Cryospheric Processes Responsible for Lake Formation: A Review on Lake Types, Threats, Status, and Their Distribution within the Himalaya

Identification of critical lakes in the Himalaya is a crucial job for glacial lake hazard assessment, risk mitigation and disaster management planning. This study investigates the role of climate driven cryospheric processes controlling lake formation and evolution, along with the identification and distribution of critical lakes with their hazard potential in the Himalaya. Datasets were gathered from a few related literatures and compared with research generated datasets, confirming that majority of the lakes are found to be concentrated in the Langtang, Everest, Sikkim, and Bhutan regions. New lakes are continuously forming higher elevation along with up glacial expansion of existing lakes. Additionally, most of these lakes are gathered at an elevation between 4500–5500 m. A total of 10,101 lakes with size >0.01 km2 are located in the Himalayas which have been extracted from all the used inventories in this study. Besides, the lake count is maximum in Koshi basin (sub basin Arun = 1125) followed by Yarlung Zangbo (773), Manas (sub basin Dangme Chu = 715) and Upper Indus (619). In terms of total lake size distribution, the largest contributions come from the Qinghai-Tibetan, Yarlung Zangbo, Panjnad, Kosi, Manas, and Upper Indus basins. Moreover, the basin wise average lake size change rate is higher in Upper Indus, Karnali, Tista, Yamuna and Manas, while maximum lake size change rate is seen in Kosi, Yarlung Zangbo, Manas, Karnali, Upper Indus and Tista basin, indicating future GLOF prone basins among the Himalaya. Here, a total of 221 critical lakes were found in the Himalaya. Critical lake density is higher in Kosi River basin followed by (47), Yarlung Zangbo (22), Tista (22), Manas (21), Qinghai-Tibetan (15), Panchnad (12) and Phelku (8). Different research groups are working on ways to minimize the impact of GLOF in many different ways, such as by using remote sensing identification of critical lakes, modelling and field surveys to find potential impacted zone and hazard mapping, reducing lake volumes artificially, building concrete dams and making artificial drainage systems, etc. For the management of the GLOF, governing bodies have also set up early warning systems and information dissemination to the local people for community awareness.