainage basin, which is challenging as the basin area is so big that it is difBcult to pinpoint the source of pollution. Invariably, as the pollutants move into the drains under gravity, it is possible to identify the drains and their corresponding catchment areas that have higher pollution load. Thus, the study aims to Bnd the sources of pollution in a larger river basin by integrating Beld observation, GIS approach, and qualitative interviews. Water samples from 43 monitoring locations are collected in the various storm drains of the Barapullah drainage basin, in various primary, secondary, and tertiary drains, and analyzed the water quality parameters in the Delhi Jal Board (DJB) water quality laboratory. The locality-wise spatial contribution of pollution is mapped in the context of the Barapullah basin. The study results found excessive BOD values ranging from 37 to 430 mg/L, and six major pollution hotspots were identiBed. The qualitative interview conducted in the six major pollution hotspots regarding the source of pollution and results indicated that the discharge of domestic sewage from planned colonies, unauthorized colonies, and JJCs, as well as market waste disposal, are the potential reasons for pollution in the six major pollution hotspots. This pilot-level study provides a useful and eAective approach to investigating and identifying pollution sources, mitigating the pollution at the source, and ultimately reducing the pollution level at river Yamuna.