Supraglacial debris influences the glacier-climate relationship by altering the ablation patterns of the debris-covered glaciers. The intricate surface morphology of debris-covered glaciers renders difficulties in their assessment through satellite remote sensing alone. In this context, unmanned aerial vehicles (UAVs) have the advantage of providing ultra-high-resolution maps of the debris-covered glacier surfaces, thus, aid in inferring the complexity in their behavior. Considering the limitations and to help elucidate the morpho-dynamic evolution of the debris-covered glacier surface, an in-depth investigation is conducted on the Panchi Nala-A glacier (area: 3 km2; debris percentage: 60

The Himalaya plays a vital role in regulating the freshwater availability for nearly a billion people living in the Indus, Ganga, and Brahmaputra River basins. Due to climate change and constantly evolving human-hydrosphere interactions, including land use/cover changes, groundwater extraction, reservoir or dam construction, water availability has undergone significant change, and is expected to change further in the future. Therefore, understanding the spatiotemporal evolution of the hydrological cycle over the Himalaya and its river basins has been one of the most critical exercises toward ensuring regional water security. However, due to the lack of extensive in-situ measurements, complex hydro-climatic environment, and limited collaborative efforts, large gaps in our understanding exist. Moreover, there are several significant issues with available studies, such as lack of consistent hydro-meteorological datasets, very few attempts at integrating different data types, limited spatiotemporal sampling of hydro-meteorological measurements, lack of open access to in-situ datasets, poorly accounted anthropogenic climate feedbacks, and limited understanding of the hydro-meteorological drivers over the region. These factors result in large uncertainties in our estimates of current and future water availability over the Himalaya, which constraints the development of sustainable water management strategies for its river catchments hampering our preparedness for the current and future changes in hydro-climate. To address these issues, a partnership development workshop entitled “Water sEcurity assessment in rIvers oriGinating from Himalaya (WEIGH),” was conducted between the 07th and 11th September 2020. Based on the intense discussions and deliberations among the participants, the most important and urgent research questions were identified. This white paper synthesizes the current understanding, highlights, and the most significant research gaps and research priorities for studying water availability in the Himalaya.

Role of Unmanned Aerial Vehicle (UAV)-based remote sensing (RS) applications in glaciology have increased in recent years. UAV-based RS studies on mountain glaciers are mainly focussing on obtaining accurate ultra-high-resolution data from UAV images for different glaciological applications. However, studies understanding the challenges involved during UAV surveys on complex terrains of high mountain glaciers are inadequate and they are not available for places like Himalayas. Therefore, this study aims to examine and derive strategies to minimize those challenges on such complex glacier and their margin topography. Here, UAV surveys were conducted using a fixed-wing commercial-grade off-the-shelf UAV (eBee series, SenseFly) on three glacier sites (East Rathong, Hamtah and Panchinala-A) located in different climate regimes within the Indian part of Himalayas. From the UAV collected images, ultra-high-resolution ortho-mosaicked images and Digital Elevation Models were generated at 0.1 m ground sample distance and their accuracies were assessed using the collected ground control points. Based on the challenges observed, the study recommends criteria for selection of best-suited take-off/landing locations on a mountain glacier and its margins for conducting efficient UAV surveys in the complex terrain such as in the Himalayas and possibly beyond. Recommendations reported in this article shall be useful to minimize the challenges and associated risks during UAV data acquisition using fixed-wing UAVs.