Climate warming-induced glacier recession has resulted in the development and rapid expansion of glacial lakes in the Himalayan region. The increased melting has enhanced the susceptibility for Glacial Lake Outburst Floods (GLOFs) in the region. The catastrophic failure of potentially dangerous glacial lakes could be detrimental to human life and infrastructure in the adjacent low-lying areas. This study attempts to assess the GLOF hazard of Gangabal lake, located in the Upper Jhelum basin of Kashmir Himalaya, using the combined approaches of remote sensing, GIS, and dam break modeling. The parameters, such as area change, ice thickness, mass balance, and surface velocity of the Harmukh glacier, which feeds Gangabal lake, were also assessed using multitemporal satellite data, GlabTop-2, and the Cosi–Corr model. In the worst-case scenario, 100% volume (73 × 10⁶ m³) of water was considered to be released from the lake with a breach formation time (bf) of 40 min, breach width (bw) of 60 m, and producing peak discharge of 16,601.03 m³/s. Our results reveal that the lake area has increased from 1.42 km² in 1972 to 1.46 km² in 1981, 1.58 km² in 1992, 1.61 km² in 2001, 1.64 km² in 2010, and 1.66 km² in 2020. The lake area experienced 17 ± 2% growth from 1972 to 2020 at an annual rate of 0.005 km². The feeding glacier (Harmukh) contrarily indicated a significant area loss of 0.7 ± 0.03 km² from 1990 (3.36 km²) to 2020 (2.9 km²). The glacier has a maximum, minimum, and average depth of 85, 7.3, and 23.46 m, respectively. In contrast, the average velocity was estimated to be 3.2 m/yr with a maximum of 7 m/yr. The results obtained from DEM differencing show an average ice thickness loss of 11.04 ± 4.8 m for Harmukh glacier at the rate of 0.92 ± 0.40 m/yr between 2000 and 2012. Assessment of GLOF propagation in the worst-case scenario (scenario-1) revealed that the maximum flood depth varies between 3.87 and 68 m, the maximum flow velocity between 4 and 75 m/s, and the maximum water surface elevation varies between 1548 and 3536 m. The resultant flood wave in the worst-case scenario will reach the nearest location (Naranaag temple) within 90 min after breach initiation with a maximum discharge of 12,896.52 m³ s⁻¹ and maximum flood depth and velocity of 10.54 m and 10.05 m/s, respectively. After evaluation of GLOF impacts on surrounding areas, the area under each inundated landuse class was estimated through the LULC map generated for both scenarios 1 and 2. In scenario 1, the total potentially inundated area was estimated as 5.3 km², which is somewhat larger than 3.46 km² in scenario 2. We suggest a location-specific comprehensive investigation of Gangbal lake and Harmukh glacier by applying the advanced hazard and risk assessment models/methods for better predicting a probable future GLOF event.

In the Himalayan Mountain region, a large number of glacial lakes had developed during the recent past in response to glacier recession under the influence of climate change. In this study, we used high resolution (5.8 m) Indian Remote Sensing (IRS) LISS IV data and Google earth images to generate an updated glacial lake inventory of Upper Jhelum Basin (UJB) of North-western Himalaya. A total of 393 glacial lakes covering an area of 21.55 ± 3.8 km² were identified, mapped and inventoried. The lake inventory includes 102 proglacial lakes, 31 supraglacial lakes and 278 unconnected glacial lakes. Using the weighted indices-based approach, 21 glacial lakes were found as Potentially Dangerous Glacial Lakes (PDGLs). Out of which, 7 lakes were identified as High, 9 Medium and 5 Low hazard glacial lakes. The total area of PDGLs showed an increase of 5.92 km² (1980) to 8.46 km² (2020), with an overall growth of 2.51 Km² (42.2%) at the rate of 0.063 km²/year, alongside glacier retreat and increasing warming trend. This study will be an important instrument for future GLOF studies in the Himalayan region.

The climate warming has accelerated glacier mass loss in the Eastern Himalayas, resulting in the formation of new glacial lakes and the expansion of existing ones. The release of water from such lakes has the potential to cause Glacial Lake Outburst Floods (GLOFs), with negative consequences for the downstream community. This study used Remote Sensing (Landsat-8 and Sentinel-2A) data to prepare an updated and detailed glacial lake inventory of Dibang River Basin for the year 2020 in the Geographic Information System (GIS) environment. The data from Landsat-5 TM (1985) was used to examine the spatio-temporal dynamics of glacial lakes larger than 0.1 km². The important parameters derived from previous glacial lake hazard assessment studies were used to identify the Potentially Dangerous Glacial Lakes (PDGLs) and to carry out their hazard assessment. Finally, the Indian Monsoon Data Assimilation and Analysis (IMDAA) data was used to analyse Temperature and Precipitation trends from 1980 to 2020 to understand the impact of climate change on lake behavior. According to our findings, the study region has 403 glacial lakes with a total area of 55.73 km² in 2020. The area of selected glacial lakes increased from 29.96 km² in 1985 to 32.56 km² in 2020 at a rate of 0.07 km² per year. We identified Twelve (12) lakes as PDGLs. Using weighted index method 4 lake were categorized as high, 5 as medium and 3 as low hazard glacial lakes. Mann Kendal test of the Tmin, Tmax and Tmean reveals an increasing trend with a Z statics value of >0, whereas mean precipitation on the other hand has shown a significant decreasing trend with a Z statics value of <0. The increasing temperatures and decreasing precipitation indicate that warmer conditions prevail in the study region, which are resulting in glacier retreat, the formation of new lakes and the expansion of existing ones. Hence, we propose continuous monitoring and assessment of high hazard glacial lakes in the study region.